Experimental study on automotive cooling and heating air conditioning system using CO2 as a refrigerant

Recently, as one of the countermeasures against the global warming and energy conservation problems, natural refrigerants such as CO2 are now paid attention as substitutes for HFCs in automotive air conditioning systems. Also, in recent years because the heat release from the eco-car's engine decreases, there is a problem that the present automotive heating air conditioning system cannot provide sufficient heating capacity. As an alternative approach, we focused on a solution utilizing a CO2-based heat pump, whereby the waste heat from the heat pump cycle during dehumidification of the incoming air (referred to as the dehumidifying condition) is recovered and used as an auxiliary heat source instead of an electric heater. Based on this concept, we aimed to develop an effective automotive cooling and heating air conditioning system using CO2 as a refrigerant. As the result, a prototype CO2 automotive cooling and heating air conditioning system for medium-sized cars was successfully developed. With this system, performance superior to that of the present HFC134a system can be achieved. (C) 2005 Elsevier Ltd and IIR. All rights reserved.