Executive Summary : | The automotive sector is transitioning to electric vehicles (EVs) due to concerns over pollution, climate change, and environmental sustainability. The use of EVs has increased by 422% in recent years, with Li-ion batteries being a potential solution. However, the charging and discharging of battery packs involve chemical reactions that generate heat, increasing the temperature. The safe operating temperature for Li-ion batteries is between 15°C to 40°C, and the surface temperature of Li-ion cells needs to be kept below 40°C to maintain performance and reliability. In tropical countries like India, maintaining safe operating temperatures is a challenge. Conventional passive cooling techniques are not sufficient to tackle heat generation. Two phase immersion cooling can provide stable and efficient thermal management of the battery pack. Pool boiling can affect the surface temperature of Li-ion cells, while coating them with Teflon enhances heat transfer from the surface. This leads to lower surface temperatures and higher charging and discharging rates.
Predicting heat generation within Li-ion cells is crucial for developing accurate models for numerical studies. A machine learning model based on bubble dynamics parameters will be developed to predict surface heat flux. A compact battery pack module for two phase immersion cooling will be designed to house cells and suppress thermal runaway. High-speed camera bubble visualization will be performed to understand and evaluate the thermal behavior of the single cell/battery pack. Experiments will be conducted at varying C rates while charging and discharging with different ambient temperatures. |