Role Of Surface Texturing On Heat Transfer Coefficient Enhancement In Spray Impingement Cooling

The role of micro-scale surface roughness on wetting characteristics and heat transfer performance were studied by conducting spray cooling experiments using deionized water. Microtextured surfaces were fabricated using standard lithography technique and etching process. Experimental results obtained reveal a 100% increment in the CHF for micro-textured surfaces with pin fin diameter of 5 microns. Heat transfer coefficients in the two-phase regime were calculated by subtracting the sensible heat from the total heat flux. Surfaces with bigger pillar size and larger spacing (~50 microns) exhibits greater heat transfer coefficient values due to availability of additional floor area for evaporation. Effect of liquid/air flow rates were also studied. Results show improved heat transfer performance for higher liquid flow rates; however, the lowest liquid flow rate tested (30 ml/min) showcased highest values of heat transfer coefficients obtained, indicating the capability of surface to form very thin liquid films at an optimum value of liquid and air flow rates.