The primary purpose of this study is to evaluate effects of waste-cooking-oil biodiesel on the particle number (PN), size distribution and particulate-phase compositions including organic carbon ...(OC), elemental carbon (EC), polycyclic aromatic hydrocarbons (PAHs), N-alkanes, fatty acids and inorganic ions from a diesel bus. Experiments were conducted based on chassis dynamometer with three biodiesel blends at 5%, 10% and 20% by volume, i.e., B5, B10 and B20; and a petroleum diesel D100 was used as a baseline. Results showed that the biodiesel resulted in a reduction in the PN emission, and this reduction increased linearly with the biodiesel ratio. For B20, the reduction in PN emission reached 42.2% in comparison with D100. The particle size distribution indicated that the utilization of the biodiesel increased the proportion of nucleation mode particles, and correspondingly diminished the proportion of accumulation mode particles. Compared with D100, 14.8%, 21.2% and 27.6% reduction in the OC emission was observed for B5, B10 and B20, whereas the EC emission increased slightly, consequently, the ratio OC/EC presented a declining trend. The PAHs, dominated by 3- and 4- rings ones, as well as their toxic equivalent were also reduced with the biodiesel. Additionally, using biodiesel led to lower N-alkanes and fatty acids emissions in the particles, and the reduction of emissions showed a decreased and increased trend with the biodiesel ratio, respectively. In terms of the inorganic ions in the particles, the Cl−, NO2−, NO3−, SO42−, as well as the Na+, NH4+, K+ and Ca2+ emissions were increased with the biodiesel. To sum up, the refining of biodiesel from waste cooking oil is a cleaner production, and as an alternative fuel to petroleum diesel, the biodiesel is also environment-friendly.
Display omitted
•Reduction in PN emission is proportional to the biodiesel content in the blends.•The proportion of nucleation mode particles was enhanced by using biodiesel.•The use of biodiesel decreased the OC emission but increased the EC emission.•Higher biodiesel content led to lower PAHs, as well as less toxic equivalent.•Lower N-alkanes, fat acids but higher inorganic ions were observed with biodiesel.
•B20 was more effective in reducing accumulation particles compared with nucleation ones.•The fractal dimension of the particles from B20 was larger than that of D100.•B20 led to increased lattice ...defect degree but lower graphitization degree of the particles.•The oxidation activity of the particle from B20 was higher than that from D100.
Biodiesel is a promising alternative clean fuel for vehicles. In this paper, comprehensive particulate characteristics, including the particle number (PN), particle mass (PM), particle size distribution, particle micromorphology, chemical functional groups and particle oxidation activity from biodiesel blend B20 (20% biodiesel and 80% diesel by volume), were investigated based on a diesel bus using a heavy chassis dynamometer bench. Results showed that B20 could reduce the PN by 18.8% and the PM by 27.3%. The reduction efficiency of B20 on the accumulation mode particles was higher than that of the nucleation mode ones, which were 43.2 and 7.6%, respectively, thereby causing the proportion of the nucleation mode particles in B20 to increase from 54 to 66% in comparison with that of D100 (pure diesel). In terms of the particle micromorphology, the average fractal dimension of the particles from B20 was higher than that of D100, indicating that the particles from B20 were more compact. The proportion of typical core–shell structure particles in the basic carbon particles of B20 was higher than that of D100, and the coincidence degree between particles was also higher for B20; additionally, B20 preferred to produce basic carbon particles with a regular spherical shape. The graphitization degree of the particles increased with increasing oxidation temperature, but the lattice defect degree decreased. The Raman analysis reflected that the particles of B20 had a higher lattice defect degree but a lower graphitization degree compared with the particles of D100. The ratio of O/C, as well as the sp3/sp2 ratio of the B20 particles, were higher than those of the D100 particles, also indicating that more defects were present in the B20 particles. The particles from B20 exhibited higher oxidation activity in comparison with the particles from D100.
In this study, the effect of new and used catalyzed diesel particulate filter (CDPF) with different catalyst loadings on the particulate emissions including the particle mass (PM), particle number ...(PN), particle size distribution (PSD) and geometric mean diameter (GMD) from a diesel vehicle were investigated based on a heavy chassis dynamometer. Results showed that more than 97.9% of the PN and 95.4% of the PM were reduced by the CDPF, and the reduction efficiency was enhanced by the catalyst loading. After using the CDPF, the PSD transformed from bimodal to trimodal with the peak shifting towards smaller particle size, more nucleation mode particles were reduced compared with accumulation mode ones, but the reduction effect on the accumulation mode particles was more significantly influenced by the catalyst loading. Notably, the CDPF increased the accumulation mode particles proportion, producing a larger GMD. For the used CDPF, its reduction effect on the particulate emissions enhanced, especially for the PM in accumulation mode. The PSD returned to bimodal, but the peak at accumulation mode began to be higher than that at nucleation mode, illustrating that more nucleation mode particles was removed. The aging of the CDPF resulted in greater effect on the PN-based PSD than that of PM-based PSD, but the effect of catalyst loading on the PN and PM emission factors was weakened. The used CDPF further increased the GMD, and the effect of catalyst loading on the GMD was strengthened, a higher catalyst loading led to a reduction in the GMD.
Display omitted
The real-world gaseous and particulate emission characteristics of an agricultural tractor retrofitted with a catalysed diesel particulate filter (CDPF) with different catalyst loadings were ...investigated. The tests were carried out using a portable emission measurement system (PEMS) under idling, running and working conditions. The results showed that the emissions of the tractor strongly depended on the operating conditions. From idling to running then to working condition, the emission rates increased but emission factors based on fuel consumption decreased, and the proportion of nucleation particles and geometric mean diameter presented a slight downward trend. The reduction effect of CDPF on the CO and total hydrocarbon (THC) improved from idling to running then to working condition, and it was enhanced by increasing catalyst loading. The particle number (PN) and particle mass (PM) reduction performance of CDPF was less affected by operating condition but enhanced with the increase of the catalyst loading. After the tractor was equipped with the CDPF, the particle size distribution maintained a bimodal shape, but the decrease of nucleation particles was significantly higher than that of accumulation particles, causing a decrease in the nucleation particles proportion and a shift of the peak towards smaller particle size. With the increase of the CDPF catalyst loading, the proportion of the accumulation particles increased, and the geometric mean particle size also increased. The findings of this paper can provide scientific references to design and optimize CDPF for non-road mobile machinery to achieve clean emissions.
Display omitted
•Tractor retrofitted by CDPF with different PGM loadings were studied using PEMS.•CDPF reduction performance strongly depended on the operation conditions.•CDPF had better reduction effect on nucleation particles than accumulation ones.•CDPF reduction performance enhanced with increasing catalyst loading.•Geometric mean diameter of particles increased with CDPF catalyst loading.
Particulate emissions from an urban bus fueled with B20 (20% biodiesel from waste cooking oil and 80% diesel by volume) were investigated using portable emissions measurement system (PEMS), then the ...effect of a catalyzed continuously regeneration trap (CCRT) on the particulate emissions of the B20-fueled bus were ascertained. Results show that compared with a D100 (pure diesel), B20 reduced particulate number (PN) and particulate mass (PM) emission rates of the bus by 13.9% and 24.3% under cruise control. Under transient condition, B20 reduced the PN and PM emission rates by 18.4% and 16.3%. B20 decreased the total PN concentration by 6.6% whereas increased the proportion of nucleation particles from 89.0% to 92.0%. Correspondingly causing a decrease in the GMD (geometric mean diameter) from 43.02 nm to 41.25 nm under cruise condition, and from 41.26 nm to 39.57 nm under transient condition. Using a CCRT exhibited an excellent filtration effect on both PN and PM from the B20-fueled bus. Both under cruise and transient conditions, CCRT could reduce more than 93% of the PN and PM. In addition, CCRT had a better filtration effect on accumulation particles. The use of CCRT also changed the particle size bimodal distribution of the B20 by removing the accumulation mode peak.
•Effect of B20 and aftertreatment CCRT on particles of bus was studied using PEMS.•B20 reduced total PN by 6.6% but increased the nucleation mode particle proportion.•B20 resulted in smaller geometric mean diameter (GMD) of particles.•CCRT reduced >93% of PN and PM emissions, especially for accumulation particles.•CCRT changed the bimodal particle size distribution and removed accumulation peak.
Non-precious metal catalysts with good soot catalytic properties and a low cost have great potential for application in diesel particulate filters (DPF). In this study, we compared the effects of DPF ...supported by Cs
2
V
4
O
11
(Cs-V-based) non-precious metal catalysts and conventional Pt-Pd-based precious metal catalysts on the performance of a non-road diesel engine. Furthermore, the effects of on-wall coating and in-wall coating of Cs-V-based catalysts on DPF performance were also investigated. The results indicated that the particulate emissions from DPF with Cs-V-based catalysts were reduced slightly less than that with Pt-Pd-based catalysts; however, the particle number (PN) and particulate matter (PM) emissions were still reduced by 94.4% and 91.7%, respectively, meeting the non-road China IV limits under the non-road steady cycle (NRSC). In addition, CO, HC, and NO can also be slightly oxidized by the non-precious metal catalysts. On the other hand, the DPF with in-wall coating induced comparatively higher gaseous substances and particulate emissions and caused a higher exhaust back pressure (EBP), which was 9.6% higher than the on-wall coating under NRSC, negatively affecting engine performance. Additionally, the geometric mean diameter (GMD) for the DPF with in-wall coating was only 33.3 nm because of the large emission proportion of nuclear mode particles.
•Morphology, nanostructure, functional group composition, and oxidation reaction of soot particles with different fuels are analyzed.•Soot particles from WCO biodiesel combustion exhibit more ...disordered nanostructure.•The surface functional group content and sp3/sp2 of biodiesel soot particles are higher.•Soot particles from WCO biodiesel is easier to be oxidized than fossil diesel soot particles.•The nanostructure definite correlations with soot particles reactivity.
Biodiesel is one of carbon neutral fuels for diesel engine and waste cooking oil (WCO) would be the most viable source for biodiesel production in China. This paper studied the micromorphology, nanostructure, surface functional group composition, and oxidation activity characteristics of particles emitted from a China V bus fueled by pure WCO biodiesel and petroleum diesel, respectively. Compared with petroleum diesel, the results showed that particle mass (PM) and particle number (PN) of WCO biodiesel decreased by 38.66% and 38.12%, respectively, while the proportion of nucleation mode particles increased by about 10%. The soot particles of WCO biodiesel have higher disordered nanostructure, smaller primary particle size and fringe length, larger fringe separation distance and tortuosity, and lower graphitization degree than those of petroleum diesel. Moreover, the oxygen-containing surface functional groups content and carbon atom hybrid ratio of soot particles of WCO biodiesel were higher than those of petroleum diesel under the same oxidation temperature. And then the activation energy of soot particles from WCO biodiesel which contained more lattice defect structures was 38.43 kJ/mol, 37.8% lower than petroleum diesel, which is easier to be oxidized.
This study aims to investigate the effect of durability on the regulated and unregulated emissions, as well as the power and fuel economy performance of a biodiesel-powered engine equipped with a ...diesel oxidation catalyst (DOC) and a selective catalytic reduction (SCR) system based on a 500-h durability test. Furthermore, a BET (Brunauer-Emmett-Teller) test was employed to analyze the specific surface area changes of the DOC and SCR. Results show that after the durability, the power performance improved and the brake-specific fuel consumption (BSFC) reduced due to the running-in effect. Although the deterioration of the DOC and SCR after the durability resulted in an increase in the carbon monoxide (CO), total hydrocarbon (THC) and nitrogen oxide (NOX) emission factors of the biodiesel-powered engine based on European steady state cycle (ESC) by 41.3%, 36.1% and 39.2%, respectively, these emissions were still below China-Ⅴ limits. For unregulated emissions, the reduced BSFC caused by the durability led to a decrease in the carbon dioxide (CO2) and sulfur dioxide (SO2) emissions, but the durability resulted in higher aldehyde emission. The BET specific surface areas of the DOC and SCR decreased by 40.2% and 35.0%, respectively after the durability, which accounted for their catalytic performance deterioration.
•The durability of a biodiesel-powered engine with DOC and SCR were investigated.•The durability improved the power and decreased the BSFC due to running-in effect.•The durability increased the CO, THC and NOX emissions, but they were still below China-V limits.•Reduced BSFC led to lower CO2 and SO2 emissions while deteriorated DOC resulted in higher aldehyde emission.•The BET specific surface areas of DOC and SCR decreased by 40.2% and 35.0% after durability.
•Pressure characteristics of the soot loading process in CDPF is clarified.•Temperature characteristics of active regeneration process in CDPF is proposed.•The effect of the flow parameters on ...pressure and temperature are studied.•A self-defined transient cycle is used to reflect the actual road conditions.•The soot oxidation process is divided into stages I and II.
Catalyzed Diesel Particulate Filter (CDPF) provides an efficient method for removing particulate matter emissions to meet stringent soot emission legislation for diesel engines. In order to clarify the temperature and pressure characteristics of CDPF during the soot loading and regeneration process, in this study, a self-defined transient cycle is used for the soot loading test and combined with 1D simulations to reveal the pressure field. In addition, the effect mechanism of initial soot loading and inlet parameters on temperature and soot characteristics was investigated through the results of regeneration experiments and 3D simulations. The results show that the initial soot loading amount and exhaust flow rate affected the pressure drop of CDPF more than that of the engine. The total pressure drop of the CDPF varied linearly with the increasing exhaust flow rate and soot loading. Among the four pressure drops, the soot layer pressure drop had the highest proportion and the most significant change. During the active regeneration of CDPF, the temperature near the CDPF outlet was the highest (TS3), and TS1 was the lowest, in the axial direction, TS4 and TS5 in the radial direction were the highest. In addition, the soot combustion process can be divided into stages I and II based on the soot oxidation speed. The larger initial soot loading, the higher inlet temperature, the faster exhaust flow rate, and greater O2 concentration all resulted in the shorter stage I, the larger soot oxidation speed, the faster temperature rise, the larger region of high temperature in CDPF. And the inlet temperature had the greatest impact on the regeneration process, followed by initial soot loading and O2 concentration, and the exhaust flow rate had the least impact. There is a reversed change in the propagation direction during the oxidation of soot.
