Denso Corporation has developed with Toyota Motor Corporation a claimed world-first non-fluorocarbon car air conditioner using natural refrigerant, carbon dioxide (CO2). Toyota's fuel cell hybrid vehicle FCHV, launched on Dec. 2, uses this new CO2 car air conditioner.

The majority of the world's car air conditioners use hydrofluorocarbon refrigerant (HFC-134a) that is a substitute of chlorofluorocarbon (CFC-12) and is harmless to the ozone layer.  However, HFC-134a's impact on global warming is still large, although smaller than that of CFC-12, a Denso spokesman said.

Denso claims the impact of CO2 on global warming is 1/1,300 of HFC-134a.
In addition, a conventional fluorocarbon air conditioner requires a heater core to use heat from the vehicle engine to heat air in the cabin. In contrast, the non-fluorocarbon air conditioner heats air to rapidly raise cabin temperature by heat exchange between the CO2 refrigerant and air, without using heat from the engine.

CO2 can be produced by purifying and distilling gas discharged from chemical plants.  Unlike fluorocarbon refrigerant, complicated manufacturing processes are not required to produce CO2.

In the CO2 air conditioner, the refrigerating cycle needs to operate under higher pressure than that of HFC-134a.  Because of this need, the system is equipped with a heat exchanger featuring tubes and tanks resistant to high pressure, and a compressor structure that is resistant to high load and which prevents internal leakage.

The Denso spokesman said: "While aiming to widely apply CO2 car air conditioners to vehicles, we will attempt to further improve the performance, reduce cost and weight, and secure reliability. Also, we will cooperate with industry and governmental bodies to create infrastructure, such as developing safe refrigerant filling devices to enable safe handling of CO2."

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