Emission reduction characteristics of a catalyzed continuously regenerating trap after-treatment system and its durability performance

The primary purpose of this study was to investigate the effect of a catalyzed continuously regenerating trap (CCRT) system composed of a diesel oxidation catalyst (DOC) and a catalyzed diesel particulate filter (CDPF) on the main gaseous and particulate emissions from an urban diesel bus, as well as the durability performance of the CCRT system. Experiments were conducted based on a heavy chassis dynamometer, and a laboratory activity test as well as X-ray photoelectron spectroscopy (XPS) test were applied to evaluate the changes of the aged CCRT catalyst. Results showed that the CCRT could reduce the CO by 71.5% and the total hydrocarbons (THC) by 88.9%, and meanwhile promote the oxidation of NO. However, the conversion rates for CO and THC dropped to 25.1% and 55.1%, respectively, after the CCRT was used for one year (~ 60,000 km), and the NO oxidation was also weakened. For particulate emissions, the CCRT could reduce 97.4% of the particle mass (PM) and almost 100% of the particle number (PN). The aging of the CCRT resulted in a reduced PM trapping efficiency but had no observable effect on the PN; however, it increased the proportion of nucleation mode particles. The activity test results indicated that the deterioration of the CCRT was directly relevant to the increase in the light-off temperatures of the catalyst for CO, C3H8 and NO2. In addition, the decreased concentrations of the active components Pt2+ and Pt4+ in the catalyst are also important factors in the CCRT deterioration

Multi-objective optimization of cassava-based fuel ethanol used as an alternative automotive fuel in Guangxi, China

Multi-objective optimization of net energy, external costs of environment pollutant-emissions, and cost of using cassava-based fuel ethanol as an alternative automotive fuel in Guangxi has been conducted based on its holistic life cycle, from feedstock production to fuel combustion. A new indicator, cost of net energy (CNE), linking net energy-yield, external cost of environment pollutant-emissions, and production cost (the lower the CNE reading, the better the total performance) of ethanol-gasoline blends, is proposed for carrying out multi-objective optimization. On the life-cycle basis, CNE of ethanol-gasoline blends is found to obtain its lowest value, i.e. 0.119  RMB/MJ, when processing fuel during the ethanol conversion stage was natural gas and the ratio of ethanol blended with gasoline was 5%. From the standpoint of the CNE indicator, the most viable implement form of cassava-based fuel ethanol should be used as one of oxygenate additives. The recommended processing fuel during ethanol conversion stage should be natural gas.Energy Environment Cost Life cycle multi-objective optimization Cassava-based ethanol Guangxi China

Effect of structure parameters of catalyst substrate on the performance of diesel particulate filter

The filtration efficiencies of the particulate matter and the particulate number in DPF, the no-load pressure drop of DPF, and the load pressure drop of DPF were selected as key performance parameters of DPF. The influence of the cell density and the wall thickness of the DPF on these key performance parameters of DPF was studied in detail. Firstly, a calculation model of DPF was established, and the compensation mathematical model was added. Secondly, the key performance parameters of DPF were defined. Finally, based on the model, the key performance parameters are numerically investigated under different cell density and wall thickness of the DPF. Consequently, with the increase of cell density of DPF, the filtration efficiency of DPF increases, the load pressure drop of DPF decreases, but the no-load pressure drop of DPF increases. With the decrease of the wall thickness of the DPF, the no-load pressure drop of the DPF decreases, the load pressure drop of the DPF decreases, but the filtration efficiency of the DPF decreases. The most suitable combination scheme is a cell density of 200-300 CPSI and a wall thickness of 11-16 mil

The microscopic characteristics of particle matter and image algorithm based on fractal theory

The effects of ash and sulfur content on the morphology of particulate matter (PM) in diesel particle filter (DPF) were investigated with five different components of lubricants. The aggregate morphology of primary particles in diesel were analyzed using transmission electron microscopy (TEM). The fractal dimensions of carbon particles were calculated by box-counting method (BCM), differential box-counting method (DBC), relative differential box-counting method (RDBC) and MAD-based box counting method (MAD-DBC), and the results were compared. The results showed that the microstructure of PM developed from chain-like structure to agglomerate structure with the increase of sulfur and ash content in lubricating oil. The fractal dimension of carbon particles increased with the increase of sulfur and ash content. The SSE of RDBC fitting results was smaller, and the R-square is larger. MAD-DBC fitting results had stronger anti-noise interference performance

Impacts of lubricating oil and its formulations on diesel engine particle characteristics

© 2020 Lubricating oil-related engine emission reduction is now a key path to further control the engine-out emission level and to meet the restrict regulations, especially in the manner of particulate number emission. This work experimentally studied the contribution of lubricating oil and its key constituents to the particle emission via monitoring the combustion process and analyzing the particle physic-chemical characteristics. Two sets of experiments were conducted to understand how the lubricating oil alters the regular combustion cycles and to study the effects of oil sulfur and metallic-ash constituents on the particle chemical characteristics, respectively. Details of the surface oxygenated functional groups and carbon chemical state on the particle surface were analyzed by XPS, while the FTIR was employed to characterize the possible functional groups in the bulk particle samples and the bonding patterns of the sulfur element. The effects on the particle morphology and elemental compositions were analyzed by SEM-EDS. Results show that the lubricating oil could shorten the ignition-delay phase combustion effectively, for instance, by 20% when 1wt% oil is burned along with diesel. Furthermore, more oxygenated surface functional groups and relatively more sp3 hybridization carbon shows up in the oil-derived particles. The sulfur element in the oil increases the oxygenated functional groups and lowers the aliphatic C[sbnd]H group by forming –SH radical. On the contrary, the metallic-ash fraction reduces the amount of oxygenated functional groups because the inorganic sulfates/phosphates occupy some oxygen atoms during the combustion reaction. Both the sulfur and ash tend to generate more un-substituted and meta-disubstituted benzene instead of the mono-disubstituted benzene structure, which is popular in diesel fuel-related particles mainly. Last but not the least, the sulfur and ash content significantly increase the concentration of the sulfates and phosphates of Iron, Calcium, and Zinc in the particles

An experimental study on particle number, micromorphology and nanostructure characteristics of particulate matter from a China Ⅵ gasoline direct injection engine

This study investigated the variation of particle number (PN), morphological features and nano structural parameters of particulate matter (PM) from a China Ⅵ GDI engine under different working conditions, oxidation temperatures, and aerodynamic diameters. The results showed that, particles with a diameter less than 10 nm or 23 nm accounted for 40–65% and 68–94% of total PN respectively. Engine speed has a larger effect on PN emissions with the diameter less than 10 nm. PM emitted from the GDI engine were mainly consisted of primary particles with a diameter of 12–72 nm. Primary particles were composed of numerous graphite fringes with a length of 0.1–1.8 nm, tortuosity of 1.10–2.65, and separation distance of 0.2–1.6 nm. The boundaries of primary particles became vague, the fringe tortuosity and separation distance decreased with the progress of oxidation. Particles in larger aerodynamic diameters were more likely to form cluster-like PM in micromorphology. PM accumulated by particles with an aerodynamic diameter of 52.1 nm had larger fractal dimension, smaller fringe length, higher fringe tortuosity, and greater fringe separation distance, and was more easily be oxidized

Joint Study of Impingement Combustion Simulation and Diesel Visualization Experiment of Variable Injection Pressure in Constant Volume Vessel

In this paper, the visualization experiments of spray, ignition, and combustion of diesel under variable injection pressure (from 90 to 130 MPa) were studied by using a constant volume vessel and impinging combustion plate system. With the development of the down-sizing of diesel engines, the wall impinging combustion without liquid spray collision will be the research focus in the diesel engine combustion process. The flame natural luminosity in the experiment represents the soot formation of diesel combustion. Besides, the detailed information of diesel spray mixing combustion was obtained by using the CFD (Computational Fluid Dynamics) simulation of alternative fuels in CONVERGE™. The specific conclusions are as follows. The high velocity of the spray under the higher injection pressure could reduce the low-mixing area near the impinging wall by entraining more air. Under higher injection pressure in simulation, the gas diffused more extensively, and more heat was released after combustion. Therefore, a large amount of soot formed in the early stage of combustion and then oxidized in high-temperature regions, which agreed with the conclusions in the experiments. Under the influence of the superposition of image pixels of the flame, the change of soot generation with injection pressure is smaller than the actual value, so the visualization experiment can be used as the basis of combustion prediction