Regular emission characteristics of HFC-134a from mobile air conditioners

This paper describes the regular emission characteristics and model of HFC-134a from the mobile air conditioners (MACs) of passenger vehicles excluding van and sports utility vehicle (SUV) at the use- and disposal-phase. The fugitive emission model of HFC-134a from MAC developed here assumed that the emission process would be expressed by the first-order kinetics. The apparent fugitive emission constant of HFC-134a from MAC in passenger vehicles is estimated to be 0.0526 ± 0.0024 yr−1 within a confidence interval of 95%, leading to the emission factor (EF) of 5.1 ± 0.4% yr−1. The average residual rate of HFC-134a is 55.6 ± 1.1% in scrap passenger vehicles with an average age of 12.4 years. The average emission rate per vehicle is determined to be 24.6 g yr−1 at the use-phase and 383.4 g per scrap passenger. Based on the excellent duplication of the measured residual rates of scrap passenger vehicles by the predicted ones by the emission model developed here, it is concluded that the emission model and apparent fugitive emission constants are reasonably appropriate for representing the regular emission characteristics of HFC-134a from MAC of passenger vehicles.