Study on the helium liquefaction characteristics in the Laval nozzle

Abstract

Achieving helium liquefaction is fundamental to the widespread utilization of liquid helium in various industrial processes. This study innovatively proposes a new type of device for helium liquefaction, the Laval nozzle. Compared with the traditional helium liquefaction equipment, it can achieve isentropic expansion and direct liquefaction without any moving components. Based on CFD calculations, the distribution patterns of temperature, pressure, Mach number and other flow parameters of helium in the Laval nozzle are obtained, and the effects of the inlet parameters and the structure of the Laval nozzle on the liquefaction process are also explored. The results show that when the inlet temperature is 14 K, the inlet pressure is 1700 kPa, the outlet pressure is 45.021 kPa and the outlet temperature can be as low as 3.23 K, which is lower than the saturation temperature corresponding to the outlet pressure, which validates the feasibility of helium liquefaction in the Laval nozzle. Lower inlet temperature or higher inlet pressure is conducive to promoting the liquefaction of helium in the Laval nozzle and enhance its refrigeration effect. The structure of the Laval nozzle has an insignificant effect on helium liquefaction characteristics, but it can be used as a reference for optimizing the structure of the Laval nozzle in the future.