Characteristics of wetting temperature during spray cooling. 2nd report, results for nonuniform spray impingement

An experimental study has been done to elucidate effects of mass flux G, degree of subcooling ΔTsub, initial solid temperature Tb0 and thermal properties of test liquid and hot block on wetting temperature during spray cooling of a hot block. The heated surface was cooled nonuniformly with spray, which impinged partially on the surface. This experiment partly simulates actual spray cooling with multiple sprays. The experiments were done up to maximum mass flux of 72 kg/(m2s) with fixed subcooling of 60 K with copper and carbon steel blocks for ethanol spray. Transient transition region is categorized into two regions from history of heat flux change. The wetting temperature corresponding to the minimum heat flux point wall temperature and the quench temperature were also evaluated. The wetting temperature increases with GΔTsub beyond the surface temperature corresponding to liquid superheat limit temperature. (author)