No abstract

High temperatures and non-uniform temperatures both have a negative bearing on the performance of proton exchange membrane fuel cells. The temperature of proton exchange membrane fuel cells can be lowered by reasonably distributed cooling channels. The flow field distribution of five different cooling plates is designed, and the temperature uniformity, pressure drop and velocity of each cooling flow field are analyzed by computational fluid dynamics technology. The results show that while the pressure drop is high, the flow channel distribution of a multi-spiral flow field and honeycomb structure flow field contribute more to improving the temperature uniformity. As the coolant is blocked by the uniform plate, it is found that although the flow field channel with a uniform plate has poor performance in terms of temperature uniformity, its heat dissipation capacity is still better than that of the traditional serpentine flow field. The multi-spiral flow field has the strongest ability to maintain the temperature stability in the cooling plate when the heat flux increases. The increase in Reynolds number, although increasing the pressure drop, can reduce the maximum temperature and temperature difference of the flow field, ameliorate the temperature uniformity and improve the heat transfer capacity of the cooling plate.

No abstract

No abstract

The flow field structure and cooling medium of tubes have major influence on the heat transfer performance of automotive radiator. In this study, two novel types of radiator tube (wasp-waisted tube 2# and wasp-waisted tube 3#) are developed, six types radiator tubes with different flow field structures and equal flow cross-sectional area are numerically simulated. In addition, four nanofluids with different concentrations (Al2O3/water, SiO2/water, TiO2/water and CuO/water) were studied in Reynolds number 2500-7500. The results show that the heat transfer capacity of the wasp-waisted tube 2# and the wasp-waisted tube 3# is significantly better than that of the other radiator tubes, followed by the wasp-waisted tube. Compared with the wasp-waisted tube, the heat transfer coefficient of the wasp-waisted tube 2# and the wasp-waisted tube 3# increased by 10.6% and 3.5% respectively. On the other hand, nanoparticles improve the heat transfer efficiency of base fluid. When Re reaches 7500 and the volume concentration is 3%, the Nunf/Nubf of SiO2/water is 5.52%, 5.22% and 8.70% higher than that of Al2O3 /water, TiO2/water and CuO/water, respectively. The comprehensive heat transfer capacity of SiO2/water-3% in the wasp-waisted tube is the best.