22 May 2008
In low-heating-energy buildings heat pumps have become an attractive heating
system, due to a notable reduction of the space heating requirements and the introduction of
low temperature heating systems, which enable high efficiencies. Comfort cooling becomes
also more interesting in the residential sector, especially in lightweight buildings with large
south-oriented windows, which partially tend to overheat in summer.
A heat pump has the unique feature that heating and cooling can be provided with the same
system and also at the same time (domestic hot water and cooling). Thus an integrated heat
pump system with the functions heating, cooling and preparation of domestic hot water is an
interesting solution for the energy supply of low-heating-energy buildings.
Three different system concepts for integrated heat pump systems have been analyzed in
detail by means of simulations. The heat pump cycle was modelled including all heat
exchangers and was analyzed concerning the efficiency and possible improvements using
different refrigerants (R134a, R290, R744). For the further investigations, which will include
the construction of a prototype and a detailed dynamic simulation of the system, a
brine/water system with the refrigerant R744 will be used.