Heat transfer characteristics of non-uniform channels flat heat pipe with micro pillar arrays and its application in power battery cooling

Abstract

Heat pipe is a promising technology that can be applied to power batteries. However, it is associated with the challenge of countercurrent flow in gas–liquid two-phase working fluid. For this, this work proposes a non-uniform channels flat heat pipe with micro pillar arrays to form the internal “unidirectional flow”. The feasibility of such a strategy in alleviating the heat pipe burning dry is experimentally analyzed, along with the synergistic strengthening mechanism. Effects of heat pipe internal structures and micro pillar arrays area on thermal resistance and thermal conductivity are discussed. It is found that the maximum thermal conductivity of the optimized heat pipe could reach 3749.53 W·m−1·℃-1. On this basis, a battery cooling system coupled with the new heat pipe and localized serpentine passage cooling plate is then developed. The performance of the module is numerically evaluated by optimizing the key parameters including the passage height and operating conditions. It is shown that the system can control the average temperature of the battery pack within 27℃ at the end of 3C discharge with a coolant flow rate of 2 L/min and a channel structure of 7 mm × 7 layers. The maximum temperature difference between cells during the whole process is only 3.8℃.