Introduction and analysis of a concept for decentralized heat pumping in hydronic networks

This work describes a system that utilizes small distributed circulation and heat pumps in order to locally adjust the heating and cooling capacity of a hydronic heat pump system. Thereby, flexibility of the whole system is increased, which allows for better control of heating capacity, increases comfort and at the same time reduces the temperature lift of the main heat pump.Those pumps are integrated in a conventional distribution network. The small heat pumps transfer energy between the unit's supply and return thereby influencing the overall system temperature lift.A mathematical model of a hydronic heating system was used in order to determine required efficiencies of decentralized heat pumps for different evaporation temperatures of the central heat pump and different geometries. A setup with conventional centralized temperature setting served as reference.As a result, the efficiency of the decentralized heat pump should be at least 0.2 for a system with low evaporation temperatures of 0 °C, whereas for a system with high source temperatures this value increased to 0.32. A small reduction in electric power was observed even when compared to a highly efficient setup. The system is feasible with available technology, but the sizing of the unit is depending on the whole system and the desired operating regime.

► A new concept for decentralized heat pumps in hydronic systems on a building scale is being introduced.
► Analysis is carried out to find optimal efficiency of those decentralized heat pumps.
► It is found that efficiency of decentralized heat pumps is depending on heating system.