Numerical simulation of Gifford McMahon Cryocooler via a Lagrangian Approac

In this research, a numerical code has been developed to investigate physics of Gifford McMahon cryocooler via a Lagrangian approach. In this respect, set of governing equations have been written in a general form. Applying the developed code, temperature, pressure and existing mass in each chamber were estimated. In addition, the influence of cryocooler operating conditions, including cooling temperature and minimum and maximum working pressures of cryocooler on effective cooling load was estimated. Results showed that two groups of elements are responsible for producing the effective cooling capacity. First group consists of mass elements which are extracted from cold head due to partial pressure drop in chamber 3 and second group are mass elements which are forced to pass over the cold head due to displacer movement. Results from Lagrangian approach were compared with that of thermodynamic model and a good agreement was observed at temperatures more than 40 K.