Abstract
In this study, effects of the droplet flow density and mean droplet diameter on film boiling heat transfer and collapse temperature of film boiling (MHF point temperature) of spray nozzle cooling were examined experimentally. A test heater was Nichrome foil with 0.2 mm thickness, 5 mm width and 100 mm length. The droplet flow density was 50, 100 and 200 l/min m^2, respectively. The mean diameter of droplet was 130, 198, 301, 352, 415 and 472μm, respectively. The test heater was heated by DC current through DC power supply. The temperature of test heater was measured by using a K-type thermocouple. The present experimental results showed that film boiling heat transfer increased with increasing mean droplet diameter. The effect of the mean droplet diameter on MHF point temperature was weak. On the other hand, film boiling heat transfer and MHF point temperature increased with increasing droplet flow density. The correlations were obtained for film-boiling heat transfer and MHF-temperature. Large temperature fluctuations near the MHF temperature condition was confirmed.
