This thesis investigates a novel approach to battery thermal management based on capillary driven evaporative cooling (CDEC) by integrating a wick structure directly on to the surface of a battery utilizing the advantages of capillary pumping pressure to drive the working fluid passively, thereby directly wet cooling the surface of the battery. The main aim of this thesis was to establish this novel concept through experimental and theoretical studies.

Initially a proof-of-concept study was conducted to establish the applicability of CDEC using an emulated battery block, copper foam and two working fluids. The results revealed the capability of CDEC by maintaining the battery’s maximum temperature around 40℃ from an initial temperature of 20℃ when subjected to a continuous heat load of 50W for a duration of 20 minutes, even with a partially wetted battery. To further ascertain this concept, a mathematical model for wick saturation was developed to realize the effect of wick parameters such as pore size, porosity, wick thickness and thermal resistance on the dry-out location of the structure. This model provides a starting point for designing the wick structure of the CDEC system. It was found that porosity had the most influence on both wick saturation and dry-out while parameters such as pore size, wick thickness, contact angle, liquid density and surface tension also play a major role in dry-out heat loads and dry-out location.

Moreover, an experimental study on the wettability transition of metal porous structures was conducted using surface characterisation techniques and droplet absorption to determine the effect of liquid-solid interaction at pore scale. The tests revealed that, while volatile organic compounds (VOCs) hinder the hydrophilicity of metal structures, high microscopic scale roughness ratios and formation of oxides on the pore surface, particularly in aluminium sintered porous structures could retain its wettability for several weeks even after exposure to ambient air. Finally, a scalable battery model integrated with CDEC was developed using a parameterized equivalent circuit model (ECM) to investigate the temperature response of CDEC under different current loads and driving conditions and cooling conditions. Studies on the effect of flow rates and configurations of modules integrated with a top cooling channel revealed that series arrangements are capable of minimizing the average module temperature while parallel arrangements can retain the temperature difference across modules at a minimum. Therefore, it is recommended that the physical connection of the modules integrated with a top cooling channel are designed using a combination of series-parallel configuration. The thesis was concluded by detailing the potential of CDEC in battery cooling and the recommendations for future studies to establish this novel concept.