Performance evaluation of a R-290 dual-source heat pump for heating and cooling

Abstract

In this paper, the performance of a 10 kW reversible heat pump using R290 as refrigerant and using a dual source/sink is presented. The heat pump design is oriented for its integration with solar photovoltaic energy in multifamily near Zero Energy Buildings, with the objective to reach a high onsite renewable share. The development is part of TRI-HP project: Trigeneration systems based on heat pumps with natural refrigerants and multiple renewable sources. The heat pump has a specifically designed dual source heat exchanger (DSHX) working as the outdoor unit of the heat pump. This element is able to work as a condenser (cooling mode) or evaporator (heating mode), exchanging heat between the refrigerant and air or water/brine as heat source (in heating mode) or sink (in cooling mode). Both sources can also be simultaneously used as heat source or sink. The design procedure and used correlations for the DSHX are described. The heat pump has been experimentally tested in a climatic chamber in all the possible different working modes (Heating with air, heating with brine, cooling with air, cooling with brine), showing in general a good agreement with the design values. Results for coefficient of performance, heating/cooling capacities and compressor consumption are presented for different air/brine temperatures and different compressor velocities. The experimental campaign has served to validate the developed models for designing the DSHX. Future work includes an improved redesign of the heat pump with a more compact DSHX and a simplified refrigerant circuit, which will be experimentally tested in an analogous experimental campaign.