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

Determining
the leakage rates of halogenated refrigerants from
operating mobile air conditioning systems (MACs) is a challenging
task. Here, we take advantage of a heavily trafficked tunnel with
a traffic flow of over 40,000 motor vehicles per day in south China.
We carried out measurements in 2014 on hot and humid days, and therefore,
it is reasonable to assume that essentially all of the MAC units would
be turned on to ensure the thermo-comfort of the occupants. Thus,
we obtained the leakage rates of the three most important refrigerants
from the operating MACs aboard the on-road vehicles. The emission
factors (EFs) of HFC-134a, HCFC-22, and CFC-12 from the on-road operating
MACs are 1.27 ± 0.11, 0.47 ± 0.04, and 0.17 ± 0.04
mg km–1 veh–1, respectively. Normalized
by the percentages of vehicles using different refrigerants in their
MACs, the emission rates of HFC-134a, HCFC-22, and CFC-12 are 52.2,
329, and 59.5 mg h–1 veh–1, respectively.
This emission rate of HFC-134a is approximately 10 times higher than
those previously reported in Europe for stationary conditions and
a whole-lifetime average of fugitive losses. The unusually high leakage
rates suggest that improving the leak tightness of MACs in China would
help to greatly lower their emissions. The global warming potentials
associated with refrigerant leakage is equal to 1.4% of the CO2 directly emitted due to fuel consumptions.