Vapor chamber Hysteresis

a b s t r a c t We constructed a low thermal resistance, multi-artery heat pipe spreader vapor chamber by designing a thin (monolayer) evaporator wick and distributed permeable columnar arteries supplying liquid (water) to highly concentrated heat source region. The condenser wick is layered copper screens in intimate con-tact with the columnar arteries. The vapor chamber is sealed and externally surface-convection cooled on the condenser side. For the evaporator wick and arteries, sintered, surface etched-oxidized copper parti-cles are used to enhance wettability. The measured evaporator thermal resistance is less than 0.05 K/(W/cm2) using a 1 cm2 heat source, and the critical heat flux is about 380W/cm2. This is in good agreement with thermal–hydraulic network models prediction, 389 W/cm2. The resistance is dominated by the small effective thermal conductivity of the evaporator wick and by the small conduction path through the receding meniscus within it. This resistance decreases nonlinearly with the heat flux, due to a decrease in the radius of the receding meniscus. 2010 Published by Elsevier Ltd. 1