Processes

22 pages, 9169 KiB

Open AccessEditor’s ChoiceArticle

Optimizing Pressure Prediction Models for Pneumatic Conveying of Biomass: A Comprehensive Approach to Minimize Trial Tests and Enhance Accuracy

by Hossein Rajabnia, Ognjen Orozovic, Kenneth Charles Williams, Aleksej Lavrinec, Dusan Ilic, Mark Glynne Jones and George Klinzing

Processes 2023, 11(6), 1698; https://doi.org/10.3390/pr11061698 - 2 Jun 2023

Cited by 1 | Viewed by 2136

Abstract

This study investigates pneumatic conveying of four different biomass materials, namely cottonseeds, wood pellets, wood chips, and wheat straw. The performance of a previously proposed model for predicting pressure drop is evaluated using biomass materials. Results indicate that the model can predict pressure [...] Read more.

This study investigates pneumatic conveying of four different biomass materials, namely cottonseeds, wood pellets, wood chips, and wheat straw. The performance of a previously proposed model for predicting pressure drop is evaluated using biomass materials. Results indicate that the model can predict pressure with an error range of 30 percent. To minimize the number of trial tests required, an optimization algorithm is proposed. The findings show that with a combination of three trial tests, there is a 60 percent probability of selecting the right subset for accurately predicting pressure drop for the entire range of tests. Further investigation of different training subsets suggests that increasing the number of tests from 3 to 7 can improve the probability from 60% to 90%. Moreover, thorough analysis of all three-element subsets in the entire series of tests reveals that when considering air mass flow rate as the input, having air mass flow rates that are not only closer in value but also lower increases the likelihood of selecting the correct subset for predicting pressure drop across the entire range. This advancement can help industries to design and optimize pneumatic conveying systems more effectively, leading to significant energy savings and improved operational performance. Full article

(This article belongs to the Special Issue Biomass Combustion and Energy Production Processes)

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13 pages, 2888 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Synergistic Ball Milling–Enzymatic Pretreatment of Brewer’s Spent Grains to Improve Volatile Fatty Acid Production through Thermophilic Anaerobic Fermentation

by Can Liu, Ahamed Ullah, Xin Gao and Jian Shi

Processes 2023, 11(6), 1648; https://doi.org/10.3390/pr11061648 - 28 May 2023

Cited by 2 | Viewed by 1470

Abstract

Brewer’s spent grain (BSG) as the major byproduct in the brewing industry is a promising feedstock to produce value-added products such as volatile fatty acids (VFAs). Synergistic ball mill–enzymatic hydrolysis (BM-EH) process is an environmentally friendly pretreatment method for lignocellulosic materials before bioprocessing. [...] Read more.

Brewer’s spent grain (BSG) as the major byproduct in the brewing industry is a promising feedstock to produce value-added products such as volatile fatty acids (VFAs). Synergistic ball mill–enzymatic hydrolysis (BM-EH) process is an environmentally friendly pretreatment method for lignocellulosic materials before bioprocessing. This study investigated the potential of raw and BM-EH pretreated BSG feedstocks to produce VFAs through a direct thermophilic anaerobic fermentation process without introducing a methanogen inhibitor. The highest VFA concentration of over 30 g/L was achieved under the high-solid loading fermentation (HS) of raw BSG. The synergistic BM-EH pretreatment helps to increase the cellulose conversion to 70%. Under conventional low TS fermentation conditions, compared to the controlled sample, prolonged pretreatment of the BSG substrate resulted in increased VFA yields from 0.25 to 0.33 g/g_VS, and butyric acid became dominant instead of acetic acid. Full article

(This article belongs to the Special Issue Fermentation and Bioprocess Engineering Processes)

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20 pages, 7294 KiB

Open AccessEditor’s ChoiceArticle

Kinetic Monte Carlo Convergence Demands for Thermochemical Recycling Kinetics of Vinyl Polymers with Dominant Depropagation

by Eli K. C. Moens, Yoshi W. Marien, Alessandro D. Trigilio, Kevin M. Van Geem, Paul H. M. Van Steenberge and Dagmar R. D’hooge

Processes 2023, 11(6), 1623; https://doi.org/10.3390/pr11061623 - 26 May 2023

Cited by 3 | Viewed by 1815

Abstract

As societal interest in recycling of plastics increases, modeling thermochemical recycling of vinyl polymers, e.g., via pyrolysis or reactive extrusion, becomes increasingly important. A key aspect remains the reliability of the simulation results with fewer evaluation studies regarding convergence as in the polymerization [...] Read more.

As societal interest in recycling of plastics increases, modeling thermochemical recycling of vinyl polymers, e.g., via pyrolysis or reactive extrusion, becomes increasingly important. A key aspect remains the reliability of the simulation results with fewer evaluation studies regarding convergence as in the polymerization or polymer reaction engineering field. Using the coupled matrix-based Monte Carlo (CMMC) framework, tracking the unzipping of individual chains according to a general intrinsic reaction scheme consisting of fission, β-scission, and termination, it is however illustrated that similar convergence demands as in polymerization benchmark studies can be employed, i.e., threshold values for the average relative error predictions on conversion and chain length averages can be maintained. For this illustration, three theoretical feedstocks are considered as generated from CMMC polymer synthesis simulations, allowing to study the effect of the initial chain length range and the number of defects on the convergence demands. It is shown that feedstocks with a broader chain length distribution and a long tail require a larger Monte Carlo simulation volume, and that the head–head effects play a key role in the type of degradation mechanism and overall degradation rate. A minimal number of chains around 5 × 10⁵ is needed to properly reflect the degradation kinetics. A certain degree of noise can be allowed at the higher carbon-based conversions due to the inevitable decrease in number of chains. Full article

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14 pages, 3732 KiB

Open AccessEditor’s ChoiceArticle

Improvements in the Modeling and Kinetics Processes of the Enzymatic Synthesis of Pentyl Acetate

by Beatriz Lorenzo, Luis Fernández, Juan Ortega and Leandro Domínguez

Processes 2023, 11(6), 1640; https://doi.org/10.3390/pr11061640 - 26 May 2023

Cited by 3 | Viewed by 1711

Abstract

In this work, the enzymatic synthesis of pentyl acetate obtained from acetic acid and pentan-1-ol using the commercial immobilized lipase Lipozyme^®435 was studied. Specifically, the effects of several variables of the process on the kinetics were shown, such as the initial [...] Read more.

In this work, the enzymatic synthesis of pentyl acetate obtained from acetic acid and pentan-1-ol using the commercial immobilized lipase Lipozyme^®435 was studied. Specifically, the effects of several variables of the process on the kinetics were shown, such as the initial concentration of the acetic acid, the alcohol/acid molar ratio, and the possible reuse of the enzyme, while other variables, such as temperature, agitation, and the enzyme/acid ratio were held constant. The kinetics were determined by assessing the acetic acid concentration throughout the reactive process. Experimental data were correlated with the rate equation consisting of a modified version of the Bi–Bi Ping-Pong mechanism. The results showed that when no hydrophobic solvents were used with the reagents in stoichiometric proportion, a high molar fraction of acetic acid (x_0,acid ≈ 0.50) caused the loss of enzymatic activity, achieving a conversion of only 5%. However, when there was an excess of pentan-1-ol, the reaction occurred successfully. Under optimal conditions (solvent-free conditions, x_0,alcohol/x_0,acid = 2, and x_0,acid = 0.33), it was found that the enzyme could be reused up to 10 times without a loss of activity, reaching conversions higher than 80% after 8 h. Therefore, those conditions are advantageous in terms of productivity. Full article

(This article belongs to the Special Issue Recent Advances in Green Synthesis Catalysis)

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26 pages, 23160 KiB

Open AccessEditor’s ChoiceArticle

Gas/Liquid Operations in the Taylor-Couette Disc Contactor: Continuous Chemisorption of CO₂

by Georg Rudelstorfer, Rafaela Greil, Max Vogi, Matthäus Siebenhofer, Susanne Lux and Annika Grafschafter

Processes 2023, 11(6), 1614; https://doi.org/10.3390/pr11061614 - 25 May 2023

Viewed by 1546

Abstract

Gas/liquid contactors are widely used in chemical and biotechnological applications. The selection and design of bubble-column-type gas/liquid contactors requires knowledge about the gas distributor design to provide appropriate gas flow patterns. This study presents the continuous chemisorption of CO₂ in 0.1 molar [...] Read more.

Gas/liquid contactors are widely used in chemical and biotechnological applications. The selection and design of bubble-column-type gas/liquid contactors requires knowledge about the gas distributor design to provide appropriate gas flow patterns. This study presents the continuous chemisorption of CO₂ in 0.1 molar sodium hydroxide solution in a counter currently operated gas/liquid Taylor-Couette disc contactor (TCDC). This vertical-column-type contactor is a multi-stage agitated gas/liquid contactor. The performance of a lab-size TCDC contactor in gas/liquid mass transfer operations was investigated. The apparatus design was adjusted for gas/liquid operations by installing perforated rotor discs to provide a rotational-speed-dependent dispersed gas phase holdup in the column. The parameters of dispersed gas phase holdup, volumetric mass transfer coefficient and residence time distribution were measured. In the first step, hydraulic characterization was performed. Then, the efficiency in gas/liquid operations was investigated by continuous neutralization of 0.1 molar sodium hydroxide with a gas mixture of 30 vol% CO₂ and 70 vol% N₂. Temperature, rotational speed and gas flow rate were varied. The desired pH value of pH 9 at the column outlet was kept constant by adjusting the sodium hydroxide feed. From the experimental results, the volume-based liquid-side mass transfer coefficient k_La was deduced in order to model the reaction according to the two-film theory over the column height. The CSTR cascade model fitted the experimental data best. The experimental results confirm stable and efficient reactive gas/liquid contact in the Taylor-Couette disc contactor. Full article

(This article belongs to the Special Issue Multiphase Reaction Process Design and Optimization)

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33 pages, 24644 KiB

Open AccessEditor’s ChoiceArticle

Remote Monitoring the Parameters of Interest in the ¹⁸O Isotope Separation Technological Process

by Adrian Codoban, Helga Silaghi, Sanda Dale and Vlad Muresan

Processes 2023, 11(6), 1594; https://doi.org/10.3390/pr11061594 - 23 May 2023

Viewed by 1389

Abstract

This manuscript presents the remote monitoring of the main parameters in the ¹⁸O isotope separation technological process. It proposes to monitor the operation of the five cracking reactors in the isotope production system, respectively, the temperature in the preheating furnaces, the converter [...] Read more.

This manuscript presents the remote monitoring of the main parameters in the ¹⁸O isotope separation technological process. It proposes to monitor the operation of the five cracking reactors in the isotope production system, respectively, the temperature in the preheating furnaces, the converter reactors and the cracking reactors. In addition, it performs the monitoring of the two separation columns from the separation cascade structure, respectively, the concentrations of the produced ¹⁸O isotope and the input nitric oxides flows. Even if the production process is continuously monitored by teams of operators, the professionals who designed the technical process and those who can monitor it remotely have the possibility to intervene with the view of making the necessary adjustments. Based on the processing of experimental data, which was gathered from the actual plant, the proposed original model of the separation cascade functioning was developed. The process computer from the monitoring system structure runs the proposed mathematical model in parallel with the real plant and estimates several signal values, which are essential to be known by the operators in order to make the appropriate decisions regarding the plant operation. The separation process associated with the final separation column from the separation cascade structure is modeled as a fractional-order process with variable and adjustable differentiation order, which represents another original aspect. Neural networks have been employed in order to implement the proposed mathematical model. The accuracy, validity and efficiency in the operation of the proposed mathematical model is demonstrated through the simulation results presented in the final part of the manuscript. Full article

(This article belongs to the Special Issue Dynamics Analysis and Intelligent Control in Industrial Engineering)

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12 pages, 1602 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Rapeseed Meal Waste Biomass as a Single-Cell Protein Substrate for Nutritionally-Enhanced Feed Components

by Dawid Dygas, Wiktoria Liszkowska, Aleksandra Steglińska, Michael Sulyok, Dorota Kręgiel and Joanna Berłowska

Processes 2023, 11(5), 1556; https://doi.org/10.3390/pr11051556 - 19 May 2023

Cited by 2 | Viewed by 2467

Abstract

Rapeseed meal (RM) is produced in large quantities as a byproduct of oil extraction from rapeseeds. However, the efficient utilization of RM as animal feed is limited by its low metabolizable energy, poor palatability, and high levels of fiber and anti-nutritional components. Here, [...] Read more.

Rapeseed meal (RM) is produced in large quantities as a byproduct of oil extraction from rapeseeds. However, the efficient utilization of RM as animal feed is limited by its low metabolizable energy, poor palatability, and high levels of fiber and anti-nutritional components. Here, we investigate the potential of enriching RM with single-cell protein through fermentation with conventional and unconventional yeasts. The process of simultaneous saccharification and fermentation improved the parameters of the waste biomass, especially the protein content, while reducing the amount of crude fiber and enhancing the biotransformation of isoflavone compounds present in the waste. Fermentation yielded the highest protein gain for the Saccharomyces cerevisiae Ethanol Red strain (ΔN = 2.38%) at a biomass load of 12.5 g and for Scheffersomyces stipitis (ΔN = 2.34%) at an enzyme dose of 0.125 mL/10 g DM. The crude fiber content (CF) was reduced by 2.55–7.18%. The simultaneous saccharification and fermentation (SSF) process resulted in the conversion of isoflavones to forms with fewer adverse effects and a lower estrogenic activity. The results show the potential of using RM as a substrate for making a nutritionally improved feed components. Full article

(This article belongs to the Special Issue Biomass Materials: Conversion Routes and Modern Applications)

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25 pages, 6503 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Optimal Operation of a Benchmark Simulation Model for Sewer Networks Using a Qualitative Distributed Model Predictive Control Algorithm

by Antonio Cembellín, Mario Francisco and Pastora Vega

Processes 2023, 11(5), 1528; https://doi.org/10.3390/pr11051528 - 17 May 2023

Cited by 3 | Viewed by 1179

Abstract

This article presents a distributed model predictive control algorithm including fuzzy negotiation among subsystems and a dynamic setpoint generation method, applied to a simulated sewerage network. The methodology considers WWTP as an additional objective of control. To improve the performance of a DMPC [...] Read more.

This article presents a distributed model predictive control algorithm including fuzzy negotiation among subsystems and a dynamic setpoint generation method, applied to a simulated sewerage network. The methodology considers WWTP as an additional objective of control. To improve the performance of a DMPC using a hydraulic model for prediction, a more detailed model has been considered including suspended solids concentration (TSS). The results obtained with the proposed methodology have been validated on a benchmark simulation model for sewer systems developed to test and compare methodologies, showing good performance. Full article

(This article belongs to the Special Issue Optimization and Control of Integrated Water Systems (Volume II))

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14 pages, 1780 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Exploring Different Designs in Thieno[3,4-b]pyrazine-Based Dyes to Enhance Divergent Optical Properties in Dye-Sensitized Solar Cells

by Daniele Franchi, Matteo Bartolini, Francesco D’Amico, Massimo Calamante, Lorenzo Zani, Gianna Reginato, Alessandro Mordini and Alessio Dessì

Processes 2023, 11(5), 1542; https://doi.org/10.3390/pr11051542 - 17 May 2023

Cited by 6 | Viewed by 1737

Abstract

Two novel organic sensitizers for Dye-Sensitized Solar Cells (DSSC), called TP1 and TP2, based on the electron-poor thieno[3,4-b]pyrazine (TPz) π-bridge and the electron-rich N,N-bis(4-(hexylthio)phenyl)aniline (TPA) were designed following two different approaches: the classical D-A-π-A design and a [...] Read more.

Two novel organic sensitizers for Dye-Sensitized Solar Cells (DSSC), called TP1 and TP2, based on the electron-poor thieno[3,4-b]pyrazine (TPz) π-bridge and the electron-rich N,N-bis(4-(hexylthio)phenyl)aniline (TPA) were designed following two different approaches: the classical D-A-π-A design and a symmetric structure with double anchoring functions. Both compounds were prepared exploiting short synthetic pathways based on direct arylation strategies and possibly one-pot desymmetrization. The two novel dyes displayed opposite optical properties: a broad and intense light absorption over the entire visible spectrum for TP1, and a localized absorption that peaked in the center of the visible region for TP2, resulting in a pitch-dark coloration and a green tone, respectively. When assembling the photovoltaic devices, different electrolyte compositions were explored to enhance the optical properties of the dyes. Power conversion efficiencies as high as 5.2% under full sun intensity were recorded for small test devices. The composition of the light transmitted through the TP2-containing transparent DSSC fits well with the human eye sensitivity spectrum, thus fulfilling the transparency requirements for building-integrated photovoltaics (BIPV). Full article

(This article belongs to the Section Energy Systems)

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12 pages, 2018 KiB

Open AccessEditor’s ChoiceArticle

Thermal Methane Cracking on Molten Metal: Kinetics Modeling for Pilot Reactor Design

by Emma Palo, Vittoria Cosentino, Gaetano Iaquaniello, Vincenzo Piemonte and Emmanuel Busillo

Processes 2023, 11(5), 1537; https://doi.org/10.3390/pr11051537 - 17 May 2023

Cited by 1 | Viewed by 2459

Abstract

Up to 80% of hydrogen production is currently carried out through CO₂ emission-intensive natural gas reforming and coal gasification. Water-splitting electrolysis using renewable energy (green H₂) is the only process that does not emit greenhouses gases, but it is a [...] Read more.

Up to 80% of hydrogen production is currently carried out through CO₂ emission-intensive natural gas reforming and coal gasification. Water-splitting electrolysis using renewable energy (green H₂) is the only process that does not emit greenhouses gases, but it is a quite energy-demanding process. To significantly contribute to the clean energy transition, it is critical that low-carbon hydrogen production routes that can replace current production methods and can expand production capacity to meet new demands are developed. A new path, alternative to steam reforming coupled with CCS (blue H₂) that is based on methane cracking, in which H₂ production is associated with solid carbon instead of CO₂ (turquoise H₂), has received increasing attention recent years. The reaction takes place inside the liquid bath, a molten metal reactor. The aim of this article is to model the main kinetic mechanisms involved in the methane cracking reaction with molten metals. The model developed was validated using experimental data produced by the University of La Sapienza. Finally, such a model was used to scale up the reactor architecture. Full article

(This article belongs to the Special Issue Industrial Chemistry Reaction: Kinetics, Mass Transfer and Industrial Reactor Design (II))

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16 pages, 4366 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

NiCoAl-Based Monolithic Catalysts for the N₂O Intensified Decomposition: A New Path towards the Microwave-Assisted Catalysis

by Olga Muccioli, Eugenio Meloni, Simona Renda, Marco Martino, Federico Brandani, Pluton Pullumbi and Vincenzo Palma

Processes 2023, 11(5), 1511; https://doi.org/10.3390/pr11051511 - 16 May 2023

Cited by 2 | Viewed by 1594

Abstract

Nitrous oxide (N₂O) is considered the primary source of NO_x in the atmosphere, and among several abatement processes, catalytic decomposition is the most promising. The thermal energy necessary for this reaction is generally provided from the external side of the [...] Read more.

Nitrous oxide (N₂O) is considered the primary source of NO_x in the atmosphere, and among several abatement processes, catalytic decomposition is the most promising. The thermal energy necessary for this reaction is generally provided from the external side of the reactor by burning fossil fuels. In the present work, in order to overcome the limits related to greenhouse gas emissions, high heat transfer resistance, and energy losses, a microwave-assisted N₂O decomposition was studied, taking advantages of the microwave’s (MW) properties of assuring direct and selective heating. To this end, two microwave-susceptible silicon carbide (SiC) monoliths were layered with different nickel–cobalt–aluminum mixed oxides. Based on the results of several characterization analyses (SEM/EDX, BET, ultrasound washcoat adherence tests, Hg penetration technique, and TPR), the sample showing the most suitable characteristics for this process was reproduced in the appropriate size to perform specific MW-assisted catalytic activity tests. The results demonstrated that, by coupling this catalytic system with an opportunely designed microwave heated reactor, it is possible to reach total N₂O conversion and selectivity of a highly concentrated N₂O stream (50 vol%) at T = 550 °C, the same required in the conventionally heated process to remove N₂O from a less concentrated gas stream (20 vol%). Full article

(This article belongs to the Special Issue 10th Anniversary of Processes: Design of the Chemical Industry of the Future)

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14 pages, 276 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Alternative Sources of Energy in Transport: A Review

by Kristýna Pustějovská, Kamila Janovská and Simona Jursová

Processes 2023, 11(5), 1517; https://doi.org/10.3390/pr11051517 - 16 May 2023

Cited by 4 | Viewed by 3946

Abstract

Alternative sour2ces of energy are on the rise primarily because of environmental concerns, in addition to the depletion of fossil fuel reserves. Currently, there are many alternatives, approaches, and attempts to introduce alternative energy sources in the field of transport. This article centers [...] Read more.

Alternative sour2ces of energy are on the rise primarily because of environmental concerns, in addition to the depletion of fossil fuel reserves. Currently, there are many alternatives, approaches, and attempts to introduce alternative energy sources in the field of transport. This article centers around the need to explore additional energy sources beyond the current ones in use. It delves into individual energy sources that can be utilized for transportation, including their properties, production methods, and the advantages and disadvantages associated with their use across different types of drives. The article not only examines the situation in the Czech Republic but also in other nations. In addition to addressing future mobility, the thesis also considers how the utilization of new energy sources may impact the environment. Full article

(This article belongs to the Section Energy Systems)

32 pages, 3616 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Abatement of Greenhouse Gas Emissions from Ventilation Air Methane (VAM) Using Ionic Liquids: A Review of Experimental Methods and Modelling Approaches

by Hamid Reza Rahimpour, Jafar Zanganeh and Behdad Moghtaderi

Processes 2023, 11(5), 1496; https://doi.org/10.3390/pr11051496 - 15 May 2023

Cited by 1 | Viewed by 1979

Abstract

Ventilation Air Methane (VAM) refers to the release of fugitive methane (CH₄) emissions into the atmosphere during underground coal mining operations. Growing concerns regarding the greenhouse effects of CH₄ have led to a worldwide effort in developing efficient and cost-effective [...] Read more.

Ventilation Air Methane (VAM) refers to the release of fugitive methane (CH₄) emissions into the atmosphere during underground coal mining operations. Growing concerns regarding the greenhouse effects of CH₄ have led to a worldwide effort in developing efficient and cost-effective methods of capturing CH₄. Among these, absorption-based processes, particularly those using Ionic Liquids (ILs) are appealing due to their advantages over conventional methods. In this study, the solubility of CH₄ in various ILs, expressed by Henry’s law constant, is first reviewed by examining a wide range of experimental techniques. This is followed by a review of thermodynamic modelling tools such as the extended Henry’s law model, extended Pitzer’s model, Peng–Robinson (PR) equation of state, and Krichevsky−Kasarnovsky (KK) equation of state as well as computational (Artificial Neural Network) modelling approaches. The comprehensive analysis presented in this paper aims to provide a deeper understanding of the factors that significantly influence the process of interest. Furthermore, the study provides a critical examination of recent advancements and innovations in CH₄ capture by ILs. ILs, in general, have a higher selectivity for methane compared to conventional solvents. This means that ILs can remove methane more effectively from VAM, resulting in a higher purity of the recovered methane. Overall, ILs offer several advantages over conventional solvents for the after treatment of VAM. They are more selective, less volatile, have a wider temperature range, are chemically stable, and can be made from renewable materials. As a result of their many advantages, ILs are becoming increasingly popular for the after treatment of VAM. They offer a more sustainable, efficient, and safe alternative to conventional solvents, and they are likely to continue gaining market share in the coming years. Full article

(This article belongs to the Special Issue Applications of Ionic Liquids and Deep Eutectic Solvents in Separation Processes for the Circular Economy)

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14 pages, 6658 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Investigation of Synechocystis sp. CPCC 534 Motility during Different Stages of the Growth Period in Active Fluids

by Zahra Samadi, Malihe Mehdizadeh Allaf, Thomas Vourc’h, Christopher T. DeGroot and Hassan Peerhossaini

Processes 2023, 11(5), 1492; https://doi.org/10.3390/pr11051492 - 15 May 2023

Viewed by 1454

Abstract

The motility behavior of suspended microorganisms plays an essential role in the properties of active fluids. Despite the important progress in our understanding of microorganisms’ motility in recent years, there are still several open questions about the dynamics of cell motility in active [...] Read more.

The motility behavior of suspended microorganisms plays an essential role in the properties of active fluids. Despite the important progress in our understanding of microorganisms’ motility in recent years, there are still several open questions about the dynamics of cell motility in active suspensions. Of special interest is the relationship between cell motility and age. In this study, cyanobacterium Synechocystis sp. CPCC 534 was used as the model microorganism, and the cell trajectories were tracked for 78 days during the cell growth period. Results showed that the length of cell trajectories had substantially increased from the exponential growth phase to the stationary phase and had declined at the end of the stationary phase. Similar trends were observed for the cells’ mean squared displacement (MSD), the time-dependent diffusion coefficient of cell suspensions, and the cell displacement probability density function (PDF). These results suggest that the cellular age of microorganisms has a significant effect on various metrics of cell motility and, therefore, can impact the transport properties of active suspensions. Full article

(This article belongs to the Special Issue Advances in Bioprocess Technology)

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24 pages, 11274 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Hybrid Cooling-Based Thermal Management of Containerised Vanadium Flow Battery Systems in Photovoltaic Applications

by Bing Shu, Maria Skyllas-Kazacos, Jie Bao and Ke Meng

Processes 2023, 11(5), 1431; https://doi.org/10.3390/pr11051431 - 8 May 2023

Cited by 2 | Viewed by 1906

Abstract

The integration of industrial batteries with photovoltaic applications is a common practice to charge the batteries using solar energy. Long-duration flow batteries are useful in dealing with the intermittency of renewable energy sources and offer a great opportunity for total fossil fuel replacement. [...] Read more.

The integration of industrial batteries with photovoltaic applications is a common practice to charge the batteries using solar energy. Long-duration flow batteries are useful in dealing with the intermittency of renewable energy sources and offer a great opportunity for total fossil fuel replacement. In this study, the effects of different battery operation time and load profiles on the temperature dynamics of a containerised vanadium flow battery system are modelled and simulated for a range of locations and seasons to identify active cooling or heating requirements that might be needed to maintain safe operating temperatures. This paper explores and analyses the stack, tank, and container temperature dynamics of 6 h and 8 h containerised vanadium flow batteries (VFBs) during periods of higher charge and discharge current using computer simulations that apply insulation with passive or active hybrid cooling thermal management where needed to keep the battery temperature within a safe operating range under a range of climate conditions. According to the simulation results, when adopting the hybrid cooling strategy as described in the case study, for a 30 kW–240 kWh VFB system with ambient temperatures fluctuating between 25 °C and 45 °C, the monthly electricity consumption of the air conditioning system, calculated using average power, can be maintained at a relatively low level of approximately 330 kWh. By employing an air conditioning system with an airflow rate of 0.2 m³/s and a suitable thermal management strategy, it is sufficient to keep an 8 h system operating within a safe temperature range when the ambient temperature is between 15 °C and 35 °C. This study presents the first application of our previously developed containerised VFB thermodynamic model to explore the necessity of active cooling or heating in PV (photovoltaic) applications across different geographical locations and seasons. This analysis provides valuable insights for battery designers and manufacturers to understand the performance of containerised battery systems under various climate conditions. Furthermore, this paper is the first to apply this model for simulating 6 and 8 h batteries and to adopt a hybrid thermal management strategy. The simulation data offer guidance on whether active cooling or heating is required for industrialised vanadium batteries with capacities exceeding 6 h. Full article

(This article belongs to the Special Issue Optimal Design for Renewable Power Systems)

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27 pages, 24632 KiB

Open AccessEditor’s ChoiceArticle

Effect of the Freezing Step on Primary Drying Experiments and Simulation of Lyophilization Processes

by Alex Juckers, Petra Knerr, Frank Harms and Jochen Strube

Processes 2023, 11(5), 1404; https://doi.org/10.3390/pr11051404 - 5 May 2023

Cited by 4 | Viewed by 4193

Abstract

Lyophilization is a widely used preservation method for thermosensitive products. It consists of three process steps: freezing, primary and secondary drying. One of the major drawbacks is the long processing time. The main optimization effort was put into the primary drying phase since [...] Read more.

Lyophilization is a widely used preservation method for thermosensitive products. It consists of three process steps: freezing, primary and secondary drying. One of the major drawbacks is the long processing time. The main optimization effort was put into the primary drying phase since it is usually the longest phase. However, the freezing step is of immense importance for process efficiency and product quality. The lack of control during freezing comprises a challenge for process design and tech transfer. In this study, four different freezing steps (shelf-ramped freezing with and without holding step, precooled shelves and an ice fog method for controlled nucleation) are used and their impact on primary drying experiments and simulations is shown. Only the ice fog method is able to control the nucleation temperature leading to low dry layer resistances with low deviations. During the primary drying simulations, the control of the nucleation temperature drastically increases the precision and accuracy of the product temperature prediction. For optimal primary drying design and model predictive control, the nucleation temperature is strongly recommended to be controlled inside a Process Analytical Technology (PAT) concept to achieve reliable and reproducible process conditions. Full article

(This article belongs to the Special Issue Features, Reviews and Perspectives for the 10th Anniversary of Processes)

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20 pages, 4659 KiB

Open AccessEditor’s ChoiceArticle

Product Yields Dependency on the Carbide Phase Presence in Cobalt and Iron SBA-15 Catalysts Structure in the Fischer–Tropsch Synthesis

by Nikita Sharkov, Zahra Gholami, Ivana Hradecká, Zdeněk Tišler and Josef Šimek

Processes 2023, 11(5), 1391; https://doi.org/10.3390/pr11051391 - 4 May 2023

Cited by 1 | Viewed by 1774

Abstract

The use of carbide catalysts in Fischer–Tropsch synthesis (FTS) is an active area of research, as carbide phases have been shown to improve the stability and performance of catalysts in this reaction. This study compared the catalytic activity and product selectivity of cobalt [...] Read more.

The use of carbide catalysts in Fischer–Tropsch synthesis (FTS) is an active area of research, as carbide phases have been shown to improve the stability and performance of catalysts in this reaction. This study compared the catalytic activity and product selectivity of cobalt and iron catalysts supported on SBA-15, with and without a carbide phase and reduction treatment before the reaction. Results showed that the presence of the carbide phase had a noticeable influence on the catalytic behavior of the catalysts, and the reduction of the catalyst with hydrogen also affected the product selectivity. The presence of the carbide phase in non-reduced cobalt catalysts resulted in increased selectivity to liquid phase products, as evidenced by a CO conversion of 37% with 68% selectivity to the products in the liquid phase. The catalytic activity of the iron carbide catalyst for CO dissociation was found to be 38% after reducing the catalyst with hydrogen, leading to the formation of more active sites. The presence of metal carbides and formation of metallic cobalt and iron during the FT reaction and reduction step was found to have a significant effect on the catalytic performance and product selectivity. The findings of this research provide new insights into the role of carbide in the performance of cobalt and iron catalysts in Fischer–Tropsch synthesis. Full article

(This article belongs to the Section Catalysis Enhanced Processes)

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11 pages, 2259 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Denaturation and Digestion Increase the Antioxidant Capacity of Proteins

by Kacper Kut, Grzegorz Bartosz and Izabela Sadowska-Bartosz

Processes 2023, 11(5), 1362; https://doi.org/10.3390/pr11051362 - 29 Apr 2023

Cited by 3 | Viewed by 3541

Abstract

It has been estimated and demonstrated that the antioxidant capacity of proteins is increased as a result of digestion in the gastrointestinal tract, which can be contributed by denaturation and digestion. This study aimed to evaluate the effect of denaturation and proteolytic digestion [...] Read more.

It has been estimated and demonstrated that the antioxidant capacity of proteins is increased as a result of digestion in the gastrointestinal tract, which can be contributed by denaturation and digestion. This study aimed to evaluate the effect of denaturation and proteolytic digestion on the antioxidant activity of bovine serum albumin (BSA) and chicken egg white proteins in model systems. Denaturation with an anionic detergent (sodium dodecyl sulfate) and digestion with papain and trypsin increased the antioxidant activity/capacity of the proteins, apparently due to the increased exposure of amino acid residues responsible for the antioxidant activity of proteins (tyrosine, tryptophan, cysteine, histidine, arginine, and cystine in the ABTS^● decolorization assay; cysteine, tryptophan, tyrosine, and cystine in the FRAP assay). As the increase in the protein antioxidant activity/capacity was limited in extent, it does not invalidate the use of the antioxidant capacity of proteins to be consumed as a rough measure of their antioxidant capacity after modifications in the gastrointestinal tract. Full article

(This article belongs to the Section Biological Processes and Systems)

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13 pages, 2861 KiB

Open AccessEditor’s ChoiceArticle

Fixed Bed Batch Slow Pyrolysis Process for Polystyrene Waste Recycling

by Galo Albor, Amin Mirkouei, Armando G. McDonald, Ethan Struhs and Farid Sotoudehnia

Processes 2023, 11(4), 1126; https://doi.org/10.3390/pr11041126 - 6 Apr 2023

Cited by 7 | Viewed by 3443

Abstract

This study evaluates the potential of recycling polystyrene (PS) plastic wastes via a fixed bed (batch) slow pyrolysis reactor. The novelty lies in examining the reactor design, conversion parameters, and reaction kinetics to improve the process yield, activation energy, and chemical composition. PS [...] Read more.

This study evaluates the potential of recycling polystyrene (PS) plastic wastes via a fixed bed (batch) slow pyrolysis reactor. The novelty lies in examining the reactor design, conversion parameters, and reaction kinetics to improve the process yield, activation energy, and chemical composition. PS samples were pyrolyzed at 475–575 °C for 30 min under 10–15 psi. Process yield and product attributes were evaluated using different methods to understand PS thermal degradation characteristics better. The results show that PS decomposition started within 2 min from all temperatures, and the total decomposition point of 97% at 475 °C at approximately 5 min. Additionally, analytical results indicate that the average necessary activation energy is 191 kJ/mol. Pyrolysis oil from PS was characterized by gas chromatography–mass spectrometry. The results show that styrene was produced 57–60% from all leading oil compounds (i.e., 2,4-diphenyl-1-butene, 2,4,6-triphenyl-1-hexene, and toluene), and 475 °C has the major average of conversion effectiveness of 91.3%. The results show that the reactor temperature remains the main conversion parameter to achieve the high process yield for oil production from PS. It is concluded that pyrolysis provides a sustainable pathway for PS waste recycling and conversion to value-added products, such as resins and polymers. The proposed method and analytical results are compared with earlier studies to identify directions for future studies. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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8 pages, 1637 KiB

Open AccessEditor’s ChoiceCommunication

Comparison Study on the Water-to-Biomass Ratio in Hydrothermal Carbonization of Fresh Seaweed

by Sepideh Soroush, Frederik Ronsse, Jihae Park and Philippe M. Heynderickx

Processes 2023, 11(4), 1123; https://doi.org/10.3390/pr11041123 - 5 Apr 2023

Cited by 1 | Viewed by 1688

Abstract

Upgrading wet biomass to char via hydrothermal carbonization is a promising method to produce valuable resources for adsorption of organic impurities. In this work, a fresh green seaweed, Ulva pertusa, was investigated to demonstrate the effects of pre-drying and pre-washing on the [...] Read more.

Upgrading wet biomass to char via hydrothermal carbonization is a promising method to produce valuable resources for adsorption of organic impurities. In this work, a fresh green seaweed, Ulva pertusa, was investigated to demonstrate the effects of pre-drying and pre-washing on the process and the hydrochar production. Surface moisture and bound moisture were found to affect this process. Hydrochar produced from fresh seaweed with additional water showed similar adsorption capacity to fresh seaweed without additional water and 38% higher than hydrochar from soaked dry seaweed. This was supported by FTIR spectra analysis, which showed that these hydrochars produced from fresh seaweed without additional water have the highest proportion of carboxyl functional groups. Full article

(This article belongs to the Special Issue Synthesis and Applications of Novel Functional Materials)

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20 pages, 6613 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Engineered Biomaterials for Reducing Phosphorus and Nitrogen Levels from Downstream Water of Aquaculture Facilities

by W. F. Rance Bare, Ethan Struhs, Amin Mirkouei, Kenneth Overturf and Brian Small

Processes 2023, 11(4), 1029; https://doi.org/10.3390/pr11041029 - 29 Mar 2023

Cited by 2 | Viewed by 2084

Abstract

The United States (U.S.) has a nearly USD 17 billion seafood trade deficit annually. However, the U.S. aquaculture industry faces strict micronutrient (e.g., phosphorus and nitrogen) level mandates that negatively impact fish production, especially for the state of Idaho, which produces 70–75% of [...] Read more.

The United States (U.S.) has a nearly USD 17 billion seafood trade deficit annually. However, the U.S. aquaculture industry faces strict micronutrient (e.g., phosphorus and nitrogen) level mandates that negatively impact fish production, especially for the state of Idaho, which produces 70–75% of the nation’s rainbow trout. This study investigates the sustainability benefits of producing engineered biomaterials from lignocellulosic-based feedstocks near collection sites via portable biorefineries for use by fish farms to reduce eutrophication (oversupply of micronutrients) impacts. In this study, sustainability assessments are performed on a case study in southern Idaho, the largest U.S. commercial producer of rainbow trout. The results show that 20 and 60 min of water treatment, using small particle size biomaterial from lodgepole pine, has the highest total phosphorus removal rate, at 150–180 g of phosphorus per 1 metric ton of engineered biomaterials. The results of techno-economic and environmental impacts studies indicate that pinewood-based biomaterials production cost ranges from USD 213 USD 242 per ton and reduces the eutrophication potential by 5–17 kg PO₄eq/ton. Additionally, the environmental impact results show that the total greenhouse gas emission for biomaterial production is 47–54 kg CO₂eq/ton; however, the used biomaterials after water treatment can be sold for around USD 850 per ton as nutrient-rich soil conditioners. This study concluded that engineered biomaterials from lignocellulosic-based feedstocks could be a sustainable solution to the challenge that aquaculture faces, particularly capturing micronutrients from eutrophic water and reusing them as fertilizers. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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13 pages, 1633 KiB

Open AccessEditor’s ChoiceArticle

Extraction and Recovery of Critical Metals from Electronic Waste Using ISASMELT™ Technology

by Stuart Nicol, Benjamin Hogg, Oscar Mendoza and Stanko Nikolic

Processes 2023, 11(4), 1012; https://doi.org/10.3390/pr11041012 - 27 Mar 2023

Cited by 5 | Viewed by 5040

Abstract

Electronic goods are a major consumer of many critical metals, including copper, nickel, tin, zinc, lead, and precious metals. The processing of end-of-life electronic equipment (E-Scrap) is becoming increasingly important to maintain the supply of the critical metals required globally, and to reduce [...] Read more.

Electronic goods are a major consumer of many critical metals, including copper, nickel, tin, zinc, lead, and precious metals. The processing of end-of-life electronic equipment (E-Scrap) is becoming increasingly important to maintain the supply of the critical metals required globally, and to reduce environmental pollution. Currently, the dominant route for E-Scrap processing is pyrometallurgical processing, with the first stage of processing being reductive smelting to produce a black copper and a ‘clean’ discard slag. The management of the slag in this first step is central to the success of the E-Scrap recycling process. The E-Scrap ISASMELT™ furnace has a highly turbulent bath, providing conditions that generate high rates of zinc fuming and allow a wide range of operable slag conditions. This enables efficient E-Scrap smelting to occur, whilst overcoming the challenges associated with alternative technologies. Operable slag compositions and high zinc fuming are heavily influenced by kinetic processes, with piloting critical to understanding the performance of this process. ISASMELT™ pilot tests were performed, with a wide range of fluxing targets tested to confirm these benefits. The testing demonstrated that high levels of zinc fuming (>80%) are obtained in the E-Scrap ISASMELT™ furnace, decreasing the iron and silica flux additions required to manage the detrimental viscosity effects of zinc in the slag. In addition, it was demonstrated that slags containing high concentrations of alumina (>10 wt%) are operable in an ISASMELT™ furnace. The ISASMELT™ technology was demonstrated to be the only E-Scrap furnace technology able to produce a ‘clean’ discard slag with low concentrations of zinc and minimal fluxing requirements. Full article

(This article belongs to the Special Issue Pyrometallurgical Extraction of Critical Metals for Sustainable Development)

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20 pages, 4383 KiB

Open AccessEditor’s ChoiceArticle

Biological Methanation in an Anaerobic Biofilm Reactor—Trace Element and Mineral Requirements for Stable Operation

by Joseph Tauber, Daniel Möstl, Julia Vierheilig, Ernis Saracevic, Karl Svardal and Jörg Krampe

Processes 2023, 11(4), 1013; https://doi.org/10.3390/pr11041013 - 27 Mar 2023

Cited by 3 | Viewed by 2683

Abstract

Biological methanation of carbon dioxide using hydrogen makes it possible to improve the methane and energy content of biogas produced from sewage sludge and organic residuals and to reach the requirements for injection into the natural gas network. Biofilm reactors, so-called trickling bed [...] Read more.

Biological methanation of carbon dioxide using hydrogen makes it possible to improve the methane and energy content of biogas produced from sewage sludge and organic residuals and to reach the requirements for injection into the natural gas network. Biofilm reactors, so-called trickling bed reactors, offer a relatively simple, energy-efficient, and reliable technique for upgrading biogas via ex-situ methanation. A mesophilic lab-scale biofilm reactor was operated continuously for nine months to upgrade biogas from anaerobic sewage sludge digestion to a methane content >98%. To supply essential trace elements to the biomass, a stock solution was fed to the trickling liquid. Besides standard parameters and gas quality, concentrations of Na, K, Ca, Mg, Ni, and Fe were measured in the liquid and the biofilm using ICP-OES (inductively coupled plasma optical emission spectrometry) to examine the biofilms load-dependent uptake rate and to calculate quantities required for a stable operation. Additionally, microbial community dynamics were monitored by amplicon sequencing (16S rRNA gene). It was found that all investigated (trace) elements are taken up by the biomass. Some are absorbed depending on the load, others independently of it. For example, a biomass-specific uptake of 0.13 mg·g⁻¹·d⁻¹ for Ni and up to 50 mg·g⁻¹·d⁻¹ for Mg were measured. Full article

(This article belongs to the Special Issue New Trends and Perspectives on Anaerobic Digestion)

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12 pages, 6438 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Oxidative Conversion of Chars Generated from the Fixed-Bed Pyrolysis of Wood Torrefied at Different Temperatures and Holding Times

by Carmen Branca and Colomba Di Blasi

Processes 2023, 11(4), 997; https://doi.org/10.3390/pr11040997 - 24 Mar 2023

Cited by 1 | Viewed by 1197

Abstract

Fixed-bed pyrolysis of torrefied spruce wood, for a heating temperature of 800 K, results in char yields between about 27–57 wt% (versus 23 wt% for untreated wood), depending on both pre-treatment temperatures (533–583 K) and holding times (8–25 min). In this study char [...] Read more.

Fixed-bed pyrolysis of torrefied spruce wood, for a heating temperature of 800 K, results in char yields between about 27–57 wt% (versus 23 wt% for untreated wood), depending on both pre-treatment temperatures (533–583 K) and holding times (8–25 min). In this study char oxidation behavior and kinetics are investigated by means of thermogravimetric analysis. The differential thermogravimetric curves always showed a low-temperature zone of slow rates (oxidative devolatilization), followed by a high-rate zone with a well-defined peak (oxidation). As the torrefaction severity increases, the temperature range of the oxidative devolatilization enlarges. Moreover, the oxidation rates become slower (both burning and burnout temperatures tend to increase). As already found for untreated wood chars, the two stages are well described by a linear and a power-law rate reaction, respectively. Volatiles released from the devolatilizations are approximately around 20 wt%, but torrefaction causes lower activation energies (66–92 kJ/mol versus 117 kJ/mol). The oxidation activation energies also decreas (170–168 kJ/mol versus 193 kJ/mol), accompanied by small variations in the reaction order. Full article

(This article belongs to the Special Issue Kinetic Modeling of Biomass Pyrolysis Processes)

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23 pages, 6685 KiB

Open AccessEditor’s ChoiceArticle

Coupled CFD-DEM Simulation of Seed Flow in Horizontal-Vertical Tube Transition

by Leno Guzman, Ying Chen and Hubert Landry

Processes 2023, 11(3), 909; https://doi.org/10.3390/pr11030909 - 16 Mar 2023

Cited by 5 | Viewed by 2539

Abstract

A series of computational fluid dynamics–discrete element method (CFD-DEM) simulations were applied to seed flow in horizontal-vertical 90-degree elbows. The performance of one-way and two-way CFD-DEM coupling methods was compared. Additionally, simulated seed velocities were compared to the current pneumatic conveying theory for [...] Read more.

A series of computational fluid dynamics–discrete element method (CFD-DEM) simulations were applied to seed flow in horizontal-vertical 90-degree elbows. The performance of one-way and two-way CFD-DEM coupling methods was compared. Additionally, simulated seed velocities were compared to the current pneumatic conveying theory for each coupling method. Simulated field peas (Pisum sativum) were pneumatically conveyed to study the effect of air velocity (20, 25, and 30 m/s), seed rate (0.07, 0.21, and 0.42 kg/s), elbow diameter, D, (48.3, 60.3, and 72.4 mm), and elbow bend radius (1.5D, 2.5D, 3.5D, and 4.5D) on seed attributes (trajectory, velocity, and force). Results showed that seed velocity was significantly different between one-way and two-way coupling. Both methods resulted in nearly identical seed trajectory and force. Overall, simulated seed velocities had a strong correlation to values calculated through the current pneumatic conveyance theory. Dimensional analysis revealed that seed contact force was proportional to the elbow diameter to the power of 0.26 and inversely proportional to the elbow bend radius to the power of 0.5. Simulation results indicated that one-way coupling could be suitable to describe seed flow when two-way coupling may not be possible or practical. Full article

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11 pages, 1688 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Removable Pressure-Sensitive Adhesives Based on Acrylic Telomer Syrups

by Mateusz Weisbrodt and Agnieszka Kowalczyk

Processes 2023, 11(3), 885; https://doi.org/10.3390/pr11030885 - 15 Mar 2023

Viewed by 2050

Abstract

Removable pressure-sensitive adhesives (PSAs) are used in the production of self-adhesive materials such as protective films, masking tapes or biomedical electrodes. This work presents a new and environmentally friendly method of obtaining this type of adhesive materials, i.e., photochemically induced free radical telomerization. [...] Read more.

Removable pressure-sensitive adhesives (PSAs) are used in the production of self-adhesive materials such as protective films, masking tapes or biomedical electrodes. This work presents a new and environmentally friendly method of obtaining this type of adhesive materials, i.e., photochemically induced free radical telomerization. Adhesive binders to removable PSAs, i.e., the photoreactive acrylic telomer syrups (ATS) were prepared from n-butyl acrylate, acrylic acid, and 4-acrylooxybenzophenone. Tetrabromomethane (CBr₄) or bromotrichloromethane (CBrCl₃) were used as the telogens. ATS was modified with unsaturated polybutadiene resin and a radical photoinitiator. Adhesive compositions were coated onto a carrier and UV cross-linked. The effects of the chemical nature of telomers (i.e., terminal Br or Cl atoms) and their molecular weight (K-value), as well as the cross-linking degree on adhesive properties of PSAs, were studied. It was found that with the increase in telogen content in the system, the dynamic viscosity of ATS and K-value of acrylic telomers decrease, and the conversion of monomers increases. CBr₄ turned out to be a more effective chain transfer agent than CBrCl₃. Moreover, telomers with terminal Br-atoms (7.5 mmol of CBr₄), due to slightly lower molecular weights and viscosity, showed a higher photocrosslinking ability (which was confirmed by high cohesion results at 20 and 70 °C, i.e., >72 h). Generally, higher values of the temperature at which adhesive failure occurred were noted for PSAs based on ATS with lower telogen content (7.5 mmol), both CBr₄ and CBrCl₃. The excellent result for removable PSA was obtained in the case of telomer syrup Br-7.5 crosslinked with a 5 J/cm² dose of UV-radiation (adhesion ca.1.3 N/25 mm, and cohesion > 72 h). Full article

(This article belongs to the Special Issue Design of Adhesive Bonded Joints)

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20 pages, 3996 KiB

Open AccessEditor’s ChoiceReview

The Perspective of Using the System Ethanol-Ethyl Acetate in a Liquid Organic Hydrogen Carrier (LOHC) Cycle

by Elio Santacesaria, Riccardo Tesser, Sara Fulignati and Anna Maria Raspolli Galletti

Processes 2023, 11(3), 785; https://doi.org/10.3390/pr11030785 - 7 Mar 2023

Cited by 3 | Viewed by 3448

Abstract

Starting from bioethanol it is possible, by using an appropriate catalyst, to produce ethyl acetate in a single reaction step and pure hydrogen as a by-product. Two molecules of hydrogen can be obtained for each molecule of ethyl acetate produced. The mentioned reaction [...] Read more.

Starting from bioethanol it is possible, by using an appropriate catalyst, to produce ethyl acetate in a single reaction step and pure hydrogen as a by-product. Two molecules of hydrogen can be obtained for each molecule of ethyl acetate produced. The mentioned reaction is reversible, therefore, it is possible to hydrogenate ethyl acetate to reobtain ethanol, so closing the chemical cycle of a Liquid Organic Hydrogen Carrier (LOHC) process. In other words, bioethanol can be conveniently used as a hydrogen carrier. Many papers have been published in the literature dealing with both the ethanol dehydrogenation and the ethyl acetate hydrogenation to ethanol so demonstrating the feasibility of this process. In this review all the aspects of the entire LOHC cycle are considered and discussed. We examined in particular: the most convenient catalysts for the two main reactions, the best operative conditions, the kinetics of all the reactions involved in the process, the scaling up of both ethanol dehydrogenation and ethyl acetate hydrogenation from the laboratory to industrial plant, the techno-economic aspects of the process and the perspective for improvements. In particular, the use of bioethanol in a LOHC process has three main advantages: (1) the hydrogen carrier is a renewable resource; (2) ethanol and ethyl acetate are both green products benign for both the environment and human safety; (3) the processes of hydrogenation and dehydrogenation occur in relatively mild operative conditions of temperature and pressure and with high energetic efficiency. The main disadvantage with respect to other more conventional LOHC systems is the relatively low hydrogen storage density. Full article

(This article belongs to the Special Issue Industrial Chemistry Reaction: Kinetics, Mass Transfer and Industrial Reactor Design (II))

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14 pages, 2695 KiB

Open AccessEditor’s ChoiceArticle

The Influence of Sample Size on Long-Term Performance of a 6σ Process

by Andrei Alexandru Boroiu, Aurel Mihail Titu, Alexandru Boroiu, Mihai Dragomir, Alina Bianca Pop and Stefan Titu

Processes 2023, 11(3), 779; https://doi.org/10.3390/pr11030779 - 6 Mar 2023

Cited by 1 | Viewed by 1452

Abstract

There are many criticisms for the association between the Six Sigma concept and the two statistical metrics associated to 6σ processes: 1.5σ shift for maximum deviation and 3.4 PPM non-conformities for the long-term performance. As a result, the paper aims to carry out [...] Read more.

There are many criticisms for the association between the Six Sigma concept and the two statistical metrics associated to 6σ processes: 1.5σ shift for maximum deviation and 3.4 PPM non-conformities for the long-term performance. As a result, the paper aims to carry out an analysis of this problem, and the first result obtained is that a stable process can reach a maximum drift, but its value depends on the volume of the sample. It is also highlighted that, using only the criterion “values outside the control limits” for monitoring stability through the Xbar chart, a minimum value can be calculated for the long-term performance of a process depending on the sample size. The main conclusion resulting from the calculations is that, in the case of a 6σ process, the long-term performance is much better than the established value of 3400 PPB: For small volume samples of two pieces it is below 700 PPB, for three pieces it is below 200 PPB, and for samples with a volume greater than or equal to four pieces the performance already reaches values below 100 PPB! So, the long-term performance of 6σ processes is certainly even better than the known value of 3.4 PPM. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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16 pages, 7754 KiB

Open AccessEditor’s ChoiceArticle

Adiabatic Cooling System Working Process Investigation

by Rolandas Bleizgys, Jonas Čėsna, Savelii Kukharets, Oleksandr Medvedskyi, Indrė Strelkauskaitė-Buivydienė and Ieva Knoknerienė

Processes 2023, 11(3), 767; https://doi.org/10.3390/pr11030767 - 5 Mar 2023

Cited by 2 | Viewed by 2225

Abstract

Avoiding heat stress in cows is an important condition for animal productivity and the maintaining of animal health. For this, it is necessary to provide an optimal microclimate in cowsheds using systems of air cooling. The paper analyzes one of these systems—an air [...] Read more.

Avoiding heat stress in cows is an important condition for animal productivity and the maintaining of animal health. For this, it is necessary to provide an optimal microclimate in cowsheds using systems of air cooling. The paper analyzes one of these systems—an air humidification–cooling system. The research was carried out in a semi-insulated box-type cowshed containing 244 places. The changes in temperature, relative humidity, and temperature humidity index (THI) were studied for the air coming from outside and for the air inside the cowshed. Considering the fact that the cows were in the cowshed most of the time (51.5%) under heat stress, the use of a cooling system is appropriate. It was established that a cooling system is capable of compensating for heat released by animals. It was determined that with an increase in air temperature the relative efficiency of a cooling system increases. An intensive constant air exchange provided using fan operation avoids an excessive growth of relative humidity in a cowshed. To reduce the consumption of electricity and water, the paper suggests regulation of both the power of the fans of the system and the water supply to the nozzles not using temperature but using THI. Theoretically, when THI is used to regulate the operation of the cooling system, the consumption of electrical energy is reduced by 17.8%, and the consumption of water is reduced by 43.2% when compared to the option when the temperature is used to regulate the operation of a cooling system. Full article

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15 pages, 979 KiB

Open AccessEditor’s ChoiceArticle

Effect of Addition of Zero-Valent Iron (Fe) and Magnetite (Fe₃O₄) on Methane Yield and Microbial Consortium in Anaerobic Digestion of Food Wastewater

by Jun-Hyeong Lee, Jae-Hyuk Lee, Sang-Yoon Kim and Young-Man Yoon

Processes 2023, 11(3), 759; https://doi.org/10.3390/pr11030759 - 4 Mar 2023

Cited by 5 | Viewed by 1845

Abstract

Direct interspecies electron transfer (DIET), which does not involve mediation by electron carriers, is realized by the addition of conductive materials to an anaerobic digester, which then activates syntrophism between acetogenic and methanogenic microorganisms. This study aimed to investigate the effect of the [...] Read more.

Direct interspecies electron transfer (DIET), which does not involve mediation by electron carriers, is realized by the addition of conductive materials to an anaerobic digester, which then activates syntrophism between acetogenic and methanogenic microorganisms. This study aimed to investigate the effect of the addition of two conductive materials, zero-valent iron (ZVI) and magnetite, on the methane production and microbial consortium via DIET in the anaerobic digestion of food wastewater. The operation of a batch reactor for food wastewater without the addition of the conductive materials yielded a biochemical methane potential (B_u), maximum methane production rate (R_m), and lag phase time (λ) of 0.380 Nm³ kg⁻¹-VS_added, 15.73 mL day⁻¹, and 0.541 days, respectively. Upon the addition of 1.5% ZVI, B_u and R_m increased significantly to 0.434 Nm³ kg⁻¹-VS_added and 19.63 mL day⁻¹, respectively, and λ was shortened to 0.065 days. Simultaneously, Methanomicrobiales increased from 26.60% to 46.90% and Methanosarcinales decreased from 14.20% to 1.50% as the ZVI input increased from 0% to 1.50%. Magnetite, at an input concentration of 1.00%, significantly increased the B_u and R_m to 0.431 Nm³ kg⁻¹-VS_added and 18.44 mL day⁻¹, respectively. However, although magnetite improves the efficiency of methanogenesis via DIET, the effect thereof on the methanogen community remains unclear. Full article

(This article belongs to the Section Environmental and Green Processes)

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22 pages, 6686 KiB

Open AccessEditor’s ChoiceArticle

Parametric Analysis of a Double Shaft, Batch-Type Paddle Mixer Using the Discrete Element Method (DEM)

by Jeroen Emmerink, Ahmed Hadi, Jovana Jovanova, Chris Cleven and Dingena L. Schott

Processes 2023, 11(3), 738; https://doi.org/10.3390/pr11030738 - 2 Mar 2023

Cited by 4 | Viewed by 2865

Abstract

To improve the understanding of the mixing performance of double shaft, batch-type paddle mixers, the discrete element method (DEM) in combination with a Plackett–Burman design of experiments simulation plan is used to identify factor significance on the system’s mixing performance. Effects of several [...] Read more.

To improve the understanding of the mixing performance of double shaft, batch-type paddle mixers, the discrete element method (DEM) in combination with a Plackett–Burman design of experiments simulation plan is used to identify factor significance on the system’s mixing performance. Effects of several factors, including three material properties (particle size, particle density and composition), three operational conditions (initial filling pattern, fill level and impeller rotational speed) and three geometric parameters (paddle size, paddle angle and paddle number), were quantitatively investigated using the relative standard deviation (RSD). Four key performance indicators (KPIs), namely the mixing quality, mixing time, average mixing power and energy required to reach a steady state, were defined to evaluate the performance of the double paddle mixer. The results show that the material property effects are not as significant as those of the operational conditions and geometric parameters. In particular, the geometric parameters were observed to significantly influence the energy consumption, while not affecting the mixing quality and mixing time, showing their potential towards designing more sustainable mixers. Furthermore, the analysis of granular temperature revealed that the centre area between the two paddles has a high diffusivity, which can be correlated to the mixing time. Full article

(This article belongs to the Special Issue Challenges of Applying Discrete Element Method (DEM) to Industrial Applications)

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24 pages, 11333 KiB

Open AccessEditor’s ChoiceArticle

Effect of the Mixer Design Parameters on the Performance of a Twin Paddle Blender: A DEM Study

by Behrooz Jadidi, Mohammadreza Ebrahimi, Farhad Ein-Mozaffari and Ali Lohi

Processes 2023, 11(3), 733; https://doi.org/10.3390/pr11030733 - 1 Mar 2023

Cited by 5 | Viewed by 4615

Abstract

The design parameters of a mixing system have a major impact on the quality of the final product. Therefore, identifying the optimum parameters of mixing systems is highly relevant to various industrial processes dealing with particulate flows. However, the studies on the influences [...] Read more.

The design parameters of a mixing system have a major impact on the quality of the final product. Therefore, identifying the optimum parameters of mixing systems is highly relevant to various industrial processes dealing with particulate flows. However, the studies on the influences of the mixer’s design features are still insufficient. In this study, the Discrete Element Method (DEM) is used to examine the impact of paddle angle, width, and gap on the mixing performance of a twin paddle blender. The mixing performance and particle flow are assessed using the relative standard deviation (RSD) mixing index, velocity field, diffusivity coefficient, granular temperature, the force acting on particles, and the mixer’s power consumption. The mixing performance is highest for a paddle angle of 0° at the cost of the highest forces acting on particles. The paddle width is indicated as a critical factor for achieving better mixing quality. In contrast, the powder mixing efficiency and the mixer’s power consumption are not significantly affected by the paddle gap. The results regarding the power consumption denote that the mixer using the paddle angle of 60° has the minimum power consumption. Moreover, increasing the paddle width results in the enhancement of the mixer’s power consumption. Full article

(This article belongs to the Special Issue Challenges of Applying Discrete Element Method (DEM) to Industrial Applications)

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16 pages, 3058 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

A Study on the Corrosion Behaviour of Laser Textured Pure Aluminium in Saltwater

by Juan Ignacio Ahuir-Torres, Hiren Ramniklal Kotadia, Tahsin Tecelli Öpoz and Martin Charles Sharp

Processes 2023, 11(3), 721; https://doi.org/10.3390/pr11030721 - 28 Feb 2023

Cited by 6 | Viewed by 1715

Abstract

Commercially pure aluminium is employed in several industrial applications. On some applications, the surface of this material needs to be functionalised. Laser surface texturing is a powerful tool to functionalise aluminium and aluminium alloy surfaces. However, the corrosion resistance of the laser textured [...] Read more.

Commercially pure aluminium is employed in several industrial applications. On some applications, the surface of this material needs to be functionalised. Laser surface texturing is a powerful tool to functionalise aluminium and aluminium alloy surfaces. However, the corrosion resistance of the laser textured aluminium alloy can be modified, and this has rarely been investigated in the literature. Consequently, the corrosion resistance of the laser textured commercially pure aluminium in saltwater was evaluated using several electrochemical techniques: asymmetric electrochemical noise, potentiodynamic polarisation curve and electrochemical impedance spectroscopy. Although the non-laser surface textured samples possessed higher kinetic corrosion resistance in the first hours of immersion, the corrosion mechanism (process group of the corrosion) was found to be more unstable than the laser textured specimens. The oxidised layer of the textured samples was also nobler than the native passive film. Full article

(This article belongs to the Section Chemical Processes and Systems)

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16 pages, 859 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Current, Projected Performance and Costs of Thermal Energy Storage

by Laura Pompei, Fabio Nardecchia and Adio Miliozzi

Processes 2023, 11(3), 729; https://doi.org/10.3390/pr11030729 - 28 Feb 2023

Cited by 14 | Viewed by 7352

Abstract

The technology for storing thermal energy as sensible heat, latent heat, or thermochemical energy has greatly evolved in recent years, and it is expected to grow up to about 10.1 billion US dollars by 2027. A thermal energy storage (TES) system can significantly [...] Read more.

The technology for storing thermal energy as sensible heat, latent heat, or thermochemical energy has greatly evolved in recent years, and it is expected to grow up to about 10.1 billion US dollars by 2027. A thermal energy storage (TES) system can significantly improve industrial energy efficiency and eliminate the need for additional energy supply in commercial and residential applications. This study is a first-of-its-kind specific review of the current projected performance and costs of thermal energy storage. This paper presents an overview of the main typologies of sensible heat (SH-TES), latent heat (LH-TES), and thermochemical energy (TCS) as well as their application in European countries. With regard to future challenges, the installation of TES systems in buildings is being implemented at a rate of 5%; cogeneration application with TES is attested to 10.2%; TES installation in the industry sector accounts for 5% of the final energy consumption. From the market perspective, the share of TES is expected to be dominated by SH-TES technologies due to their residential and industrial applications. With regard to the cost, the SH-TES system is typically more affordable than the LH-TES system or the TCS system because it consists of a simple tank containing the medium and the charging/discharging equipment. Full article

(This article belongs to the Special Issue State-of-the-Art Energy Conversion and Storage)

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14 pages, 5472 KiB

Open AccessEditor’s ChoiceArticle

Candidatus Scalindua, a Biological Solution to Treat Saline Recirculating Aquaculture System Wastewater

by Federico Micolucci, Jonathan A. C. Roques, Geoffrey S. Ziccardi, Naoki Fujii, Kristina Sundell and Tomonori Kindaichi

Processes 2023, 11(3), 690; https://doi.org/10.3390/pr11030690 - 24 Feb 2023

Cited by 3 | Viewed by 2575

Abstract

Recirculating aquaculture systems (RAS) are promising candidates for the sustainable development of the aquaculture industry. A current limitation of RAS is the production and potential accumulation of nitrogenous wastes, ammonium (NH₄⁺), nitrite (NO₂⁻) and nitrate (NO₃ [...] Read more.

Recirculating aquaculture systems (RAS) are promising candidates for the sustainable development of the aquaculture industry. A current limitation of RAS is the production and potential accumulation of nitrogenous wastes, ammonium (NH₄⁺), nitrite (NO₂⁻) and nitrate (NO₃⁻), which could affect fish health and welfare. In a previous experiment, we have demonstrated that the marine anammox bacteria Candidatus Scalindua was a promising candidate to treat the wastewater (WW) of marine, cold-water RAS. However, the activity of the bacteria was negatively impacted after a direct exposure to RAS WW. In the current study, we have further investigated the potential of Ca. Scalindua to treat marine RAS WW in a three-phase experiment. In the first phase (control, 83 days), Ca. Scalindua was fed a synthetic feed, enriched in NH₄⁺, NO₂⁻ and trace element (TE) mix. Removal rates of 98.9% and 99.6% for NH₄⁺ and NO₂⁻, respectively, were achieved. In the second phase (116 days), we gradually increased the exposure of Ca. Scalindua to nitrogen-enriched RAS WW over a period of about 80 days. In the last phase (79 days), we investigated the needs of TE supplementation for the Ca. Scalindua after they were fully acclimated to 100% RAS WW. Our results show that the gradual exposure of Ca. Scalindua resulted in a successful acclimation to 100% RAS WW, with maintained high removal rates of both NH₄⁺ and NO₂⁻ throughout the experiment. Despite a slight decrease in relative abundance (from 21.4% to 16.7%), Ca. Scalindua remained the dominant species in the granules throughout the whole experiment. We conclude that Ca. Scalindua can be successfully used to treat marine RAS WW, without the addition of TE, once given enough time to acclimate to its new substrate. Future studies need to determine the specific needs for optimal RAS WW treatment by Ca. Scalindua at pilot scale. Full article

(This article belongs to the Special Issue Wastewater and Waste Treatment: Overview, Challenges and Current Trends (Volume II))

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25 pages, 9740 KiB

Open AccessEditor’s ChoiceArticle

Dynamic Parameter Simulations for a Novel Small-Scale Power-to-Ammonia Concept

by Pascal Koschwitz, Daria Bellotti, Miguel Cámara Sanz, Antonio Alcaide-Moreno, Cheng Liang and Bernd Epple

Processes 2023, 11(3), 680; https://doi.org/10.3390/pr11030680 - 23 Feb 2023

Cited by 8 | Viewed by 2267

Abstract

Ammonia is a promising carbon-free energy vector, hydrogen carrier, and efficient means for long-time hydrogen storage. Power-to-ammonia-to-power concepts, powered exclusively by electricity from renewable sources, will leave the carbon economy behind and enter a truly renewable era. However, the fluctuating nature of renewables [...] Read more.

Ammonia is a promising carbon-free energy vector, hydrogen carrier, and efficient means for long-time hydrogen storage. Power-to-ammonia-to-power concepts, powered exclusively by electricity from renewable sources, will leave the carbon economy behind and enter a truly renewable era. However, the fluctuating nature of renewables requires a good dynamic behavior of such concepts. Employing the software Aspen Plus Dynamics^®, this paper investigates the dynamic behavior of a novel containerized power-to-ammonia solution to be tested at the University of Genova in 2023. Implementing a novel kinetic reaction model, the impacts of several deviations from the optimal values of the cycle parameters are investigated. The simulations provide practical guidance on how to best and safely operate the cycle. A total of ten scenarios were simulated, of which six are acceptable, two are desirable, and two should be avoided. However, all scenarios can be safely controlled by the control infrastructure. Full article

(This article belongs to the Section Energy Systems)

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18 pages, 4941 KiB

Open AccessEditor’s ChoiceArticle

A Tool Condition Monitoring System Based on Low-Cost Sensors and an IoT Platform for Rapid Deployment

by Johanna Marie Failing, José V. Abellán-Nebot, Sergio Benavent Nácher, Pedro Rosado Castellano and Fernando Romero Subirón

Processes 2023, 11(3), 668; https://doi.org/10.3390/pr11030668 - 22 Feb 2023

Cited by 8 | Viewed by 2857

Abstract

Tool condition monitoring (TCM) systems are key technologies for ensuring machining efficiency. Despite the large number of TCM solutions, these systems have not been implemented in industry, especially in small- and medium-sized enterprises (SMEs), mainly because of the need for invasive sensors, time-consuming [...] Read more.

Tool condition monitoring (TCM) systems are key technologies for ensuring machining efficiency. Despite the large number of TCM solutions, these systems have not been implemented in industry, especially in small- and medium-sized enterprises (SMEs), mainly because of the need for invasive sensors, time-consuming deployment solutions and a lack of straightforward, scalable solutions from the laboratory. The implementation of TCM solutions for the new era of the Industry 4.0 is encouraging practitioners to look for systems based on IoT (Internet of Things) platforms with plug and play capabilities, minimum interruption time during setup and minimal experimental tests. In this paper, we propose a TCM system based on low-cost and non-invasive sensors that are plug and play devices, an IoT platform for fast deployment and a mobile app for receiving operator feedback. The system is based on a sensing node by Arduino Uno Wi-Fi that acts as an edge-computing node to extract a similarity index for tool wear classification; a machine learning node based on a BeagleBone Black board that builds the machine learning model using a Python script; and an IoT platform to provide the communication infrastructure and register all data for future analytics. Experimental results on a CNC lathe show that a logistic regression model applied on the machine learning node can provide a low-cost and straightforward solution with an accuracy of 88% in tool wear classification. The complete solution has a cost of EUR 170 and only a few hours are required for deployment. Practitioners in SMEs can find the proposed approach interesting since fast results can be obtained and more complex analysis could be easily incorporated while production continues using the operator’s feedback from the mobile app. Full article

(This article belongs to the Special Issue Modeling, Simulation and Control of Flexible Manufacturing Systems)

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24 pages, 12743 KiB

Open AccessEditor’s ChoiceArticle

Process-Specific Topology Optimization Method Based on Laser-Based Additive Manufacturing of AlSi10Mg Components: Material Characterization and Evaluation

by Steffen Czink, Jan Holoch, Robert Renz, Volker Schulze, Albert Albers and Stefan Dietrich

Processes 2023, 11(3), 648; https://doi.org/10.3390/pr11030648 - 21 Feb 2023

Cited by 2 | Viewed by 2078

Abstract

In the laser powder bed fusion process (PBF-LB), components are built up incrementally by locally melting metal powder with a laser beam. This process leads to inhomogeneous material properties of the manufactured components. By integrating these specific material properties into a topology optimization [...] Read more.

In the laser powder bed fusion process (PBF-LB), components are built up incrementally by locally melting metal powder with a laser beam. This process leads to inhomogeneous material properties of the manufactured components. By integrating these specific material properties into a topology optimization algorithm, product developers can be supported in the early phases of the product development process, such as design finding. For this purpose, a topology optimization method was developed, which takes the inhomogeneous material properties of components fabricated in the PBF-LB process into account. The complex pore architecture in PBF-LB components was studied with micro-computed tomography (µCT). Thereby, three characteristic regions of different porosity were identified and analyzed. The effective stiffness in each of these regions was determined by means of resonant ultrasonic spectroscopy (RUS) as well as finite element analysis. Afterward, the effective stiffness is iteratively considered in the developed topology optimization method. The resulting design proposals of two optimization cases were analyzed and compared to design proposals derived from a standard topology optimization. To evaluate the developed topology optimization method, the derived design proposals were additionally manufactured in the PBF-LB process, and the characteristic pore architecture was analyzed by means of µCT. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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21 pages, 1297 KiB

Open AccessEditor’s ChoiceReview

Fenton Reaction–Unique but Still Mysterious

by Frantisek Kastanek, Marketa Spacilova, Pavel Krystynik, Martina Dlaskova and Olga Solcova

Processes 2023, 11(2), 432; https://doi.org/10.3390/pr11020432 - 1 Feb 2023

Cited by 16 | Viewed by 6335

Abstract

This study is devoted to the Fenton reaction, which, despite hundreds of reports in a number of scientific journals, provides opportunities for further investigation of its use as a method of advanced oxidation of organic macro- and micropollutants in its diverse variations and [...] Read more.

This study is devoted to the Fenton reaction, which, despite hundreds of reports in a number of scientific journals, provides opportunities for further investigation of its use as a method of advanced oxidation of organic macro- and micropollutants in its diverse variations and hybrid systems. It transpires that, for example, the choice of the concentrations and ratios of basic chemical substances, i.e., hydrogen peroxide and catalysts based on the Fe²⁺ ion or other transition metals in homogeneous and heterogeneous arrangements for reactions with various pollutants, is for now the result of the experimental determination of rather randomly selected quantities, requiring further optimizations. The research to date also shows the indispensability of the Fenton reaction related to environmental issues, as it represents the pillar of all advanced oxidation processes, regarding the idea of oxidative hydroxide radicals. This study tries to summarize not only the current knowledge of the Fenton process and identify its advantages, but also the problems that need to be solved. Based on these findings, we identified the necessary steps affecting its further development that need to be resolved and should be the focus of further research related to the Fenton process. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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16 pages, 7175 KiB

Open AccessEditor’s ChoiceArticle

Adhesive Thickness and Ageing Effects on the Mechanical Behaviour of Similar and Dissimilar Single Lap Joints Used in the Automotive Industry

by Raffaele Ciardiello, Carlo Boursier Niutta and Luca Goglio

Processes 2023, 11(2), 433; https://doi.org/10.3390/pr11020433 - 1 Feb 2023

Cited by 5 | Viewed by 1912

Abstract

The effects of the adhesive thickness and overlap of a polyurethane adhesive have been studied by using different substrate configurations. Single lap joint (SLJ) specimens have been tested with homologous substrates, carbon fibre-reinforced plastics and painted metal substrates. Furthermore, a configuration with dissimilar [...] Read more.

The effects of the adhesive thickness and overlap of a polyurethane adhesive have been studied by using different substrate configurations. Single lap joint (SLJ) specimens have been tested with homologous substrates, carbon fibre-reinforced plastics and painted metal substrates. Furthermore, a configuration with dissimilar substrates has been included in the experimental campaign. Both types of these adhesive and substrates are used in the automotive industry. The bonding procedure has been carried out without a surface treatment in order to quantify the shear strength and stiffness when surface treatments are not used on the substrates, reproducing typical mass production conditions. Three different ageing cycles have been used to evaluate the effects on SLJ specimens. A finite element model that uses cohesive modelling has been built and optimised to assess the differences between the different adopted SLJ configurations. Full article

(This article belongs to the Special Issue Design of Adhesive Bonded Joints)

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16 pages, 2652 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Prediction of Molecular Weight of Petroleum Fluids by Empirical Correlations and Artificial Neuron Networks

by Dicho Stratiev, Sotir Sotirov, Evdokia Sotirova, Svetoslav Nenov, Rosen Dinkov, Ivelina Shishkova, Iliyan Venkov Kolev, Dobromir Yordanov, Svetlin Vasilev, Krassimir Atanassov, Stanislav Simeonov and Georgi Nikolov Palichev

Processes 2023, 11(2), 426; https://doi.org/10.3390/pr11020426 - 31 Jan 2023

Cited by 9 | Viewed by 3258

Abstract

The exactitude of petroleum fluid molecular weight correlations affects significantly the precision of petroleum engineering calculations and can make process design and trouble-shooting inaccurate. Some of the methods in the literature to predict petroleum fluid molecular weight are used in commercial software process [...] Read more.

The exactitude of petroleum fluid molecular weight correlations affects significantly the precision of petroleum engineering calculations and can make process design and trouble-shooting inaccurate. Some of the methods in the literature to predict petroleum fluid molecular weight are used in commercial software process simulators. According to statements made in the literature, the correlations of Lee–Kesler and Twu are the most used in petroleum engineering, and the other methods do not exhibit any significant advantages over the Lee–Kesler and Twu correlations. In order to verify which of the proposed in the literature correlations are the most appropriate for petroleum fluids with molecular weight variation between 70 and 1685 g/mol, 430 data points for boiling point, specific gravity, and molecular weight of petroleum fluids and individual hydrocarbons were extracted from 17 literature sources. Besides the existing correlations in the literature, two different techniques, nonlinear regression and artificial neural network (ANN), were employed to model the molecular weight of the 430 petroleum fluid samples. It was found that the ANN model demonstrated the best accuracy of prediction with a relative standard error (RSE) of 7.2%, followed by the newly developed nonlinear regression correlation with an RSE of 10.9%. The best available molecular weight correlations in the literature were those of API (RSE = 12.4%), Goosens (RSE = 13.9%); and Riazi and Daubert (RSE = 15.2%). The well known molecular weight correlations of Lee–Kesler, and Twu, for the data set of 430 data points, exhibited RSEs of 26.5, and 30.3% respectively. Full article

(This article belongs to the Special Issue Petroleum Characterization and Bioprocesses: Numerical and Experimental Investigation)

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12 pages, 586 KiB

Open AccessEditor’s ChoiceArticle

Essential Oil of Greek Citrus sinensis cv New Hall - Citrus aurantium Pericarp: Effect upon Cellular Lipid Composition and Growth of Saccharomyces cerevisiae and Antimicrobial Activity against Bacteria, Fungi, and Human Pathogenic Microorganisms

by Eleni Bozinou, Vassilis Athanasiadis, Theodoros Chatzimitakos, Christos Ganos, Olga Gortzi, Panagiota Diamantopoulou, Seraphim Papanikolaou, Ioanna Chinou and Stavros I. Lalas

Processes 2023, 11(2), 394; https://doi.org/10.3390/pr11020394 - 28 Jan 2023

Cited by 3 | Viewed by 1823

Abstract

In this study, the essential oil (EO) from the peel of the Greek citrus hybrid Citrus sinensis cv New Hall - Citrus aurantium was studied in terms of its antimicrobial properties as well as its effect on Saccharomyces cerevisiae. According to the analysis [...] Read more.

In this study, the essential oil (EO) from the peel of the Greek citrus hybrid Citrus sinensis cv New Hall - Citrus aurantium was studied in terms of its antimicrobial properties as well as its effect on Saccharomyces cerevisiae. According to the analysis of the EO, 48 compounds are contained in it, with the main compounds being limonene, β-pinene, myrcene, α-pinene, valencene, and α-terpineol. As regards its antimicrobial properties, the EO was evaluated against nine human pathogenic microorganisms, six bacteria, and three fungi. Taking the results into account, it was apparent that Gram-negative bacteria were the most susceptible to the addition of the EO, followed by the Gram-positive bacteria, and finally the examined yeasts. The minimum inhibitory concentrations were found to be lower compared to other studies. Finally, the effect of the EO on the biochemical behavior of the yeast Saccharomyces cerevisiae LMBF Y-16 was investigated. As the concentration of the EO increased, the more the exponential phase of the microbial growth decreased; furthermore, the biomass yield on the glucose consumed significantly decreased with the addition of the oil on the medium. The addition of the EO in small concentrations (e.g., 0.3 mL/L) did not present a remarkable negative effect on both the final biomass concentration and maximum ethanol quantity produced. In contrast, utilization of the extract in higher concentrations (e.g., 1.2 mL/L) noticeably inhibited microbial growth as the highest biomass concentration achieved, maximum ethanol production, and yield of ethanol produced per glucose consumed drastically declined. Concerning the composition of cellular lipids, the addition of the EO induced an increment in the concentration of cellular palmitic, stearic, and linoleic acids, with a concomitant decrease in the cellular palmitoleic acid and oleic acids. Full article

(This article belongs to the Special Issue Microbial Cultures in Food Production)

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13 pages, 6910 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Polycaprolactone with Glass Beads for 3D Printing Filaments

by Mária Kováčová, Anna Vykydalová and Zdenko Špitálský

Processes 2023, 11(2), 395; https://doi.org/10.3390/pr11020395 - 28 Jan 2023

Cited by 5 | Viewed by 2849

Abstract

At present, 3D printing is experiencing a great boom. The demand for new materials for 3D printing is also related to its expansion. This paper deals with manufacturing innovative polymer composite filaments suitable for the Fused Filament Fabrication method in 3D printing. As [...] Read more.

At present, 3D printing is experiencing a great boom. The demand for new materials for 3D printing is also related to its expansion. This paper deals with manufacturing innovative polymer composite filaments suitable for the Fused Filament Fabrication method in 3D printing. As a filler, common and uncostly glass beads were used and mixed with biocompatible and biodegradable poly (ε-caprolactone), as a polymer matrix. This material was characterized via several physical-chemical methods. The Youngs modulus was increasing by about 30% with 20% loading of glass beads, and simultaneously, brittleness and elongations were decreased. The glass beads do not affect the shore hardness of filaments. The rheological measurement confirmed the material stability in a range of temperatures 75–120 °C. The presented work aimed to prepare lightweight biocompatible, cheap material with appropriate mechanical properties, lower printing temperature, and good printing processing. We can assess that the goal was fully met, and these filaments could be used for a wide range of applications. Full article

(This article belongs to the Special Issue Advances in Innovative Engineering Materials and Processes (II))

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18 pages, 4882 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Brown Seaweed Sargassum-Based Sorbents for the Removal of Cr(III) Ions from Aqueous Solutions

by Natalia Niedzbała, Katarzyna Dziergowska, Maja Wełna, Anna Szymczycha-Madeja, Jacek Chęcmanowski, Nathalie Bourgougnon and Izabela Michalak

Processes 2023, 11(2), 393; https://doi.org/10.3390/pr11020393 - 27 Jan 2023

Cited by 1 | Viewed by 2037

Abstract

In this study, zinc oxide nanoparticles (ZnO NPs) were biosynthesized with the use of an extract derived from seaweed (Sargassum sp.) and used as a sorbent for the removal of Cr(III) ions from wastewater. The biosorption properties of the seaweed itself as [...] Read more.

In this study, zinc oxide nanoparticles (ZnO NPs) were biosynthesized with the use of an extract derived from seaweed (Sargassum sp.) and used as a sorbent for the removal of Cr(III) ions from wastewater. The biosorption properties of the seaweed itself as well as of the post-extraction residue were investigated for comparison. ZnO NPs were characterized with UV–vis, ICP-OES, FTIR, XRD, and SEM techniques. The sorption capacity of the (bio)sorbents was investigated as a function of contact time at different pH values and initial concentrations of metal ions. Sorption kinetics and isotherms were studied in order to comprehend the sorption nature and mechanism. The sorption kinetic data were well-fitted with the pseudo-second-order model, and the highest sorption capacity was calculated for ZnO NPs (137 mg/g), whereas those calculated for Sargassum sp. (82.0 mg/g) and the post-extraction residue (81.3 mg/g) were comparable (at pH 5 and 300 mg of Cr(III) ions/L). The adsorption isotherms for all sorbents were well described using the Langmuir model. According to these findings, ZnO NPs were superior to the sorption properties of the tested biosorbents and can be used as a potential sorbent for the removal of metal ions from wastewater. Renewable seaweed biomass can be used for the sustainable biosynthesis of nanoparticles used for environmental protection. Full article

(This article belongs to the Section Chemical Processes and Systems)

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19 pages, 3556 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Geometallurgical Detailing of Plant Operation within Open-Pit Strategic Mine Planning

by Aldo Quelopana, Javier Órdenes, Rodrigo Araya and Alessandro Navarra

Processes 2023, 11(2), 381; https://doi.org/10.3390/pr11020381 - 26 Jan 2023

Cited by 5 | Viewed by 1958

Abstract

Mineral and metallurgical processing are crucial within the mineral value chain. These processes involve several stages wherein comminution is arguably the most important due to its high energy consumption, and its impact on subsequent extractive processes. Several geological properties of the orebody impact [...] Read more.

Mineral and metallurgical processing are crucial within the mineral value chain. These processes involve several stages wherein comminution is arguably the most important due to its high energy consumption, and its impact on subsequent extractive processes. Several geological properties of the orebody impact the efficiency of mineral processing and extractive metallurgy; scholars have therefore proposed to deal with the uncertain ore feed in terms of grades and rock types, incorporating operational modes that represent different plant configurations that provide coordinated system-wide responses. Even though these studies offer insights into how mine planning impacts the ore fed into the plant, the simultaneous optimization of mine plan and metallurgical plant design has been limited by the existing stochastic mine planning algorithms, which have only limited support for detailing operational modes. The present work offers to fill this gap for open-pit mines through a computationally efficient adaptation of a strategic mine planning algorithm. The adaptation incorporates a linear programming representation of the operational modes which forms a Dantzig-Wolfe decomposition, nested within a high-performing stochastic mine planning algorithm based on a variable neighborhood descent metaheuristic. Sample calculations are presented, loosely based on the Mount Isa deposit in Australia, in which a metallurgical plant upgrade is evaluated, showing that the upgraded design significantly decreases the requirement on the mining equipment, without significantly affecting the NPV. Full article

(This article belongs to the Special Issue Process Analysis and Simulation in Extractive Metallurgy)

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22 pages, 666 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Robustness Evaluation Process for Scheduling under Uncertainties

by Sara Himmiche, Pascale Marangé, Alexis Aubry and Jean-François Pétin

Processes 2023, 11(2), 371; https://doi.org/10.3390/pr11020371 - 25 Jan 2023

Cited by 1 | Viewed by 1795

Abstract

Scheduling production is an important decision issue in the manufacturing domain. With the advent of the era of Industry 4.0, the basic generation of schedules becomes no longer sufficient to face the new constraints of flexibility and agility that characterize the new architecture [...] Read more.

Scheduling production is an important decision issue in the manufacturing domain. With the advent of the era of Industry 4.0, the basic generation of schedules becomes no longer sufficient to face the new constraints of flexibility and agility that characterize the new architecture of production systems. In this context, schedules must take into account an increasingly disrupted environment while maintaining a good performance level. This paper contributes to the identified field of smart manufacturing scheduling by proposing a complete process for assessing the robustness of schedule solutions: i.e., its ability to resist to uncertainties. This process focuses on helping the decision maker in choosing the best scheduling strategy to be implemented. It aims at considering the impact of uncertainties on the robustness performance of predictive schedules. Moreover, it is assumed that data upcoming from connected workshops are available, such that uncertainties can be identified and modelled by stochastic variables This process is supported by stochastic timed automata for modelling these uncertainties. The proposed approach is thus based on Stochastic Discrete Event Systems models and model checking techniques defining a highly reusable and modular process. The solution process is illustrated on an academic example and its performance (generecity and scalability) are deeply evaluated using statistical analysis. The proposed application of the evaluation process is based on the technological opportunities offered by the Industry 4.0. Full article

(This article belongs to the Special Issue Manufacturing Industry 4.0: Trends and Perspectives)

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25 pages, 970 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Enzymatic Hydrolysis of Complex Carbohydrates and the Mucus in a Mathematical Model of a Gut Reactor

by Thulasi Jegatheesan, Arun S. Moorthy and Hermann J. Eberl

Processes 2023, 11(2), 370; https://doi.org/10.3390/pr11020370 - 25 Jan 2023

Cited by 1 | Viewed by 1817

Abstract

The human gut microbiota rely on complex carbohydrates for energy and growth, particularly dietary fiber and host-produced mucins. These complex carbohydrates must first be hydrolysed by certain microbial groups to enable cross-feeding by the gut microbial community. We consider a mathematical model of [...] Read more.

The human gut microbiota rely on complex carbohydrates for energy and growth, particularly dietary fiber and host-produced mucins. These complex carbohydrates must first be hydrolysed by certain microbial groups to enable cross-feeding by the gut microbial community. We consider a mathematical model of the enzymatic hydrolysis of complex carbohydrates into monomers by a microbial species. The resulting monomers are subsequently digested by the microbial species for growth. We first consider the microbial species in a single compartment continuous stirred-tank reactor where dietary fiber is the only available substrate. A two compartment configuration in which a side compartment connected by diffusion is also studied. The side compartment is taken to be the mucus layer of the human colon, providing refuge from washout and an additional source of complex carbohydrate in the form of mucins. The two models are studied using stability analysis, numerical exploration, and sensitivity analysis. The delay in substrate availability due to hydrolysis results in bistability and the unconditional asymptotic stability of the trivial equilibrium. The addition of the mucus compartment allows the microbial species to survive under conditions that would otherwise result in washout in a comparable single compartment reactor. This would suggest that depending on the features of the gut microbiota being studied, extracellular hydrolysis and a representation of the mucus layer should be included in mathematical and lab reactor models of the human gut microbiota. Full article

(This article belongs to the Section Biological Processes and Systems)

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16 pages, 2641 KiB

Open AccessEditor’s ChoiceArticle

Influence of Prefermentative Cold Maceration on the Chemical and Sensory Properties of Red Wines Produced in Warm Climates

by Cristina Lasanta, Cristina Cejudo, Juan Gómez and Ildefonso Caro

Processes 2023, 11(2), 374; https://doi.org/10.3390/pr11020374 - 25 Jan 2023

Cited by 11 | Viewed by 2333

Abstract

Red wines produced in warm climates generally possess a lower content of phenolic compounds and color structure than those produced in colder climates, which hinders bottle evolution. To improve these properties, cold maceration could be a useful procedure. To study the effect of [...] Read more.

Red wines produced in warm climates generally possess a lower content of phenolic compounds and color structure than those produced in colder climates, which hinders bottle evolution. To improve these properties, cold maceration could be a useful procedure. To study the effect of this technique, Tempranillo, Merlot and Syrah grape varieties cultivated in the Jerez area (Southwest Spain) were cold macerated at 4 °C for ten days before alcoholic fermentation. Their composition and characteristics compared to the directly fermented control grapes were analyzed for phenolic content, color, volatile compounds, and sensory properties. It has been verified that phenolic content increased by around 10% during the treatment, which was maintained after the alcohol fermentation, along with an increase in color intensity and aromatic profile. This modification on the composition provided better scores for appearance, aroma intensity, and aroma quality in sensory analysis. The evolution of all studied parameters during 12 months of aging in the bottle is also studied, confirming the advantages of this technique in preserving the compositional and sensory characteristics throughout the period studied. Full article

(This article belongs to the Special Issue Advances in Production, Processing and Analysis of Must, Wine and Derivatives)

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18 pages, 6081 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Single-Step Fabrication of a Dual-Sensitive Chitosan Hydrogel by C-Mannich Reaction: Synthesis, Physicochemical Properties, and Screening of its Cu²⁺ Uptake

by John Rey Apostol Romal and Say Kee Ong

Processes 2023, 11(2), 354; https://doi.org/10.3390/pr11020354 - 22 Jan 2023

Cited by 5 | Viewed by 2539

Abstract

Uncovering the value of waste materials is one of the keys to sustainability. In this current work, valorization of chitosan was pursued to fabricate a novel modified chitosan functional hydrogel using a process-efficient protocol. The fabrication proceeds by a one-pot and single-step C-Mannich [...] Read more.

Uncovering the value of waste materials is one of the keys to sustainability. In this current work, valorization of chitosan was pursued to fabricate a novel modified chitosan functional hydrogel using a process-efficient protocol. The fabrication proceeds by a one-pot and single-step C-Mannich condensation of chitosan (3% w/v), glutaraldehyde (20 eq.), and 4-hydroxycoumarin (40 eq.) at 22 °C in 3% v/v acetic acid. The Mannich base modified chitosan hydrogel (CS-MB) exhibits a dual-responsive swelling behavior in response to pH and temperature that has not been observed in any other hydrogel systems. Combining the pre-defined optimal swelling pH (pH = 4) and temperature (T = 22 °C), the CS-MB was screened for its Cu²⁺ adsorption capacity at this condition. The CS-MB achieved an optimal adsorption capacity of 12.0 mg/g with 1.2 g/L adsorbent dosage after 36 h with agitation. The adsorption of Cu²⁺ on the surface of CS-MB was verified by EDS, and an overview of the adsorption sites was exhibited by FT-IR. The simply fabricated novel CS-MB hydrogel under investigation presents a unique response to external stimuli that exhibits a promise in heavy metal removal from aqueous media. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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21 pages, 12086 KiB

Open AccessEditor’s ChoiceArticle

Microwave-Assisted Freeze-Drying with Frequency-Based Control Concepts via Solid-State Generators: A Simulative and Experimental Study

by Till Sickert, Isabel Kalinke, Jana Christoph and Volker Gaukel

Processes 2023, 11(2), 327; https://doi.org/10.3390/pr11020327 - 19 Jan 2023

Cited by 10 | Viewed by 3588

Abstract

Freeze-drying is a common process to extend the shelf life of food and bioactive substances. Its main drawback is the long drying time and associated high production costs. Microwaves can be applied to significantly shorten the process. This study investigates the effects of [...] Read more.

Freeze-drying is a common process to extend the shelf life of food and bioactive substances. Its main drawback is the long drying time and associated high production costs. Microwaves can be applied to significantly shorten the process. This study investigates the effects of modulating the electromagnetic field in microwave-assisted freeze-drying (MFD). Control concepts based on microwave frequency are evaluated using electromagnetic simulations. The concepts are then applied to the first part of primary drying in a laboratory-scale system with solid-state generators. Targeted frequency modulation in the electromagnetic simulations enabled an increase in energy efficiency or heating homogeneity throughout MFD while having negligible effects on the power dissipation ratio between frozen and dried product areas. The simulations predicted the qualitative effects observed in the experimental proof of concept regarding energy efficiency and drying homogeneity. Additionally, shortened drying times were observed in the experiments with a targeted application of energy-efficient frequencies. However, differences occurred in the quantitative validation of the electromagnetic models for energy efficiency in dependence on frequency. Nevertheless, the models can be used for a time-efficient investigation of the qualitative effects of the control concepts. In summary, frequency-based control of MFD represents a promising approach for process control and intensification. Full article

(This article belongs to the Special Issue Advances in Drying Technologies—Selected Papers from the 22nd International Drying Symposium (IDS 2022))

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