Comparative Evaluation and Multi-Objective Optimization of Cold Plate Designed for the Lithium-Ion Battery Pack of an Electrical Pickup by Using Taguchi–Grey Relational Analysis

It is aimed to minimize carbon emissions and the spread of electric vehicles is supported for a more sustainable future. To increase the safety and life of these vehicles, cooling systems are added and developed to their energy storage systems. The aim of this study is to design and optimize the cooling plate for the lithium-ion battery pack used in a lightweight commercial electrical vehicle. Multi-objective optimization using Taguchi–grey relational analysis was performed by considering maximum temperature, the standard deviation of temperature, and pressure drop for the design of the cold plate. Channel number, channel height, and mass flow rate values were determined as parameters to be examined, and three different levels were selected for each parameter. Analysis was performed using water and 25% and 50% ethylene glycol–water solutions, which can work under sub-zero environmental conditions, employed as cooling fluid. It is shown that increasing the ethylene glycol ratio in the coolant allows it to work in colder environmental conditions, it is relatively worsening thermal performances in the cold plate applications. A new empirical correlation is proposed to predict the Nusselt number for the three coolants under all geometric and operating conditions considered in this study. Statistical analysis shows that the number of channels is the most effective parameter for the relatively low and homogenous temperature distribution on the cold plate surface. A sensitivity analysis was performed for Reynolds number ranges from 2500 to 15,000 using the optimum configurations of the three coolant fluids. It is shown that the same cooling effects could be obtained by using 1.56 times and 2.66 times more mass flow rates for 25% and 50% ethylene glycol–water solutions, respectively, compared to the water. However, rising mass flow rates result in a significant increase in the required pumping power.