CO_2 EXPANDER-COMPRESSOR-UNIT (ECU) IN REFRIGERATION SYSTEMS

摘要

CO_2 has a high volumetric capacity and a good heat transfer performance but a disadvantage in terms of the coefficient of performance (COP) at high gas cooler temperatures. The reasons are the thermodynamic losses during the throttling process and the high discharge temperatures. The high pressure levels in such a system are a further disadvantage. In our laboratory a piston expander-compressor-unit has been developed and tested to improve the CO_2 system COP. Our latest prototype has been integrated in two supermarket refrigeration systems. These first field tests started in a Swiss cash & carry market as well as in an experimental plant with a demo market. In this publication operational experiences and test results at sub-and transcritical conditions are presented.