Research Projects

Electric Vehicles (EVs) are currently the best alternatives to conventional vehicles to reduce greenhouse gas emissions when they run on the decarbonized grid. Li-ion batteries are predominantly used as power sources in EVs due to their higher energy density and low self-discharge rate. As Li-ion battery generates heat during charging and discharging, this heat needs to dissipate effectively to avoid a catastrophic thermal runaway where a chain of exothermic chemical reactions leads to fire or explosion. Batteries must be maintained at 20-50 °C, and temperature uniformity within the pack should be less than 5°C for optimal performance. A robust and efficient thermal management system for battery cooling is essential. The prominent cooling techniques utilized in the present EVs in the market majorly involve air and indirect liquid cooling. In forced air cooling, the ram air of a moving EV cools the battery. However, forced air cooling fails one or the combination of the following conditions are met: (a) during peak summers, (b) vehicle stuck in a traffic jam, and (c) aggressive drive cycle. Such a scenario might lead to a thermal runaway. Last summer, newspapers reported a few fire incidents in EVs, particularly two and three-wheelers, when the maximum temperature breached a record of 49 °C. The indirect liquid cooling system uses cold plates with coolant channels attached to the battery walls. This technique does not address the temperature uniformity requirements of the battery. Wall temperature is low adjacent to the coolant channels and high away from it. Phase change materials (PCMs) provide excellent thermal uniformity by absorbing the heat generated by the battery pack. However, their lower thermal conductivity hinders their performance. It is proposed to work on hybrid cooling by combining the merits of the PCM and forced air and indirect liquid cooling. Such a combination helps overcome the limitations of individual cooling techniques. We intend to investigate the battery performance with PCM-air and PCM-indirect liquid hybrid cooling systems for extreme and abusive conditions in the proposed work. An exhaustive literature review has revealed that most of the research works undertaken in India are numerical simulations. The battery pack is modeled mostly by considering it a lumped system, ignoring its electrochemical characteristics. However, a few studies have considered electrochemistry in the modeling, but the focus is mostly on a single-cell and two-dimensional battery packs. Therefore, there is a need to electrochemically model the three-dimensional battery pack and experimental evaluation of the same under extreme conditions. In fact, we have already developed a numerical model based on the multi-scale multi-dimensional framework (MSMD) for a 3D battery pack. The numerical and experimental evaluation of the hybrid BTMSs under different charging-discharging cycles will be evaluated in the proposed work.