Thermal Performance of Integrated Plate Heat Pipe With a Heat Spreader

The air flow rate available for cooling of notebook computers is very limited. Thus, notebook computer manufacturers desire a “passive” cooling method. Heat pipes are typically used to transport the heat from the CPU to a forced convection, air-cooled condenser. This paper describes a passive, keyboard sized aluminum Integrated Plate Heat Pipe (IP-HP) that has been developed for notebook computers. Analysis was performed to estimate the several thermal resistances in the heat pipe, including the effect of the vapor pressure drop. The modified design using a heat spreader at the evaporator significantly reduces the heat pipe resistance. Further work was done to evaluate the thermal contact resistance at the IP-HP/CPU interface. Test results show that the IP-HP can reject 18 W while maintaining the CPU 65°C above ambient temperature.