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 finite 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 $^{\circ}$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 $^{\circ}$C and CPU+GMCH TDP is improved only by 4.9%. Although Peltier integration provides no benefit 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.

Keywords: Thermal management, notebook systems, passive cooling, Peltier cooling

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