A Computational Model for Two-stage 4K-Pulse Tube Cooler: Part I. Theoretical Model and Numerical Method

A new mixed Eulerian-Lagrangian computational model for simulating and visualizing the internal processes and the variations of dynamic parameters of a two-stage pulse tube cooler (PTC) operating at 4 K-temperature region has been developed. We use the Lagrangian method, a set of moving grids, to follow the exact tracks of gas particles as they move with pressure oscillation in the pulse tube to avoid any numerical false diffusion. The Eulerian approach, a set of fixed computational grids, is used to simulate the variations of dynamic parameters in the regenerator. A variety of physical factors, such as real thermal properties of helium, multi-layered magnetic regenerative materials, pressure drop and heat transfer in the regenerator, and heat exchangers, are taken into account in this model. The present modeling is very effective for visualizing the internal physical processes in 4 K-pulse tube coolers.