Energy analysis of dedicated and integrated mechanical subcooled CO2 boosters for supermarket applications

Abstract

Energy improvements offered by dedicated and integrated mechanical subcooling systems in CO2 booster systems for supermarket applications are analyzed here through the use of thermodynamic models close to reality. Using a reference supermarket with 41 kW and 140 kW thermal loads at low and medium temperature, respectively, and considering as state-of-the-art system the CO2 booster with parallel compressor and flash gas by-pass, it has been concluded that both systems allow to reduce energy consumption. However, its operation is highly dependent on environmental conditions. The dedicated mechanical subcooling system offers annual energy reductions for tempered places from 1.5% to 2.9%, for warm between 2.9% and 3.4% and for hot from 3.0% to 5.1%. The integrated subcooling system obtains reductions between 3.1% and 4.0% for cold regions, from 1.4% to 2.9% for tempered, from 2.9% to 3.4% for warm and from 1.3% to 2.4% for hot regions.