Abstract
The enhancement of a critical heat flux in pool boiling was investigated by supplying liquid-jets to a heated surface, as a proposal of the high heat removal technology for future. Experiments were conducted using a pure copper block and saturated water for a pool condition at atmospheric conditions. Two or three jet-nozzles were set away a certain distance from the test surface for supplying liquid-jets to the heated surface. In the present study, the effects of the distance between the nozzles and the test surface, the diameter of jet-nozzles, the liquid flow rate and the jet-velocity on the enhancement rate of the critical heat flux were examined experimentally.
The critical heat flux obtained in the present experiments was enhanced a factor of about two for the flow rate per nozzle of 2.5 × 10−6 m3/s by supplying two liquid-jets. However, it was little affected for the supplied liquid when the distance between the jet-nozzles and the heated surface was 15 mm. The enhancement rate increased with the liquid flow rate and liquid jet velocity except for the 15 mm nozzle distance. The dependency of the enhancement rate on the flow rate for the nozzle-diameter of 0.9 mm was similar to that for the 0.5 mm in diameter. The dependency on the jet-velocity for the case of 0.9 mm, however, was difference to that of 0.5 mm. In other words, the enhancement rate of the critical heat flux is related to the flow rate of the liquid-jets. These results suggest that the enhancement of the critical heat flux is affected additionally by the quantity of supplied liquid to the macrolayer on the heated surface.
