The Li-ion battery operation life is strongly dependent on the operating temperature and the temperature variation that occurs within each individual cell. Liquid-cooling is very effective in removing substantial amounts of heat with relatively low flow rates. On the other hand, air-cooling is simpler, lighter, and easier to maintain. However, for achieving similar cooling performance, a much higher volumetric air flow rate is required due to its lower heat capacity. This paper describes the fundamental differences between air-cooling and liquid-cooling applications in terms of basic flow and heat transfer parameters for Li-ion battery packs in terms of QITD (inlet temperature difference). For air-cooling concepts with high QITD, one must focus on heat transfer devices with relatively high heat transfer coefficients (100–150 W/m2/K) at air flow rates of 300–400 m3/h, low flow induced noise, and low-pressure drops. This can be achieved by using turbulators, such as delta winglets. The results show that the design concepts based on delta winglets can achieve QITD of greater than 150 W/K.

Li-Ion batteries are currently used in hybrid and electric vehicles. Battery life and performance requires temperature control in narrow range. One of the method considered is use of specially designed heat pipe. The study includes a heat pipe between two battery simulators. The heat pipe was cooled by air flow of 3 l/s and with temperature range of from 9°С to 40°С.We have compared the measured surface temperature distributions to those which were received from computer simulation in order to obtain effective thermal conductivity of the heat pipe and its thermal performance. This effective thermal conductivity increases, as the inlet air temperature increases and reaches the value of 2500 W/(m×K).

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