Article
Chemistry, Physical
Zhifeng Xia, Huicui Chen, Wanchao Shan, Ruirui Zhang, Tong Zhang, Pucheng Pei
Summary: In this study, a 25 cm2 segmented PEMFC engine was assembled to investigate reactant starvation phenomenon, and contour maps of current distribution were used to analyze the mechanism. The experimental results showed that the current distribution had high-quality homogeneity with the tripleserpentine configuration even under starvation conditions. Air starvation experiments indicated the migration of the lowest current region and a variation in standard deviation with increasing stoichiometry. It was concluded that ORR played a dominant role in the specific current distribution, and this study provided insights for improving the lifespan and potential commercialization of PEMFC engines.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Electrochemistry
Tatyana Reshetenko, Olga Polevaya
Summary: This study demonstrates the applicability and validity of a novel method for determining oxygen mass transport resistance in proton exchange membrane fuel cells. The method is based on measuring the limiting current when a cathode is fed with highly diluted O-2 mixtures, allowing for separation of different sources of mass transport resistance. Evaluation and comparison of different cell designs under varied conditions reveal the importance of gas phase transport and efficient oxygen diffusion through the ionomer.
ELECTROCHIMICA ACTA
(2021)
Article
Electrochemistry
Qiong Wang, Zhiguo Qu, Zhiyuan Jiang, Jin Xuan, Huizhi Wang
Summary: This study presents a novel pluggable current collector for in-operando current distribution measurements in VRFBs with flow field, which greatly simplifies the current density measurement process and improves reliability. Insufficient supplemental reactant in electrode border region is identified as the main cause for non-uniform current density distribution, with unevenness intensified in the initial and final stages of cycling process. The developed method is believed to enhance the understanding of local reactions and transport processes in VRFBs and guide future battery design.
ELECTROCHIMICA ACTA
(2021)
Article
Thermodynamics
Jonathan Valentin-Reyes, Maria I. Leon, Tzayam Perez, Tatiana Romero-Castanon, Jose Beltran, Jose R. Flores-Hernandez, Jose Luis Nava
Summary: This short communication discusses the design of an interdigitated flow channel in a PEMFC and evaluates its performance using CFD simulations and experiments. The results show good agreement between experimental and simulated data at low current densities. This study provides valuable insights for the design and performance optimization of fuel cells.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Physics, Fluids & Plasmas
Palak Dugar, Chih-Chun Chien
Summary: In this study, a geometry-based mechanism for generating steady-state internal circulation of local thermal currents is demonstrated in two different systems. The results highlight the ubiquity and robustness of this mechanism in both quantum and classical systems.
Article
Chemistry, Physical
Mingxin Liu, Wenxuan Fan, Guolong Lu
Summary: A three-dimensional numerical model is established to compare different types of locally improved structures in PEM fuel cells. The new variable diameter structure improves oxygen uniformity, while the block structure enhances local mass transfer. The presence of locally improved structures in the middle of the flow field achieves the best performance.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Energy & Fuels
Zongyi Cheng, Lizhong Luo, Bi Huang, Qifei Jian
Summary: This article uses transient simulation to analyze the distribution of reactants and water content in a full flow field fuel cell during anode purge. The study found that water content changes in different stages of purge, but after multiple purge, hydrogen distribution in the anode flow channel reaches dynamic equilibrium.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2021)
Article
Energy & Fuels
Xun Zhang, Xiaolong Yang, Weitao Gao, Cheng Wang
Summary: In this study, the performance of PEM fuel cells with different baffled flow field plates was experimentally tested, showing that adding baffles can improve the fuel cell's performance and current density distribution uniformity. However, increasing baffle height will also increase pressure drop. To address this issue, a half-baffled flow field design was proposed to maintain current density distribution uniformity while reducing pressure drop.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2021)
Article
Chemistry, Physical
Guanguang Li, Minhua Wu, Deyang Zeng, Mingfeng Wu, Yinghui Zhang, YouKun Tao, Jing Shao
Summary: This study investigates the effect of discrete cylindrical landing flow fields on the internal distribution and overall power output of SOFCs. It is found that the cylindrical landing flow fields significantly reduce the local variation of mass distribution and improve the uniformity of current distribution, leading to improved overall output performance.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Thermodynamics
Zhuo Zhang, Qi-yao Wang, Fan Bai, Li Chen, Wen-quan Tao
Summary: Commercial fuel cell stacks with large electrode area are used for high power output. The uniformity in-plane distribution of key parameters is important for improving cell performance. This study analyzed the in-plane distribution characteristics of a large-scale PEMFC using a three-dimensional two-fluid multiphase model, showing that gap zones near the edge affect cell performance and that coolant flow direction has a significant impact. The results provide insights for optimizing fuel cells.
Article
Energy & Fuels
Jie Sun, Yansong Luo, Menglian Zheng, Zitao Yu
Summary: Flow fields can enhance the peak power density of redox flow batteries through distributing the electrolyte and reactants uniformly in the porous electrode. This study establishes an analytical model for quantifying mass transfer and electrochemical overpotentials in flow cells with serpentine or interdigitated flow fields. Parametric study results show that changes in properties have paradoxical effects on flow cells implemented with different flow fields.
JOURNAL OF ENERGY STORAGE
(2023)
Article
Energy & Fuels
Jie Sun, Baichen Liu, Menglian Zheng, Yansong Luo, Zitao Yu
Summary: The study proposes modified serpentine flow field designs to improve the uniformity of electrolyte penetration. Experimental results show that the modified designs can significantly improve the current density. Simulation results indicate that the effectiveness of the modified designs is more significant in large-scale flow cells and depends on the magnitude of the under-the-rib hydraulic resistance and the applied flow rate.
JOURNAL OF ENERGY STORAGE
(2022)
Article
Geosciences, Multidisciplinary
Denise Degen, Mauro Cacace
Summary: This paper focuses on the significant influence of transient processes on conductive heat transfer problems in sedimentary basin systems, highlighting the importance of time-stepping approach and simulation duration. Global sensitivity analyses are used to quantify the impact of thermal properties and parameter correlations, providing further insights into complex geological systems. The computationally demanding workflow is made feasible through high-precision surrogate models based on the reduced basis (RB) method.
GEOSCIENTIFIC MODEL DEVELOPMENT
(2021)
Article
Multidisciplinary Sciences
Felix J. Meigel, Thomas Darwent, Leonie Bastin, Lucas Goehring, Karen Alim
Summary: This study investigates dispersive transport through complex media and reveals the nonlinear dependence between microscopic morphology and macroscopic transport characteristics by studying the statistics of pore-junction units. It is of great significance for understanding and controlling transport in complex media.
NATURE COMMUNICATIONS
(2022)
Article
Energy & Fuels
Meng-Yue Lu, Yu-Hang Jiao, Xin-Yuan Tang, Wei-Wei Yang, Miao Ye, Qian Xu
Summary: The blocked serpentine flow field design significantly enhances the discharge voltage of the VRFB, reaching optimal overall battery performance at a 1.4mm block height, attributed to a tradeoff between increased pump loss and improved charge-discharge performance.
JOURNAL OF ENERGY STORAGE
(2021)
Article
Thermodynamics
Mahsa Taghavi, Swapnil Sharma, Vemuri Balakotaiah
Summary: This study investigates the natural convection effects in the insulation layers of spherical storage tanks and their impact on the tanks' performance. The permeability and Rayleigh number of the insulation material are considered as key factors. The results show that as the Rayleigh number increases, new convective cells emerge and cause the cold boundary to approach the external hot boundary. In the case of large temperature differences, multiple solutions may coexist.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyang Xu, Fangjun Hong, Chaoyang Zhang
Summary: This study introduces a self-induced jet impingement device for enhancing pool boiling performance in high power electronic cooling. Through visualization and parametric investigations, the effects of this device on pool boiling performance are studied, revealing the promotion of additional liquid supply and vapor exhausting. The flow rate of the liquid jet is found to positively impact boiling performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Wenchao Ke, Yuan Liu, Fissha Biruke Teshome, Zhi Zeng
Summary: Underwater wet laser welding (UWLW) is a promising and labor-saving repair technique. A thermal multi-phase flow model was developed to study the heat transfer, fluid dynamics, and phase transitions during UWLW. The results show that UWLW creates a water keyhole, making the welding environment similar to in air laser welding.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Xingrong Lian, Lin Tian, Zengyao Li, Xinpeng Zhao
Summary: This study investigates the heat transfer mechanisms in natural fiber-derived porous structures and finds that thermal radiation has a significant impact on the thermal conductivity in low-density regions, while natural convection rarely occurs. Insulation materials derived from micron-sized natural fibers can achieve minimum thermal conductivity at specific densities. Strategies to lower the thermal conductivity include increasing porosity and incorporating nanoscale pores using nanosize fibers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Yasir A. Malik, Kilian Koebschall, Stephan Bansmer, Cameron Tropea, Jeanette Hussong, Philippe Villedieu
Summary: Ice crystal icing is a significant hazard in aviation, and accurate modeling of sticking efficiency is essential. In this study, icing wind tunnel experiments were conducted to quantify the volumetric liquid water fraction, sticking efficiency, and maximum thickness of ice layers. Two measurement techniques, calorimetry and capacitive measurements, were used to measure the liquid water content and distribution in the ice layers. The experiments showed that increasing wet bulb temperatures and substrate heat flux significantly increased sticking efficiency and maximum ice layer thickness.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinqi Hu, Tongtong Geng, Kun Wang, Yuanhong Fan, Chunhua Min, Hsien Chin Su
Summary: This study experimentally examined the heat dissipation of vibrating fans and demonstrated its inherent mechanism through numerical simulation. The results showed that the flow fields induced by the vibrating blades exhibited pulsating features and formed large-scale and small-scale vortical structures, significantly improving heat dissipation. The study also identified the impacts of different blade structures and developed a trapezoidal-folding blade, which effectively reduced the maximum temperature of the heat source and alleviated high-temperature failure crisis.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Dan-Dan Su, Xiao-Bin Li, Hong-Na Zhang, Feng-Chen Li
Summary: The boiling heat transfer of low-boiling-point working fluid is a common heat dissipation technology in electronic equipment cooling. This study analyzed the interfacial boiling behavior of R134a under different conditions and found that factors such as the initial thickness of the liquid film, solid-liquid interaction force, and initial temperature significantly affect the boiling mode and thermal resistance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyi Wu, Dongke Sun, Wei Chen, Zhenhua Chai
Summary: A unified lattice Boltzmann-phase field scheme is proposed to simulate dendrite growth of binary alloys in the presence of melt convection. The effects of various factors on the growth are investigated numerically, and the model is validated through comparisons and examinations.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shaokun Ge, Ya Ni, Fubao Zhou, Wangzhaonan Shen, Jia Li, Fengqi Guo, Bobo Shi
Summary: This study investigated the temperature distribution of main cables in a suspension bridge during fire scenarios and proposed a prediction model for the maximum temperature of cables in different lane fires. The results showed that vehicle fires in the emergency lane posed a greater thermal threat to the cables.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shuang-Ying Wu, Shi-Yao Zhou, Lan Xiao, Jia Luo
Summary: This paper investigates the two-phase flow and heat transfer characteristics of low-velocity jet impacting on a cylindrical surface. The study reveals that the heat transfer regimes are non-phase transition and nucleate boiling with the increase of heat transfer rate. The effects of jet impact height and outlet velocity on local surface temperatures are pronounced at the non-phase transition stage. The growth rates of heat transfer rate and liquid loss rate increase significantly from the non-phase transition to nucleate boiling stage.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Emad Hasani Malekshah, Wlodzimierz Wlodzimierz, Miros law Majkut
Summary: Cavitation has significant practical importance and can be controlled by air injection. This study investigates the natural to ventilated cavitation process around a hydrofoil through numerical and experimental methods. The results show that the location and rate of air injection have a meaningful impact on the characteristics of cavitation.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Feriel Yahiat, Pascale Bouvier, Antoine Beauvillier, Serge Russeil, Christophe Andre, Daniel Bougeard
Summary: This study explores the enhancement of mixing performance in laminar flow equipment by investigating the generation of chaotic advection using wall deformations in annular geometries. The findings demonstrate that the combined geometry can achieve perfect mixing at various Reynolds numbers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Hui He, Ning Lyu, Caihua Liang, Feng Wang, Xiaosong Zhang
Summary: This study investigates the condensation, frosting, and defrosting processes on superhydrophobic surfaces with millimeter-scale structures. The results reveal that the structures can influence the growth and removal of frost crystals, with the bottom grooves creating a frost-free zone and conical edges promoting higher frost crystal heights. Two effective methods for defrosting are observed: hand-lifting the groove and airfoil retraction contraction on protruding structures. This research provides valuable insights into frost formation and defrosting on millimeter-structured superhydrophobic surfaces, with potential applications in anti-frost engineering.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Thiwanka Arepolage, Christophe Verdy, Thibaut Sylvestre, Aymeric Leray, Sebastien Euphrasie
Summary: This study developed two thermal concentrators, one with a 2D design of uniform thickness and another with a 3D design, using the coordinate transformation technique and metamaterials. By structuring the thermal conductor, the desired local density-heat capacity product and anisotropic thermal conductivities were achieved. The homogenized thermal conductivities were obtained from finite element simulations and cylindrical symmetry consideration. A 3D concentrator was fabricated using 3D metal printing and characterized using a thermal camera. Compared to devices that solely consider anisotropic conductivities, the time evolution characteristics of the metadevice designed with coordinate transformation were closer to those of an ideal concentrator.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Liangyuan Cheng, Qingyang Wang, Jinliang Xu
Summary: In this study, we investigated the supercritical heat transfer of CO2 in a horizontal tube with a diameter of 10.0 mm, covering a wide range of pressures, mass fluxes, and heat fluxes. The study revealed a non-monotonic increase in wall temperatures along the flow direction and observed both positive and negative wall temperature differences between the bottom and top tube. The findings were explained by the thermal conduction in the solid wall interacting with the stratified-wavy flow in the tube.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)