Battery Thermal Management System Using Phase Change Material on Trapezoidal Battery Pack with Liquid Cooling System
The usage of Electric Vehicles (EVs) is rapidly increasing in recent years as they are eco-friendly and due to shortage of fossil fuels in future. Lithium ion battery cells are widely used batteries for EVs and hybrid electric vehicles. Because of their high specific charge, power densities and long life. In Battery Thermal Management System (BTMS) liquid cooling strategy has its own advantages and disadvantages. Liquid cooling strategy has some issues like leakage of Phase Change Material (PCM) when it completely melts and low heat transfer rate from cells to tubes. In this paper, novel design of trapezoidal battery pack is proposed with Composite Phase Change Material (CPCM) based liquid cooling system. Paraffin wax (PA) is used as PCM and graphite powder as high thermal conductive particles. CPCM is prepared in three compositions and filled in between the cells having 5mm gap.As PCM has low thermal conductivity, graphite powder (high thermal conductive particle) is employed into PCM. Thermal conductivity is enhanced from 0.25up to 2.7 W/mK and heat transfer rate is enhanced dramatically.The performance of battery pack is investigated by varying various flow velocities of coolant atdifferent discharge rates. And compare with the normal trapezoidal battery pack, battery packwith pure PCM and CPCM. Experimental tests carried at 28-30 ambient temperature and discharge rateslike 1C,2C and 3C.From the results, it is observed that CPCM based trapezoidal battery pack shows effective heat transfer rate than PCM based battery pack. And also, in liquid cooling system based BTMS uniform temperature distribution is achieved and Maximum Temperature (Tmax)is maintained at optimum range i.e. below 45 in all test conditions.