Dynamic simulation optimization of the hydrogen liquefaction process

Abstract

Liquid hydrogen has attracted much attention due to its high energy storage density and suitability for long-distance transportation. An efficient hydrogen liquefaction process is the key to obtaining liquid hydrogen. In an effort to determine the parameter optimization of the hydrogen liquefaction process, this paper employed process simulation software Aspen HYSYS to simulate the hydrogen liquefaction process. By establishing a dynamic model of the unit module, this study carried out dynamic simulation optimization based on the steady-state process and process parameters of the hydrogen liquefaction process and analyzed the dynamic characteristics of the process. Based on the pressure drop characteristic experiment, an equation for the pressure drop in the heat exchanger was proposed. The heat transfer of hydrogen conversion was simulated and analyzed, and its accuracy was verified by comparison with the literature. The dynamic simulation of a plate-fin heat exchanger was carried out by coupling heat transfer simulation and the pressure drop experiment. The results show that the increase in inlet temperature (5 °C and 10 °C) leads to an increase in specific energy consumption (0.65 % and 1.29 %, respectively) and a decrease in hydrogen liquefaction rate (0.63 % and 2.88 %, respectively). When the inlet pressure decreases by 28.57 %, the hydrogen temperature of the whole liquefaction process decreases and the specific energy consumption increases by 52.94 %. The research results are of great significance for improving the operating efficiency of the refrigeration cycle and guiding the actual liquid hydrogen production.