TRANSIENT THERMAL ANALYSIS OF PHASE CHANGE MATERIAL BASED HEAT SINKS

Abstract

Integrated circuits operate best in a limited range of temperature hence their package must be designed to remove the excessive heat. As an alternative passive cooling technique means, phase change materials or PCMs have been widely investigated for such transient cooling applications considering their advantage such as high latent heat of fusion, high specific heat, controllable temperature stability and small volume change during phase change, etc. This PCM based cooling techniques have great potential application in the devices which are not operated continuously over a long period, but in intermittently using devices like cellular phones, digital cameras, notebook etc. The PCM absorbs heat from the electronic component when it operates and melts, the molten PCM needs to be re-solidified by dissipating heat to the surroundings while the electronic device are idle, such a cooling system is applicable only for intermittent use devices and not those in continuous operation. To achieve effective cooling it is important to ensure that the operating duration of the electronic device does not exceed the time of full melting of PCM. Advanced transient analysis is required for clear understanding of the mechanism behind this method of cooling while practical implementations are considered. Controlled convective cooling techniques can be implemented for continuous operation such kind of systems. The present work is a numerical study consists of thermal analysis of various configurations of finned heat sink with PCM. The configurations considered are finned heat sink without PCM and with PCM, Half-filled PCM towards the fin tip side and cases which includes forced convection for systems with continuous operation. The unsteady analyses were performed to record the transient nature of problem. The characteristic of PCM and the design of operational time of convective cooling are estimated. By analyzing these different configurations a vivid picture of the physics of heat transfer in PCM based heat sink is figured out.