In this study, the dependence of dust budgets on dust emission schemes is investigated through the simulation of dust storm events, which occurred during 14–25 March 2002, over East Asia, by the Weather Research and ...In this study, the dependence of dust budgets on dust emission schemes is investigated through the simulation of dust storm events, which occurred during 14–25 March 2002, over East Asia, by the Weather Research and Forecasting with Chemistry(WRF/Chem) model coupled with six dust emission schemes. Generally, this model can reasonably reproduce the spatial distribution of surface dust concentration; however, the simulated total dust budget differs significantly with different emission schemes. Moreover, uncertainties in the simulated dust budget vary among regions. It is suggested that the dust emission scheme affects the regional dust budget directly through its impact on the total emitted dust amount; however, the inflow and outflow of dust aerosols simulated by different schemes within a region also depend on the geographical location of the dust emission region. Furthermore, the size distribution of dust particles for a specific dust emission scheme has proven to be important for dust budget calculation due to the dependence of dust deposition amount on dust size distribution.展开更多
To fully analyze emission characteristics of VOCs (Volatile Organic Compounds) from automobile coating industry in Chongqing city, related enterprises in the city were investigated in detail. The results show that t...To fully analyze emission characteristics of VOCs (Volatile Organic Compounds) from automobile coating industry in Chongqing city, related enterprises in the city were investigated in detail. The results show that the emission of VOCs from the automobile industry in Chongqing city was approximately 20,000 t in 2012, and the contribution rate of automobile coating was 83%. Most VOCs discharged from automobile coating industry were mainly from the use of coatings, diluents, curing agents and other materials containing VOCs. During the process of automobile coating, VOCs were mainly produced during the processes of spraying and drying. Besides, VOCs are partly produced during the processes of mixing paint, gluing, waxing and repairing. The major ingredients of VOCs discharged during the process of automobile coating were methylbenzene, dimethylbenzene, trimethylbenzene, cumene, ethyl acetate, butyl alcohol, n-butyl alcohol, isobutyl alcohol, formaldehyde, butanone, acetone, cyclohexanone and methyl ethyl ketone. Besides, the ingredients of naphtha and aromatic hydrocarbon in VOCs need to be determined. The maximum OFP (Ozone Formation Potential) of the above pollutants by the typical enterprises was 900-1,300 mg/m^3. The production of SOA (Secondary Organic Aerosol) was 3,636-11,073 t/a, which didn’t include the contribution of aldehydes, ketones, ethers and esters to SOA. This research could provide scientific reference for the establishment of emission standard, control technology and management methods of VOCs from automobile coating industry that accord with economic and social development in Chongqing city.展开更多
The ultimate solution to anthropogenic air pollution depends on an adjustment and upgrade of industrial and energy structures. Before this process can be completed, reducing the anthropogenic pollutant emissions is an...The ultimate solution to anthropogenic air pollution depends on an adjustment and upgrade of industrial and energy structures. Before this process can be completed, reducing the anthropogenic pollutant emissions is an effective measure. This is a problem belonging to "Natural Cybernetics", i.e., the problem of air pollution control should be solved together with the weather prediction; however, this is very complicated. Considering that heavy air pollution usually occurs in stable weather conditions and that the feedbacks between air pollutants and meteorological changes are insufficient, we propose a simplified natural cybernetics method. Here, an off-line air pollution evolution equation is first solved with data from a given anthropogenic emission inventory under the predicted weather conditions, and then, a related "incomplete adjoint problem" is solved to obtain the optimal reduction of anthropogenic emissions. Usually, such solution is sufficient for satisfying the air quality and economical/social requirements. However, a better solution can be obtained by iteration after updating the emission inventory with the reduced anthropogenic emissions. Then, this paper discusses the retrieval of the pollutant emission source with a known spatio-temporal distribution of the pollutant concentrations, and a feasible mathematical method to achieve this is proposed. The retrieval of emission source would also help control air pollution.展开更多
The soot surface growth plays significant role on the soot mass accumulation,which starts with H(hydrogen)atom abstraction forming activated soot surface sites,and is followed by the acetylene addition process.In this...The soot surface growth plays significant role on the soot mass accumulation,which starts with H(hydrogen)atom abstraction forming activated soot surface sites,and is followed by the acetylene addition process.In this study,the effect of the mixture inhomogeneity and combustion temperature on the soot surface activity and soot formation was investigated by developing a new multi-step phenomenological(MSP)soot model of diesel engines.A new detailed soot surface growth mechanism was proposed by correlation analysis of combustion parameters with soot formation.The inhomogeneity coefficient of soot surface activityαCH and the specific rate of soot surface growth R CH were derived to highlight the effect of inhomogeneity of mixture and combustion temperature on soot formation.The predicted diesel engine-out soot agreed well with experimental findings in wide ranges of combustion conditions.In the case of lower engine load with single fuel injection and higher EGR(exhaust gas recirculation)rate,it had quiet homogeneous mixtures before ignition when the combustion temperature dominated the soot surface activity.At medium engine load with multi-pulse fuel injections,it got mixture slightly stratified before ignition and revealed that the mixture inhomogeneity became more dominated on soot surface activity than the combustion temperature.An increased soot surface activity led to increased soot emission.Under the full engine loads with single fuel injection but quite high boost pressure over 0.4 MPa,it led to the combustion conditions of higher mixture density and higher mixture heat capacity,which benefits the mixture homogeneity.The decay rate of soot surface activity became lower due to the decreased combustion temperature and the soot surface activity decreased due to improved mixture homogeneity.In addition,the lowered intake oxygen concentration due to usage of EGR played a role to lower the specific rate of soot surface growth R CH,but to increase the soot surface activityαCH.展开更多
In recent decades, there have been a number of debates on climate warming and its driving forces. Based on an extensive literature review, we suggest that (1) climate warming occurs with great uncertainty in the mag...In recent decades, there have been a number of debates on climate warming and its driving forces. Based on an extensive literature review, we suggest that (1) climate warming occurs with great uncertainty in the magnitude of the temperature increase; (2) both human activities and natural forces contribute to climate change, but their relative contributions are difficult to quan- tify; and (3) the dominant role of the increase in the atmospheric concentration of greenhouse gases (including CO2) in the global warming claimed by the Intergovernrnental Panel on Climate Change (IPCC) is questioned by the scientific communities because of large uncertainties in the mechanisms of natural factors and anthropogenic activities and in the sources of the increased atmospheric CO2 concentration. More efforts should be made in order to clarify these uncertainties.展开更多
The DLE (dry low emission) technology has already been used on industrial gas turbine combustor and the NO X emission can be limited to 25 ppmv (@15% O 2 ), but one of the destructive effects is combustion instability...The DLE (dry low emission) technology has already been used on industrial gas turbine combustor and the NO X emission can be limited to 25 ppmv (@15% O 2 ), but one of the destructive effects is combustion instability. In this paper, the dynamic and emission characteristics of a DLE gas turbine combustor have been researched in the authors' laboratory, and the results show that the key source of combustion instability is the non-uniformity of fuel in the flame zone. Two main fuel supply methods have been used to form different fuel distribution types; it is shown that in the perfectly premixed case the emission level is low and combustion process is stable. The PPF also has an obvious effect on the combustor's emission and dynamic characteristics.展开更多
基金jointly supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA05110200)the International Science and Technology Cooperation Program of China(2011DFG23450)
文摘In this study, the dependence of dust budgets on dust emission schemes is investigated through the simulation of dust storm events, which occurred during 14–25 March 2002, over East Asia, by the Weather Research and Forecasting with Chemistry(WRF/Chem) model coupled with six dust emission schemes. Generally, this model can reasonably reproduce the spatial distribution of surface dust concentration; however, the simulated total dust budget differs significantly with different emission schemes. Moreover, uncertainties in the simulated dust budget vary among regions. It is suggested that the dust emission scheme affects the regional dust budget directly through its impact on the total emitted dust amount; however, the inflow and outflow of dust aerosols simulated by different schemes within a region also depend on the geographical location of the dust emission region. Furthermore, the size distribution of dust particles for a specific dust emission scheme has proven to be important for dust budget calculation due to the dependence of dust deposition amount on dust size distribution.
文摘To fully analyze emission characteristics of VOCs (Volatile Organic Compounds) from automobile coating industry in Chongqing city, related enterprises in the city were investigated in detail. The results show that the emission of VOCs from the automobile industry in Chongqing city was approximately 20,000 t in 2012, and the contribution rate of automobile coating was 83%. Most VOCs discharged from automobile coating industry were mainly from the use of coatings, diluents, curing agents and other materials containing VOCs. During the process of automobile coating, VOCs were mainly produced during the processes of spraying and drying. Besides, VOCs are partly produced during the processes of mixing paint, gluing, waxing and repairing. The major ingredients of VOCs discharged during the process of automobile coating were methylbenzene, dimethylbenzene, trimethylbenzene, cumene, ethyl acetate, butyl alcohol, n-butyl alcohol, isobutyl alcohol, formaldehyde, butanone, acetone, cyclohexanone and methyl ethyl ketone. Besides, the ingredients of naphtha and aromatic hydrocarbon in VOCs need to be determined. The maximum OFP (Ozone Formation Potential) of the above pollutants by the typical enterprises was 900-1,300 mg/m^3. The production of SOA (Secondary Organic Aerosol) was 3,636-11,073 t/a, which didn’t include the contribution of aldehydes, ketones, ethers and esters to SOA. This research could provide scientific reference for the establishment of emission standard, control technology and management methods of VOCs from automobile coating industry that accord with economic and social development in Chongqing city.
基金supported by the National Natural Science Foundation of China (Grant No. 41630530the National Key Research and Development Program of China (Grant No. 2016YFC0209000)
文摘The ultimate solution to anthropogenic air pollution depends on an adjustment and upgrade of industrial and energy structures. Before this process can be completed, reducing the anthropogenic pollutant emissions is an effective measure. This is a problem belonging to "Natural Cybernetics", i.e., the problem of air pollution control should be solved together with the weather prediction; however, this is very complicated. Considering that heavy air pollution usually occurs in stable weather conditions and that the feedbacks between air pollutants and meteorological changes are insufficient, we propose a simplified natural cybernetics method. Here, an off-line air pollution evolution equation is first solved with data from a given anthropogenic emission inventory under the predicted weather conditions, and then, a related "incomplete adjoint problem" is solved to obtain the optimal reduction of anthropogenic emissions. Usually, such solution is sufficient for satisfying the air quality and economical/social requirements. However, a better solution can be obtained by iteration after updating the emission inventory with the reduced anthropogenic emissions. Then, this paper discusses the retrieval of the pollutant emission source with a known spatio-temporal distribution of the pollutant concentrations, and a feasible mathematical method to achieve this is proposed. The retrieval of emission source would also help control air pollution.
基金supported by the National Natural Science Foundation of China through its key project funding CNFS(Grant No.51236005)the Ministry of Science and Technology through its 973 National Key Project(Grant No.2013CB228401)
文摘The soot surface growth plays significant role on the soot mass accumulation,which starts with H(hydrogen)atom abstraction forming activated soot surface sites,and is followed by the acetylene addition process.In this study,the effect of the mixture inhomogeneity and combustion temperature on the soot surface activity and soot formation was investigated by developing a new multi-step phenomenological(MSP)soot model of diesel engines.A new detailed soot surface growth mechanism was proposed by correlation analysis of combustion parameters with soot formation.The inhomogeneity coefficient of soot surface activityαCH and the specific rate of soot surface growth R CH were derived to highlight the effect of inhomogeneity of mixture and combustion temperature on soot formation.The predicted diesel engine-out soot agreed well with experimental findings in wide ranges of combustion conditions.In the case of lower engine load with single fuel injection and higher EGR(exhaust gas recirculation)rate,it had quiet homogeneous mixtures before ignition when the combustion temperature dominated the soot surface activity.At medium engine load with multi-pulse fuel injections,it got mixture slightly stratified before ignition and revealed that the mixture inhomogeneity became more dominated on soot surface activity than the combustion temperature.An increased soot surface activity led to increased soot emission.Under the full engine loads with single fuel injection but quite high boost pressure over 0.4 MPa,it led to the combustion conditions of higher mixture density and higher mixture heat capacity,which benefits the mixture homogeneity.The decay rate of soot surface activity became lower due to the decreased combustion temperature and the soot surface activity decreased due to improved mixture homogeneity.In addition,the lowered intake oxygen concentration due to usage of EGR played a role to lower the specific rate of soot surface growth R CH,but to increase the soot surface activityαCH.
基金supported by the Academic Division of the Chinese Academy of Sciencesthe National Natural Science Foundation of China (Grant No. 31021001)the National Basic Research Program of China (Grant No. 2010CB950600)
文摘In recent decades, there have been a number of debates on climate warming and its driving forces. Based on an extensive literature review, we suggest that (1) climate warming occurs with great uncertainty in the magnitude of the temperature increase; (2) both human activities and natural forces contribute to climate change, but their relative contributions are difficult to quan- tify; and (3) the dominant role of the increase in the atmospheric concentration of greenhouse gases (including CO2) in the global warming claimed by the Intergovernrnental Panel on Climate Change (IPCC) is questioned by the scientific communities because of large uncertainties in the mechanisms of natural factors and anthropogenic activities and in the sources of the increased atmospheric CO2 concentration. More efforts should be made in order to clarify these uncertainties.
基金supported by the National Natural Science Foundation of China(No.50976116and No.50806077)
文摘The DLE (dry low emission) technology has already been used on industrial gas turbine combustor and the NO X emission can be limited to 25 ppmv (@15% O 2 ), but one of the destructive effects is combustion instability. In this paper, the dynamic and emission characteristics of a DLE gas turbine combustor have been researched in the authors' laboratory, and the results show that the key source of combustion instability is the non-uniformity of fuel in the flame zone. Two main fuel supply methods have been used to form different fuel distribution types; it is shown that in the perfectly premixed case the emission level is low and combustion process is stable. The PPF also has an obvious effect on the combustor's emission and dynamic characteristics.