Combining a detailed catalytic surface reaction mechanism with noble metal and promoter elementary reactions, a new three-way catalytic converter(TWC) reaction mechanism is established. Based on the new mechanism, ste...Combining a detailed catalytic surface reaction mechanism with noble metal and promoter elementary reactions, a new three-way catalytic converter(TWC) reaction mechanism is established. Based on the new mechanism, steady condition numerical simulation is carried out, and the change of light-off temperatures and conversion efficiency with various SO2 contents is obtained. By grey relational analysis(GRA), the relational grade between conversion efficiency and SO2 content is obtained. And, the result shows that SO2 content has the most important influence on C3H6 and NOX conversion efficiency. This provides an important reference to the improvement of activity design of TWC, and may provide guidance for the condition design and optimization of TWC.展开更多
Regulated and unregulated emissions from four passenger cars fueled with methanol/gasoline blends at different mixing ratios （M15,M20,M30,M50,M85 and M100） were tested over the New European Driving Cycle （NEDC）.Vo...Regulated and unregulated emissions from four passenger cars fueled with methanol/gasoline blends at different mixing ratios （M15,M20,M30,M50,M85 and M100） were tested over the New European Driving Cycle （NEDC）.Volatile organic compounds （VOCs） were sampled by Tenax TA and analyzed by thermal desorption-gas chromatograph/mass spectrometer （TD-GC/MS）.Carbonyls were trapped on dinitrophenylhydrazine （DNPH） cartridges and analyzed by high performance liquid chromatography （HPLC）.The results showed that total emissions of VOCs and BTEX （benzene,toluene,ethylbenzene,p,m,o-xylene） from all vehicles fueled with methanol/gasoline blends were lower than those from vehicles fueled with only gasoline.Compared to the baseline,the use of M85 decreased BTEX emissions by 97.4%,while the use of M15 decreased it by 19.7%.At low-to-middle mixing ratios （M15,M20,M30 and M50）,formaldehyde emissions showed a slight increase while those of high mixing ratios （M85 and M100） were three times compared with the baseline gasoline only.When the vehicles were retrofitted with new three-way catalytic converters （TWC）,emissions of carbon monoxide （CO）,total hydrocarbon （THC）,and nitrogen oxides （NOx） were decreased by 24%–50%,10%–35%,and 24%–58% respectively,compared with the cars using the original equipment manufacture （OEM） TWC.Using the new TWC,emissions of formaldehyde and BTEX were decreased,while those of other carbonyl increased.It is necessary that vehicles fueled with methanol/gasoline blends be retrofitted with a new TWC.In addition,the specific reactivity of emissions of vehicles fueled with M15 and retrofitted with the new TWC was reduced from 4.51 to 4.08 compared to the baseline vehicle.This indicates that the use of methanol/gasoline blend at a low mixing ratio may have lower effect on environment than gasoline.展开更多
In this study,ammonia emissions characteristics of typical light-duty gasoline vehicles were obtained through laboratory vehicle bench test and combined with New European Driving Cycle(NEDC)condition and Worldwide Har...In this study,ammonia emissions characteristics of typical light-duty gasoline vehicles were obtained through laboratory vehicle bench test and combined with New European Driving Cycle(NEDC)condition and Worldwide Harmonized Light Vehicles Test Cycle(WLTC)condition.The influence of ambient temperature on ammonia emissions is mainly concentrated in the cold start stage.The influence of ambient temperature on ammonia emission is shown that the ammonia emissions of light-duty gasoline vehicles under ambient temperature conditions(14 and 23℃)are lower than those under low ambient temperature conditions(-7℃)and high ambient temperature conditions(35 and 40℃).The influence of TWC on ammonia emission is shown that ammonia is a by-product of the catalytic reduction reaction of conventional gas pollutants in the exhaust gas in the TWC.Under NEDC operating conditions and WLTC operating conditions,ammonia emissions after the catalyst are 45 times and 72 times that before the catalyst,respectively.In terms of ammonia emissions control strategy research,Pd/Rh combination can reduce NH3 formation more effectively than catalyst with a single Pd formula.Precise control of the engine’s air-fuel ratio and combination with the optimized matched precious metal ratio TWC can effectively reduce ammonia emissions.展开更多
基金Project(2009CK2001) supported by the Science & Technology Development Key Program of Hunan Province STA of ChinaProject supported by the Young Teachers Program of Hunan University,China
文摘Combining a detailed catalytic surface reaction mechanism with noble metal and promoter elementary reactions, a new three-way catalytic converter(TWC) reaction mechanism is established. Based on the new mechanism, steady condition numerical simulation is carried out, and the change of light-off temperatures and conversion efficiency with various SO2 contents is obtained. By grey relational analysis(GRA), the relational grade between conversion efficiency and SO2 content is obtained. And, the result shows that SO2 content has the most important influence on C3H6 and NOX conversion efficiency. This provides an important reference to the improvement of activity design of TWC, and may provide guidance for the condition design and optimization of TWC.
基金supported by the National Natural Science Foundation of China(No.50876013)
文摘Regulated and unregulated emissions from four passenger cars fueled with methanol/gasoline blends at different mixing ratios （M15,M20,M30,M50,M85 and M100） were tested over the New European Driving Cycle （NEDC）.Volatile organic compounds （VOCs） were sampled by Tenax TA and analyzed by thermal desorption-gas chromatograph/mass spectrometer （TD-GC/MS）.Carbonyls were trapped on dinitrophenylhydrazine （DNPH） cartridges and analyzed by high performance liquid chromatography （HPLC）.The results showed that total emissions of VOCs and BTEX （benzene,toluene,ethylbenzene,p,m,o-xylene） from all vehicles fueled with methanol/gasoline blends were lower than those from vehicles fueled with only gasoline.Compared to the baseline,the use of M85 decreased BTEX emissions by 97.4%,while the use of M15 decreased it by 19.7%.At low-to-middle mixing ratios （M15,M20,M30 and M50）,formaldehyde emissions showed a slight increase while those of high mixing ratios （M85 and M100） were three times compared with the baseline gasoline only.When the vehicles were retrofitted with new three-way catalytic converters （TWC）,emissions of carbon monoxide （CO）,total hydrocarbon （THC）,and nitrogen oxides （NOx） were decreased by 24%–50%,10%–35%,and 24%–58% respectively,compared with the cars using the original equipment manufacture （OEM） TWC.Using the new TWC,emissions of formaldehyde and BTEX were decreased,while those of other carbonyl increased.It is necessary that vehicles fueled with methanol/gasoline blends be retrofitted with a new TWC.In addition,the specific reactivity of emissions of vehicles fueled with M15 and retrofitted with the new TWC was reduced from 4.51 to 4.08 compared to the baseline vehicle.This indicates that the use of methanol/gasoline blend at a low mixing ratio may have lower effect on environment than gasoline.
基金supported by the National Natural Science Foundation of China(Nos.51508304 and 41275133)。
文摘In this study,ammonia emissions characteristics of typical light-duty gasoline vehicles were obtained through laboratory vehicle bench test and combined with New European Driving Cycle(NEDC)condition and Worldwide Harmonized Light Vehicles Test Cycle(WLTC)condition.The influence of ambient temperature on ammonia emissions is mainly concentrated in the cold start stage.The influence of ambient temperature on ammonia emission is shown that the ammonia emissions of light-duty gasoline vehicles under ambient temperature conditions(14 and 23℃)are lower than those under low ambient temperature conditions(-7℃)and high ambient temperature conditions(35 and 40℃).The influence of TWC on ammonia emission is shown that ammonia is a by-product of the catalytic reduction reaction of conventional gas pollutants in the exhaust gas in the TWC.Under NEDC operating conditions and WLTC operating conditions,ammonia emissions after the catalyst are 45 times and 72 times that before the catalyst,respectively.In terms of ammonia emissions control strategy research,Pd/Rh combination can reduce NH3 formation more effectively than catalyst with a single Pd formula.Precise control of the engine’s air-fuel ratio and combination with the optimized matched precious metal ratio TWC can effectively reduce ammonia emissions.
