Optimization of a Thermoelectric Cooler-Heat Sink Combination for Active Processor Cooling

This study was carried out to explore the possibility of extending the limits of air cooling by using a thermoelectric cooler (TEC) enhanced cooling system which consists of a TEC used in conjunction with a fan-cooled heat sink to cool a processor. A systematic methodology for characterizing and comparing the performance of the TEC enhanced system with that of a heat sink only system is proposed. The performance of each cooling system is characterized using two criteria: its ability to produce lower junction temperatures (Tf) and its ability to allow the use of larger heat sink thermal resistances (Rhs), both for specified heat dissipation requirements. The effect of variations in the coefficient of performance (COP) of the TEC on the TEC enhanced system's performance is also explored, followed by identification of the conditions under which the system will perform better than the heat sink only system and vice versa. Both cooling systems are modeled using one dimensional thermal resistance networks, after which iterative algorithms are derived to determine their performance. Using the method proposed, the performance of an off-the- shelf TEC used together with a fan-cooled extruded aluminum heat sink in cooling a Pentium processor package is analyzed and compared with the performance of only the heat sink. Results revealed that the TEC enhanced system favors low heat loads and small RHS to produce lower Tf than the heat sink only system, while it favors low heat loads and low Tf to allow the use of larger RHS. The results also revealed a trade-off for increasing the COP of the TEC, where the TEC enhanced system's performance in terms of the two criteria degrades as its COP is increased.