Lithium-ion batteries store energy and release it when required; however, during these processes, they generate heat, which can affect their performance, lifespan, and safety. Traditionally, air cooling and liquid cooling have been the predominant methods used for battery thermal management. Air cooling is simple and cost-effective, but it is not very efficient for high-performance applications due to its low heat transfer capability. On the other hand, liquid cooling, typically using coolants like water-glycol mixtures, offers better heat transfer but increases system complexity, weight, and cost. Also, the cooling is often uneven, leading to temperature gradients within the battery pack and uneven aging of the cells.
"Immersion cooling" offers a solution to these challenges. It involves submerging battery cells directly into a dielectric liquid coolant. These coolants are specially engineered fluids that are electrically non-conductive, thus preventing short-circuiting, and they have superior heat transfer characteristics compared to air and traditional liquid coolants.
Performance Evaluation of Immersion Cooling:
- Researchers have been conducting numerous investigations to gauge the efficacy of immersion cooling and compare it with current methods.
- The research carried out by Zhou Y. et. al. sheds light on the performance of thermal management using immersion cooling, providing the following summary:
- Increasing the flow rate and specific heat capacity of the coolant significantly reduces the Maximum Allowable Temperature (MAT) and Maximum Allowable Temperature Difference (MATD) of the cell (3C charge & Discharge).
- Enhancing the thermal conductivity of the coolant can lower the MAT and the Minimum Inlet Temperature (MIT) of the cell.
- The viscosity of the coolant doesn't have a significant effect on the cell's temperature but impacts the coolant's pressure drop proportionally.
- A lower flow rate and smaller viscosity in the coolant can reduce the system's energy consumption, thereby improving the overall efficiency of the BTMS.
Application in Electric Vehicles:
- BTMS with immersion cooling holds potential for electric vehicles due to its efficient heat management, reduced power consumption, and the possibility of improvements in design and operating parameters for better temperature uniformity.
- The addition of thermally conductive micro-particles to the coolant can further improve its thermal conductivity, thereby enhancing BTMS performance.
- Continued research and exploration into this technology will contribute to more efficient thermal management solutions for the expanding electric vehicle industry.
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