Ammonia (NH<sub>3</sub>) dissociation and oxidation in a cylindrical quartz reactor has been experimentally studied for various inlet NH<sub>3</sub> concentrations (5%, 10%, and 15%) and reacto...Ammonia (NH<sub>3</sub>) dissociation and oxidation in a cylindrical quartz reactor has been experimentally studied for various inlet NH<sub>3</sub> concentrations (5%, 10%, and 15%) and reactor temperatures between 700 K and 1000 K. The thermal effects during both NH<sub>3</sub> dissociation (endothermic) and oxidation (exothermic) were observed using a bundle of thermocouples positioned along the central axis of the quartz reactor, while the corresponding NH<sub>3</sub> conversions and nitrogen oxides emissions were determined by analysing the gas composition of the reactor exit stream. A stronger endothermic effect, as indicated by a greater temperature drop during NH<sub>3</sub> dissociation, was observed as the NH<sub>3</sub> feed concentration and reactor temperature increased. During NH<sub>3</sub> oxidation, a predominantly greater exothermic effect with increasing NH<sub>3</sub> feed concentration and reactor temperature was also evident;however, it was apparent that NH<sub>3</sub> dissociation occurred near the reactor inlet, preceding the downstream NH<sub>3</sub> and H<sub>2</sub> oxidation. For both NH<sub>3</sub> dissociation and oxidation, NH<sub>3</sub> conversion increased with increasing temperature and decreasing initial NH<sub>3</sub> concentration. Significant levels of NO<sub>X</sub> emissions were observed during NH<sub>3</sub> oxidation, which increased with increasing temperature. From the experimental results, it is speculated that the stainless-steel in the thermocouple bundle may have catalysed NH<sub>3</sub> dissociation and thus changed the reaction chemistry during NH<sub>3</sub> oxidation.展开更多
The application of nitrogen（N） fertilizer to increase crop yields has a significant influence on soil methane（CH_4） and nitrous oxide（N_2O） emission/uptake.A meta-analysis was carried out on the effect of N appl...The application of nitrogen（N） fertilizer to increase crop yields has a significant influence on soil methane（CH_4） and nitrous oxide（N_2O） emission/uptake.A meta-analysis was carried out on the effect of N application on（i） CH_4 emissions in rice paddies,（ii） CH_4 uptake in upland fields and（iii） N_2O emissions.The responses of CH_4 emissions to N application in rice paddies were highly variable and overall no effects were found.CH_4 emissions were stimulated at low N application rates（〈100 kg N ha^（-1）） but inhibited at high N rates（〉200 kg N ha^（-1）） as compared to no N fertilizer（control）.The response of CH_4 uptake to N application in upland fields was 15%lower than control,with a mean CH_4 uptake factor of-0.001 kg CH_4-C kg^（-1） N.The mean N_2O emission factors were 1.00 and 0.94%for maize（Zea mays） and wheat（Triticum aestivum）,respectively,but significantly lower for the rice（Oryza sativa）（0.51%）.Compared with controls,N addition overall increased global warming potential of CH_4 and N_2O emissions by 78%.Our result revealed that response of CH_4 emission to N input might depend on the CH_4concentration in rice paddy.The critical factors that affected CH_4 uptake and N_2O emission were N fertilizer application rate and the controls of CH_4 uptake and N_2O emission.The influences of application times,cropping systems and measurement frequency should all be considered when assessing CH_4 and N_2O emissions/uptake induced by N fertilizer.展开更多
Emissions of exhaust gases and particulate matter from a dual fuel marine engine using methanol as fuel with marine gasoil as pilot fuel have been examined for a ferry during operation.The emission factor for nitrogen...Emissions of exhaust gases and particulate matter from a dual fuel marine engine using methanol as fuel with marine gasoil as pilot fuel have been examined for a ferry during operation.The emission factor for nitrogen oxides is lower than what is typically found for marine gasoil but does not reach the tier III limit.The emissions of particulate matter are significantly lower than for fuel oils and similar to what is found for LNG engines.The main part of the particles can be found in the ultrafine range with the peak being at around 18 nm.About 93%of the particles are evaporated and absorbed when using a thermodenuder,and thus a large majority of the particles are volatile.Methanol is a potential future marine fuel that will reduce emissions of air pollutants and can be made as a biofuel to meet emission targets for greenhouse gases.展开更多
This paper presents a comparatively experimental study of nitrogen oxide (NOx) emissions from an internal combustion engine fed by gasoline available in the Saudi Arabian market rating octane number (RON 91 and RON 95...This paper presents a comparatively experimental study of nitrogen oxide (NOx) emissions from an internal combustion engine fed by gasoline available in the Saudi Arabian market rating octane number (RON 91 and RON 95) with admixtures of syngas with 0% E0, 5% E5 and 10% E10—by volume of pure ethanol—and HE5 and HE10 with water concentrations of 5%, 10%, 30% and 40%—by volume of hydrous ethanol—at stoichio-metric mixtures. An on-board plasma system used to produce syngas through the partial oxidation of gasoline with air in a plasma-assisted fuel reformer. The syngas injected in a gasoline engine with a fuel injection system modified for operation with addition of some amount of syngas. The experimental results demonstrated a significant total reduction in NOx emissions and slightly increased in fuel consumption when mixing gasoline (RON 91 and RON 95), ethanol (E5 and E10) and hydrous ethanol (HE5 and HE10) with syngas. For the use of hydrous ethanol (HE5 and HE10) along with the addition of syngas, for both RON 91 and RON 95, the lowest NOx emissions are found 72% with a water concentration of 40%.展开更多
为解决在选择性催化还原技术(selective catalytic reduction,SCR)的控制策略开发中局部线性模型树(local linear model tree,LOLIMOT)排放模型预测精度不足的问题,提出一种通过优化空间边界,将原模型的超矩形输入空间约束在物理意义范...为解决在选择性催化还原技术(selective catalytic reduction,SCR)的控制策略开发中局部线性模型树(local linear model tree,LOLIMOT)排放模型预测精度不足的问题,提出一种通过优化空间边界,将原模型的超矩形输入空间约束在物理意义范围内的改进LOLIMOT模型。通过某天然气发动机的辨识试验,从分布特征和计算原理角度,分析了该方法对预测结果的影响。结果表明:与原算法相比,改进算法的线性相关度R2提升了1.9%,验证了改进策略的有效性。改进LOLIMOT算法具备较高的收敛速度和稳定性,在排放模型领域具备一定的应用优势。展开更多
【目的】探讨不同氮素管理模式对玉米产量、N_(2)O排放的影响,为黄土旱塬区合理施用氮肥和减缓温室气体排放提供理论依据。【方法】依托中国科学院长武黄土高原农业生态试验站,以春玉米先玉335为研究对象,开展为期2年的田间定位试验。...【目的】探讨不同氮素管理模式对玉米产量、N_(2)O排放的影响,为黄土旱塬区合理施用氮肥和减缓温室气体排放提供理论依据。【方法】依托中国科学院长武黄土高原农业生态试验站,以春玉米先玉335为研究对象,开展为期2年的田间定位试验。试验共设置5种不同氮素管理模式:不施氮(no fertilizer)、传统施氮(Con,250 kg N·hm^(-2))、减量施氮(Opt,200 kg N·hm^(-2))、减量施氮+缓控释肥(Opt+SR,200 kg N·hm^(-2))、减量施氮+硝化抑制剂(Opt+DCD,200 kg N·hm^(-2))。用静态箱-气相色谱法监测N_(2)O排放通量,并计算全球增温潜势和N_(2)O气体排放强度,分析不同氮素管理模式对春玉米产量和N_(2)O排放的影响。【结果】(1)氮肥施用后N_(2)O排放迅速升高,在施肥后2 d左右达到峰值,维持10 d后快速下降。减量施氮模式显著降低N_(2)O排放量(P<0.05)。与Con处理相比,Opt、Opt+DCD和Opt+SR处理N_(2)O排放量降低幅度分别为21.4%、27.6%和26.0%。Con、Opt、Opt+DCD和Opt+SR处理的N_(2)O增温潜势依次为425.01、334.01、307.83、314.57 kg CO_(2)-eq·hm^(-2)。与Con处理相比,Opt+DCD显著降低了N_(2)O排放强度,降幅为30.1%(P<0.05)。(2)N_(2)O排放量与表层土壤NH4+-N含量呈极显著正相关(P<0.01),而与土壤水分、温度无明显相关性。(3)与Con处理相比,Opt、Opt+DCD和Opt+SR处理能显著提高氮肥农学效率(增幅依次为25.5%、25.7%、22.2%)及氮肥偏生产力(增幅依次为29.9%、28.7%、25.4%)(P<0.05),但对春玉米的产量无显著影响。【结论】在黄土旱塬地区,适当减量施氮、缓控释肥及添加硝化抑制剂均能取得N_(2)O减排和玉米增产的效果,其中减氮20%并添加硝化抑制剂在保证玉米产量的同时,N_(2)O减排效果最好。展开更多
模块化移动床人工湿地(Modular Moving Bed Constructed Wetland,MMB-CW)因其去除效率高和抗堵塞等优势逐渐成为研究热点。本研究构建了轻质陶粒填充的MMB-CW,研究了不同填充度条件下MMB-CW的脱氮效果与N_(2)O的排放特征。结果表明:陶...模块化移动床人工湿地(Modular Moving Bed Constructed Wetland,MMB-CW)因其去除效率高和抗堵塞等优势逐渐成为研究热点。本研究构建了轻质陶粒填充的MMB-CW,研究了不同填充度条件下MMB-CW的脱氮效果与N_(2)O的排放特征。结果表明:陶粒填充的MMB-CW具有良好的NH_(4)^(+)-N和NO_(3)^(-)-N去除效果,脱氮效果随陶粒填充度升高而增强(P<0.05)。在MMB-CW系统启动运行过程中,高陶粒填充度有利于促进硝化-反硝化耦合脱氮。当MMB-CW系统稳定时,100%填充度NH_(4)^(+)-N和NO_(3)^(-)-N的去除率分别为21.8%和43.7%,N_(2)O排放通量为0.6 mg/(m^(2)·d),与现有研究人工湿地N_(2)O排放通量相比处于较低水平。该研究为扩大MMB-CW技术的实际应用提供了一定的理论依据。展开更多
文摘Ammonia (NH<sub>3</sub>) dissociation and oxidation in a cylindrical quartz reactor has been experimentally studied for various inlet NH<sub>3</sub> concentrations (5%, 10%, and 15%) and reactor temperatures between 700 K and 1000 K. The thermal effects during both NH<sub>3</sub> dissociation (endothermic) and oxidation (exothermic) were observed using a bundle of thermocouples positioned along the central axis of the quartz reactor, while the corresponding NH<sub>3</sub> conversions and nitrogen oxides emissions were determined by analysing the gas composition of the reactor exit stream. A stronger endothermic effect, as indicated by a greater temperature drop during NH<sub>3</sub> dissociation, was observed as the NH<sub>3</sub> feed concentration and reactor temperature increased. During NH<sub>3</sub> oxidation, a predominantly greater exothermic effect with increasing NH<sub>3</sub> feed concentration and reactor temperature was also evident;however, it was apparent that NH<sub>3</sub> dissociation occurred near the reactor inlet, preceding the downstream NH<sub>3</sub> and H<sub>2</sub> oxidation. For both NH<sub>3</sub> dissociation and oxidation, NH<sub>3</sub> conversion increased with increasing temperature and decreasing initial NH<sub>3</sub> concentration. Significant levels of NO<sub>X</sub> emissions were observed during NH<sub>3</sub> oxidation, which increased with increasing temperature. From the experimental results, it is speculated that the stainless-steel in the thermocouple bundle may have catalysed NH<sub>3</sub> dissociation and thus changed the reaction chemistry during NH<sub>3</sub> oxidation.
基金financed by the Chinese Academy of Sciences for Strategic Priority Research Program(XDA05050602)the Key Technologies R&D Program of China during the 12th Five-Year Plan period of China(2012BAD14B01-1)
文摘The application of nitrogen（N） fertilizer to increase crop yields has a significant influence on soil methane（CH_4） and nitrous oxide（N_2O） emission/uptake.A meta-analysis was carried out on the effect of N application on（i） CH_4 emissions in rice paddies,（ii） CH_4 uptake in upland fields and（iii） N_2O emissions.The responses of CH_4 emissions to N application in rice paddies were highly variable and overall no effects were found.CH_4 emissions were stimulated at low N application rates（〈100 kg N ha^（-1）） but inhibited at high N rates（〉200 kg N ha^（-1）） as compared to no N fertilizer（control）.The response of CH_4 uptake to N application in upland fields was 15%lower than control,with a mean CH_4 uptake factor of-0.001 kg CH_4-C kg^（-1） N.The mean N_2O emission factors were 1.00 and 0.94%for maize（Zea mays） and wheat（Triticum aestivum）,respectively,but significantly lower for the rice（Oryza sativa）（0.51%）.Compared with controls,N addition overall increased global warming potential of CH_4 and N_2O emissions by 78%.Our result revealed that response of CH_4 emission to N input might depend on the CH_4concentration in rice paddy.The critical factors that affected CH_4 uptake and N_2O emission were N fertilizer application rate and the controls of CH_4 uptake and N_2O emission.The influences of application times,cropping systems and measurement frequency should all be considered when assessing CH_4 and N_2O emissions/uptake induced by N fertilizer.
文摘Emissions of exhaust gases and particulate matter from a dual fuel marine engine using methanol as fuel with marine gasoil as pilot fuel have been examined for a ferry during operation.The emission factor for nitrogen oxides is lower than what is typically found for marine gasoil but does not reach the tier III limit.The emissions of particulate matter are significantly lower than for fuel oils and similar to what is found for LNG engines.The main part of the particles can be found in the ultrafine range with the peak being at around 18 nm.About 93%of the particles are evaporated and absorbed when using a thermodenuder,and thus a large majority of the particles are volatile.Methanol is a potential future marine fuel that will reduce emissions of air pollutants and can be made as a biofuel to meet emission targets for greenhouse gases.
文摘This paper presents a comparatively experimental study of nitrogen oxide (NOx) emissions from an internal combustion engine fed by gasoline available in the Saudi Arabian market rating octane number (RON 91 and RON 95) with admixtures of syngas with 0% E0, 5% E5 and 10% E10—by volume of pure ethanol—and HE5 and HE10 with water concentrations of 5%, 10%, 30% and 40%—by volume of hydrous ethanol—at stoichio-metric mixtures. An on-board plasma system used to produce syngas through the partial oxidation of gasoline with air in a plasma-assisted fuel reformer. The syngas injected in a gasoline engine with a fuel injection system modified for operation with addition of some amount of syngas. The experimental results demonstrated a significant total reduction in NOx emissions and slightly increased in fuel consumption when mixing gasoline (RON 91 and RON 95), ethanol (E5 and E10) and hydrous ethanol (HE5 and HE10) with syngas. For the use of hydrous ethanol (HE5 and HE10) along with the addition of syngas, for both RON 91 and RON 95, the lowest NOx emissions are found 72% with a water concentration of 40%.
文摘为解决在选择性催化还原技术(selective catalytic reduction,SCR)的控制策略开发中局部线性模型树(local linear model tree,LOLIMOT)排放模型预测精度不足的问题,提出一种通过优化空间边界,将原模型的超矩形输入空间约束在物理意义范围内的改进LOLIMOT模型。通过某天然气发动机的辨识试验,从分布特征和计算原理角度,分析了该方法对预测结果的影响。结果表明:与原算法相比,改进算法的线性相关度R2提升了1.9%,验证了改进策略的有效性。改进LOLIMOT算法具备较高的收敛速度和稳定性,在排放模型领域具备一定的应用优势。
文摘【目的】探讨不同氮素管理模式对玉米产量、N_(2)O排放的影响,为黄土旱塬区合理施用氮肥和减缓温室气体排放提供理论依据。【方法】依托中国科学院长武黄土高原农业生态试验站,以春玉米先玉335为研究对象,开展为期2年的田间定位试验。试验共设置5种不同氮素管理模式:不施氮(no fertilizer)、传统施氮(Con,250 kg N·hm^(-2))、减量施氮(Opt,200 kg N·hm^(-2))、减量施氮+缓控释肥(Opt+SR,200 kg N·hm^(-2))、减量施氮+硝化抑制剂(Opt+DCD,200 kg N·hm^(-2))。用静态箱-气相色谱法监测N_(2)O排放通量,并计算全球增温潜势和N_(2)O气体排放强度,分析不同氮素管理模式对春玉米产量和N_(2)O排放的影响。【结果】(1)氮肥施用后N_(2)O排放迅速升高,在施肥后2 d左右达到峰值,维持10 d后快速下降。减量施氮模式显著降低N_(2)O排放量(P<0.05)。与Con处理相比,Opt、Opt+DCD和Opt+SR处理N_(2)O排放量降低幅度分别为21.4%、27.6%和26.0%。Con、Opt、Opt+DCD和Opt+SR处理的N_(2)O增温潜势依次为425.01、334.01、307.83、314.57 kg CO_(2)-eq·hm^(-2)。与Con处理相比,Opt+DCD显著降低了N_(2)O排放强度,降幅为30.1%(P<0.05)。(2)N_(2)O排放量与表层土壤NH4+-N含量呈极显著正相关(P<0.01),而与土壤水分、温度无明显相关性。(3)与Con处理相比,Opt、Opt+DCD和Opt+SR处理能显著提高氮肥农学效率(增幅依次为25.5%、25.7%、22.2%)及氮肥偏生产力(增幅依次为29.9%、28.7%、25.4%)(P<0.05),但对春玉米的产量无显著影响。【结论】在黄土旱塬地区,适当减量施氮、缓控释肥及添加硝化抑制剂均能取得N_(2)O减排和玉米增产的效果,其中减氮20%并添加硝化抑制剂在保证玉米产量的同时,N_(2)O减排效果最好。
