In uence of unsuitable operational conditions on the transient performance of a small hydrogen lique er

Joule-Thomson cooling systems are used in refrigeration processes such as cryogenic gas liquefaction. Although extensive studies have been carried out by researchers, most studies include cryogenic heat exchangers and their associated  elds. In the current study, an attempt was made to indicate the effect of using inappropriate operational conditions in a cryogenic Joule-Thomson cooling system including a recuperative heat exchanger, expansion valve, and collector. Mass  ow rate and operational pressure were selected as design parameters while cool-down time and  nal temperature of highpressure gas at heat exchanger outlet were considered as responses. The results showed that using a mass  ow rate smaller than the design value led to considerable decrease in performance. Operational pressure had less effect on cool-down time. Increasing the pressure had no signi cant effect on the gas temperature at the expansion valve inlet for high mass  ow rates. Using unsuitable values for the mass  ow rate and operational pressure might lead to failed liquefaction despite using a heat exchanger with high effectiveness

Keywords:

Heat exchanger , Joule-Thomson , Transient , Hydrogen , Refrigeration