Analysis of configurations for coupling an active magnetic regenerator with heat exchangers for hydrogen liquefaction

Abstract

This paper presents a study of four different configurations for performing the heat exchange between helium—supplied by an active magnetic regenerator (AMR)—and hydrogen in the 82–20 K range for hydrogen liquefaction. We evaluate helium mass flow requirements and analyse the configurations considering both technical and exergetic aspects. Results show a strong influence of the temperature difference of helium at the AMR cold end on the required helium mass flow rate, which ranges from 35 to over 75 times the liquid hydrogen mass flow rate. The exergy efficiency of the cooling stage, not including AMR losses, ranges between 33 % and 49 %. The use of a single AMR causes significant temperature differences between helium and hydrogen in the heat exchangers leading to large exergy losses (representing over 95 % of the overall losses). We finally show that this issue can be overcome using multiple AMR in parallel with increasing cold-end temperatures.