Testing Issues of Automotive Air-Conditioning Systems Using R-744 (Carbon Dioxide) Refrigerant 2001-01-0295
Global environmental issues require that new alternatives to R-134a refrigerant be investigated by the automotive air-conditioning (A/C) industry. Test facilities must be able to handle the challenges that these refrigerants pose. One refrigerant currently under investigation is Carbon Dioxide (CO2). The high pressure and toxicity of CO2, require the test facility to institute more stringent guidelines and add equipment to safeguard personnel. The operating characteristics of this refrigerant, and the additional equipment needed for the test A/C system, necessitate more complex automated test data acquisition and control. The addition of an internal heat exchanger in the CO2 A/C system is an example of the changes required. Different thermal characteristics introduced by this refrigerants mean that new measurement devices such as higher-pressure transducers are required. Compatibility between test stand sealing materials, hose assemblies, etc., and the refrigerant must be addressed. Due to the research nature of R-744 refrigerant, the test facility must be flexible and robust enough to accommodate engineering challenges and changes in program direction.