Experimental study on liquid oxygen chill-down in a horizontal exit-contracted pipe

Liquid oxygen chill-down in a horizontal exit-contracted pipe was investigated experimentally. The outer wall temperatures were recorded in the detailed manner. Results show the temperatures in the center length of the pipe decrease first, which shows much different manners from those in the transport pipe. This indicates that liquid accumulates in the center length to form quenching head, which propagates to the both sides of the pipe during the liquid oxygen chill-down process in the exit-contracted pipe. Based on the present set of data, the correlations on temperature of Leidenfrost point was corrected, and critical heat flux was well correlated by new expression from bubble separation theories. Results show that, for high pressure or high flow rate cases, Leidenfrost point is controlled by the increase of instable wave on the liquid propagation area. However, for other cases, Leidenfrost point is controlled by heat transfer.