Développement d'un compresseur semi-hermétique biétagé au CO2.

A semi-hermetic CO2 compressor series in the range of 0.5-12.6 m3/h swept volume is under development (single- and two-stage compressors with two cylinders, running at nominal speeds of 2900 rpm). This corresponds to cooling capacities in the range of 0.6-15 kW at -35 °C evaporating temperature. Different design issues are being discussed. Measurements of compressor efficiencies, temperatures and pressures are presented for two-stage compressors in the 4-pole assembly (1450 rpm) and also for 2900 rpm. At this stage of the development, the performance is very acceptable. Compared to using a one-stage compressor for low-temperature supermarket refrigeration, a gain in COP of 20% could be realized and probably an additional 30% by using two-stage throttling.