Experimental Investigation of the Effect of Hybrid Cooling on Battery Module with Phase Change Material and Different Fin Structure

Abstract

The battery generates heat during charging and discharging and this generated heat must be removed from the battery. So, battery thermal management system is very important in rechargeable battery. Lithium-ion batteries with different capacities and internal structures could require different cooling types and designs for effective battery thermal management systems. In this study, battery thermal performance is investigated in both passive and hybrid cooling with the newly designed cooling system. In this cooling system, first natural convection and then forced convection are studied. The battery module is created by placing PCM, copper tube and fins around the battery and battery temperatures are investigated at different discharge rates. Three different types of fins are used in flat, triangular and branched models. Three different ranges are examined as Re number 2148, 4296 and 8592. The pressure drops in the test chambers under these conditions are also measured. Considering the safety temperature, the battery module is discharged at 4C-rate in natural convection, while it was applied in forced convection at 5C-rate. When the temperatures are examined, battery temperature with natural convection is 74.2 degrees C, while with forced convection it is 52 degrees C. Thanks to the designed hybrid cooling system, the temperature decreased by 22 degrees C. The maximum temperature difference between the cells in the battery module is 6 degrees C at most. It is determined that the temperature difference is highest in natural convection. The best thermal management is achieved in the hybrid cooling design with forced convection and flat fins. The maximum temperature difference increases as the discharge rate increases. Thanks to this designed hybrid cooling system, more effective thermal performance is provided for the battery module by providing passive cooling at low discharge rates and hybrid cooling at high discharge rates.