High Heat Flux Electronics Cooling Cycle

The area/volume power densities of packaged electronics will continue to increase until the method of heat rejection is the sole performance limiter. Perhaps the most reliable long-life cooling systems finding applications in space are passive; namely, heat pipes. Unfortunately, the balance between capillary pressure and viscous resistance limits the performance of these devices. Overall fluxes of 100W/cm^2 may be achievable with such systems, but local fluxes will never exceed pool boiling critical heat flux values that peak at approximately 100W/cm^2, but are normally much less. The novel thermal cycle proposed here circumvents this limitation. The cycle is passive yet generates pressure gradients substantially larger (up to 100-fold) than capillary systems. Such pressure differentials may be exploited to achieve very high forced-convection phase-change cooling rates (i.e. flow boiling/spray cooling) in coupled evaporators by direct contact with MCMs, or by more traditional flow-through designs. Heat fluxes obtained in this manner exceed those of capillary systems and are O(500W/cm^2). In Phase I we will demonstrate the high heat flux capability of the cycle exceeding 100W/cm^2 from simulated 2-D surfaces or 3-D MCM stacks. In Phase II we will produce an optimized design for high flux space electronics (i.e. satellite) heat rejection.