Experimental and numerical studies on the spray cooling of deionized water in non-boiling regime

High-efficiency spray cooling technology has received increase of interest for high heatflux applications. Experimental and numerical investigations on spray heat transfer in single-phase deionized water are reported in this paper. The 3D numerical model is established based on Discrete Phase Model and Lagrange Wall Film model, comprehensively considering the exchange of mass, momentum and energy between the air (continuous phase) and water droplets (discrete phase), and the heat transfer in liquid film at the heated surface. PDA is adopted to measure Sauter Mean Diameter (SMD) of near-wall droplets. The influences of mass flow rates, nozzle diameters and spray heights on spray heat transfer characteristics are discussed. Results indicate that increasing mass flow rate can reduce SMD due to high We number and improve heat transfer coefficient. Liquid-film thickness is high at either low or high mass flow rate, but has minor influence on cooling performance. The optimal nozzle diameter is 0.6 mm rather than the smaller or higher diameter because the spray area is similar to the heated area. Similar reason is for the optimal spray height of 20 mm.