Impact of an internal heat exchanger on a transcritical CO2 heat pump under optimal pressure conditions

Transcritical R744 (CO2) heat pumps are a low-GWP high-efficiency alternative for domestic hot water generation and space heating. For high set-point temperatures, however, the COP drops optimum operating pressure increases. this reason, effect on system performance achieved by inclusion of an Intermediate Heat Exchanger (IHX) is analyzed in depth. This carried out means numerical-experimental approach which effectiveness IHX other characteristic parameters pump cycle studied as function transfer area. The numerical modeling components implemented transient simulations heating-up process. Experimental tests with without water-to-water that feeds accumulator tank, to assess its influence system’s electrical consumption. Simulations reveal improving efficiency IHX, increasing exchange area, improves performance. cases higher lower. heating experiments, resulting thermodynamic 7.55 % case while effective increases 4.26 %. In consequence, use recommended conditions analyzed.