CO2 transcritical plant with optimized dedicated mechanical subcooling

In CO2 refrigerating system, one of the most effective techniques for the improvement of energy efficiency is subcooling the fluid at the exit of the gas cooler. This can be achieved by taking advantage of cooling capacity supplied by HVAC chillers or dedicated mechanical refrigeration units. Furthermore, in the presence of subcooling the settings of the CO2 system can be modified in order to further reduce the energy use of the plant. In this paper, the effect of Dedicated Mechanical Subcooling on the performance of a CO2 booster system is investigated, and compared to a plant scheme where subcooling is performed via the HVAC, at two different climate conditions. The effect of optimisation of the gas cooler pressure is also investigated, and shows to be effective especially at hot climate conditions.