Experimental study on Start-Up and heat transfer characteristics in loop heat pipes with dual heat sources for battery thermal management system

Electric vehicles represent a breakthrough in sustainable transportation, significantly diminishing global emissions. The efficacy of lithium-ion batteries is significantly influenced by the operating temperature, with elevated temperatures potentially resulting in thermal runaway. A proficient battery thermal management system (TMS) must resolve this concern and uphold safe temperatures. Loop heat pipes (LHPs) offer passive cooling technology and have garnered the attention of researchers. Nonetheless, research on LHPs for battery thermal management systems is scarce, and prior investigations have concentrated on a singular heat source. A liquid heat pipe with a dual heat source evaporator has been engineered to simulate the battery arrangement of electric vehicles, which typically comprises multiple battery cells. This study seeks to examine the starting and heat transmission characteristics of LHP. Two battery simulators are fabricated from steel blocks equipped with cartridge heaters. A copper evaporator (121 x 56 x 20 mm) is equipped with a stainless-steel screen mesh capillary wick, and thermocouples are linked to a National Instruments data acquisition (NI DAQ) system for the LHP. Ethanol serves as the working fluid at a filling ratio of 60 %. The startup characteristics of the LHP are examined by altering the heat load, coolant flow rate, and coolant temperature. The experimental findings indicate that the LHP effectively initiates operation at heat loads ranging from 20 to 100 W. The LHP with multiple heat sources demonstrates reduced temperatures compared to a single heat source. The best performance of coolant flow rate and temperature for the quickest startup times are 1.5 L/min and 25 degrees C, respectively. The lowest thermal resistance achieved is 0.17 degrees C/W.