Computational study of a 4 K two-stage pulse tube cooler with mixed Eulerian-Lagrangian method

A new mixed Eulerian-Lagrangian numerical 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 moving grid, 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 fixed computational grid, 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 time-variations of gas temperature, pressure, mass flow rate, enthalpy flow in a cycle, in first- and second-stage regenerators are presented in the paper. More attention is paid to the effects of different regenerative materials on the performance of the 4 K two-stage PTC. (C) 2001 Elsevier Science Ltd. All rights reserved.