Attaining a higher flexibility degree in CO2 compressor racks

Abstract

CO2 compressor racks have shown their suitability for commercial and industrial refrigeration systems at any location and climate. Even if some references state that CO2 units can compete in capital cost with any other alternative solution, often investment costs are still the main barrier for the global expansion of CO2. This work explores, numerically and experimentally, the implementation of “pivoting” compressors, i.e. compressors that can operate in the medium temperature (MT) and parallel compressor suction groups, depending on ambient conditions, cooling loads and use of ejector. The objective is to increase the flexibility of CO2 compressor racks, keeping the efficiency and, potentially, reducing the investment. This study shows that this solution with “pivoting” compressors is beneficial in ejector-supported systems, since the investment cost of the ejectors is compensated by a lower number of installed compressors, as compressor capacities can be applied in more flexible ways. Keywords: Refrigeration, Carbon Dioxide, Compressors, Switching, Pivoting.