The kinetic study of the reaction of 1-hydroxyethyl radicals (CH3CHOH) with nitric oxide (NO) was performed over the temperature range of 200-1100 K and the pressure range of 1.0 × 10-5 to 10.0 bar. The geometries of all of the stationary points were optimized at the B3LYP/6-311++G(df,pd) level of theory, and the energetics were refined at the CCSD(T)/cc-pVTZ level of theory. Eight reaction pathways were explored, and they all consisted of a common first step involving the formation of a deep potential well. Three favorable pathways were confirmed, and they were the channels producing the adducts CH3CO(NHOH) and CH3NOHCHO and the products H2O and CH3CNO. The Rice-Ramsperger-Kassel -Marcus-canonical variational transition state theory method with Eckart tunneling correction was used to calculate the rate coefficients of the system. The predicted total rate coefficients agree well with the available literature data and show negative temperature dependence and positive pressure dependence. The reaction producing the adduct CH3CHOHNO in the entrance channel is dominant at 1.0 bar, and its branching ratio is almost 100% at a temperature less than 670 K. At 3.0 Torr, it is only dominant at a temperature less than 600 K.
Experiments by TA2100 and STA409 C/3/F derived different kinetic parameters for same reaction. The difference changed greatly with sample load, due to mass transfer. A model was built to describe the influence of intraparticle, interparticle, and external diffusions on the thermogravimetric process. Model analysis showed that the influences of three diffusions were determined by adjustable parameters (Rp/re, e, e(L − e), and T) once the reaction was set and became significant with the increases in Rp/re, e, e(L − e), and T. These influences can be figured out by numerical simulation. For carbon black oxidation, when the particle size was small (Rp/re < 139.3), the sample layer was thin (e < 0.3 mm), and the crucible height was short (L < 2 mm), the influences of diffusions can be neglected. A data process method was presented to eliminate the influence of diffusions and the thermogravimetric experimental data by STA409 C/3/F were reprocessed and consistent kinetic parameters were obtained.
On the diesel particulate filter(DPF) regeneration bench with additional heating sources,temperature distribution inside the filter was measured under high temperature gas flow shock condition,effects on maximum temperature T_(max),maximum heated rate K_(max)and maximum end radial temperature gradient of the DPF(dT/dy)_(max) were analyzed.Experimental results show that with gas flow temperature increasing,T_(max) increases linearly and K_(max) nearly keeps constant,while the(dT/dy)_(max) increases also.With increase of gas flow,T_(max) rises slightly,K_(max) increases linearly,while the(dT/dy)_(max) decreases slightly.Both gas flow temperature and rate increase can enhance the filter heat transfer performance.With increase of the filter length,all of T_(max),K_(max) and(dT/dy)_(max) decrease,and the filter heat transfer performance is weakened.With increase of CPSI,T_(max) and K_(max) increase,while(dT/dy)_(max) decreases,and the filter heat transfer performance is enhanced.Added a thermal inertia substance after filter end,the T_(max) and K_(max) nearly keep constant,while the(dT/dy)_(max) decreases significantly.Though the influence on temperature distribution inside the DPF substrate is little,while it can greatly reduce the thermal stress appeared in DPF outlet.
With the acceleration of urban construction, the pollutant emission of non-road mobile machinery such as construction machinery is becoming more and more prominent. In this paper, a portable emissions measurement system (PEMS) tested the emissions of eight different types of construction machinery under actual operating conditions and was used for idling, walking, and working under the different emission reduction techniques. The results showed that the pollutant emission of construction machinery is affected by the pollutant contribution of working conditions. According to different emission reduction techniques, the diesel oxidation catalyst (DOC) can reduce carbon monoxide (CO) by 41.6-94.8% and hydrocarbon (HC) by 92.7-95.1%, catalytic diesel particulate filter (CDPF) can reduce particulate matter (PM) by 87.1-99.5%, and selective catalytic reduction (SCR) using urea as a reducing agent can reduce nitrogen oxides (NO
Based on a visualized filtration testing system for diesel particulate filter(DPF),the bulk density,permeability and porosity of particles deposited on DPF substrate piece were investigated under different filtration velocities.The experimental results show that under natural deposition condition or when the filtration velocity is less than 0.15m/s,the bulk density of soot presents to be about 90kg/m3;when the filtration velocity is less than 0.15m/s,the bulk densities of diesel particulate matter from ZS1100 and DK4A engines are both larger than that of soot,presenting to be about 100kg/m3.With the increase of filtration velocity,with the decrease of particle size and the increase of SOF content,the bulk density of particle increases rapidly at first,then gradually up to a steady value.With the increase of particle layer thickness,the pressure drop curve presentes to be varied with typical three stages under the same filtration velocity.With the increase of filtration velocity,the permeability and porosity of particle layer decreases rapidly at first,then gradually down to a steady value.
The aftertreatment system is a technology designed to effectively reduce particulate emissions. However, under cold start conditions, there is still a substantial amount of particulate emissions at the outlet of the aftertreatment system due to engine combustion issues and the reduced filtration efficiency of the aftertreatment system. This study aimed to investigate the impact of preheating aftertreatment systems on particulate matter (PM) emissions from diesel engines during cold starts using an engine bench. The research findings indicate that preheating the aftertreatment system before the cold start can significantly reduce the number of emitted particulate matters during this phase. However, it also leads to an increase in the number of particles in the nucleation mode. Following filtration by the catalytic diesel particulate filter (CDPF), the shape of soot aggregates tends to resemble a chain-like structure, and preheating the aftertreatment system inhibits the surface growth of primary particles. Additionally, when the catalyst is preheated, the oxidation of the soluble organic fraction (SOF) results in the fragmentation of aggregated particles, leading to a significant increase in the number of sub-23 nm particles. This phenomenon is the primary reason for the increased concentration of sub-23 nm particles after preheating the aftertreatment system during the cold start process.
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