Implications of novel cold plate design with hybrid cooling on thermal management of fast discharging lithium-ion battery

摘要

Electric cars powered by a green power Lithium-ion battery (LIB) system are realistic options for reducing greenhouse gas emissions and rely on fossil energy supplies. However, the heat dissipation of LIB is critical, especially at high discharge rates. In order to guarantee safety, the present work proposes a novel hybrid cooling approach for the thermal management of fast discharging LIB modules. A dual cooling approach wherein composite phase change material (CPCM) is coupled with forced convection cooling via nanofluid flow through convergent channels is analyzed. Two CPCM configurations viz., CPCM sandwiched between the cold plate (D1) and CPCM wrapped around the width of the cell (D2) are considered. The numerical simulations are performed using the finite element method to study the effects of inlet velocity, nanofluid volume fraction, and the direction of flow on the thermal management of the module. The results show that the module temperature is reduced below the safety limit when hybrid cooling is applied. Further, better cooling performance is observed when CPCM is wrapped around the battery cell as compared to when CPCM is sandwiched in between the cold plates and battery cell both in terms of uniform distribution of temperature and maximum temperature. This is evident from the reduction in maximum temperature (T-max) by 1.55 K and temperature difference (delta T) of 2.04 K at Reynolds number (Re) = 150. The effectiveness of the hybrid cooling improves with the increase in Re and becomes thermally stable when Re > 200. The maximum temperature decreases substantially by 8.76 K when the Reynolds number increases from Re = 50 to Re = 200. In addition, the increase in the nanofluid concentration of flowing fluid through the convergent channel in cold plates reduces the maximum temperature of the battery module by 3.05 K at phi = 5 % and Re = 200 although does not seem to affect the uniformity in temperature distribution substantially. Further, the temperature distribution is found more uniform when the direction of flow reverses in converging channels in alternate cold plates.