| Autor: |
Smit R; EMISIA SA , Antoni Tritsi 21 , GR 57001 , Pylaia , Greece.; School of Civil Engineering , University of Queensland , Brisbane , Queensland 4001 , Australia., Keramydas C; EMISIA SA , Antoni Tritsi 21 , GR 57001 , Pylaia , Greece., Ntziachristos L; Laboratory of Heat Transfer and Environmental Engineering, Mechanical Engineering Department , Aristotle University Thessaloniki , GR 54124 , Thessaloniki , Greece., Lo TS; Environmental Protection Department , Hong Kong SAR Government , 33/F, Revenue Tower, 5 Gloucester Road , Wan Chai , Hong Kong., Ng KL; Environmental Protection Department , Hong Kong SAR Government , 33/F, Revenue Tower, 5 Gloucester Road , Wan Chai , Hong Kong., Wong HA; Environmental Protection Department , Hong Kong SAR Government , 33/F, Revenue Tower, 5 Gloucester Road , Wan Chai , Hong Kong., Wong CK; Environmental Protection Department , Hong Kong SAR Government , 33/F, Revenue Tower, 5 Gloucester Road , Wan Chai , Hong Kong. |
| Abstrakt: |
This study reports on the results of gaseous pollutants emission measurements of double-decker buses in an urban road network, using portable emission measurement systems (PEMS). Measured vehicles were tested by following in-service buses on regular routes. Six Euro II and Euro III buses were retrofitted with diesel particulate filters (DPF) and selective catalytic reduction (SCR) or a combined SCR+DPF (SCRT) device. Substantial and statistically significant technology impacts were observed for several pollutants. Optimized SCR and SCRT retrofit technology reduced real-world NO x emissions by approximately 70%, on average. Retrofit DPF slightly reduced NO x emissions but increased direct NO 2 emissions by more than a factor of 8, on average. SCRT led to about 70% lower NO 2 levels than DPF alone, but for some vehicles higher NO 2 levels were observed as compared with the "no retrofit" situation, warranting further investigation. None of the SCR systems were found to lead to a substantial increase in NH 3 emissions after operation optimization. High NH 3 and N 2 O emissions were occasionally observed while experience with the system calibration was being accumulated. Observed average N 2 O emission levels for "DPF+SCR" technology were relatively high at 182 mg/kg fuel, corresponding to 1.5% of total greenhouse gas emissions. The study shows that SCR retrofit programs can be effective for NO x reduction of transit buses but that proper calibration and regular emission monitoring are required. |
