Experimental Study on the Effect of Low Conductivity Coating on Cryogenic Transfer Lines

Abstract

To optimize the cryogenic chilldown of transfer lines and to improve the efficiency of the cryogenic systems, chilldown time should be reduced. Shortening the chill down time is related to saving in consumption of cryogenic fluid and hence energy saving. Experiments were performed on copper test section with low conductivity coating for different inlet pressures. The performance of the regular copper tubes and one with coating at corresponding pressures were compared. The results indicated that there is substantial savings in chilldown time with coated surfaces compared to the noncoated ones. Liquid nitrogen was used as the cryogen and it is passed through the test section made of copper. The significant reduction in chilldown time is observed only after the arrival of nucleate boiling region as depicted on the average surface temperature versus time graph. In the course of this study it was discovered that a large increase in heat flux could be attained by interposing an insulating coating between the boiling liquid and the surface across which the heat is to be transferred.