Heat transfer characteristics of plug-in oscillating heat pipe with binary-fluid mixtures for electric vehicle battery thermal management

Abstract

The development of highly-efficient, cost-effective, and reliable cooling schemes of electric vehicle (EV) battery is still a big challenge for massive commercialization of EVs. In this work, a proof-of-concept plug-in oscillating heat pipe (OHP) with flat-plate evaporator and tube condenser has been developed and experimentally tested for the potential applications in EV battery thermal management. Pure water, ethanol, and binary-fluid mixtures of them at different mixing ratios (MRs) ranging from 1:1 to 4:1 were used at volumetric filling ratios (FRs) of 30%, 40% and 50%. Owing to the zeotropic properties in phase transition and the complex molecular interactions between the ethanol component and water component, the OHP charged with ethanol-water mixtures exhibited better start-up and heat transfer performance. The average battery pack temperature could be controlled below 46.5 °C under the power input of 56 W. Besides, well-satisfied temperature uniformity was achieved on the battery module and the maximum temperature differences were mostly in the range of 1–2 °C. The complementary features for ethanol-water mixture thermo-physical properties and temperature/concentration gradients induced mass transport account for the OHP performance improvement. The novel plug-in OHP associated with desirable heat transfer performance provides a promising candidate for battery thermal management system.