Experimental study on heat transfer characteristics of liquid nitrogen through coated transfer line

The effective and efficient utilisation of cryogen is made possible by optimised transfer lines which ensures reduction in chilldown time and cryogen usage. Cryogenic chill-down experiments were conducted on coated and regular copper tubes. Liquid nitrogen at different mass flux condition was used as the working fluid and Polyurethane coatings belonging to the family of Teflon was used as coating material. The performance of the regular and coated copper tubes at corresponding mass flux were compared. An increase in heat flux and heat transfer coefficient along with reduction in chilldown time was obtained by providing a low thermal conductive coating between the cryogen and wall material.