Wave-shaping of pulse tube cryocooler components for improved performance

• Wave-shaping of pulse tube cryocooler components is investigated for an inertance type cryogenic pulse tube refrigerator (IPTR).
• High resolution numerical simulations of the spatio-temporal flow and temperature fields.
• A thermal non-equilibrium model to couple the gas and solid (porous media) energy equations.
• Wave shaped regenerator and pulse tube are investigated.
• Better cooling is predicted for the cryocooler using wave-shaped components oriented in the diffuser mode.

The method of wave-shaping acoustic resonators is applied to an inertance type cryogenic pulse tube refrigerator (IPTR) to improve its performance. A detailed time-dependent axisymmetric experimentally validated computational fluid dynamic (CFD) model of the PTR is used to predict its performance. The continuity, momentum and energy equations are solved for both the refrigerant gas (helium) and the porous media regions (the regenerator and the three heat-exchangers) in the PTR. An improved representation of heat transfer in the porous media is achieved by employing a thermal non-equilibrium model to couple the gas and solid (porous media) energy equations. The wave-shaped regenerator and pulse tube studied have cone geometries and the effects of different cone angles and the orientation (nozzle v/s diffuser mode) on the system performance are investigated. The resultant spatio-temporal pressure, temperature and velocity fields in the regenerator and pulse tube components are evaluated. The performance of these wave-shaped PTRs is compared to the performance of a non wave-shaped system with cylindrical components. Better cooling is predicted for the cryocooler using wave-shaped components oriented in the diffuser mode.