Efficiency increase in carbon dioxide refrigeration technology with parallel compression

Abstract

In this article, we will review the comparison between a CO2 refrigeration system with a parallel compressor and a conventional carbon dioxide refrigeration machine. In order to carry out the comparison, a numerical model has been generated showing a good correlation to experimental data obtained with a fully instrumented test rig machine. We can determine under which conditions an increase in the energy efficiency ratio (EER) of 10% and more can be expected with a parallel compression system. The results will help users to decide upon economically viable refrigeration systems, depending on the operational conditions of the machine. In usual operating conditions, the achievable increase in the EER by the parallel compressor has been determined; furthermore, it showed that a low evaporation temperature and a high temperature at the outlet of the gas cooler have a positive effect on the parallel compression circuit. With respect to the intermediate pressure, an optimum can be specified at low evaporation temperatures.