Experimental Investigation of a Novel Hybrid Heat Pump
Abstract
Heat pumps are a technology to utilize renewable electrical energy to generate domestic heat without the use of fossil fuels. Hybrid heat pumps aim at utilizing different low-temperature heat sources. In this study, a hybrid heat pump is developed which can draw ambient energy from either a ground source heat exchanger or an air source heat exchanger depending on their temperature levels. To fully exploit the potential, additional operation modes are enabled. These include efficient parallel operation of both ambient heat sources, novel defrosting interconnections as well as active regeneration of the soil. The hybrid heat pump is tested in a laboratory under realistic conditions. The results promise comparable efficiencies with traditional heat pumps as well as stable novel operation modes. Parallel operation shows high efficiency at low ambient temperatures. The novel defrosting interconnection shows lowered heat losses compared to reverse cycle defrosting. Active regeneration of the soil is operational. The refrigerant cycle concept proves to be feasible.