TABLE OF CONTENTS A key issue in successfully using cryocoolers is obtaining data on their performance with respect to the wide range of parameters involved in a successful application. This chapter focuses on what coolers do and how their performance is measured.
Although the chapter emphasizes the important parameters of regenerative cryocoolers Stirling, pulse tube, and Gifford-McMahon (GM) because this is the most common type, many of the measurement topics covered herein are equally valid for recuperative cryocoolers such as Brayton and Joule-Thomson. Included are descriptions of the analysis fundamentals underlying performance, descriptions of experimental methods for measuring performance, illustrations of particularly useful ways of displaying performance, and tables and graphs of representative performance.
[*]Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California.
The most fundamental performance attribute of a cryocooler is its ability to cool a refrigeration load to a particular temperature. Depending on the type of cryocooler, refrigeration performance generally depends on a wide variety of performance variables such as cold-load temperature, expander heat-sink temperature, compressor heat-sink temperature, compressor input power, compressor stroke, compressor drive frequency or speed (rpm), expander stroke and phase, and working-fluid fill pressure. As a result, understanding and predicting cryocooler performance in a given application can require an extensive set of performance data, together with a knowledge of how to interpolate and extrapolate the data trends for the type of cooler being examined.
The historical Oxford Stirling cooler [11.1] , [11.2]
