UCLA

Flash boiling is a two-phase cooling method based on the phenomenon of flash boiling in which a working fluid is rapidly vaporized upon sudden depressurization, allowing for rapid cooling through conversion of the fluid’s sensible heat to latent heat. In this process, the sensible heat of surrounding environment around the working fluid decreases. Therefore, flash cooling is a promising candidate for transient thermal management. The phase-change process associated with flash boiling differs from traditional thermally-driven boiling, as flash boiling inception is controlled by a different thermodynamic variable – pressure. Consequently, by allowing pressure to be the driving factor, temperature becomes a variable performance metric for flash cooling in practical devices. To better understand the nature of flash boiling incipience and measure flash cooling rates, experiments were constructed to measure depressurization wave propagation through a tube and transient flash cooling in a vapor chamber for various configurations and heating loads. Additionally, a metric for flash cooling based on time constants is presented to help quantify transient cooling performance.