UCLA

As demand for high performance computing continues its rapid growth, the required digital processing capabilities necessitate more powerful integrated circuits. High power density chips produce a challenging thermal engineering problem by generating heat fluxes greater than 0.5 W/mm2 while sometimes providing diminishing provisions for heat spreading. A pressure-driven boiling approach, termed flash cooling, is considered here as a solution for high heat flux thermal management. The thesis study aims to improve the Technology Readiness Level of flash cooling for high heat flux electronic cooling applications, especially targeted for wafer-scale systems. Furthermore, the objective is also extended to understand the physics involved in flash cooling and associated limitations. A closed-loop flash cooling system is developed with evaporator, accumulator, vacuum pump, condenser, and reservoir. Experiments are conducted by varying the heat flux from 0.2 W/mm2 to 1 W/mm2. The important control parameters are determined to be heat flux, pulse cycle time and flow rate. The results are interpreted to identify dominant parameters and to develop basic correlations among them. The experiments not only prove the dynamic and transient cooling ability of pulsed flash cooling but also exhibit dry-out recovery characteristics under short pulse cycle times. Further research directions are also suggested to improve the flash cooling technology.