Experimental study on heat transfer characteristics of flash evaporation of water film in open system

Heat transfer characteristics of flash evaporation of water film in an open system were studied. The tests were conducted at superheat temperature differences of 1-15 K, flash evaporation pressures of 20.4, 30.2 and 47.4 kPa, water film thicknesses of 100 and 300 mm, and mass flux of 0.028, 0.056, 0.083 kg/s. The results show that under the operating condition, heat transfer coefficient ranges from 60 to 140 kW/(m²K) which decreases with the increase of superheat, increases with the increase of flash evaporation pressure and decreases with the increase of water film thickness. According to the results in this experiment, based on the similarity between flash evaporation and nuclear boiling, an experimental expression of heat transfer coefficient with all of the influence parameters was presented with the maximum error of 27%.