An Optimization Program for Modeling Pulse Tube Coolers

Abstract

ARCOPTR is a program developed at NASA-Ames Research Center for modelingpulse tube coolers. The ARCOPTR is a 1-D model that treats all thecomponents of an orifice pulse tube cooler or a pulse tube cooleremploying an inertance tube. It analyzes the thermodynamic equations forthe regenerator and assumes that all mass flows, pressure oscillationsand temperature oscillations are small and sinusoidal. The resultingmass flows and pressures are matched at the boundaries with the othercomponents of the cooler: compressor, aftercooler, cold heat exchanger,pulse tube, hot heat exchanger, orifice/inertance tube and reservoir.The results of the calculation are oscillating pressures, mass flows andenthalpy flows in the main components of the cooler. An optimizer hasbeen built into the ARCOPTR that allows optimization of the coolerparameters to attain maximum efficiency. The parameters that can beoptimized are the length and the diameter of the regenerator and thoseof the pulse tube, the wire diameter and the mesh size of theregenerator screen, and the orifice opening or in the case of aninertance tube, its length and diameter. In this study, pulse tubecooler configurations, employing an orifice or an inertance tube, havebeen optimized using the ARCOPTR. The optimum parameters are plotted asa function of the regenerator diameter. In the optimization the pressureratio in the pulse tube is maintained at 1.2 by adjusting the compressorstroke.