Evaluation of the influence of the subcooling on the performance of vapor injection scroll compressors.

In this work, the influence of subcooling in the performance of an injection scroll compressor is analyzed as a function of evaporating and condensing temperature. In order to do that, a test campaign has been developed. The test campaign has included experimental evaporation temperatures from -20°C to 10°C, condensing temperatures from 40°C to 60°C and subcooling from 0°C to 20°C using R407C as refrigerant. The obtained data have been used to determine the influence of the subcooling in cycle efficiency and compressor performance (through the modification of the intermediate pressure injection).Two main results have been obtained from all this work: a) a correlation for the compressor intermediate pressure as a function of the operating conditions, b) The difficulty to control the compressor intermediate conditions with the expansion valve when the subcooling increases. The explanation for this phenomenon has been made in terms of the compressor design in this kind of cycle.