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.