Experimental study on heat transfer performance of vapor chambers with potential applications in thermal management of proton exchange membrane fuel cells

Thermal management is one of the key factors affecting the performance and durability of proton exchange membrane fuel cells. In this study, a new concept of thermal management of proton exchange membrane fuel cells using vapor chambers is proposed, and a novel vapor chamber with a thickness of only 1.32 mm is developed. The effects of heat transfer direction, heating power, tilt angle, and cooling water flow rate on the heat transfer performance of the vapor chamber are investigated experimentally. The results show that the vapor chamber has high thermal conductivity and excellent isothermal characteristics. In the longitudinal heat transfer tests, when the heating power is 44 W, the average temperature difference of the vapor chamber is less than 6 degrees C, and the thermal resistance is only about 0.111 degrees C/W. While in the lateral heat transfer tests, the average temperature difference and thermal resistance are smaller and the temperature distribution is more uniform. Moreover, the vapor chamber has a very fast thermal response speed, requiring only a few tens of seconds to less than 200 s to quickly reach the new thermal equilibrium. The experimental results also show that the vapor chamber is not very sensitive to the change of tilt angle in the lateral heat transfer tests, and only a weak cooling condition is required to achieve the ideal isothermal operation of the vapor chamber. These results prove that the designed vapor chamber can meet the heat transfer requirements of low-power PEMFCs, and therefore may have great potential for thermal management of fuel cells in portable applications.