Modeling Pulse Tube Coolers with the MS*2 Stirling Cycle Code

Abstract

The MS*2 Stirling Cycle Code implements a numerical model originally designed to analyze Stirling cycle engines and refrigerators on a PC. It can also be used to create usefully accurate models of pulse tube cryocoolers. The technique requires preparation of higher and lower resolution files from which a hypothetical file of infinite resolution can be projected. By varying heat transfer area assigned to the cold heat exchanger, different cooling loads are applied. From the resulting equilibrium cold end temperatures, load curves are developed. Separate determination of load, including load represented by losses not modelled by the code (principally, conduction in pulse tube and regenerator housing) leads to an estimate of temperatures achievable at various assumed loads by reference to the load curve. Output of the code includes projections of pressure drop loss in the system, enthalpy flow in the regenerator, PV work input in the compressor and temperatures, heat flows, mass flows as well as mean Reynolds, Nusselt and Mach numbers for each control volume. Material options include several working fluids and regenerator materials. Regenerator configuration options include screens, spheres and parallel plates of any density and element size. Phase shift between flows at the compression piston and orifice is an adjustable input.