Effect of fluid property variations on the effectiveness of a cryogenic heat exchanger

Abstract

Cryogenic heat exchangers are commonly used for industrial processes, such as air separation and natural gas liquefaction. Generally, the performance of heat exchangers is analyzed adopting constant properties for the working fluid. But, in cryogenic heat exchangers, fluids reach their critical states with significant variations in their properties. The current work is based on the effect of fluid property variations in the performance analysis of a two‐fluid countercurrent cryogenic heat exchanger subject to ambient heat in a leak. Finite element method–subdomain method is used to conduct the performance analysis. The effect of fluid property variations is analyzed considering effectiveness, ∈, as the performance parameter. The percentage deviation in the effectiveness value on considering fluid property variation is determined. The relationship between effectiveness ∈ and the number of transfer units (NTUs) is obtained by plotting the ∈‐NTU curve by varying the mass flow rate of the fluid flow. A maximum deviation of 16.108% in the effectiveness and 58.734% in the hot fluid exit temperature is obtained by considering fluid property variation.