Executive Summary : | Cooling surfaces is a significant challenge in the modern world, especially for electronic equipment that dissipates thermal loads as high as 1000 W/cm2. Current cooling technologies, such as forced convection cooling, can only handle heat fluxes of approximately 20 W/cm2. Spray cooling is a promising technique for cooling surfaces, involving the impact of small droplets on surfaces generated by a spray. This leads to significant convection and phase change heat transfer, with heat flux removal from the surface being three order magnitude larger than traditional forced cooling.
However, there is debate on the uniformity of surface cooling by impacting droplets, heat flux removal rate, and the underlying hydrodynamic and heat transfer physics. Researchers have only recently started investigating the multiple droplet impact on surfaces, focusing on the behavior of droplet spread and splash due to surface temperature. This proposal aims to study the droplet-droplet interaction during their impact on the surface and their effect on heat transfer from the surface. Experiments will be performed by injecting spray on a surface while recording the impingement of droplets at high speed. The heat transfer variation over the surface will be studied by measuring surface temperatures, and numerical simulations of projected lamella coalescence and mixing will be performed to understand the effect of coalescence on enhanced mixing and surface cooling. |