Experimental and Computational Study of Liquid Nitrogen Transfer Line Chilldown

Abstract

Cryogenic fluids are widely used in industrial, aerospace, and many other scientific applications and systems. In these systems, proper transport, handling and storage of cryogenic fluids are of great importance. Chill-down of a transfer line is a natural consequence of routine cryogenic fluid transfer. The chill down time has its importance as the primary objective is to quickly cool the line, so as to promote homogeneous liquid transfer and/or to continue an ongoing test. The present work is a computational study of cryogenic transfer line chill down using a numerical code written in Matlab backed up by its experimental validation. The experiments were carried out with liquid Nitrogen (LN2) as the cryogen through a fluid transfer line made of stainless steel. A lumped system analysis in which the liquid cryogen and its vapour in the pipe are considered to flow as lumps of fluid, is used for the prediction of chilldown time and thermodynamic property variations during the transient process. The numerical results show good agreement with the experimental measurements and the predicted chilldown time is close to the field data. The generated code can be extended to predict the chill down parameters for any cryogenic transfer operation by providing the respective fluid and pipeline material properties, and the geometric measurements, along with necessary boundary conditions (thermal & flow) and ambient conditions.