Flow of Neon-Nitrogen-Hydrocarbon mixture through adiabatic capillary tube at cryogenic temperatures

Abstract

Capillary tubes are widely used in J-T refrigerators owing to their simplicity, easy operation, and zero maintenance. J-T refrigerators are mainly used for domestic and commercial refrigeration and air conditioning and hence the study on flow through capillary tubes is highly focused on conventional refrigerants at relatively higher temperatures. The present work is an extension of previous work done by the authors and focuses on the flow of refrigerant mixtures consisting of neon, nitrogen, and hydrocarbons at cryogenic temperatures for the capillary tube of a J-T cryocooler. The mass flow rate through the capillary tube is studied experimentally by changing refrigerant mixture composition and inlet temperature to the capillary tube. A mathematical model is developed based on a length feedback loop to predict the mass flow rate through the capillary tubes using the homogenous flow model. The model is found to predict mass flow rate through the capillary tube with an average error of 10 % for almost all the experimental values.