HEAT-TRANSFER MEASUREMENTS OF EVAPORATING LIQUID DROPLETS

The heat transfer to simulated (porous sphere) water and methanol droplets were measured in an atmospheric vertical hot air tunnel. The experiments were limited to a Reynolds number range of 200-2000, a free stream air temperature range of 150-960°C and a velocity range of 2.1-11.4 m/s. The experimental data can best be correlated by Nuf(1 + B) = 2 + 0.6Re 1 2M Pr 1 3f where properties are evaluated at film conditions except for the density in the Reynolds number which is the free stream density. Thus the data show that at higher temperatures, evaporation reduces heat-transfer rates directly by a factor of (1 + B). Indirectly evaporation affects heat-transfer rates through the changes in both the compositions and the temperatures of the surrounding gaseous medium. © 1978.