EFFECT OF SURFACE MATERIAL PROPERTIES AND SURFACE CHARACTERISTICS IN EVAPORATIVE SPRAY COOLING

In the spray cooling of a heated surface, variations in the surface contact angle cause a change in nucleation characteristics and, thereby, influence the heat transfer process; a higher contact angle shows an enhanced heat transfer due to the ease in nucleation caused by the lowered free energy associated with bubble formation. Results are presented for different surface coatings and spray configurations. The surface roughness variation influences the flowfield, altering the maximum liquid film thickness, the bubble diameter, vapor entrapment, bubble departure characteristics, and, thereby, the ability of the surface to transfer heat. The effect of surface roughness on spray cooling is also studied.