Session: 11-03-01: Heat Transfer in Batteries and Energy Storage Technologies

Paper Number: 96031

96031 - Numerical Investigation on the Suitability of a PCM/Refrigerant Hybrid Cooling System for Lithium-Ion Batteries 

As electric vehicles become more prevalent, the need for safe, efficient battery packs will drastically increase. Lithium-ion batteries are at the forefront of this technology due to their high voltage, high energy density, long lifespan, and low self discharge rate. The performance and lifespan of a lithium-ion battery pack is closely related to the temperature of the battery pack. Safety is also a concern as thermal runaway can occur at temperatures above 353K. As a result, battery thermal management systems (BTMS) are required to maintain the temperature at a safe level.

The performance of a convective heat transfer and phase change hybrid BTMS has been evaluated numerically using Ansys Fluent. The BTMS consists of three component systems, each of which has been validated individually. These systems are a simple battery model that has a uniform heat generation source term, a phase chage region that utilizes Fluent's built-in melting methodology, and a small coolant channel that experiences heat transfer in the thermal entry region of laminar flow.

Refrigerant R134a is the primary focus of this paper due to its use in the existing air conditioning system. Its performance is then compared to that of water and air cooling. A parametric study with respect to the inlet velocity is conducted at Reynold's numbers of 200, 1000, and 2000 for each fluid. Paraffin and a paraffin/graphite composite are used as the phase change material (PCM), and their performance is compared to that of aluminum, representing the absence of PCM. Finally, the diameter of the cooling channel is altered to evaluate its effects on heat removal from the battery pack.

It was determined that for all cases water cooling was sufficient to keep the batteries within their optimal range. By contrast, there were no circumstances where air cooling was sufficient to keep the batteries beneath their thermal runaway temperature. At higher Reynold’s numbers, R134a was able to maintain the battery below the thermal runaway temperature, but resulted in temperatures well above the optimal operating temperature. With respect to the performance of the PCM materials, it was found that before the onset of melting, the use of aluminum resulted in a lower battery temperature than either of the PCM materials. During the melting process, the battery temperature was significantly lower when either the paraffin or paraffin/graphite composite were used. After melting, the rate at which the temperature in the PCM cases was increasing exceeded the rate at which the temperature increased with the use of aluminum, meaning after sufficient time has passed the temperature of the PCM cases would exceed that of the aluminum case. All cases studied generated a temperature difference within the battery of around 1K; however, these results are questionable due to the simplicity of the battery model considered.

Presenting Author: Jesse Kittleson California State University, Northridge

Presenting Author Biography: Jesse Kittleson is currently a graduate student at California State University, Northridge. He has been studying the development of thermal management systems for lithium-ion batteries under the guidance of Dr. Abhijit Muhkerjee. Due to the pandemic, extensive use has been made of the Ansys Fluent software suite. After graduation, he is seeking to pursue employment within the renewable energy sector, with a special interest in the development of solar, battery, and fuel cell technologies.

Authors:

Jesse Kittleson California State University, Northridge
Abhijit Muhkerjee California State University Northridge