Characteristics of Wetting Temperature and Maximum Heat Flux During Spray Cooling of Hot Surface

An experimental investigation has been done to elucidate the effects of mass flux G, degree of subcooling ΔT_sub and initial solid temperature T_b0 on transient spray cooling of a downward facing φ89 mm hot block surface. The spray impact diameter was adjusted to φ110mm and φ36mm which simulate uniform and non-uniform spray cooling of the surface. The block made of copper, brass and carbon steel at an initial temperature of 200–500 °C was cooled with subcooled water and ethanol spray. The subcooling was from 10 to 80 K and the mass flux was from 1 to 72 kg/m²s. Surface temperature and surface heat flux were evaluated with an axisymmetric 2D inverse heat conduction analysis. A transient transition regime was characterized with a wetting temperature and a quenching temperature. The wetting and quenching temperatures were correlated fairly with GΔT_sub. Effects of G, ΔT_sub, T_b0 and a thermal inertia of the solid (ρcλ)_s on a maximum heat flux are evaluated.