17 October 2006

Brine-to-water CO2 heat pump systems for heating and cooling of non-residential buildings

Carbon dioxide (CO2) has been identifi ed as an interesting working fl uid in brine-to-water heat pumps for
heating and cooling of non-residential buildings. Connecting such a heat pump in series with a hydronic
radiator and ventilation heater system provides a relatively low return temperature in the system, and thus
favourable operating conditions for a CO2 heat pump. Preheating and reheating of domestic hot water will
lead to a further increase in the COP of the CO2 heat pump system. Computer simulations have demonstrated
that a CO2 heat pump system in non-residential buildings can achieve the same or higher seasonal performance
factor (SPF) than heat pumps using conventional working fl uids, as long as the heat distribution
system is designed for a low return temperature. The operational time of the ventilation system will have a
major impact on the SPF of the CO2 heat pump, since the return temperature in the heat distribution system
is considerably lower when the ventilation system is in operation.