Numerical model of free warm expander pulse tube cooler Original Research Article

The free warm expander pulse tube (FWEPT) is a novel type of cooler for long life applications. The design is similar to the orifice pulse tube cooler but with the orifice and the reservoir replaced by a secondary piston which is driven by the pressure cycle in the pulse tube. In this article we discuss the thermodynamics and develop a numerical model of the FWEPT cooler. Measurements of the loss mechanisms in the regenerator are presented and optimisation of the geometry and operating conditions are discussed. An accompanying paper reports on the development of a prototype of the FWEPT cooler.