In-line and staggered design for hybrid thermal management of Li-ion cells utilized in green vehicles

Nowadays. according to high rate of oil well depletion and also toxic contaminants emitted from exhaust of conventional internal combustion engines, human has come to this conclusion that in order to mitigate this issue, there is no other solution but to utilize green cars such as hybrid electric vehicles, battery electric vehicles and fuelcell electric vehicles. The main power source of the aforementioned vehicles is Lithium-ion battery which possesses higher power and current density and also usagesafety in comparison with the other cells available in the market. The main drawback of the mentioned cell is generating great amount of energy (heat) while being charged/discharged. Engineers benefit from active and passive battery thermal management systems to solve this issue. Active systems rely on cold air to be blown to thebattery pack in order to create cooling effect or a liquid to be circulated around each individual cell via pumps. The passive BTMS benefit from phase change material whichcan cause cooling effect by being melted at a specific point called solidus tetnpcrature. These systems seem to be more efficient because of less energy consumption andtemperature gradient of cells inside a battery pack. In this paper, two common configurations of cells inside the battery pack of a green vehicle is studied and contour plotsof liquid fraction of phase change are plotted. It is concluded that the parallel configuration owns higher rate of PCM melting which means this BTMS creates bettercooling effect and preserves the cells at preferred temperature range. F inally, it should be mentioned that although the solidification/melting rate for both PCMsinside BTMSS are close, the parallel one is suggested to be widely utilized in automotive applications due to easier and low-cost production and also fewer maintenance andrepair expenses.

Keywords:

battery thermal management system (BTMS) , active BTMS , passive BTMS , phase change material(PCM) , heat transfer enhancement