Advanced Heat and Mass Transfer Technologies

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Applied Sciences applsci	2.5	5.3	2011	18.4 Days	CHF 2400
Energies energies	3.0	6.2	2008	16.8 Days	CHF 2600
Materials materials	3.1	5.8	2008	13.9 Days	CHF 2600
Processes processes	2.8	5.1	2013	14.9 Days	CHF 2400
Fluids fluids	1.8	3.4	2016	21.1 Days	CHF 1800

16 pages, 4423 KiB

Open AccessArticle

Experimental Study on Flow Boiling Heat Transfer Characteristics in Top-Connected Microchannels with a Ni/Ag Micro/Nano Composite Structure

by Zeyu Xu, Wei Zhang, Qianqian Zhang, Xiangrui Zhai, Xufei Yang, Yajun Deng and Xi Wang

Energies 2025, 18(7), 1756; https://doi.org/10.3390/en18071756 (registering DOI) - 1 Apr 2025

Viewed by 16

Abstract

Microchannel heat exchangers, with their large specific surface area, exhibit high heat/mass transfer efficiency and have a wide range of applications in chemical engineering and energy. To enhance microchannel flow boiling heat transfer, a top-connected microchannel heat exchanger with a Ni/Ag micro/nano composite [...] Read more.

Microchannel heat exchangers, with their large specific surface area, exhibit high heat/mass transfer efficiency and have a wide range of applications in chemical engineering and energy. To enhance microchannel flow boiling heat transfer, a top-connected microchannel heat exchanger with a Ni/Ag micro/nano composite surface was designed. Using anhydrous ethanol as the working fluid, comparative flow boiling heat transfer experiments were conducted on regular parallel microchannels (RMC), top-connected microchannels (TCMC), and TCMC with a Ni/Ag micro/nano composite surface (TCMC-Ni/Ag). Results show that the TCMC-Ni/Ag’s maximum local heat transfer coefficient reaches 179.84 kW/m²·K, which is 4.1 times that of RMC. Visualization reveals that its strongly hydrophilic micro/nano composite surface increases bubble nucleation density and nucleation frequency. Under medium-low heat flux, the vapor phase converges in the top-connected region while bubbles form on the microchannel surface; under high heat flux, its capillary liquid absorption triggers a thin-liquid-film convective evaporation mode, which is the key mechanism for improved heat transfer performance. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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12 pages, 4060 KiB

Open AccessArticle

Experimental Investigation of Rotating Wheel Speed and Regeneration Temperature Effects on Marine Dual-Stage Desiccant Dehumidification Fresh-Air Pre-Treatment System Performance

by Guanghai Yang, Wensheng Yu, Wu Chen and Shilong Jiao

Processes 2025, 13(3), 669; https://doi.org/10.3390/pr13030669 - 27 Feb 2025

Viewed by 246

Abstract

Marine air-conditioning systems face high energy consumption, particularly in humid marine environments. This study is an experimental investigation of the effects of rotating wheel speed and regeneration temperature on the performance of the system, which is a dual-stage desiccant dehumidification fresh-air pre-treatment system [...] Read more.

Marine air-conditioning systems face high energy consumption, particularly in humid marine environments. This study is an experimental investigation of the effects of rotating wheel speed and regeneration temperature on the performance of the system, which is a dual-stage desiccant dehumidification fresh-air pre-treatment system using ship waste heat as the regeneration heat source and seawater-assisted cooling to improve the efficiency of energy use. The results showed that the dehumidification capacity and efficiency of the system improved with an increase in the rotating wheel speed from 6 to 10 r/h and in the regeneration temperature from 80 °C to 110 °C. Optimal performance was achieved with a rotating wheel speed of 10 r/h and a regeneration temperature of 110 °C, balancing the maximum dehumidification capacity, energy efficiency, and waste heat utilization. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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23 pages, 8472 KiB

Open AccessArticle

Research on the Arrangement Scheme of Spirally Twisted Tape Inserts in a Grate Furnace

by Chen Yang, Jingxian Kong, Xinji Chen, Zhijiang Jin and Jinyuan Qian

Energies 2024, 17(21), 5292; https://doi.org/10.3390/en17215292 - 24 Oct 2024

Viewed by 683

Abstract

To eliminate the flow dead zone and homogenize the asymmetric flow field of a grate furnace, spirally twisted tape inserts (STTIs) with a pitch ratio of 1.5 were installed in the vertical flues of an SCL1000-13.5/450 grate boiler. The arrangement schemes found to [...] Read more.

To eliminate the flow dead zone and homogenize the asymmetric flow field of a grate furnace, spirally twisted tape inserts (STTIs) with a pitch ratio of 1.5 were installed in the vertical flues of an SCL1000-13.5/450 grate boiler. The arrangement schemes found to be present inside the chosen 1000 t/d grate furnace, determined using the orthogonal experimental method, included separate installation in chamber II, separate placement in chamber III, and simultaneous arrangement in both chamber II and chamber III. The effects of row spacing H, column spacing W, and mounting angle φ were investigated by means of the practicable and feasible numerical simulation method. With a focus on the uniformity degree of the flue gas, the results showed that temperature distribution is directly correlated with the velocity field. When it comes to the uniformity of the flow field, the exclusive use of STTIs in chamber II was better than that in chamber III. Under the optimal combination scheme of STTIs in both chamber II and chamber III (scheme N3₂₃), the exhaust gas temperature reached the minimum value and the uniformity index of temperature increased to the range of 0.994~0.997. The findings in this work could provide a reference for the optimization of the flow field in a grate furnace. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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13 pages, 3240 KiB

Open AccessArticle

Mass Transfer Kinetics of Volatile Organic Compound Desorption from a Novel Adsorbent

by Jiale Zheng, Chuanruo Yang, Ming Xue, Xingchun Li and Xinglei Zhao

Processes 2024, 12(9), 2031; https://doi.org/10.3390/pr12092031 - 20 Sep 2024

Viewed by 1107

Abstract

The adsorption isotherms and intraparticle mass transfer coefficients of a novel adsorbent with various VOCs at different temperatures during the desorption process are investigated. Firstly, the adsorption isotherms of an HCP-5 adsorbent with o-xylene and ethyl acetate systems were determined at temperatures ranging [...] Read more.

The adsorption isotherms and intraparticle mass transfer coefficients of a novel adsorbent with various VOCs at different temperatures during the desorption process are investigated. Firstly, the adsorption isotherms of an HCP-5 adsorbent with o-xylene and ethyl acetate systems were determined at temperatures ranging from 30 to 160 °C, and the data were fitted using the Langmuir adsorption isotherm equation. Subsequently, a mathematical model for the fixed-bed desorption breakthrough of VOCs was established. By combining with fixed-bed desorption breakthrough experiments, the intraparticle mass transfer coefficients of o-xylene and ethyl acetate during the desorption process at different temperatures were obtained through the least squares method. This study revealed that the intraparticle mass transfer coefficients of o-xylene and ethyl acetate during the desorption process were basically equal. The intraparticle mass transfer coefficients increased and then decreased with temperature during the desorption process. Compared with the adsorption process, the contribution of surface diffusion inside the adsorbent pores to intraparticle mass transfer decreased during the desorption process, leading to a significant decrease in the intraparticle mass transfer coefficients, which were approximately one-twentieth of those during the adsorption process. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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13 pages, 1927 KiB

Open AccessArticle

Experimental and Theoretical Investigation of Thermal Parameters Influencing the Freezing Process of Ice Cream

by Ömer Alp Atici and Derya Burcu Özkan

Appl. Sci. 2024, 14(14), 6194; https://doi.org/10.3390/app14146194 - 16 Jul 2024

Viewed by 1267

Abstract

Freezing time stands out as the most critical parameter in ice cream production, significantly influencing the final product’s quality and production efficiency. Therefore, it is essential to accurately estimate the freezing time based on ice cream recipes. This research paper focuses on determining [...] Read more.

Freezing time stands out as the most critical parameter in ice cream production, significantly influencing the final product’s quality and production efficiency. Therefore, it is essential to accurately estimate the freezing time based on ice cream recipes. This research paper focuses on determining the thermal properties of ice cream samples by leveraging insights from previous studies. Moreover, a new specific heat correlation is proposed to account for the latent heat effect of water during the freezing process. The results demonstrated that the new specific heat correlation aligns well with established formulas from previous research as well as experimental results with maximum 2.5% deviation. To validate the accuracy of the proposed numerical model, experimental studies were compared with numerical results for the first time in the context of ice cream freezing inside a mold. Additionally, a parametric analysis was conducted using numerical modelling to discern the relative importance of various production process parameters. Notably, the glycol–water mixture temperature emerged as the most influential parameter affecting freezing time, while the amount of air inside the ice cream was identified as the least significant factor. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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16 pages, 2899 KiB

Open AccessArticle

Estimation of Multiple Parameters in Semitransparent Mediums Based on an Improved Grey Wolf Optimization Algorithm

by Kefu Li, Lang Xie, Jianhua Zhou, Xiaofang Wu, Ding Ding and Caibin Li

Processes 2024, 12(7), 1445; https://doi.org/10.3390/pr12071445 - 10 Jul 2024

Viewed by 871

Abstract

This work investigates the inverse coupled radiation–conduction problem for estimating thermophysical parameters and source terms by an improved grey wolf optimization (GWO). The transient coupled radiation–conduction heat transfer problem in participating slab media is solved by the finite volume method. The radiative intensities [...] Read more.

This work investigates the inverse coupled radiation–conduction problem for estimating thermophysical parameters and source terms by an improved grey wolf optimization (GWO). The transient coupled radiation–conduction heat transfer problem in participating slab media is solved by the finite volume method. The radiative intensities on both boundaries are adopted as known measurement information in the inverse model. To overcome the disadvantages of the original GWO algorithm, an improved grey wolf algorithm (IGWO) is developed by introducing the weight strategy and nonlinear factors. Three benchmark functions are adopted to prove that the IGWO has a faster convergence speed and higher estimation accuracy than the original one. The IGWO is applied to inverse the thermophysical parameters and source terms based on the coupled radiation–conduction model; the results indicate that the IGWO is accurate and effective for estimating refractive index, absorption coefficient, and source terms. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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15 pages, 9611 KiB

Open AccessArticle

Experimental and Theoretical Study of Heat Transfer in a Chilled Ceiling System

by Cüneyt Deniz Küheylan and Derya Burcu Özkan

Appl. Sci. 2024, 14(13), 5908; https://doi.org/10.3390/app14135908 - 6 Jul 2024

Cited by 1 | Viewed by 1419

Abstract

Radiant cooling has been growing in recent years due to energy savings and improved comfort and health. The aim of this study was to reduce energy consumption and provide comfort using a chilled ceiling panel in the zone. In the experimental part of [...] Read more.

Radiant cooling has been growing in recent years due to energy savings and improved comfort and health. The aim of this study was to reduce energy consumption and provide comfort using a chilled ceiling panel in the zone. In the experimental part of this study, a test room was created to investigate the change in the heat transfer performance of a chilled ceiling panel according to different water temperatures, different water flow rates and different heat source values. As a result of the experimental study, it was found that optimum conditions were achieved with a heat rate of 280 Watts and the lowest supply water temperature of 14 °C, with indoor comfort conditions being achieved with water flow rates of 0.93 m³/h. In the theoretical part of this study, a thermal balance was established for ceiling panel cooling applications. An analytical model of the heat transfer between the cold ceiling panel and the room air was also developed. The convection coefficient, convective heat transfer and total heat transfer coefficient were compared using the values obtained from the experiments and those reported in the literature. It was found that the convection coefficient was within the range reported in the literature, and the radiation heat coefficient was within 99.8% of the literature values. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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17 pages, 3366 KiB

Open AccessArticle

Experimental Investigation of the Performance of a Novel Ejector–Diffuser System with Different Supersonic Nozzle Arrays

by Dachuan Xu, Yunsong Gu, Wei Li and Jingxiang Chen

Fluids 2024, 9(7), 155; https://doi.org/10.3390/fluids9070155 - 2 Jul 2024

Cited by 4 | Viewed by 1644

Abstract

The supersonic–supersonic ejector–diffuser system is employed to suck supersonic low-pressure and low-temperature flow into a high-pressure environment. A new design of a supersonic–supersonic ejector–diffuser was introduced to verify pressure control performance under different operating conditions and vacuum background pressure. A 1D analysis was [...] Read more.

The supersonic–supersonic ejector–diffuser system is employed to suck supersonic low-pressure and low-temperature flow into a high-pressure environment. A new design of a supersonic–supersonic ejector–diffuser was introduced to verify pressure control performance under different operating conditions and vacuum background pressure. A 1D analysis was used to predict the geometrical structure of an ejector–diffuser with a rectangular section based on the given operating conditions. Different numbers and types of nozzle plates were designed and installed on the ejector to study the realizability of avoiding or postponing the aerodynamic choking phenomenon in the mixing section. The effects of different geometrical parameters on the operating performance of the ejector–diffuser system were discussed in detail. Experimental investigation of the effects of different types of nozzle plates and the back pressures on the pressure control performance of the designed ejector–diffuser system were performed in a straight-flow wind tunnel. The results showed that the position, type and number of the nozzle plates have a significant impact on the beginning of the formation of aerodynamic choking. The geometry of the ejector and the operating conditions, especially the backpressure and inlet pressure of the ejecting stream, determined the entrainment ratio of the two supersonic streams. The experimental results showed that long nozzle-plate had a better performance in terms of maintaining pressure stability in the test section, while short a nozzle-plate had a better pressure matching performance and could maintain a higher entrainment ratio under high backpressure conditions. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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15 pages, 8088 KiB

Open AccessArticle

Determination of Contact Resistance of Thermal Interface Materials Used in Thermal Monitoring Systems of Electric Vehicle Charging Inlets

by Monika Pieszka-Łysoń, Paweł Rutkowski, Magdalena Kawalec and Dominik Kawalec

Materials 2024, 17(13), 3103; https://doi.org/10.3390/ma17133103 - 25 Jun 2024

Cited by 2 | Viewed by 1336

Abstract

The rapid growth of the electric vehicle (EV) market is observed. This is challenging from a materials point of view when it comes to the thermal monitoring systems of charging inlets, for which requirements are very restrictive. Because the thermal conductivity of the [...] Read more.

The rapid growth of the electric vehicle (EV) market is observed. This is challenging from a materials point of view when it comes to the thermal monitoring systems of charging inlets, for which requirements are very restrictive. Because the thermal conductivity of the thermal interface material is usually measured, there is a significant research gap on the contact thermal resistance of novel materials used in the electric vehicle industry. Moreover, researchers mainly focus on electrically conductive materials, while for thermal monitoring systems, the most important requirement is a high dielectric breakdown voltage. In this paper, the thermal contact resistance of materials for EV applications was thoroughly analyzed. This study consisted of experimental measurements with the Laser Flash Analysis (LFA) method, as well as a theoretical analysis of thermal contact resistance. The main focus was on the extraction of contact and material thermal resistance. The obtained results have great potential to be used as input data for further numerical modeling of solutions that meet strict thermal accuracy requirements. Additionally, the chemical composition and internal structure were analyzed using scanning electron microscopy, to better describe the material. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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11 pages, 2103 KiB

Open AccessArticle

Multiphase Numerical CFD Simulation of the Hydrothermal Liquefaction Process (HTL) of Sewage Sludge in a Tubular Reactor

by Artur Wodołażski

Appl. Sci. 2024, 14(11), 4513; https://doi.org/10.3390/app14114513 - 24 May 2024

Cited by 1 | Viewed by 1198

Abstract

This article presents multiphase numerical computational fluid dynamics (CFD) for simulating hydrothermal liquefaction of sewage sludge in a continuous plug-flow reactor. The discrete particle method (DPM) was used to analyze the solid particles’ interaction in liquid–solid high shear flows to investigate coupling computational [...] Read more.

This article presents multiphase numerical computational fluid dynamics (CFD) for simulating hydrothermal liquefaction of sewage sludge in a continuous plug-flow reactor. The discrete particle method (DPM) was used to analyze the solid particles’ interaction in liquid–solid high shear flows to investigate coupling computational fluid dynamics (CFD). Increasing solid particles’ interactions were observed with the increasing liquid velocity. The study examined the influence of parameters such as flow rate, temperature, and residence time on the efficiency of bio-oil production. An increase in temperature from 500 to 800 K caused an increase in the amount of biocrude oil produced from 12.4 to 32.9% within 60 min. In turn, an increase in the flow rate of the suspension from 10 to 60 mL/min caused a decrease in the amount of biocrude oil produced from 38.9 to 12.9%. This study offers insights into optimizing the flow channel of tubular reactors to enhance the HTL conversion efficiency of sewage sludge into biocrude oil. A parametric study was performed to investigate the effect of the slurry flow rate, temperature, and the external heat transfer coefficient on the biocrude oil production performance. The simulation data will be used in the future to design and scale up a large-scale HTL reactor. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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21 pages, 2119 KiB

Open AccessArticle

Simulation and Experimental Study of Circulatory Flash Evaporation System for High-Salt Wastewater Treatment

by Hao Feng, Wei Chen, Rui Sun, Zhen Zhang, Wei Li and Bin Zhang

Energies 2024, 17(10), 2382; https://doi.org/10.3390/en17102382 - 15 May 2024

Viewed by 1155

Abstract

Treatment methods for high-salt wastewater mainly consist of physical methods, chemical methods and biological methods. However, there are some problems, such as slow treatment speed, high investment costs and low treatment efficiency. To address NaCl solutions, in this study, a circulatory flash system [...] Read more.

Treatment methods for high-salt wastewater mainly consist of physical methods, chemical methods and biological methods. However, there are some problems, such as slow treatment speed, high investment costs and low treatment efficiency. To address NaCl solutions, in this study, a circulatory flash system was designed based on gas–liquid equilibrium, mass conservation equation and energy conservation equation. A circulatory flash evaporation simulation and a static flash evaporation experiment were conducted on NaCl solutions under various operating conditions to investigate the effects of heating temperature, flash pressure and initial NaCl concentration on the circulatory flash evaporation system. The significance of each factor’s influence on the evaporation fraction and energy consumption was examined through static flash experiments. The simulation results demonstrated that increasing the heating temperature, decreasing the flash pressure and having a higher initial NaCl concentration could enhance the treatment capacity of high-salt wastewater. The flow rate of vapor outlets increased with higher heating temperature but decreased as the flash pressure rose. The experimental results demonstrated that flash evaporation pressure was the primary factor influencing both the evaporation fraction and the energy consumption per unit mass of vapor produced. It was observed that with an increase in heating temperature, the flash pressure decreased and there was a corresponding decrease in energy consumption per unit mass of vapor produced. The optimal experimental conditions were achieved at a heating temperature of 99 °C, a flash pressure of 15 kPa, and an initial NaCl concentration of 20%. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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23 pages, 12047 KiB

Open AccessArticle

Modeling of Yb:YAG Laser Beam Caustics and Thermal Phenomena in Laser–Arc Hybrid Welding Process with Phase Transformations in the Solid State

by Marcin Kubiak, Zbigniew Saternus, Tomasz Domański and Wiesława Piekarska

Materials 2024, 17(10), 2364; https://doi.org/10.3390/ma17102364 - 15 May 2024

Cited by 1 | Viewed by 1125

Abstract

This paper focuses on the mathematical and numerical modeling of the electric arc + laser beam welding (HLAW) process using an innovative model of the Yb:YAG laser heat source. Laser energy distribution is measured experimentally using a UFF100 analyzer. The results of experimental [...] Read more.

This paper focuses on the mathematical and numerical modeling of the electric arc + laser beam welding (HLAW) process using an innovative model of the Yb:YAG laser heat source. Laser energy distribution is measured experimentally using a UFF100 analyzer. The results of experimental research, including the beam profile and energetic characteristics of an electric arc, are used in the model. The laser beam description is based on geostatistical kriging interpolation, whereas the electric arc is modeled using Goldak’s distribution. Hybrid heat source models are used in numerical algorithms to analyze physical phenomena occurring in the laser–arc hybrid welding process. Thermal phenomena with fluid flow in the fusion zone (FZ) are described by continuum conservation equations. The kinetics of phase transformations in the solid state are determined using Johnson–Mehl–Avrami (JMA) and Koistinen–Marburger (KM) equations. A continuous cooling transformation (CCT) diagram is determined using interpolation functions and experimental research. An experimental dilatometric analysis for the chosen cooling rates is performed to define the start and final temperatures as well as the start and final times of phase transformations. Computer simulations of butt-welding of S355 steel are executed to describe temperature and melted material velocity profiles. The predicted FZ and heat-affected zone (HAZ) are compared to cross-sections of hybrid welded joints, performed using different laser beam focusing. The obtained results confirm the significant influence of the power distribution of the heat source and the laser beam focusing point on the temperature distribution and the characteristic zones of the joint. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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10 pages, 3703 KiB

Open AccessArticle

Boil-Off Gas Generation in Vacuum-Jacketed Valve Used in Liquid Hydrogen Storage Tank

by Hae-Seong Hwang, Seong-Un Woo and Seung-Ho Han

Energies 2024, 17(10), 2341; https://doi.org/10.3390/en17102341 - 13 May 2024

Cited by 1 | Viewed by 1561

Abstract

The boiling point of liquid hydrogen is very low, at −253 °C under atmospheric pressure, which causes boil-off gas (BOG) to occur during storage and transport due to heat penetration. Because the BOG must be removed through processes such as re-liquefaction, venting to [...] Read more.

The boiling point of liquid hydrogen is very low, at −253 °C under atmospheric pressure, which causes boil-off gas (BOG) to occur during storage and transport due to heat penetration. Because the BOG must be removed through processes such as re-liquefaction, venting to the atmosphere, or incineration, related studies are required to estimate the heat transfer of storage and transport devices and to improve insulation to reduce BOG generation. In this study, a vaporization analysis was performed on a vacuum-jacketed valve used in liquid hydrogen storage and transport devices to calculate the amount of BOG generation considering the flow characteristics at the vena contracta and the saturation temperature. At a pressure of 1 bar in the liquid hydrogen storage tank, the maximum fluid flow velocity and minimum static pressure occurred at the vena contracta, with values of 62.9 m/s and −0.4 bar, respectively, and the BOG generation rate was estimated as 0.132 m³/h, where the saturation temperature was minimized at 19.3 K. Furthermore, through case studies, when the pressure in the liquid hydrogen storage tank increased to 1.5 and 2 bar, the static pressure and saturation temperature decreased, and the BOG generation rate increased to 0.221 and 0.283 m³/h, respectively. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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19 pages, 5386 KiB

Open AccessArticle

Numerical Study of Fluid Flow in a Gyroid-Shaped Heat Transfer Element

by Martin Beer and Radim Rybár

Energies 2024, 17(10), 2244; https://doi.org/10.3390/en17102244 - 7 May 2024

Cited by 2 | Viewed by 1575

Abstract

This paper deals with the design of porous geometry of a heat transfer element. The proposed geometry combines a gyroid triply periodic minimal surface with the recursive principle of geometric body creation. The designed geometry is based on an attempt to increase the [...] Read more.

This paper deals with the design of porous geometry of a heat transfer element. The proposed geometry combines a gyroid triply periodic minimal surface with the recursive principle of geometric body creation. The designed geometry is based on an attempt to increase the heat transfer surface while eliminating negative impacts on the fluid characteristics in the form of pressure loss or increase of the friction coefficient. The proposed geometry of the heat transfer element was compared with a pair of geometries based on the basic gyroid shape but with different channel size parameters. A numerical simulation was performed in Ansys Fluent 2020 R1 using the SST k-omega turbulence model for flow velocities in the range of 0.01 m.s⁻¹ to 0.5 m.s⁻¹, which covered a wide range of the Reynolds number and thus also flow forms in terms of the turbulence intensity. The presented results clearly show lower values of pressure loss and friction coefficient of the proposed geometry compared to the evaluated porous structures. Also, at the same time, they describe the factors positively influencing the mixing process of the liquid in the proposed element, which leads to an increase in the efficiency of the heat transfer process. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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11 pages, 3363 KiB

Open AccessArticle

Natural Ventilation to Manage Ammonia Concentration and Temperature in a Rabbit Barn in Central Mexico

by David Vargas Cano, Jorge Flores-Velazquez and Agustín Ruiz Garcia

Appl. Sci. 2024, 14(9), 3767; https://doi.org/10.3390/app14093767 - 28 Apr 2024

Cited by 2 | Viewed by 1483

Abstract

The concentration of ammonia (NH₃) and the temperature of the air surrounding the rabbit habitat in the farm condition basic health processes such as breathing and feeding. The indoor climate in a rabbit farm is largely conditioned by the ventilation system [...] Read more.

The concentration of ammonia (NH₃) and the temperature of the air surrounding the rabbit habitat in the farm condition basic health processes such as breathing and feeding. The indoor climate in a rabbit farm is largely conditioned by the ventilation system (air conditioning). The objective of this study was to build a numerical model based on computational fluid dynamics (CFD) in order to evaluate, by numerical simulations, the air dynamics of a rustic farm. After the validation of the computational model, the thermal gradient and ammonia concentration were analyzed under three wind incidence angles (0°, 45°, and 90° with respect to the horizontal Z axis of the facility). The results of the simulations showed that, in the area occupied by the rabbits (AOR), the concentration of ammonia with respect to the source was reduced by 37.3% in the most favorable case (wind direction at 45°), and 21.2% in the least favorable case (wind direction at 0°), and the indoor temperature presented a maximum difference of 2 °C with respect to the outside temperature. Climate control is a more expensive cost in rabbit farm exploitation; dynamics modulation can serve as an auxiliary tool for reducing health risks in rabbits. The use of models based on fluid dynamics allowed us to understand the efficiency of the ventilation system, which must be increased to reduce the found temperature gradient. Through numerical simulation it will be possible to find alternatives to increase the ventilation rate. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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18 pages, 7690 KiB

Open AccessArticle

Conjugate Heat Transfer Advancements and Applications in Aerospace Engine Technology

by Hao Zha, Yaqian Xu, Zhigong Tang, Bin Li and Dongzhi Wang

Appl. Sci. 2024, 14(9), 3556; https://doi.org/10.3390/app14093556 - 23 Apr 2024

Cited by 1 | Viewed by 2106

Abstract

Over the past few decades, conjugate heat transfer (CHT) technology has been instrumental in predicting temperature fields within aerospace engines, guiding engine design with its predictive capabilities. This paper comprehensively surveys the foundational technologies of CHT and their applications in engine design, backed [...] Read more.

Over the past few decades, conjugate heat transfer (CHT) technology has been instrumental in predicting temperature fields within aerospace engines, guiding engine design with its predictive capabilities. This paper comprehensively surveys the foundational technologies of CHT and their applications in engine design, backed by an extensive literature review. A novel coupling iteration methodology, su-F-TFTB, was proposed. Following this, it introduced grid splicing technology tailored for heat flux conservation, which significantly enhances the adaptability of CHT grids. Ultimately, this study employed the self-developed Aerospace Engine Numerical Simulation (AENS v4.0.1) software to perform CHT analyses on NASA-C3X turbine blades equipped with ten radial cooling systems. A comparative analysis of pressure distributions across various density meshes was undertaken to affirm mesh independence. Furthermore, the impacts of the Spalart–Allmaras (SA) one-equation model and k–ω Shear Stress Transport (SST) two-equation model on the temperature distribution in conjugate heat transfer were investigated. The results indicated that the k–ω SST model exhibited superior performance, aligning closely with NASA experimental data. This validation confirmed the effectiveness of the software. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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21 pages, 4977 KiB

Open AccessArticle

Darcy–Brinkman Model for Ternary Dusty Nanofluid Flow across Stretching/Shrinking Surface with Suction/Injection

by Sudha Mahanthesh Sachhin, Ulavathi Shettar Mahabaleshwar, David Laroze and Dimitris Drikakis

Fluids 2024, 9(4), 94; https://doi.org/10.3390/fluids9040094 - 18 Apr 2024

Cited by 8 | Viewed by 1713 | Correction

Abstract

Understanding of dusty fluids for different Brinkman numbers in porous media is limited. This study examines the Darcy–Brinkman model for two-dimensional magneto-hydrodynamic fluid flow across permeable stretching/shrinking surfaces with heat transfer. Water was considered as a conventional base fluid in which the copper [...] Read more.

Understanding of dusty fluids for different Brinkman numbers in porous media is limited. This study examines the Darcy–Brinkman model for two-dimensional magneto-hydrodynamic fluid flow across permeable stretching/shrinking surfaces with heat transfer. Water was considered as a conventional base fluid in which the copper (Cu), silver (Ag), and titanium dioxide (

T i O_{2}

) nanoparticles were submerged in a preparation of a ternary dusty nanofluid. The governing nonlinear partial differential equations are converted to ordinary differential equations through suitable similarity conversions. Under radiation and mass transpiration, analytical solutions for stretching sheets/shrinking sheets are obtained. Several parameters are investigated, including the magnetic field, Darcy–Brinkman model, solution domain, and inverse Darcy number. The outcomes of the present article reveal that increasing the Brinkman number and inverse Darcy number decreases the velocity of the fluid and dusty phase. Increasing the magnetic field decreases the momentum of the boundary layer. Ternary dusty nanofluids have significantly improved the heat transmission process for manufacturing with applications in engineering, and biological and physical sciences. The findings of this study demonstrate that the ternary nanofluid phase’s heat and mass transpiration performance is better than the dusty phase’s performance. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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15 pages, 4440 KiB

Open AccessArticle

The Material Balance of Complex Separation Flowsheets

by Anastasia Frolkova, Alla Frolkova, Michael Sibirtsev and Kirill Lysenko

Processes 2024, 12(4), 821; https://doi.org/10.3390/pr12040821 - 18 Apr 2024

Viewed by 1156

Abstract

The paper shows the expediency of supplementing the balance simplex method by calculating the number of free variables of separation flowsheets containing recycle flows. The need to determine and set the free variables that provide lower energy consumption when calculating the material balance [...] Read more.

The paper shows the expediency of supplementing the balance simplex method by calculating the number of free variables of separation flowsheets containing recycle flows. The need to determine and set the free variables that provide lower energy consumption when calculating the material balance of flowsheets with recycling is justified. The problem of material balance multivariance is illustrated, and ways to solve it are shown with the example of separation flowsheets for two ternary mixtures: n-butanol + water + toluene and n-butanol + butyl acetate + water. Separation flowsheets containing three distillation columns and a liquid–liquid separator are proposed for both systems. The dependence of the recycle flow values and the energy consumption of distillation columns and separation flowsheets on the selection and setting of values of free variables in solving the balance problem is shown. The dependence of energy consumption on the composition of the original mixture is studied for an n-butanol + butyl acetate + water system. Recommendations for setting free variables for flowsheets of the separation of ternary mixtures with three binary (and one ternary) azeotropes are formulated. The technique of highlighting the region of separation flowsheet operability is illustrated. The column operating parameters that ensure the production of products of a given quality with minimal energy consumption are determined. It is shown that with the incorrect selection and setting of variables (during balance task solvation), the energy consumption for mixture separation can be overestimated by more than 40%. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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13 pages, 5011 KiB

Open AccessArticle

Effect of Rotational Angle of Discrete Inclined Ribs on Horizontal Flow and Heat Transfer of Supercritical R134a

by Genxian Yang, Junrui Tang and Zhouhang Li

Energies 2024, 17(7), 1631; https://doi.org/10.3390/en17071631 - 28 Mar 2024

Viewed by 1139

Abstract

This work numerically studied the heat transfer and flow characteristics of supercritical R134a in horizontal pipes equipped with DDIR, considering variations in the rotation angle of DDIR. The aim is to improve the effects of the DDIR configuration on the heat transfer of [...] Read more.

This work numerically studied the heat transfer and flow characteristics of supercritical R134a in horizontal pipes equipped with DDIR, considering variations in the rotation angle of DDIR. The aim is to improve the effects of the DDIR configuration on the heat transfer of supercritical flow. After validation with experimental data, the AKN model was employed to examine the effects of four sets of rotation angles (0°, 30°, 45°, and 60°) on the axial and circumferential heat transfer characteristics of DDIR horizontal tubes under the influence of strong (q₁/G₁ = 0.1 kJ/kg) and medium (q₂/G₂ = 0.056 kJ/kg) buoyancy. Results show that variations in the rotation angle do not induce significant alterations in the flow field, thus exerting minimal influence on the axial heat transfer characteristics. Meanwhile, the rotation angle determines the relative positioning of the circumferential inner wall temperatures and heat flux distribution, although the magnitude of this effect remains inconspicuous. The rotational angle parameter can be reasonably neglected in the future design and installation of heat exchangers. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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22 pages, 5338 KiB

Open AccessArticle

Multi-Output Regression Algorithm-Based Non-Dominated Sorting Genetic Algorithm II Optimization for L-Shaped Twisted Tape Insertions in Circular Heat Exchange Tubes

by Shijie Li, Zuoqin Qian and Ji Liu

Energies 2024, 17(4), 850; https://doi.org/10.3390/en17040850 - 11 Feb 2024

Cited by 2 | Viewed by 1489

Abstract

In this study, an optimization method using various multi-output regression models as model proxies within the NSGA-II framework was applied to determine the geometric parameters (P, W, D) of L-shaped twisted tape inserts for achieving the optimal overall heat transfer performance in a [...] Read more.

In this study, an optimization method using various multi-output regression models as model proxies within the NSGA-II framework was applied to determine the geometric parameters (P, W, D) of L-shaped twisted tape inserts for achieving the optimal overall heat transfer performance in a circular heat exchange tube. Herein, 4 multi-output regression models, namely, MOLR, MOSVR, MOGPR, and BPNN, were selected as proxy models and trained on a dataset containing 74 groups of data. The training results indicated that the MOGPR model, balancing high accuracy and low error conditions, exhibited moderate training times among the four algorithms. BPNN showed a comparatively lower comprehensive training effect, obtaining training accuracy close to that of the MOGPR algorithm but with approximately twice the training time. The worst fitting performance was gained with the MOSVR algorithm. Due to its fitting performance, the MOSVR algorithm was excluded from the subsequent NSGA-II model proxy. Through multi-objective optimization with NSGA-II, the optimal structural dimensions for three sets of L-shaped twisted tape inserts were obtained to achieve the best overall heat transfer efficiency within the tube. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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34 pages, 38064 KiB

Open AccessReview

A Review of Cooling Technologies in Lithium-Ion Power Battery Thermal Management Systems for New Energy Vehicles

by Ping Fu, Lan Zhao, Xuguang Wang, Jian Sun and Zhicheng Xin

Processes 2023, 11(12), 3450; https://doi.org/10.3390/pr11123450 - 18 Dec 2023

Cited by 14 | Viewed by 14445

Abstract

The power battery is an important component of new energy vehicles, and thermal safety is the key issue in its development. During charging and discharging, how to enhance the rapid and uniform heat dissipation of power batteries has become a hotspot. This paper [...] Read more.

The power battery is an important component of new energy vehicles, and thermal safety is the key issue in its development. During charging and discharging, how to enhance the rapid and uniform heat dissipation of power batteries has become a hotspot. This paper briefly introduces the heat generation mechanism and models, and emphatically summarizes the main principle, research focuses, and development trends of cooling technologies in the thermal management of power batteries in new energy vehicles in the past few years. Currently, the commonly used models for battery heat generation are the electrochemical-thermal model and the electrical-thermal model. Scholars have conducted more research based on multidimensional electrochemical-thermal/electrical-thermal models because taking the actual characteristics of the battery into account can provide a more comprehensive and systematic description. Among various cooling technologies, the air-cooling system boasts the most economical manufacturing costs and a compact, reliable structure. The heat transfer coefficient of the liquid-cooling system is very high, while the temperature remains uniform in the PCMs cooling system during the material phase transition process. Against the background of increasing energy density in future batteries, immersion liquid phase change cooling technology has great development prospects, but it needs to overcome limitations such as high cost and heavy weight. Therefore, the current lithium-ion battery thermal management technology that combines multiple cooling systems is the main development direction. Suitable cooling methods can be selected and combined based on the advantages and disadvantages of different cooling technologies to meet the thermal management needs of different users. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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20 pages, 5880 KiB

Open AccessArticle

Thermal Diffusivity in the Subsoil: A Case Study in the Asturias (Northern Spain)

by Germán Marcos-Robredo, María Pilar Castro-García, Miguel Ángel Rey-Ronco and Teresa Alonso-Sánchez

Energies 2023, 16(24), 8108; https://doi.org/10.3390/en16248108 - 17 Dec 2023

Viewed by 1268

Abstract

This study presents a novel methodology for determining the apparent thermal diffusivity of subsoil in situ, employing two heat transfer models within the subsurface: one method is based on heat conduction caused by air temperature oscillations, while the other considers heat transmission via [...] Read more.

This study presents a novel methodology for determining the apparent thermal diffusivity of subsoil in situ, employing two heat transfer models within the subsurface: one method is based on heat conduction caused by air temperature oscillations, while the other considers heat transmission via both conduction and convection due to groundwater flow. Differential equations were solved, and non-linear regression analysis was employed. This method has direct applications in various engineering and environmental domains, such as underground transmission lines, oil and gas pipelines, radioactive waste management, and geothermal systems, especially in the context of implementing horizontal geothermal collectors (HGC). The apparent thermal diffusivity value of 1.514 × 10⁻⁶ m² s⁻¹, within a 95% confidence interval spanning 1.512 × 10⁻⁶ m² s⁻¹ and 1.516 × 10⁻⁶ m² s⁻¹, was obtained from the section between 1.67 and 3.86 m depth in a research borehole located in Asturias, Northern Spain, using twenty-one temperature sensors. The method allowed for the calculation of the subsoil’s apparent thermal diffusivity up to a depth of 14.55 m. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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17 pages, 7141 KiB

Open AccessArticle

Performance Evaluation of a Steam Ejector Considering Non-Equilibrium Condensation in Supersonic Flows

by Youhao Xie, Yu Han, Xiaodong Wang, Chuang Wen and Yan Yang

Energies 2023, 16(23), 7755; https://doi.org/10.3390/en16237755 - 24 Nov 2023

Cited by 2 | Viewed by 1524

Abstract

The present study established an experimental system of steam ejector refrigeration to evaluate the effect of the operating parameters, such as pressure on the diffuser wall and primary and secondary fluid, on the performance and efficiency of the ejector. The model validation of [...] Read more.

The present study established an experimental system of steam ejector refrigeration to evaluate the effect of the operating parameters, such as pressure on the diffuser wall and primary and secondary fluid, on the performance and efficiency of the ejector. The model validation of numerical methods was carried out against the experimental data, while the numerical simulation was conducted by utilizing computational fluid dynamics modeling to analyze the internal flow of the ejector. The results indicated that the escalation of the primary steam pressure in the choking position increased the Mach number and entrainment ratio as the flow area of the secondary fluid remained constant. The optimization studies show that the entrainment ratio was maximum when the primary steam pressure was 0.36 MPa. While the pressure was inordinate, the expansion core increased in size and further compressed the flow area of the secondary fluid, hence reducing the entrainment ratio. Subject to the influence of the normal shockwave, the change in back pressure did not alter the entrainment ratio before the critical back pressure. In contrast, the ejector no longer produces the normal shockwave after the critical back pressure; the entrainment ratio, therefore, was reduced with the increase in back pressure. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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17 pages, 6189 KiB

Open AccessArticle

The Impact of Ultrasound Pre-Treatment on Hot-Air-Drying Kinetics and Quality of Carrot Slices Assessed by Simulations and Experiments

by Thi Thu Hang Tran, Thi Thuy Dung Nguyen, Abdolreza Kharaghani and Kieu Hiep Le

Appl. Sci. 2023, 13(21), 11865; https://doi.org/10.3390/app132111865 - 30 Oct 2023

Cited by 2 | Viewed by 1677

Abstract

This study investigated experimentally and numerically the influence of ultrasound pre-treatment on the drying kinetics of sliced carrot samples. Drying experiments were performed under different conditions, including scenarios with and without ultrasound pre-treatment at drying temperatures of 30 °C, 40 °C, and 50 [...] Read more.

This study investigated experimentally and numerically the influence of ultrasound pre-treatment on the drying kinetics of sliced carrot samples. Drying experiments were performed under different conditions, including scenarios with and without ultrasound pre-treatment at drying temperatures of 30 °C, 40 °C, and 50 °C. A diffusion-based-drying model was developed to study the impact of ultrasound pre-treatment on drying kinetics. The effective moisture diffusivity of carrots was expressed as a function of moisture content and temperature. Given the complexity of the dehydration process in carrot slices, which depends on the spatiotemporal variations in moisture content and temperature, and is challenging to monitor experimentally, the effective moisture diffusivity is computed by minimizing the discrepancy between numerical predictions and experimental moisture-content changes over time. This study revealed that ultrasound pre-treatment significantly enhanced the moisture diffusivity of the samples, increasing it by 43% to 90% at drying temperatures of 40 °C and 50 °C, respectively. To apply this analysis of ultrasound pre-treatment in large-scale dryers where thousands of slices may be involved, the proposed diffusion model was simplified to a characteristic drying-curve model. Afterwards, this characteristic drying-curve model was incorporated into a belt-dryer model. The results indicated a 12% reduction in the length of the belt dryer when ultrasound pre-treatment was applied. Additionally, the color of carrot samples was preserved better with ultrasound pre-treatment. On the basis of these results, the application of ultrasound pre-treatment in the hot-air drying of carrot slices was favored, both in terms of improved drying kinetics and quality aspects. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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11 pages, 3445 KiB

Open AccessArticle

A Study on Temperature and Pressure Characteristics in a Vessel as Charging Time of Helium Gas Changes

by Jangwoo Park, Junho Choi and Kwonse Kim

Appl. Sci. 2023, 13(20), 11348; https://doi.org/10.3390/app132011348 - 16 Oct 2023

Viewed by 2768

Abstract

The main propose in this research work is to investigate the temperature and pressure increase resulting from the variable valve of a mass flow controller during the charging and discharging of helium gas, which is being used as an alternative to hydrogen gas [...] Read more.

The main propose in this research work is to investigate the temperature and pressure increase resulting from the variable valve of a mass flow controller during the charging and discharging of helium gas, which is being used as an alternative to hydrogen gas in a vessel. In the operation of this experiment, the high-pressure gas stored in the main tank is first reduced to low pressure using an electronic solenoid valve within a regulator to control the flow rate. Subsequently, the flow rate is precisely measured using an MFC (Mass Flow Controller) and supplied to the experimental tank. Throughout this process, temperature and pressure sensors detect changes in physical behavior, collect data using LabVIEW cDAQ, and repeat the process of analyzing and verifying reliable data according to the experiment’s conditions. The mass flow controller valve opening was set at 20%, 60%, and 100% while operating the LabVIEW programming. Also, this experiment was conducted at 20 °C ambient temperature and 0 bar gauge pressure. Both the temperature and pressure increase as the MFC valve opens further because the helium gas flow is accumulating during the valve opening time. Furthermore, in the case of helium temperature, it increases significantly when the gas is charged rapidly, compared to the pressure characteristics. Therefore, one can see that the vessel increases as the valve opening time increases, and the temperature changes; the temperature is more significant when the helium gas is charged rapidly during the valve opening time. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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23 pages, 5295 KiB

Open AccessReview

A Review on Cooling Systems for Portable Energy Storage Units

by Alireza Eslami Majd, Fideline Tchuenbou-Magaia, Agnero M. Meless, David S. Adebayo and Nduka Nnamdi Ekere

Energies 2023, 16(18), 6525; https://doi.org/10.3390/en16186525 - 11 Sep 2023

Cited by 3 | Viewed by 3395

Abstract

Achieving the global electricity demand and meeting the United Nations sustainable development target on reliable and sustainable energy supply by 2050 are crucial. Portable energy storage (PES) units, powered by solid-state battery cells, can offer a sustainable and cost-effective solution for regions with [...] Read more.

Achieving the global electricity demand and meeting the United Nations sustainable development target on reliable and sustainable energy supply by 2050 are crucial. Portable energy storage (PES) units, powered by solid-state battery cells, can offer a sustainable and cost-effective solution for regions with limited power-grid access. However, operating in high-dust and high-temperature environments presents challenges that require effective thermal management solutions. This paper is a comprehensive review of thermal management systems for PES units, with a specific focus on addressing the challenge of overheating in airtight designs. The review of various active and passive cooling systems is conducted through extensive study of the relevant literature, which is significant in providing insights into the operation, performance parameters, and design options for different cooling system technologies. The findings from this review show heat pipe (HP) technologies as key cooling-system solutions for airtight PES units. Specifically, loop and oscillating HPs, as well as the vapour chamber, offer desirable features such as compactness, low cost, and high thermal conductivity that make them superior to other alternatives for the cooling systems in PES. The insights and knowledge generated via this review will help facilitate the design and development of innovative, efficient, and reliable PES units, thereby contributing to the advancement of off-grid renewable energy applications and enabling sustainable power solutions worldwide. Furthermore, an appropriate design of PES units can help in reducing capital and maintenance costs. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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24 pages, 3661 KiB

Open AccessArticle

A Tabu-Matching Heuristic Algorithm Based on Temperature Feasibility for Efficient Synthesis of Heat Exchanger Networks

by Xiaohuang Huang, Hao Shen, Wenhao Yue, Huanhuan Duan and Guomin Cui

Processes 2023, 11(9), 2713; https://doi.org/10.3390/pr11092713 - 11 Sep 2023

Viewed by 1283

Abstract

The non-structural model of heat exchanger networks (HENs) offers a wide solution space for optimization due to the random matching of hot and cold streams. However, this stochastic matching can sometimes result in infeasible structures, leading to inefficient optimization. To address this issue, [...] Read more.

The non-structural model of heat exchanger networks (HENs) offers a wide solution space for optimization due to the random matching of hot and cold streams. However, this stochastic matching can sometimes result in infeasible structures, leading to inefficient optimization. To address this issue, a tabu matching based on a heuristic algorithm for HENs is proposed. The proposed tabu-matching method involves three main steps: First, the critical temperature levels—high, medium, and low-temperature intervals—are determined based on the inlet and outlet temperatures of streams. Second, the number of nodes is set according to the temperature intervals. Third, the nodes of streams are flexibly matched within the tabu rules: the low-temperature interval of hot streams with the high-temperature interval of cold streams; the streams crossing cannot be matched. The results revealed that by incorporating the tabu rules and adjusting the number of nodes, the ratio of the feasible zone in the whole solution domain increases, and the calculation efficiency is enhanced. To evaluate the effectiveness of the method, three benchmark problems were studied. The obtained total annual costs (TACs) of these case studies exhibited a decrease of USD 4290/yr (case 1), USD 1435/yr (case 2), and USD 11,232/yr (case 3) compared to the best published results. The results demonstrate that the proposed tabu-matching heuristic algorithm is effective and robust. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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16 pages, 10257 KiB

Open AccessArticle

Analysis of Flow and Heat Transfer Characteristics and Multi-Objective Optimization for Sinusoidal PCHE

by Qixuan Hu, Zhonglei Fan, Zhe Zhang and Yi Lu

Energies 2023, 16(15), 5763; https://doi.org/10.3390/en16155763 - 2 Aug 2023

Cited by 3 | Viewed by 1614

Abstract

A Printed Circuit Heat Exchanger (PCHE) is a compact heat exchanger with high temperature and pressure resistance and is considered one of the best choices for the recuperators in the Supercritical Carbon dioxide (S-CO₂) Brayton cycle. The flow and heat transfer [...] Read more.

A Printed Circuit Heat Exchanger (PCHE) is a compact heat exchanger with high temperature and pressure resistance and is considered one of the best choices for the recuperators in the Supercritical Carbon dioxide (S-CO₂) Brayton cycle. The flow and heat transfer performance of sinusoidal channel PCHE were analyzed and a second-order regression model was established based on the response surface method to improve the performance of the continuous channel PCHE. It was found that reducing the channel diameter, increasing the channel amplitude, and reducing the channel pitch can increase the average value of the heat transfer coefficient and pressure drop per unit length. Moreover, sensitivity coefficient analysis was used to investigate the influence of various structural parameters on flow performance, heat transfer performance, and comprehensive performance. In addition, the structure of the sinusoidal channel PCHE was optimized using a multi-objective genetic algorithm, and three sets of Pareto optimal solutions were obtained. The corresponding optimal channel diameter D, channel amplitude A, and channel pitch Lp were in the range of 1.0–1.7 mm, 2.4–3.0 mm, and 15.1–17.0 mm, respectively, which can provide theoretical basis for the design of PCHE. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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14 pages, 4893 KiB

Open AccessArticle

Biomimetic Copper Forest Structural Modification Enhances the Capillary Flow Characteristics of the Copper Mesh Wick

by Jia-Li Luo, Fan-Bin Zhao, Mou Xu, Dong-Chuan Mo and Shu-Shen Lyu

Energies 2023, 16(14), 5348; https://doi.org/10.3390/en16145348 - 13 Jul 2023

Cited by 4 | Viewed by 2005

Abstract

In a two-phase heat transfer device, achieving a high capillarity of the wick while reducing flow resistance within a limited space becomes the key to improving the heat dissipation performance. As a commonly used wick structure, mesh is widely employed because of its [...] Read more.

In a two-phase heat transfer device, achieving a high capillarity of the wick while reducing flow resistance within a limited space becomes the key to improving the heat dissipation performance. As a commonly used wick structure, mesh is widely employed because of its high permeability. However, achieving the desired capillary performance often requires multiple layers to be superimposed to ensure an adequate capillary, resulting in an increased thickness of the wick. In this study, an ultra-thin biomimetic copper forest structural modification of copper mesh was performed using an electrochemical deposition to solve the contradiction between the permeability and the capillary. The experiments were conducted on a copper mesh to investigate the effects of various conditions on their morphology and capillary performance. The results indicate that the capillary performance of the modified copper mesh improves with a longer deposition time. The capillary pressure drops can reach up to 1400 Pa when using ethanol as the working fluid. Furthermore, the modified copper mesh demonstrates a capillary performance value (ΔP_c·K) of 8.44 × 10⁻⁸ N, which is 1.7 times higher than that of the unmodified samples. Notably, this enhanced performance is achieved with a thickness of only 142 μm. The capillary limit can reach up to 45 W when the modified copper mesh is only 180 μm. Microscopic flow analysis reveals that the copper forest modified structure maintains the original high permeability of the copper mesh while providing a greater capillary force, thereby enhancing the overall flow characteristics. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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12 pages, 7482 KiB

Open AccessArticle

Organic—Inorganic Hybrid Interfaces Enable the Preparation of Nitrogen-Doped Hollow Carbon Nanospheres as High-Performance Anodes for Lithium and Potassium-Ion Batteries

by Yao Dai, Dong-Chuan Mo, Zong-Tao Qu, Wen-Kang Wang and Shu-Shen Lyu

Materials 2023, 16(14), 4936; https://doi.org/10.3390/ma16144936 - 11 Jul 2023

Cited by 4 | Viewed by 1890

Abstract

An abundant hollow nanostructure is crucial for fast Li⁺ and K⁺ diffusion paths and sufficient electrolyte penetration, which creates a highly conductive network for ionic and electronic transport. In this study, we successfully developed a molecular-bridge-linked, organic–inorganic hybrid interface that enables [...] Read more.

An abundant hollow nanostructure is crucial for fast Li⁺ and K⁺ diffusion paths and sufficient electrolyte penetration, which creates a highly conductive network for ionic and electronic transport. In this study, we successfully developed a molecular-bridge-linked, organic–inorganic hybrid interface that enables the preparation of in situ nitrogen-doped hollow carbon nanospheres. Moreover, the prepared HCNSs, with high nitrogen content of up to 10.4%, feature homogeneous and regular morphologies. The resulting HCNSs exhibit excellent lithium and potassium storage properties when used as electrode materials. Specifically, the HCNS-800 electrode demonstrates a stable reversible discharge capacity of 642 mA h g⁻¹ at 1000 mA g⁻¹ after 500 cycles for LIBs. Similarly, the electrode maintains a discharge capacity of 205 mA h g⁻¹ at 100 mA g⁻¹ after 500 cycles for KIBs. Moreover, when coupled with a high-mass-loading LiFePO₄ cathode to design full cells, the HCNS-800‖LiFePO₄ cells provide a specific discharge capacity of 139 mA h g⁻¹ at 0.1 C. These results indicate that the HCNS electrode has promising potential for use in high-energy and environmentally sustainable lithium-based and potassium-based batteries. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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28 pages, 3000 KiB

Open AccessReview

Review of Developments in Plate Heat Exchanger Heat Transfer Enhancement for Single-Phase Applications in Process Industries

by Olga Arsenyeva, Leonid Tovazhnyanskyy, Petro Kapustenko, Jiří Jaromír Klemeš and Petar Sabev Varbanov

Energies 2023, 16(13), 4976; https://doi.org/10.3390/en16134976 - 27 Jun 2023

Cited by 26 | Viewed by 7320

Abstract

A plate heat exchanger (PHE) is a modern, effective type of heat transfer equipment capable of increasing heat recuperation and energy efficiency. For PHEs, enhanced methods of heat transfer intensification can be further applied using the analysis and knowledge already available in the [...] Read more.

A plate heat exchanger (PHE) is a modern, effective type of heat transfer equipment capable of increasing heat recuperation and energy efficiency. For PHEs, enhanced methods of heat transfer intensification can be further applied using the analysis and knowledge already available in the literature. A review of the main developments in the construction and exploration of PHEs and in the methods of heat transfer intensification is presented in this paper with an analysis of the main construction modifications, such as plate-and-frame, brazed and welded PHEs. The differences between these construction modifications and their influences on the thermal and hydraulic performance of PHEs are discussed. Most modern PHEs have plates with inclined corrugations on their surface that create a strong, rigid construction with multiple contact points between the plates. The methods of PHE exploration are mostly experimental studies and/or CFD modelling. The main corrugation parameters influencing PHE performance are the corrugation inclination angle in relation to the main flow direction and the corrugation aspect ratio. Optimisation of these parameters is one way to enhance PHE performance. Other methods of heat transfer enhancement, including improving the form of the plate corrugations, use of nanofluids and active methods, are considered. Future research directions are proposed, such as improving fundamental understanding, developing new corrugation shapes and optimisation methods and area and cost estimations. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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23 pages, 5770 KiB

Open AccessReview

Insights into Induction Heating Processes for Polymeric Materials: An Overview of the Mechanisms and Current Applications

by Alberto Mariani and Giulio Malucelli

Energies 2023, 16(11), 4535; https://doi.org/10.3390/en16114535 - 5 Jun 2023

Cited by 10 | Viewed by 3353

Abstract

In polymer systems, induction heating (IH) is the physical outcome that results from the exposure of selected polymer composites embedding electrically-conductive and/or ferromagnetic fillers to an alternating electromagnetic field (frequency range: from kHz to MHz). The interaction of the applied electromagnetic field with [...] Read more.

In polymer systems, induction heating (IH) is the physical outcome that results from the exposure of selected polymer composites embedding electrically-conductive and/or ferromagnetic fillers to an alternating electromagnetic field (frequency range: from kHz to MHz). The interaction of the applied electromagnetic field with the material accounts for the creation of magnetic polarization effects (i.e., magnetic hysteresis losses) and/or eddy currents (i.e., Joule losses, upon the formation of closed electrical loops), which, in turn, cause the heating up of the material itself. The heat involved can be exploited for different uses, ranging from the curing of thermosetting systems, the welding of thermoplastics, and the processing of temperature-sensitive materials (through selective IH) up to the activation of special effects in polymer systems (such as self-healing and shape-memory effects). This review aims at summarizing the current state-of-the-art of IH processes for polymers, providing readers with the current limitations and challenges, and further discussing some possible developments for the following years. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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14 pages, 6565 KiB

Open AccessArticle

Fabrication and Experimental Study of Micro/Sub-Micro Porous Copper Coating for Anti-Icing Application

by Jingxiang Chen, Cheng Fu, Junye Li, Weiyu Tang, Xinglong Gao and Jingzhi Zhang

Materials 2023, 16(10), 3774; https://doi.org/10.3390/ma16103774 - 16 May 2023

Cited by 2 | Viewed by 1898

Abstract

Micro and sub-micro-spherical copper powder slurries were elaborately prepared to fabricate different types of porous coating surfaces. These surfaces were further treated with low surface energy modification to obtain the superhydrophobic and slippery capacity. The surface wettability and chemical component were measured. The [...] Read more.

Micro and sub-micro-spherical copper powder slurries were elaborately prepared to fabricate different types of porous coating surfaces. These surfaces were further treated with low surface energy modification to obtain the superhydrophobic and slippery capacity. The surface wettability and chemical component were measured. The results showed that both the micro and sub-micro porous coating layer greatly increased the water-repellence capability of the substrate compared with the bare copper plate. Notably, the PFDTES-fluorinated coating surfaces yielded superhydrophobic ability against water under 0 °C with a contact angle of ~150° and a contact angle of hysteresis of ~7°. The contact angle results showed that the water repellency of the coating surface deteriorated with decreasing temperature from 10 °C to −20 °C, and the reason was probably recognized as the vapor condensation in the sub-cooled porous layer. The anti-icing test showed that the ice adhesion strengths of the micro and sub-micro-coated surfaces were 38.5 kPa and 30.2 kPa, producing a 62.8% and 72.7% decrease compared to the bare plate. The PFDTES-fluorinated and slippery liquid-infused porous coating surfaces both produced ultra-low ice adhesion strengths of 11.5–15.7 kPa compared with the other non-treated surfaces, which showed prominent properties for anti-icing and deicing requirement of the metallic surface. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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21 pages, 3936 KiB

Open AccessArticle

Numerical Study of Steam–CO₂ Mixture Condensation over a Flat Plate Based on the Solubility of CO₂

by Bingran Jiang, Yi’ao Jiang, Huaduo Gu, Yaping Chen and Jiafeng Wu

Appl. Sci. 2023, 13(9), 5747; https://doi.org/10.3390/app13095747 - 6 May 2023

Cited by 1 | Viewed by 2014

Abstract

In order to successfully study the condensation and separation of a steam–CO₂ mixture, a boundary layer model was applied to the mixture condensation of steam and CO₂ on horizontal and vertical plates. The modified condensation boundary layer model of steam and [...] Read more.

In order to successfully study the condensation and separation of a steam–CO₂ mixture, a boundary layer model was applied to the mixture condensation of steam and CO₂ on horizontal and vertical plates. The modified condensation boundary layer model of steam and CO₂, given the CO₂ solubility in the condensate, was established, numerically solved, and verified with existing experimental data. Different condensation data of steam–air and steam–CO₂ mixtures were compared, and the effect of CO₂ solubility on the mixed gas condensation was analyzed under multiple pressure conditions (1 atm–10 MPa). The simulation data show that the presence of CO₂ will deteriorate the condensation heat transfer, just like air. Given that CO₂ is slightly soluble, some CO₂ can pass through the gas–liquid interface to enter the condensate film and reduce the accumulated CO₂ on the gas–liquid interface, which improves the condensation. However, the solubility of CO₂ is only significant under high-pressure conditions, inducing its effects on condensation. A comparison of the condensation coefficients of the steam–CO₂ mixture shows the lower impact of CO₂ condensation on the horizontal plate compared to that on the vertical plate. For most conditions, the steam–CO₂ mixture gas condensation heat transfer coefficient on the vertical plate surface is still larger than that on the horizontal plate surface, and the improvement in the condensation heat transfer coefficient caused by low CO₂ solubility (2 or 10%) at 10 MPa on the vertical plate is also larger than that of the horizontal plate. Full article

(This article belongs to the Topic Advanced Heat and Mass Transfer Technologies)

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