Flow and Heat Transfer Processes in an Inertance Type Pulse Tube Refrigerator
A time-dependent axisymmetric (r-z) numerical study is reported here for the investigation of the fundamental flow and heat transfer processes found in an inertance type pulse tube refrigerator (IPTR). The general design of an IPTR incorporates a pressure wave generator, a transfer line, an aftercooler, a regenerator, a pulse tube, a pair of heat exchangers for the cold and hot ends of the pulse tube, an inertance tube and a reservoir. The performance of the IPTR system is simulated using computational fluid dynamics (CFD). The IPTR is driven by a cyclically moving piston at one end of the system operating at a fixed frequency with helium as the working fluid. Both constant temperature and convective heat transfer boundary conditions are examined along the external walls of the hot heat exchangers. The simulations reveal interesting time-dependent flow patterns that develop in the pulse tube due to the fluctuations caused by the piston and the presence of the inertance tube. The secondary-flow recirculation patterns in the pulse tube reduce the heat pumping effect from the low-temperature heat exchanger to the high-temperature heat exchangers.