Much effort in the area of electronics thermal management has focused on developing cooling solutions that cater to steady-state operation. However, electronic devices are increasingly being used in applications involving time-varying workloads. These include microprocessors (particularly those used in portable devices), power electronic devices such as IGBTs, and high-power semiconductor laser diode arrays. Transient thermal management solutions become essential to ensure the performance and reliability of such devices. In this review, emerging transient thermal management requirements are identified, and cooling solutions reported in the literature for such applications are presented with a focus on time scales of thermal response. Transient cooling techniques employing actively controlled two-phase microchannel heat sinks, phase change materials (PCM), heat pipes/vapor chambers, combined PCM-heat pipes/vapor chambers, and flash boiling systems are examined in detail. They are compared in terms of their thermal response times to ascertain their suitability for the thermal management of pulsed workloads associated with microprocessor chips, IGBTs, and high-power laser diode arrays. Thermal design guidelines for the selection of appropriate package level thermal resistance and capacitance combinations are also recommended.

Effective thermal management of high power density batteries is essential for battery performance, life, and safety. This paper experimentally investigates direct mineral oil jet impingement cooling of the lithium-ion (Li-ion) battery pack. For the first time, experimental results of mineral oil-based cooling of batteries are reported. Both charging and discharging characteristics on temperature uniformity and of a Li-ion pack are considered. Temperature uniformity among cells, as well as within individual cells, is experimentally measured. As a baseline, cooling of the battery pack by free-convective airflow is also reported. Two different jetting configurations: (a) submerged jet and (b) direct-jet impingement are considered. For the highest charge-discharge rates considered (2C charge and 3C discharge), mineral oil nearly maintains uniform skin temperature among the cells (less than 1 °C) as well as within the cell. Based on the results obtained, modular jet oil cooling is an excellent cooling solution of lithium-ion packs applicable to stationary electrical storage and transportation applications.