| Diesel engine is extensively used owing to high fuel economy and power.However,the development of diesel engine industry was under enormous pressure due to energy crisis,environmental pollution and increasingly stringent emission regulations.Reducing emissions and fuel consumption is the direction of the diesel engine industry.Ethanol and n-butanol were used to replace part of diesel and aftertreatment measures were taken to reduce diesel engine emissions.The research found that,CO,NO,NOx,formaldehyde,acetaldehyde,VOCs and PM2.5 emissions with various engine speeds were 3.13?11.36 g/kW h,1.81?3.31 g/kW h,2.76?5.09 g/kW·h,0.0643?0.4193 g/kW·h,0.0574?0.3674 g/kW·h,0.164?0.9343 g/kW·h and 0.1434?1.252 g/kW h,respectively.The CO,NO,NOx,formaldehyde,acetaldehyde,VOCs and PM2.5 emissions with various engine loads were 2.51?10.14 g/kW·h,1.47?3.67 g/kW·h,2.3 15.66 g/kW·h,0.0568?0.2131 g/kW·h,0.0367?0.1521 g/kW·h,0.0568?0.2131 g/kW·h and 0.0942?0.3371 g/kW·h,respectively.As diesel-alcohol blend fuels was used as fuel for the tested diesel engine,CO,NO,NOx and PM2.5 emissions with various engine speeds decreased.However,NO2,CO2,formaldehyde,acetaldehyde,and VOCs emissions increased with various engine speeds.It was found that,NOx and PM2.5 could be reduced as diesel-ethanol-n-butanol was used as fuel.DPF was considered to be one of the most effective and commonly used technologies to reduce PM emissions.The author used zirconia foamed ceramics,silicon carbide foamed ceramics and alumina foam ceramics as the materials for DPF.After the installed DPF on diesel engines,CO?NO?NOx emissions of the diesel engine were increased by 0.79%?27.37%,2.96%?42.07%and 3.06%?27.04%,respectively.Formaldehyde,acetaldehyde and VOCs emissions decreased by 23.14%?85.56%,29.41%-81.16 and 0.28%?76.70%,respectively.PM2.5 emissions decreased 33.36%?97.55%,silicon carbide foam ceramic DPF was the best,alumina foam ceramic DPF was the second.The exhaust back pressure increased after the installation of DPF and measures should be taken to reduce exhaust back pressure.In order to reduce the increasing emissions caused by DPF installation,silicon carbide foam ceramic DPF loaded with TiO2,CeO2 and mixed catalyst(The mass ratio of CeO2 to CeO2 was 1:1).The results show that CO emission increases after the catalyst is supported on DPF.R NO,NO2 and NOx emissions of the tested diesel engine decreased and the most obvious when CeO2 catalyst was loaded.Formaldehyde,acetaldehyde and VOCs emissions of the used diesel engine decreased and most obviously when supported on TiO2 catalyst.When CeO2 catalyst was loaded,PM2.5 emissions decreased most obviously.The increasing of exhaust back pressure was still not solved with the loading of catalyst and technical measures should be taken.CO emission of the used diesel engine decreased by 3.05%?12.93 when NTP was used to deal with the exhaust emission.NO and NOx emissions decreased by 67.24%?91.15%and 51.86%?66.65%,respectively.The emissions of formaldehyde,acetaldehyde and VOCs decreased by 25.58%%?55.72%,25.72%%?60.19%and 25.72%?52.79%,respectively.PM2.5 emissions decreased by 48.77%?85.21%.NTP can realized the oxidation of particulate matter at low temperature,and solve the problem caused by the deposition of particulate matter in DPF.The synergistic of NTP and DPF decreased CO,NO,NOx,formaldehyde,acetaldehyde and VOCs emissions and more obvious than that on NTP or DPF working alone.DPF realized the regeneration of DPF at lower temperature(less than 200?)with the active components in NTP.NOx and PM2.5 emissions reduced simultaneously without cause increasing in exhaust back pressure.The synergistic effect of NTP,DPF and catalyst on emission reduction of diesel engine was much more obvious than that of NTP and DPF. |
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