Two-phase cooling using HFE-7100 for polymer electrolyte membrane fuel cell application

The aim of this paper is to investigate two-phase heat transfer of HFE-7100 in mini-channels and its cooling performance in order to determine its effectiveness for a fuel cell application. Firstly, characteristics of two-phase boiling heat transfer of HFE-7100 is analyzed. It is demonstrated that two-phase boiling heat transfer coefficient of HFE-7100 in mini-channels is strongly dependent on heat flux and vapor quality but less sensitive to mass flux. Critical heat flux is observed when wall superheat is over 25 K and flow visualization method is used to examine a flow pattern change. In the second part, cooling performance and wall temperature change is investigated. Under heat generation ranges from a fuel cell, wall temperature is maintained at desirable operating temperature of polymer electrolyte membrane fuel cell (60-80 degrees C) and temperature difference is lower than 0.5 degrees C. At critical heat flux condition, wall temperature rises to over 90 degrees C. Also, wall temperature increases from 63.5 degrees C to 71.6 degrees C when channel pressure rises from 1.0 bar to 1.5 bar. Lastly dynamic response in wall temperature with the coolant pump control is investigated. It is found that this control method is effective to maintain low temperature difference (less than 1.5 degrees C) and the intermittent pump operating mode can reduce pump energy consumption.