Performance and optimization of hydrogen liquefaction cycles

The efficiency of a thermodynamic process depends on its operating conditions and on the efficiency of the components used. While the latter is largely fixed by the level of technology available and the cost of equipment, the designer can choose the operating conditions to maximize the process efficiency. This paper presents an analysis of the thermodynamic cycles commonly used for the liquefaction of hydrogen in order to predict their performance under a given set of operating conditions and component efficiencies. The cycles considered are: (i) precooled Linde-Hampson cycle, (ii) Claude cycle and (iii) helium-hydrogen condensing cycle. Extensive calculations of liquid yield and specific work requirement have led to optimization of operating conditions such as pressure levels, expander mass fraction, etc. The optimum operating conditions also depend on the heat exchanger effectiveness, temperature of precoolant baths and number of ortho-para converters.