The thermodynamic analysis on the catalytical ortho-para hydrogen conversion during the hydrogen liquefaction process

The catalytic conversion of ortho-para hydrogen is an important part in the hydrogen liquefaction process. Isothermal conversion, adiabatic conversion and continuous conversion are three main methods of the catalytic conversion in the hydrogen liquefaction process. However, there are few studies on the analysis and comparison of the three methods. In this paper, a theoretical model of the hydrogen liquefaction process is developed and calculated by MATLAB. The influences of the conversion methods, the number of adiabatic conversion stages and the parahydrogen concentration requirements in products are discussed and analyzed. The results show that the consumption work of the hydrogen liquefaction process with continuous conversion is the lowest. The consumption work of the isothermal conversion is 29.42 % higher than that of the continuous conversion, the consumption work of the adiabatic conversion with different stage numbers is 3.00 %-15.67 % higher than that of the continuous conversion when the parahydrogen percentage requirement in the product is 95 %.