Next Issue
Previous Issue

Table of Contents

ChemEngineering, Volume 2, Issue 1 (March 2018)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-12
Export citation of selected articles as:

Editorial

Jump to: Research, Review

Open AccessEditorial Acknowledgement to Reviewers of ChemEngineering in 2017
ChemEngineering 2018, 2(1), 6; doi:10.3390/chemengineering2010006
Received: 19 January 2018 / Revised: 19 January 2018 / Accepted: 19 January 2018 / Published: 22 January 2018
PDF Full-text (146 KB) | HTML Full-text | XML Full-text
Abstract
Peer review is an essential part in the publication process, ensuring that ChemEngineering maintains high quality standards for its published papers[...] Full article

Research

Jump to: Editorial, Review

Open AccessArticle Interlayer Properties of In-Situ Oxidized Porous Stainless Steel for Preparation of Composite Pd Membranes
ChemEngineering 2018, 2(1), 1; doi:10.3390/chemengineering2010001
Received: 17 November 2017 / Revised: 11 December 2017 / Accepted: 13 December 2017 / Published: 21 December 2017
PDF Full-text (14479 KB) | HTML Full-text | XML Full-text
Abstract
Hydrogen is considered as a real alternative for improving the current energy scenario in the near future and separation processes are a crucial step for the economy of the process in both centralized and distributed production systems. In this context, Pd-based composite membranes
[...] Read more.
Hydrogen is considered as a real alternative for improving the current energy scenario in the near future and separation processes are a crucial step for the economy of the process in both centralized and distributed production systems. In this context, Pd-based composite membranes appear as an attractive technology trying to reduce the Pd thickness by modifying the commercial supports, mainly formed by metals to fit properly in conventional industrial devices. In most cases, a final calcination step is required and hence, the metallic support can be oxidized. This work analyzes in detail the properties of intermediate layers generated by in-situ oxidation of tubular PSS supports as a crucial step for the preparation of Pd/PSS membranes. The oxidation temperature determines the modification of original morphology and permeability by increasing the presence of mixed iron-chromium oxides as temperature rises. A compromise solution need to be adopted in order to reduce the average pore mouth size and the external roughness, while maintaining a high permeation capacity. Temperature of 600 °C lets to reduce the average pore size from 3.5 to 2.1 μm or from 4.5 to 2.3 μm in case of using PSS supports with 0.1 or 0.2 μm porous media grades, respectively but maintaining a hydrogen permeation beyond targets of United States of America Department of Energy (US DOE). Lower temperatures provoke an insufficient surface modification, while greater values derive in a drastic reduction of permeability. In these conditions, two composite membranes were prepared by ELP-PP, obtaining 14.7 and 18.0 μm thick palladium layers in case of modifying PSS tubes of 0.1 or 0.2 μm media grades, respectively. In both cases, the composite Pd membranes exhibited a hydrogen perm-selectivity greater than 2000 with permeances ranged from 2.83 to 5.84·10−4 mol m−2 s−1 Pa−0.5 and activation energies of around 13–14 kJ mol−1. Full article
Figures

Figure 1

Open AccessArticle Resolved-Pore Simulation of CO Oxidation on Rh/Al2O3 in a Catalyst Layer
ChemEngineering 2018, 2(1), 2; doi:10.3390/chemengineering2010002
Received: 22 November 2017 / Revised: 22 December 2017 / Accepted: 26 December 2017 / Published: 29 December 2017
PDF Full-text (7649 KB) | HTML Full-text | XML Full-text
Abstract
Computational fluid dynamics (CFD) is coupled with reaction and transport in a micro-scale pellet simulation to study CO oxidation over Rh/Al2O3 catalyst. The macro-pores are explicitly modeled to study the interaction of these phenomena in both the solid and fluid
[...] Read more.
Computational fluid dynamics (CFD) is coupled with reaction and transport in a micro-scale pellet simulation to study CO oxidation over Rh/Al2O3 catalyst. The macro-pores are explicitly modeled to study the interaction of these phenomena in both the solid and fluid phases. A catalyst layer is computationally reconstructed using a distribution of alumina particles and a simple force model. The constructed geometry properties are validated using the existing data in the literature. A surface mesh is generated and modified for the geometry using the shrink-wrap method and the surface mesh is used to create a volumetric mesh for the CFD simulation. The local pressure and velocity profiles are studied and it is shown that extreme changes in velocity profile could be observed. Furthermore, the reaction and species contours show how fast reaction on the surface of the solid phase limits the transport of the reactants from the fluid to meso- and micro-porous solid structures and therefore limits the overall efficiency of the porous structure. Finally, the importance of using a bi-modal pore structure in the diffusion methods for reaction engineering models is discussed. Full article
Figures

Open AccessArticle Effectiveness and Temporal Variation of a Full-Scale Horizontal Constructed Wetland in Reducing Nitrogen and Phosphorus from Domestic Wastewater
ChemEngineering 2018, 2(1), 3; doi:10.3390/chemengineering2010003
Received: 13 November 2017 / Revised: 13 December 2017 / Accepted: 3 January 2018 / Published: 5 January 2018
PDF Full-text (1248 KB) | HTML Full-text | XML Full-text
Abstract
Cultural eutrophication stimulated by anthropogenic-derived nutrients represents one of most widespread water quality problems worldwide. Constructed wetlands (CWs) have emerged as an aesthetic, sustainable form of wastewater treatment, but, although they have shown adequate levels of organic matter removal in wastewaters, the effectiveness
[...] Read more.
Cultural eutrophication stimulated by anthropogenic-derived nutrients represents one of most widespread water quality problems worldwide. Constructed wetlands (CWs) have emerged as an aesthetic, sustainable form of wastewater treatment, but, although they have shown adequate levels of organic matter removal in wastewaters, the effectiveness of nutrient removal has been less successful. An eleven-month monitoring program was undertaken in a horizontal subsurface flow CW (HSSF-CW) treating domestic wastewater from a village in Centre Region of Portugal, to evaluate the influence of climatic conditions (Continental-Mediterranean Climate region) and seasonal variations on removal. This CW uses gravel and sand as substrate and Phragmites australis as wetland plants. Samples were collected at the inlet and outlet from wetland bed and analyzed for pH, TN, Org-N, NH4+-N, NOx-N, TP and DP. The removal efficiencies (RE) of nitrogen and phosphorus compounds were relatively poor, but the results allow us to conclude that season had a significant (p < 0.05) effect on the RE of TN, NH4+-N, NOx-N, TP and DP, with higher values in warmest period (10.4%, 10.4%, 3.4%, 27.5% and 26.1%, respectively) than in coldest period (0%, −7.7%, −9.8%, 12.9% and 0%, respectively). Although lower hydraulic loading rate (HLR) generally resulted in better RE of all N and P compounds analyzed, no significant linear relationship was observed between these two variables. TN and NH4+-N concentrations in the effluent tend to significantly (p < 0.05) decrease with increasing respective incoming mass load rates for whole monitoring period and during spring–summer period, while the correlation between outlet TP concentrations and the inlet loading rate are not significant. The results indicate that the system is not effective for removal of nutrients, probably because it operated on overload and with a low hydraulic retention time (HRT) (average = 2.4 days). The results also showed that the RE of N and P followed seasonal trends, with higher values during spring–summer period. Full article
Figures

Figure 1

Open AccessArticle Effect of Noble Metals (Ag, Pd, Pt) Loading over the Efficiency of TiO2 during Photocatalytic Ozonation on the Toxicity of Parabens
ChemEngineering 2018, 2(1), 4; doi:10.3390/chemengineering2010004
Received: 6 December 2017 / Revised: 14 December 2017 / Accepted: 3 January 2018 / Published: 9 January 2018
PDF Full-text (1418 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The conventional wastewater treatments are inadequate for emerging contaminants detoxification. Photocatalytic ozonation with suitable catalyst can be considered as a suitable solution on the removal of these compounds. The aim of this study was to verify the effect of Ag, Pd and Pt
[...] Read more.
The conventional wastewater treatments are inadequate for emerging contaminants detoxification. Photocatalytic ozonation with suitable catalyst can be considered as a suitable solution on the removal of these compounds. The aim of this study was to verify the effect of Ag, Pd and Pt with different loadings (0.1, 0.5 and 1% wt %) onto TiO2 surface for the degradation of a mixture of parabens (methyl, ethyl, propyl, butyl and benzyl) through photocatalytic ozonation. Chemical oxygen demand (COD) and total organic carbon (TOC) was also analyzed after treatments, as well as the effect of the treatment on the samples toxicity over different species, including bacteria, clams and plants. The effect of metal loading on the parabens degradation; COD and TOC removal is very dependent upon the type of noble metal used. This can be related with the different pathways influenced by the metal load. On the one hand, it can be related with the reduction of electron–hole recombination phenomenon, and, on the other hand, the trapping of electrons by the metals reduces the amount of ozonide and hydroxyl radicals produced. In terms of toxicity, apparently the best results were achieved with the intermediate noble metal load. However, the effect of noble metal load must be analyzed case to case. Full article
Figures

Figure 1

Open AccessArticle Development of a Catalytic Fuel Processor for a 10 kW Combined Heat and Power System: Experimental and Modeling Analysis of the Steam Reforming Unit
ChemEngineering 2018, 2(1), 5; doi:10.3390/chemengineering2010005
Received: 21 November 2017 / Revised: 28 December 2017 / Accepted: 5 January 2018 / Published: 11 January 2018
PDF Full-text (4710 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this work, we address the development of a combined heat and power unit for residential applications, fed by natural gas, air and H2O; focus is on the design of the first catalytic stage of the fuel processor, that is the
[...] Read more.
In this work, we address the development of a combined heat and power unit for residential applications, fed by natural gas, air and H2O; focus is on the design of the first catalytic stage of the fuel processor, that is the steam reforming unit. A commercial catalyst was tested at the laboratory scale, under kinetically controlled conditions in order to derive information on the reaction kinetics and support the basic engineering of the full scale reactor. Analogous tests after long term steam reforming ageing were then performed to quantify the evolution of the catalyst activity under real operating conditions and estimate a lumped deactivation factor. A modelling analysis was performed to predict the expected performance of the fuel processor at varying input parameters and catalyst activity profiles. It was verified that at a space velocity below 5000 Nl/kgcat/h, the reactor output is fully controlled by the thermodynamics at 650 °C, which guarantees the best operability and efficiency of the whole fuel processor. Full article
Figures

Figure 1

Open AccessArticle Modelling of Bubbly Flow Using CFD-PBM Solver in OpenFOAM: Study of Local Population Balance Models and Extended Quadrature Method of Moments Applications
ChemEngineering 2018, 2(1), 8; doi:10.3390/chemengineering2010008
Received: 8 January 2018 / Revised: 15 February 2018 / Accepted: 22 February 2018 / Published: 27 February 2018
PDF Full-text (1411 KB) | HTML Full-text | XML Full-text
Abstract
In order to optimize and design new bubbly flow reactors, it is necessary to predict the bubble behavior and properties with respect to the time and location. In gas-liquid flows, it is easily observed that the bubble sizes may vary widely. The bubble
[...] Read more.
In order to optimize and design new bubbly flow reactors, it is necessary to predict the bubble behavior and properties with respect to the time and location. In gas-liquid flows, it is easily observed that the bubble sizes may vary widely. The bubble size distribution is relatively sharply defined, and bubble rises are uniform in homogeneous flow; however bubbles aggregate, and large bubbles are formed rapidly in heterogeneous flow. To assist in the analysis of these systems, the volume, size and other properties of dispersed bubbles can be described mathematically by distribution functions. Therefore, a mathematical modeling tool called the Population Balance Model (PBM) is required to predict the distribution functions of the bubble motion and the variation of their properties. In the present paper, two rectangular bubble columns and a water electrolysis reactor are modeled using the open-source Computational Fluid Dynamic (CFD) package OpenFOAM. Furthermore, the Method of Classes (CM) and Quadrature-based Moments Method (QBMM) are described, implemented and compared using the developed CFD-PBM solver. These PBM tools are applied in two bubbly flow cases: bubble columns (using a Eulerian-Eulerian two-phase approach to predict the flow) and a water electrolysis reactor (using a single-phase approach to predict the flow). The numerical results are compared with measured data available in the scientific literature. It is observed that the Extended Quadrature Method of Moments (EQMOM) leads to a slight improvement in the prediction of experimental measurements and provides a continuous reconstruction of the Number Density Function (NDF), which is helpful in the modeling of gas evolution electrodes in the water electrolysis reactor. Full article
(This article belongs to the Special Issue Bubble Column Fluid Dynamics)
Figures

Figure 1

Open AccessArticle Test of Two Phase Change Materials for Thermal Energy Storage: Determination of the Global Heat Transfer Coefficient
ChemEngineering 2018, 2(1), 10; doi:10.3390/chemengineering2010010
Received: 26 October 2017 / Revised: 6 February 2018 / Accepted: 6 March 2018 / Published: 9 March 2018
PDF Full-text (4064 KB) | HTML Full-text | XML Full-text
Abstract
Laboratory scale experiments on the behaviour of two phase change materials, a salt and a paraffin, during fusion and solidification cycling processes, were accomplished. To do this, a system using thermal oil as the heat transfer carrier was used and the phase change
[...] Read more.
Laboratory scale experiments on the behaviour of two phase change materials, a salt and a paraffin, during fusion and solidification cycling processes, were accomplished. To do this, a system using thermal oil as the heat transfer carrier was used and the phase change material being tested operated in a fusion and solidification cycle. The heat transfer oil transferred heat to the phase change material during the fusion step and carried heat away from the change phase material during the solidification step. The influence of the mass flow rate of the heat transfer fluid, as well as of its temperature, in the response of the phase change material, was studied. Axial and radial temperature profiles inside the phase change materials were obtained during the experiments and subsequently analysed. From these temperature profiles and through an adequate mathematical treatment, global heat transfer coefficients between the heat transfer oil and the phase change material were determined, as well as average heat transfer coefficients for the phase change materials. Full article
Figures

Figure 1

Open AccessArticle The Effects of the Properties of Gases on the Design of Bubble Columns Equipped with a Fine Pore Sparger
ChemEngineering 2018, 2(1), 11; doi:10.3390/chemengineering2010011
Received: 2 February 2018 / Revised: 1 March 2018 / Accepted: 7 March 2018 / Published: 12 March 2018
PDF Full-text (4942 KB) | HTML Full-text | XML Full-text
Abstract
This work concerns the performance of bubble columns equipped with porous sparger and investigates the effect of gas phase properties by conducting experiments with various gases (i.e., air, CO2, He) that cover a wide range of physical property values. The purpose
[...] Read more.
This work concerns the performance of bubble columns equipped with porous sparger and investigates the effect of gas phase properties by conducting experiments with various gases (i.e., air, CO2, He) that cover a wide range of physical property values. The purpose is to investigate the validity of the design equations, which were proposed in our previous work and can predict with reasonable accuracy the transition point from homogeneous to heterogeneous regime as well as the gas holdup and the mean Sauter diameter at the homogeneous regime. Although, the correlations were checked with data obtained using different geometrical configurations and several Newtonian and non-Newtonian liquids, as well as the addition of surfactants, the gas phase was always atmospheric air. The new experiments revealed that only the use of low-density gas (He) has a measurable effect on bubble column performance. More precisely, when the low-density gas (He) is employed, the transition point shifts to higher gas flow rates and the gas holdup decreases, a fact attributed to the lower momentum force exerted by the gas. In view of the new data, the proposed correlations have been slightly modified to include the effect of gas phase properties and it is found that they can predict the aforementioned quantities with an accuracy of ±15%. It has been also proved that computational fluid dynamics (CFD) simulations are an accurate means for assessing the flow characteristics inside a bubble column. Full article
(This article belongs to the Special Issue Bubble Column Fluid Dynamics)
Figures

Open AccessArticle Hydrodynamics of Bubble Columns: Turbulence and Population Balance Model
ChemEngineering 2018, 2(1), 12; doi:10.3390/chemengineering2010012
Received: 13 February 2018 / Revised: 10 March 2018 / Accepted: 12 March 2018 / Published: 19 March 2018
PDF Full-text (1037 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an in-depth numerical analysis on the hydrodynamics of a bubble column. As in previous works on the subject, the focus here is on three important parameters characterizing the flow: interfacial forces, turbulence and inlet superficial Gas Velocity (UG). The bubble
[...] Read more.
This paper presents an in-depth numerical analysis on the hydrodynamics of a bubble column. As in previous works on the subject, the focus here is on three important parameters characterizing the flow: interfacial forces, turbulence and inlet superficial Gas Velocity (UG). The bubble size distribution is taken into account by the use of the Quadrature Method of Moments (QMOM) model in a two-phase Euler-Euler approach using the open-source Computational Fluid Dynamics (CFD) code OpenFOAM (Open Field Operation and Manipulation). The interfacial forces accounted for in all the simulations presented here are drag, lift and virtual mass. For the turbulence analysis in the water phase, three versions of the Reynolds Averaged Navier-Stokes (RANS) k-ε turbulence model are examined: namely, the standard, modified and mixture variants. The lift force proves to be of major importance for a trustworthy prediction of the gas volume fraction profiles for all the (superficial) gas velocities tested. Concerning the turbulence, the mixture k-ε model is seen to provide higher values of the turbulent kinetic energy dissipation rate in comparison to the other models, and this clearly affects the prediction of the gas volume fraction in the bulk region, and the bubble-size distribution. In general, the modified k-ε model proves to be a good compromise between modeling simplicity and accuracy in the study of bubble columns of the kind undertaken here. Full article
(This article belongs to the Special Issue Bubble Column Fluid Dynamics)
Figures

Figure 1

Review

Jump to: Editorial, Research

Open AccessReview A Bibliometric Study of Scientific Publications regarding Hemicellulose Valorization during the 2000–2016 Period: Identification of Alternatives and Hot Topics
ChemEngineering 2018, 2(1), 7; doi:10.3390/chemengineering2010007
Received: 15 November 2017 / Revised: 11 January 2018 / Accepted: 26 January 2018 / Published: 30 January 2018
PDF Full-text (1931 KB) | HTML Full-text | XML Full-text
Abstract
A bibliometric analysis of the Scopus database was carried out to identify the research trends related to hemicellulose valorization from 2000 to 2016. The results from the analysis revealed an increasing number of annual publications, a high degree of transdisciplinary collaboration and prolific
[...] Read more.
A bibliometric analysis of the Scopus database was carried out to identify the research trends related to hemicellulose valorization from 2000 to 2016. The results from the analysis revealed an increasing number of annual publications, a high degree of transdisciplinary collaboration and prolific contributions by European researchers on this topic. The importance of a holistic approach to consider the simultaneous valorization of the three main components of lignocellulosic biomass (cellulose, hemicellulose and lignin) must be highlighted. Optimal pretreatment processes are critical for the correct fractionation of the biomass and the subsequent valorization. On the one hand, biological conversion of sugars derived from hemicellulose can be employed for the production of biofuel (ethanol) or chemicals such as 2,3-butadiene, xylitol and lactic acid. On the other hand, the chemical transformation of these sugars produces furfural, 5-hydroxyfurfural and levulinic acid, which must be considered very important starting blocks for the synthesis of organic derivatives. Full article
Figures

Figure 1

Open AccessReview Recent Advances in Supported Metal Catalysts for Syngas Production from Methane
ChemEngineering 2018, 2(1), 9; doi:10.3390/chemengineering2010009
Received: 21 December 2017 / Revised: 18 February 2018 / Accepted: 2 March 2018 / Published: 7 March 2018
PDF Full-text (3278 KB) | HTML Full-text | XML Full-text
Abstract
Over the past few years, great attention is paid to syngas production processes from different resources especially from abundant sources, such as methane. This review of the literature is intended for syngas production from methane through the dry reforming (DRM) and the steam
[...] Read more.
Over the past few years, great attention is paid to syngas production processes from different resources especially from abundant sources, such as methane. This review of the literature is intended for syngas production from methane through the dry reforming (DRM) and the steam reforming of methane (SRM). The catalyst development for DRM and SRM represents the key factor to realize a commercial application through the utilization of more efficient catalytic systems. Due to the enormous amount of published literature in this field, the current work is mainly dedicated to the most recent achievements in the metal-oxide catalyst development for DRM and SRM in the past five years. Ni-based supported catalysts are considered the most widely used catalysts for DRM and SRM, which are commercially available; hence, this review has focused on the recent advancements achieved in Ni catalysts with special focus on the various attempts to address the catalyst deactivation challenge in both DRM and SRM applications. Furthermore, other catalytic systems, including Co-based catalysts, noble metals (Pt, Rh, Ru, and Ir), and bimetallic systems have been included in this literature review to understand the observed improvements in the catalytic activities and coke suppression property of these catalysts. Full article
Figures

Figure 1

Back to Top