Numerical and Experimental Study of a Gifford-McMahon-Type Pulse Tube Refrigerator

Abstract

An experimental setup has been constructed to study the performance of a single-stage double-inlet Gifford‐ McMahon-type pulse tube refrigerator, where the oscillating amplitudes of the physical quantities are large and oscillating frequencies are low in the system. Temperature distributions on the surface of the regenerator and the pulse tube, as well as the refrigeration capacities at different refrigeration temperatures under optimal operation conditions, were measured. A transient one-dimensional numerical simulator has been developed to verify experimental data and to study the nonlinear dynamic characteristics in the double-inlet pulse tube refrigerator. In this numerical simulator, the state equation and the conservation equations of mass and momentum in the e uid phase, as well as the energy equations for the e uid and the solid, are spatially and temporally conjugated. The boundary conditions and the initial conditions for these governing equations are specie ed, and e nite difference solutions at cycle steady states were obtained. The assumption that the refrigeration temperature at the cold-end heat exchanger is kept at a constant and known value during a cycle in the existing simulations is relaxed in our simulator. Instead, the refrigeration capacity is given, whereas the refrigeration temperature is determined from the numerical solution. Fluctuations of all physical quantities at cycle steady states are discussed. When the cycleaveraged values of the physical quantities are analyzed, it is shown that there is a dc e ow through the double-inlet valve at a cycle steady state, and the cycle-averaged velocity in the system is negative due to the mass streaming. At cycle steady states, the cycle-averaged pressure of the compressible e ow oscillating at a low frequency is shown to have a positive gradient along the axial location with its largest value in the reservoir. Numerical results are shown to be in good agreement with experimental data.