110 Int. J. Process Systems Engineering, Vol. 3, Nos. 1/2/3, 2015 Copyright © 2015 Inderscience Enterprises Ltd. Automotive underbody diffuser for battery thermal management Rocky Khasow and Martin Agelin-Chaab* Faculty of Engineering and Applied Sciences, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario, Canada, L1H 7K4, UK Email: rocky.khasow@uoit.ca Email: martin.agelin-chaab@uoit.ca *Corresponding author Abstract: This paper investigates underbody aero-thermal management of a hypothetical battery pack. Underbody diffusers are specifically designed to channel air for cooling a surface of the battery pack without significantly increasing aerodynamic drag. Numerical simulations are conducted to study the cooling and drag effects of the new diffusers on the battery pack. The numerical results show that the temperature of the battery pack upstream decreased whereas that at the downstream slightly increased compared to the no diffuser case, in addition to having a larger range of temperatures. There are smaller hot spots in comparison to the no diffuser case, which limit the number of cells in a battery that would be affected by the temperature increase, thus preventing damage. With further studies and improved diffuser design, the present work has the potential to offer better alternative locations for installing EV and HEV battery packs for improved air cooling. Keywords: electric vehicle; hybrid electric vehicle; HEV; battery packs; aero-thermal management; numerical simulations; automotive aerodynamics; diffusers. Reference to this paper should be made as follows: Khasow, R. and Agelin-Chaab, M. (2015) ‘Automotive underbody diffuser for battery thermal management’, Int. J. Process Systems Engineering, Vol. 3, Nos. 1/2/3, pp.110–125. Biographical notes: Rocky Khasow is a graduate student at the University of Ontario Institute of Technology. His thesis focuses on aero-thermal studies. Martin Agelin-Chaab is an Assistant Professor at the UOIT. His research interests include but not limited to fluid mechanics, thermodynamics, fluid dynamic energy conversion systems, sustainable energy systems, and hydrogen energy. This paper is a revised and expanded version of a paper entitled ‘Automotive underbody diffuser effects on thermal management’ presented at the International Conference on Smart Energy Grid Engineering (SEGE 2014), UOIT, Oshawa, Canada, 11–13 August 2014.