15 May 2023

Presentation No 761 – Laboratory characterization of a cascade heat pump system with intermediate water loop – 14th IEA Heat Pump Conference, Chicago, USA

To reach the goal of decarbonization, the thermal loads of buildings are being electrified with the use of heat
pumps in replacement of traditional fossil fuel boilers. In the European project HAPPENING, a cascade heat
pump system has been designed for the renovation of a building originally heated by a gas boiler. Air-to-water
heat pumps provide heat to a water-loop which is the source for a water-to-water heat pump used to produce
domestic hot water and for different water-to-air heat pumps, located in the apartments, that cover the heating
and cooling loads. The system is controlled with a model predictive control which aim is the optimization of
renewable energy consumption. The performance characterization of the heat pumps and the system is crucial
for the definition of such advanced control. In the “Heat Pumps Lab” of Eurac research, the system has been
characterized in two phases. In this paper we present the first step which includes the investigation of the
operational limits, the definition of a performance map and the calculation of the system performance. The
second step is the dynamic whole system test where the system is installed in three climatic chambers: one for
the external unit, one for the water-loop and one for the internal units.