CO2 transcritical vapor compression cycle with thermoelectric subcooler

In this paper, the integration of two different cooling technologies: thermoelectric (TE) cooling and the vapor compression cycle (VCC), is investigated to enhance the performance of the latter. In the integrated system, the TE cooler is utilized as a subcooler of the VCC condenser or gas cooler. In this integration, the TE subcooler is operated at a small temperature lift so that it operates at higher efficiency than that of the baseline VCC efficiency while providing the additional subcooling. These two factors result in the improved capacity and coefficient of performance (COP) of the entire system. To prove the concept, a TE subcooler was designed and fabricated to subcool the CO2 exiting the gas cooler of a transcritical VCC. A 3.3% improvement in COP with a TE subcooler was experimentally demonstrated with a corresponding 7.9% capacity increase. A 18.7% capacity increase was demonstrated at a comparable COP to the baseline system.