Refrigeration Technology

Design, construction and experimental study of a Stirling chiller for refrigeration in supermarkets

The main aim of this research project, run by the Universität-Gesamthochschule-Essen, is to develop a Stirling chiller for providing refrigeration at temperatures between 50 and 20°C. Because the refrigerant R22 has been banned since 2000, various areas of refrigeration engineering have a requirement for alternative refrigerants or refrigeration methods. The project is supported by federal government funding through the organising body Jülich PTJ.

Summary

Since the CFC and halon ban came into force in 2000, there has been a need for technical changes in provision of refrigeration. There are no fully satisfactory substitutes for the R22 refrigerant previously used, which is harmful to the environment. In this research project, the partners developed and tested a refrigeration method based on a Stirling motor. The objective was to develop prototypes for use in supermarkets and thus for temperatures between -50 °C and -20 °C. Existing Stirling motors were used, and sophisticated measuring techniques were employed to test their performance in this application.

The fact that the power of Stirling chillers increases as the required refrigeration operating temperature falls was known, which is why the technology has so far primarily been used in marginal areas close to absolute zero.

However, the studies show that using a Stirling motor can be beneficial from an energy and an economic perspective even at significantly higher refrigeration temperatures.

Results:

  • Comparing the performance data for a Stirling chiller with that of a standard commercial vapour compression chillers reveals that the two are equally well suited for the relevant application. However, there is a lack of extensive operational experience.
  • Experimental studies of the heat transfer in the Stirling chiller's regenerator enables the processes taking place to be simulated more effectively than before.
  • Weaknesses were pinpointed to the heat exchanger, and a new version with an improved heat exchanger was subsequently produced, which gets 30 % closer to the optimum refrigerating capacity.
  • The range of acceptable operating parameters was determined. The Stirling chiller proved to be very reliable in operation.

More Project Informations

Project number:  0327213

Project period:  1998 - 2001

Project region:  Germany (North Rhine-Westphalia)

Project contact:

Herr Prof. Dr-Ing. Steimle

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Source:  German National Library of Science and Technology Hannover (TIB)