Pulse Tube Development Using Harmonic Simulations

Abstract

Based on the experiences with our in-house simulation model for Stirling coolers, we are developing a similar model for pulse tube coolers. This model is built on first order harmonic approximations and time averaging of the energy flows. It predicts the pressure waves, the temperatures and the cooling power with its associated loss contributions. The main benefit of this simulation model is the combination of short calculation times and sufficient accurate predictions., which is established by means of analytical simplification.

Simulations of a particular cooler are obtained from solving the model’s equations iteratively. The iterations are initiated with a chosen initial temperature profile throughout the whole system, which is used for simultaneous calculations of mass flows and pressure waves. With the results of these calculations the average temperatures and enthalpy flows are computed. These subsequent calculation steps are repeated until sufficient stability is achieved. At that point the properties of the particular pulse tube cooler in its stationary operational mode are known.

The simulation model is experimentally verified. Predictions of cooling powers, mass flows, pressure waves and temperature profiles have been checked. This has given promising results, although certain aspects of the model may need more attention and improvement.