Article
Chemistry, Physical
Wu Yujing, Zhou Hongxiu, Zhang Ao, Zhao Leqing
Summary: The research shows that flowing electrode direct methanol fuel cell (FEDMFC) effectively reduces methanol crossover rate while maintaining high power densities. Increasing flow rate can decrease crossover rate but will affect efficiency and stability, with optimal flow rate controlled at 1-3 sccm.
JOURNAL OF POWER SOURCES
(2022)
Article
Chemistry, Physical
Shurui Zhang, Yusong Yu, Jiawei Ding, Chaoran Hou, Yaobin Jiang
Summary: A numerical model was used to simulate the liquid hydrogen phase transition in a non-isothermal horizontal circular tube under different gravity conditions. The results showed that the flow fluctuations were strongest under the gravity acceleration of 10-1 g relative to other gravity conditions. The average bubble volume at 10-1 g was the smallest, which was 11.58% smaller than that at 10-3 g condition. The intermittent contact with the tube wall, which lead to intermittent long bubble and flow resistance, was the main reason.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Chemistry, Physical
Hao-Nan Wang, Nan He, Da-Wei Tang, Lin Li
Summary: The study found that increasing the current density will raise the operating temperature, increase the generation rate of methanol vapor, and reduce concentration polarization. Meanwhile, under the condition of enlarging the open area ratio, an excessive methanol supply rate may lead to deteriorated methanol crossover rates and excessively high temperatures.
JOURNAL OF POWER SOURCES
(2022)
Article
Energy & Fuels
Anders Christian Olesen, Soren Knudsen Kaer, Torsten Berning
Summary: Direct-methanol fuel cell (DMFC) systems are relatively simple, but accurately controlling the mixture of methanol and water is a key challenge. Computational fluid dynamics can provide fundamental understanding of this. This paper presents a three-dimensional, steady-state, two-phase, multi-component and non-isothermal DMFC model that can account for various transport phenomena. The model is validated against experimental measurements and used to study the impact of volume porosity and capillary pressure on performance.
Article
Thermodynamics
Xiaoyu Wang, Xing Jin, Yonggao Yin, Xing Shi, Xin Zhou
Summary: This paper presents a new transient model for coupled heat and moisture transfer in building materials based on a phase change criterion (PCC). The relations between PCC and material properties were derived to evaluate the effects of relative humidity, temperature, and temperature gradient. Numerical results showed that the sorption capacity significantly affected the PCC, and the proposed PCC model was more accurate than empirical models when the relative humidity exceeded 60%.
Article
Energy & Fuels
Haoran Zhou, Kai Meng, Wenshang Chen, Ben Chen
Summary: This study developed a model of a three-dimensional, two-phase, non-isothermal proton exchange membrane (PEM) water electrolyzer to investigate the water and heat distribution characteristics and the effects of various parameters on heat and mass transfer and electrolyzer performance. The results showed that the performance of the electrolyzer depended on the combined effect of heat and mass, particularly at high voltages. Increasing the inlet velocity accelerated bubble discharge but led to a larger temperature drop and performance degradation. Increasing the inlet temperature improved the reaction rate and reduced the membrane resistance, thus promoting performance improvement. The contact angle and porosity of the anode gas diffusion layer (A-GDL) affected the transport of liquid water and performance, with an optimal porosity range of 0.5 to 0.6.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2022)
Article
Energy & Fuels
Hongxiu Zhou, Yujing Wu, Leqing Zhao
Summary: A complete flow field and two-phase model for DMFC is developed to study the impact of anode flow fields on various aspects. Four different flow field structures are analyzed and compared. The results show that SFF has the highest power density but suffers from increased pressure drop and potential bubble blockage, while PFF has lower pressure loss but poor cell performance. The DSFF exhibits the best overall performance, followed by the PSFF, due to their higher power density, lower pressure loss, better CO2 gas removal, and superior thermal management.
Article
Thermodynamics
Mirae Kim, Heesue Jeong, Ahmad Ali Awais, Seungho Kim, Kyung Chun Kim
Summary: The thermal performance of a metal-foam heat exchanger in cryogenic environments was examined through an experiment and a CFD simulation. The results showed good agreement between the experimental data and CFD predictions, indicating that the metal-foam heat exchanger performed well in low-temperature conditions.
APPLIED THERMAL ENGINEERING
(2022)
Article
Materials Science, Multidisciplinary
Thanarajan Kumaresan, Dineshkumar Ponniyan, Mathan Chandran, Jegathishkumar Ramasamy, Velarasan Venkatachalam, Karthikeyan Palaniswamy, Senthilarasu Sundaram
Summary: In this study, the overall performance of a direct methanol fuel cell with an active area of 100 cm(2) was experimentally tested under different operating situations. The most influencing parameters, such as anode flow rate, cathode reactant, and cathode flow rate, were compared in terms of their performance output. Additionally, the performance of different cathode flow channels, namely serpentine and sinuous, were compared to improve reactant supply. Using sinuous flow field at the cathode and specific methanol and oxygen flow rates, a maximum power density of 24 mW/cm(2) was achieved.
Article
Thermodynamics
Haidong Liu, Deqi Chen, Jiang Qin, Erlei Zhao, Peigang Yan, Wei Liu, Hanzhou Liu
Summary: This paper presents a qualitative and quantitative analysis of subcooled flow boiling behavior near the heating wall and discusses the phenomena before and during the critical heat flux (CHF) based on visual experiments and image post-processing techniques. The study reveals that high thermal hydraulic parameters reduce the possibility of triggering boiling crisis and result in higher CHF values. Additionally, a prediction method for the wavelength between two-phase layers is proposed and shows good agreement with experimental data.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Chemistry, Physical
Jegathishkumar Ramasamy, Karthikeyan Palaniswamy, Thanarajan Kumaresan, Mathan Chandran, Rui Chen
Summary: The study demonstrates that modifying flow channels can enhance the performance of direct methanol fuel cells. While the serpentine channel provides better methanol distribution, it lacks in water management. The results highlight the effectiveness of zigzag and pin channels in mitigating water accumulation and ensuring better oxygen supply at the cathode.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Engineering, Aerospace
Svetlana A. Gruzd, Mikhail D. Krivilyov, Dmitry S. Samsonov, Yangyang Wu, Dusan P. Sekulic, Sinisa Dj Mesarovic
Summary: Gravity plays a significant role in multiphase flows, as it can affect the migration of free liquid surfaces similar to capillary, thermal, and compositional effects. The wetting and spreading behavior of liquid metal over solid surfaces can be substantially altered under microgravity conditions. This study investigates the viscous flow of braze Al-Si material on the surface of a metal pin through experimental and phase-field simulations. The results show that gravity does not have a considerable impact on meniscus formation for the given quantities of brazing fluids.
MICROGRAVITY SCIENCE AND TECHNOLOGY
(2022)
Article
Thermodynamics
Weixin Tong, Jie Ji, Chen Wang, Chunxiao Li, Jiping Zhu
Summary: The development of coal-based fuels is the best solution to the petroleum shortage, but fuel leakage can lead to spill fires and pose a serious threat to energy utilization. By conducting experiments on a vertical plate, the combustion behavior of spill fires can be better understood.
Article
Thermodynamics
Sameer Osman, Mahmoud Ahmed
Summary: A new design for direct methanol fuel cells has been proposed to significantly enhance performance at high current densities and has advantages in the parallel flow field configuration. Experimental studies show that the design improves cell performance and removes bubbles, reducing energy consumption.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Mechanics
Chuanshuai Dong, Ronghui Qi, Lizhi Zhang
Summary: This paper develops a novel mechanistic model for flow and heat transfer in two-phase slug flow in horizontal pipes. The model is validated by experimental results and comprehensively investigates the dependence of heat transfer performance on overall and local flow parameters.
