Abstract
This article attempts to investigate the energy performance of CO2 (R744) hybrid ground-coupled heat
pumping system for the cooling and heating application in hotels. The developed heat pumping system,
employing a reverse transcritical CO2 cycle, utilises a heat sink combination of tap water and ground in
cooling mode, while only the ground is utilized as the heat source in heating mode. When the heat pump
operates in cooling mode, part of heat on the high pressure side could be recovered for heating the tap water
to 65 ºC for the hotel hot water supply. The separated gas coolers also enable simultaneous space heating and
hot water supply in the heating mode. This CO2 hybrid ground coupled heat pump system is modelled in the
Modelica/ Dymola environment, and several types of control strategies according to the hotel heat load
demands are suggested for the energy performance investigation. Simulation result shows the COPcooling&SHW,
which could reach 4.8, is superior comparing with other cooling and heating system, and the optimal high
side pressure for different control strategy is acquired according to the optimal energy performance
pumping system for the cooling and heating application in hotels. The developed heat pumping system,
employing a reverse transcritical CO2 cycle, utilises a heat sink combination of tap water and ground in
cooling mode, while only the ground is utilized as the heat source in heating mode. When the heat pump
operates in cooling mode, part of heat on the high pressure side could be recovered for heating the tap water
to 65 ºC for the hotel hot water supply. The separated gas coolers also enable simultaneous space heating and
hot water supply in the heating mode. This CO2 hybrid ground coupled heat pump system is modelled in the
Modelica/ Dymola environment, and several types of control strategies according to the hotel heat load
demands are suggested for the energy performance investigation. Simulation result shows the COPcooling&SHW,
which could reach 4.8, is superior comparing with other cooling and heating system, and the optimal high
side pressure for different control strategy is acquired according to the optimal energy performance
