Investigation on heat transfer in line chill-down process with various cryogenic fluids

Abstract

This paper focuses on the transient process of the pipe cooling by the internal flow of cryogenic fluid, which is a so-called cryogenic line chill-down process. Due to the increasing use of cryogenic fluid in various industries, the heat transfer characteristics during the line chill-down process are followed with great interest. One of the biggest concern is that there are no universal heat transfer correlations for simulating the chill-down process. This research aims to extend the quenching database with liquid oxygen and predict the cryogenic line chill-down process with a one-dimensional homogeneous model. The line chill-down experiments are performed by liquid oxygen with the mass flux range from 15.9 kg/m(2)-s to 75.9 kg/m(2)-s. A 7 m long stainless steel 316 horizontal tube is used as the test section. The empirical correlations for heat transfer coefficient of single-phase vapor convection and film boiling are suggested based on the chill-down experimental data of liquid oxygen, liquid argon, and liquid nitrogen. The line chill-down process is simulated by applying the empirical correlations in a one-dimensional homogeneous model. The feasibility of the dynamic simulation model is verified in the mass flux up to 868 kg/m(2)-s by simulating the chill-down experimental data in the literature. Moreover, the characteristics of the critical heat flux, critical heat flux temperature, and minimum heat flux temperature are also investigated by comparing various experimental data and the empirical correlations. This study provides not only the open experimental data with liquid oxygen, which is rarely found in the literature but also the numerical simulation method, which predicts the line chill-down time within +/- 10% error.