Balanced design and commissioning of a 500W/4.5K helium refrigerator and its liquefier

A 500W/4.5K helium refrigerator for ADS (Accelerator Driven Subcritical) project of CAS (Chinese Academy of Sciences) has been designed. The functional requirements and process analysis of this helium refrigerator are described. Based on the regulation of the high pressure, a balanced design between refrigeration capacity and liquefaction capacity for equal Carnot work with the same high efficiencies is presented. The constraints of components and operation strategies in refrigeration mode and liquefaction mode are discussed. Commissioning results indicated that this 500W/4.5K helium refrigerator can provide 5.74g/s (or 165L/h) liquid helium in liquefaction mode or 550W at 4.5K in refrigeration mode with the respective FOM (Figure of Merit) of 14% or 13.2%. Existing problems were analyzed and discussed through comparing the theoretical calculation and experimental data, and some suggestions are given at the end of this paper.