Investigation of secondary cooling design enhancements in thermally limited compact notebooks

Abstract

Thermal design enhancements in a thermally limited compact notebook system are investigated in this paper. System temperature, power, and fan speed are characterized under a range of activity levels. A nite element model is developed, and validated against measurements. Design enhancements improve cooling with minimum intrusion to the existing mechanical design. A passive secondary heat pipe in the system reduces the CPU temperature by 5 ◦ C, and improves the system performance through increased CPU + Graphics and Memory Controller Hub (GMCH) thermal design power (TDP) by 6.4%. When such a secondary heat pipe is considered with an integrated off-the-shelf Peltier cooler, the CPU temperature is only reduced by 2.3 ◦ C and CPU+GMCH TDP is improved only by 4.9%. Although Peltier integration provides no bene t to thermals, it can be advantageous in generating small amount of thermoelectric power in conditions when the system is not executing thermally limited applications. Calculations suggest that a 10% increase in Seebeck coefficient and consequently a 5.5% increase in coefficient of performance (COP) of off-the-shelf thermoelectric materials can increase the TDP envelop by 7.1% using the Peltier-integrated secondary heat pipe scheme.