An Experimental Study on Effectiveness of Electronic Expansion Valve [EXV] in EV HVAC System

HVAC system maintaining passenger comfort have evolved out as vital system as any other automotive systems. As the automotive industry is in its transition to EV technology, Battery Thermal Management is critical for the life, efficiency, performance, and safety of battery pack and thus the vehicle. Liquid Cooling is one of the more common battery cooling strategies that uses Chiller as a heat exchanger between coolant and refrigerant. The added thermal load imparted during battery cooling impacts the cabin temperature with a sensible effect. Present day TXV based chiller system creates a significant impact in the vent-level and in-cabin temperatures when the battery cooling request is ON. Gaining control over refrigerant mass flow to chiller quantitatively with thermal load can reduce the effect on cabin temperatures. This in turn cut down the load on compressor which will aid the range of EV. A comparative study is performed to evaluate the effect of battery cooling on cabin temperature with the TXV based system and an advanced system with Electronic Expansion Valve. EXV with its control over refrigerant flow rate can supersede TXV and thus minimize the rise in cabin temperature. The objective of this study is to evaluate the effectiveness of EXV based liquid cooling system and its impact system COP and vehicle range. Performance parameters such as average vent temperature and the temperature drop of coolant are monitored for TXV on and different level opening of EXV is compared with TXV off and EXV off respectively for both analytical and bench level data. The results are further compared to simulation results to understand consistency.