Parametric analysis of the transient behaviour of a heat pump system intended for space heating of a commercial building in the north of Italy

The enhancement of the buildings energy efficiency and the use of the renewable energies are necessary measures for decreasing the European greenhouse gas. Among the different solutions that can be adopted to improve the efficiency of the building heating and cooling systems, the heat pump systems represent certainly a significant measure to achieve energy saving. The energy performance of the heat pumps is significantly affected by the operating conditions, such as the temperature of the heat source and sink, the heating/cooling demand schedule and the heat pump control system. This paper presents a detailed analysis of the heat pump performance, in order to assess the impact of the main parameters on the overall performance of the whole system. To this aim each component of the heat pump (i.e. compressor, condenser, evaporator, expansion valve), the heat sources/sinks, the auxiliary boiler and the building have been modelled within the Matlab/Simulink environment, by adopting a lumped parameter approach. The presented results, obtained for the space heating of a commercial building located in the north of Italy, point out that the best system performance is provided when the heat pump can switch between different heat sources, depending on the temperature level of each.