R-134a Emissions from Vehicles

Abstract

We report the first study of R-134a (also known as HFC-134a and CF3CFH2) refrigerant leakage from air conditioning (AC) systems of modern vehicles. Twenty-eight light duty vehicles from five manufacturers (Ford, Toyota, Daimler Chrysler, General Motors, and Honda) were tested according to the USEPA (Federal) extended diurnal test procedure using the Sealed Housing for Evaporative Determination (SHED) apparatus. All tests were conducted using stationary vehicles with the motor and air conditioning system turned off. R-134a was measured using gas chromatography (GC) with a flame ionization detector (FID). All vehicles exhibited measurable R-134a leakage over the 2-day diurnal test. Leak rates of R-134a ranged from 0.01 to 0.36 g/day with an average of 0.07+/-0.07 g/day. When combined with leakage associated with vehicle operation, servicing, and disposal we estimate that the lifetime average R-134a emission rate from an AC equipped vehicle is 0.41+/-0.27 g/day (the majority of emissions are associated with vehicle servicing and disposal). Assuming that the average vehicle travels 10 000 miles per year we estimate that the global warming impact of R-134a leakage from an AC equipped vehicle is approximately 4-5% of that of the CO2 emitted by the vehicle. The results are discussed with respect to the contribution of vehicle emissions to global climate change.

Global emissions of refrigerants HCFC-22 and HFC-134a: Unforeseen seasonal contributions

“…The high vapor pressures in summer, roughly 8-12 times atmospheric pressure, may promote leakage past seals in the refrigeration systems. In use, both refrigerants have much higher pressures in the compressor line compared with when not in use (e.g., ∼4 times for HFC-134a systems) (12). This even higher vapor pressure during operation, combined with more frequent use of cooling devices in summer, could lead to enhanced leak rates in summer compared with winter.…”

“…Refrigerant leakage studies suggest neither the gradual leaks (i.e., regular emissions) nor the immediate release (i.e., break of the air conditioning system) have significant seasonal dependences (12,13). In contrast, a few regional atmospheric studies suggest that emissions of HCFC-22 and HFC-134a may be seasonal due to weather-dependent patterns in refrigerator and air conditioner use (14)(15)(16)(17)(18)(19).…”

Leakage Rates of Refrigerants CFC-12, HCFC-22, and HFC-134a from Operating Mobile Air Conditioning Systems in Guangzhou, China: Tests inside a Busy Urban Tunnel under Hot and Humid Weather Conditions

“…This result implies a temperature-or use-dependent emission enhancement. While regular annual leakage rates are typically estimated based on the difference in mass between the initial and remaining refrigerants over some time interval, and the refrigerant leakage from stationary vehicles can be measured using a Sealed Housing for Evaporative Determination (SHED) apparatus, 28 it is not easy to obtain measurement-based EFs for refrigerant leakage from MACs under on-road operation conditions.…”

Rainwater trifluoroacetic acid (TFA) in Guangzhou, South China: Levels, wet deposition fluxes and source implication

“…HFC-134a, for example, as the most widely used HFCs in the world and also an important TFA precursor, was a cooling agent for mobile air conditioning systems (MACs) used in more than 80% of passenger cars and commercial vehicles worldwide (Velders et al, 2009). HFC134a would release from seals and pipelines during the whole life cycle of a car, including production, normal operation, repair and maintenance, and end-of-life disposal (Siegl et al, 2002;Stemmler et al, 2004). The global production and sales of HFC-134a grew from b0.2 Gg yr 1990(AFEAS, 2007, with an emission rate of more than 100 kt yr −1 (Ashford et al, 2004;Stohl et al, 2010).…”