CFD analysis of a single stage pulse tube cryocooler with two double inlet valves

The internal working processes in pulse tube cryocooler (PTC) are quite complex due to the unsteady, oscillating compressible gas flow in the pulse tube. Although considerable theoretical studies have been carried out as of date phenomena occurring in a pulse tube cryocooler are still to be understood. The present research work is carried out in order to understand the cooling mechanism and to ascertain the suitability of computational fluid dynamics (CFD) methods for double inlet pulse tube cryocooler. Commercial CFD software Fluent is used to solve conservation of mass, energy and momentum equations. Two single stage PTC models, one with one double inlet valve (DI valve) whose configuration parameters are identical to the experimental apparatus and the other one with two double inlet valves are simulated. The temperature at the cold end heat exchanger is considerably lower in the pulse tube cryocooler with two double inlet valves. Lowest temperatures obtained by simulation at the cold end heat exchangers are well above that of the experimental values. This may be due to the assumption that working fluid helium is treated as ideal gas. The study helps in optimization of entire pulse tube cryocooler system. The simulated cool down behavior is compared with experimental result for validation. Keywords—CFD, energy equation, momentum equation, pulse tube cryocooler, two double inlet valves