Characteristics and applications of the cold heat exergy of liquefied natural gas

A mathematical model for predicting the low temperature exergy, pressure exergy and total cold heat exergy of Liquefied Natural Gas (LNG) is developed in this paper. In the model, the liquid mixture densities are calculated by a shape factor Corresponding State method, Vapor–Liquid-Equilibrium data of LNG are predicted by an improved method and the influences of real fluid effects are considered. The model is used to determine the various exergies, and the influences of ambient temperature, system pressure and mixture component concentrations on the cold heat exergies are analyzed. Different schemes for applying the low temperature exergy and pressure exergy are proposed. Based on the modeling results, it is proposed that the schemes for applying the cold heat exergies of LNG be determined by thermodynamic cycle optimization, while considering the magnitudes of low temperature exergy and pressure exergy, as well as the required gas supply pressures.