Open Access
ARTICLE
Liang Yi, Zhiqiang Lei, Zhisheng Xu, Yaolong Yin, Houlin Ying*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2024.053688
（This article belongs to the Special Issue: Heat and Mass Transfer in Fire)
Abstract This paper explores the smoke flow characteristics in tunnel fires, giving a particular emphasis on the effects of different distances between the smoke outlets and the fire source. It examines the smoke behavior under different conditions, including variations in heat release rates, exhaust volumetric flow rates, spacing between smoke outlets, and the longitudinal fire source positions. Results indicate that altering the fire source positions and the smoke outlets in the tunnel leads to variations in the properties of smoke flow both the fire source upstream and downstream; the distance between fire source and smoke outlet… More >
Open Access
ARTICLE
Ahmed Mustaffa Saleem, Abdullah A. Badr, Bahjat Hassan Alyas, Omar Rafae Alomar*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2024.053770
Abstract This study numerically involves the performance of thermal insulation of different types of composite walls and roofs to demonstrate the best model that can be used for energy-efficient building construction in Iraq. The mathematical model is solved by building its code using the Transmission Matrix Method in MATLAB software. The weather data of 21st July 2022 in Baghdad City/Iraq is selected as a test day. The wall types are selected: the first type consists of cement mortar, brick, and gypsum, the second type consists of cement mortar, brick, gypsum, and plaster and the third type… More >
Open Access
ARTICLE
Haowei Hu1,2,*, Qi Wang1, Xinnuo Chen1, Qin Li3, Mu Du4, Dong Niu5,*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2024.054223
Abstract To investigate the microscopic mechanism underlying the influence of surface-chemical gradient on heat and mass recovery, a molecular dynamics model including droplet condensation and transport process has been developed to examine heat and mass recovery performance. This work aimed at identify optimal conditions for enhancing heat and mass recovery through the combination of wettability gradient and nanopore transport. For comprehensive analysis, the structure in the simulation was categorized into three distinct groups: a homogeneous structure, a small wettability gradient, and a large wettability gradient. The homogeneous surface demonstrated low efficiency in heat and mass transfer, More >
Open Access
ARTICLE
Jawad Raza1, F. Mebarek-Oudina2,*, Haider Ali1, I. E. Sarris3
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2024.052749
（This article belongs to the Special Issue: Advances in Computational Thermo-Fluids and Nanofluids)
Abstract The current study is dedicated to presenting the Casson nanofluid over a stretching surface with activation energy. In order to make the problem more realistic, we employed magnetic field and slip effects on fluid flow. The governing partial differential equations (PDEs) were converted to ordinary differential equations (ODEs) by similarity variables and then solved numerically. The MATLAB built-in command ‘bvp4c’ is utilized to solve the system of ODEs. Central composite factorial design based response surface methodology (RSM) is also employed for optimization. For this, quadratic regression is used for data analysis. The results are concluded More >
Graphic Abstract
Open Access
ARTICLE
Yangyiming Rong1, Weitao Su1, Shuai Wang2, Bowen Du1, Jianjian Wei2, Shaozhi Zhang2,*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2024.052415
（This article belongs to the Special Issue: Computational and Numerical Advances in Heat Transfer: Models and Methods II)
Abstract Finned-tube heat exchanger (FTHE) is often used as an evaporator in commercial products of separated heat pipe (SHP). The working conditions of FTHE in gravity-assisted SHP are significantly different from those working in refrigerators and air conditioners. Although FTHE is widely used in commercial products of SHP, previous research on its characteristics is very limited. In this paper, a mathematical model for a SHP with FTHE as the evaporator and plate heat exchanger as the condenser is established and verified with experiments. Parametric analyses are carried out to investigate the influences of evaporator design parameters:… More >
Open Access
ARTICLE
Haowei Hu1,2,*, Xinnuo Chen1, Qi Wang1, Qin Li3, Dong Niu4, Mu Du5,*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2024.054218
Abstract The self-driven behavior of droplets on a functionalized surface, coupled with wetting gradient and wedge patterns, is systematically investigated using molecular dynamics (MD) simulations. The effects of key factors, including wedge angle, wettability, and wetting gradient, on the droplet self-driving effect is revealed from the nanoscale. Results indicate that the maximum velocity of droplets on hydrophobic wedge-shaped surfaces increases with the wedge angle, accompanied by a rapid attenuation of driving force; however, the average velocity decreases with the increased wedge angle. Conversely, droplet movement on hydrophilic wedge-shaped surfaces follows the opposite trend, particularly in terms… More >
Open Access
ARTICLE
Bo Zhang1, Yunxie Huang2, Peilin Cui2, Zhiguo Wang1, Duo Ding1, Zhenhai Pan3, Zhenyu Liu2,*
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2024.053592
（This article belongs to the Special Issue: Fluid Flow, Heat and Mass Transfer within Novel Cooling Structures)
Abstract The high surface area of porous media enhances its efficacy for evaporative cooling, however, the evaporation of pure substances often encounters issues including local overheating and unstable heat transfer. To address these challenges, a volume of fluid (VOF) model integrated with a species transport model was developed to predict the evaporation processes of ternary mixtures (water, glycerol, and 1,2-propylene glycol) in porous ceramics in this study. It reveals that the synergistic effects of thermal conduction and convective heat transfer significantly influence the mixtures evaporation, causing the fluctuations in evaporation rates. The obtained result shows a More >
Open Access
ARTICLE
Zakaria Triki1, Ahmed Selloum1, Younes Chiba1, Hichem Tahraoui1,2, Dorsaf Mansour3, Abdeltif Amrane4,*, Meriem Zamouche5, Mohammed Kebir6, Jie Zhang7
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2024.052223
（This article belongs to the Special Issue: Innovative Heat Transfer Fluids for Enhanced Energy Sustainability in Thermal Systems)
Abstract Refrigeration plays a significant role across various aspects of human life and consumes substantial amounts of electrical energy. The rapid advancement of green cooling technology presents numerous solar-powered refrigeration systems as viable alternatives to traditional refrigeration equipment. Exergy analysis is a key in identifying actual thermodynamic losses and improving the environmental and economic efficiency of refrigeration systems. In this study exergy analyze has been conducted for a solar-powered vapor compression refrigeration (SP-VCR) system in the region of Ghardaïa (Southern Algeria) utilizing R1234ze(E) fluid as an eco-friendly substitute for R134a refrigerant. A MATLAB-based numerical model was… More >
Open Access
ARTICLE
Amal El Berry, Marwa M. Ibrahim*, A. A. Elfeky, Mohamed F. Nasr
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2024.050684
Abstract A photovoltaic (PV) inverter is a vital component of a photovoltaic (PV) solar system. Photovoltaic (PV) inverter failure can mean a solar system that is no longer functioning. When electronic devices such as photovoltaic (PV) inverter devices are subjected to vapor condensation, a risk could occur. Given the amount of moisture in the air, saturation occurs when the temperature drops to the dew point, and condensation may form on surfaces. Numerical simulation with “COMSOL Software” is important for obtaining knowledge relevant to preventing condensation by using two steps. At first, the assumption was that the… More >
Open Access
ARTICLE
Matiewos Mekonen Abera1,2,*, Venkata Ramayya Ancha1, Balewgize Amare1, L. Syam Sundar3, Kotturu V. V. Chandra Mouli4, Sambasivam Sangaraju5
Frontiers in Heat and Mass Transfer, DOI:10.32604/fhmt.2024.049525
（This article belongs to the Special Issue: Entropy Generation and Exergy Analysis of Thermal Devices)
Abstract This study is focused on the simulation and optimization of packed-bed solar thermal energy storage by using sand as a storage material and hot-water is used as a heat transfer fluid and storage as well. The analysis has been done by using the COMSOL multi-physics software and used to compute an optimization charging time of the storage. Parameters that control this optimization are storage height, storage diameter, heat transfer fluid flow rate, and sand bed particle size. The result of COMSOL multi-physics optimized thermal storage has been validated with Taguchi method. Accordingly, the optimized parameters… More >
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