Search

Non-road machinery is very important, but non-road machinery has problems such as working under complex operating conditions. Agricultural machinery is an important type of non-road machinery, whic...

An insufficient amount of NH3 (ammonia) will reduce the conversion efficiency of NOx, which may lead to excess NOx emissions, resulting in NH3-SCR failure. In this article, SCR failure caused by a low NH3- NOx ratio is studied systematically by experiments. The main reasons for a low NH3-NOx ratio in SCR include insufficient urea injection, hydrothermal aging of catalysts and urea crystallization. It was found from an insufficient urea injection experiment that with the increase of NH3- NOx ratio, the NOx conversion efficiency of the SCR system increased, but the ammonia leakage also increased. The main influencing factors of NOx conversion efficiency are different under different NH3- NOx ratios. A flow reactor system was used in the catalyst hydrothermal aging experiment to investigate the effect of hydrothermal aging on catalyst activity. After a 24 h hydrothermal aging experiment at 800 °C, the NOx conversion efficiency of the copper-based zeolite catalysts decreased significantly at the boundary of medium and low temperature regions. And the NO2- NOx ratio in the mixture had a significant effect on the catalytic performance. Thermogravimetry coupled to Fourier transform infrared spectroscopy (TG-FTIR) was used to analyze the composition of urea deposits in a urea deposits analysis experiment. It was found that the main components of urea deposits were urea and isocyanic acid (HNCO). Preventing HNCO polymerization, especially the formation of CYA, can decrease the formation of urea deposits.

Rotors with active flap control have considerable potential in reducing vibration and noise and improving aerodynamic performance. However, due to the movement of the flap, there are unavoidable gaps between the components that will lead to significant changes in the aerodynamic characteristics. Moreover, considering the difficulties in motion modeling and the accuracy of the simulation of the flow field in such a narrow gap, carrying out related research is challenging; thus, there has been inadequate targeted research, and that which does exist requires supplementation. To carry out this challenging flow field simulation, the overset assembly algorithm proposed by the author in previous research is adopted in the present study. It is used to successfully assemble the narrow gap, and the accuracy of the simulation is fully verified by comparing the results with the actual experimental results and a grid study. Furthermore, to compensate for the lack of research and experiments on the gap effect, cases considering a complete range of gap widths from an absence of a gap to a width of 10% of the chord length are set up and carried out under the following three case groups: steady cases with a fixed trailing-edge deflection angle, unsteady cases in which only the trailing-edge flap is flapping, and full-motion cases characterized by the periodic flap of the main airfoil and the trailing-edge flap. The results show that the gap increases the drag of the trailing-edge flap and decreases aerodynamic efficiency, especially at low speeds and high angles of attack. Nevertheless, when the gap is unavoidable, there is a range of the gap width that makes unapparent the decrease of aerodynamic efficiency. Moreover, the decrease of aerodynamic efficiency can be reduced as much as possible by a well-designed gap region geometry to ensure that the airfoil and the trailing-edge flap fit together when moving.

Selective catalytic reduction (SCR) is one of the main methods used to reduce NOx emissions from diesel engines. Vanadium-based catalysts are widely used in SCR because of their good sulfur resistances and low costs. In this paper, for improving the catalytic performance of aged SCR, experimental and simulation methods were used to study the effects of the aged SCR state, space velocity, and ammonia-to-nitrogen ratio on the NOx conversion efficiency. The experimental results showed that the catalytic performances of the aged SCR state in the low- and medium-temperature regions were not significantly different from that of the fresh SCR, and the degradation in the high-temperature region was significant. In the low- and high-temperature regions, space velocity was an important factor affecting the aged SCR. Increasing the ammonia-to-nitrogen ratio could compensate for the effect of the SCR aging in the low- and medium-temperature regions to some extent.

Catalyzed diesel particulate filters (CDPFs) have been widespread used as a technically and economically feasible mean for meeting increasingly stringent emissions limits. An important issue affecting the performance of a CDPF is its aging with using time. In this paper, the effects of noble metal loadings, regions and using mileage on the aging performance of a CDPF were investigated by methods of X-ray diffraction (XRD), X-ray photoelectron spectroscopy and catalytic activity evaluation. Results showed that aging of the CDPF shifted the XRD characteristic diffraction peaks towards larger angles and increased the crystallinity, showing a slowing downward trend with the increase of the noble metal loadings. In addition, the increase of the noble metal loading would slow down the decline of Pt and Pt4+ concentration caused by aging. The characteristic temperatures of CO, C3H8 conversion and NO2 production increased after aging, and the more the noble metal loadings, the higher the range of the increase. But noticeably, excessive amounts of noble metals would not present the corresponding anti-aging properties. Specifically, the degree of aging in the inlet region was the deepest, the following is the outlet region, and the middle region was the smallest, which were also reflected in the increase range of crystallinity, characteristic temperatures of CO, C3H8 conversion and NO2 production, as well as the decrease range of Pt and Pt4+ concentrations. The increase of aging mileage reduced the size of the aggregates of the soot and ash in CDPFs, however, improved the degree of tightness between particles. Meanwhile Carbon (C) concentration in the soot and ash increased with the aging mileage.

The durability of V2O5-WO3/TiO2 selective catalytic reduction (SCR) catalysts for heavy-duty diesel engines was evaluated based on 500 h SCR durability tests conducted using B20 fuel (20% v/v biodiesel + 80% v/v petroleum diesel). The fresh and deteriorated SCR catalysts were characterized by X-ray fluorescence, X-ray diffraction, and Brunauer-Emmett-Teller surface area measurements to investigate the deterioration mechanism of the catalysts. The results show that the SCR de-NOx performance is degraded after SCR durability testing, particularly at high engine speeds. The NOx conversion efficiency of the deteriorated SCR catalysts decreases at temperatures above 400 °C but remains high at temperatures between 250 and 400 °C. The catalyst characterization results reveal that the deterioration in the de-NOx performance is not owing to anatase-to-rutile transformation of TiO2, but because of a decrease in the specific surface area and the loss of the catalyst components, which are greater in the front cross section of the SCR than in the rear cross section. For a given catalyst cross section, the decrease in the specific surface area exhibits a positive correlation with the flow rate of the exhaust gas.

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.

Herein, through the active-peptide-functionalization, we developed a nanoscale micelles system (named HEKM) which consists of tumor microenvironment-regulated shape-changing with specific recognition abilities for enhanced cellular targeting, internalization and therapy of heterogeneic tumors. As a result, HEKMs could recognize and bind the tumor heterogeneity marker EGFR-HER2 complex, which led to an enhanced tumor targeting effect. In particular, HEKMs could self-assemble into nanorods under normal physiological conditions while transform into nanospheres in the tumor extracellular microenvironment by a sensitive response to matrix metalloproteinase-2 (MMP-2). The nanorods could prolong the blood circulation time while the nanospheres could accelerate tissue penetration in tumors. In vivo dual-modal targeted imaging was realized by FRET-fluorophore conjugation and gadolinium loading in HEKMs. Tumor cell apoptosis was achieved by proapoptotic element integration. The in vitro and in vivo studies both demonstrated that these rationally designed, shape-changing and targeting micelles could achieve maximized drug efficacy and minimum side effects.

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&trade, 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.

The elementary research of spray and combustion is of great significance to the development of compactness of modern diesel engines. In this paper, three injectors with different nozzle orifice diameters (0.23 mm, 0.27 mm and 0.31 mm) were used to study the diesel spray, ignition and flame-wall impingement visualization experiment. This paper studied the influence of different nozzle sizes on the trends of spray, ignition and flame diffusion under the flame-wall impinging combustion and used the flame luminosity to characterize the soot generation in combustion. By analyzing the quantitative data, such as spray penetration, ignition delay, flame area and flame luminosity systematically, it was shown that the smaller nozzle benefitted diesel combustion to some extent. The 0.23 mm nozzle injector in these experiments had the best fuel-air mixing effect under 800 K. The length of the spray liquid under the 0.23 mm nozzle condition was 19% and 23% shorter than that of 0.27 and 0.31 mm, respectively. Smaller orifice size of the nozzle can help to reach the gas ignition conditions more effectively. Without liquid fuel impingement, the simple flame-wall impingement will not change the trend of the nozzle influence on combustion. The total amount of accumulated soot according to the approximate luminosity spatial integral calculation in the combustion process was reduced by 37% and 43% under 0.27 mm and 0.23 mm nozzles, respectively, which is favorable for the clean combustion of diesel engines.

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.

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.

Altitude has a significant effect on the combustion of diesel engines during cold start, especially during speed-up. In this study, combustion characteristics of speed-up period were investigated using an experimental test on a heavy-duty diesel engine with an intake and exhaust pressure controlled by the plateau simulation test system to simulate altitude conditions including 0 m, 3000 m and 4500 m. Further effects of altitude on ignition characteristics of diesel engine were accomplished through a zero-dimensional thermodynamic model coupled with a detailed kinetic model. Results indicated that as the altitude rose from 0 m to 3000 m, the pressure in the cylinder was reduced, the number of diesel engine speed-up cycles increased, and the rising speed ratio decreased during speed-up. There was a misfire after the fifth cycle at an altitude of 4500 m, and the rising speed ratio was significantly reduced. Through analysis of fuel injection, air intake and ignition phase, we confirmed that the misfire at the high 4500 m altitude was caused by the ignition delay, which was mainly controlled by chemical reaction during cold start. In the detailed kinetic study, the hot-flame and blue-flame reactions slowed down in the chemical reaction of the mixture as the altitude rose. The higher altitude enhanced the H-atom abstraction, but weakened the second O2 addition and the peroxyalkylhydroperoxide isomerization. The decomposition reaction was enhanced. As a result, the overall reaction rate and the heat release fraction deteriorated, extending significantly the negative temperature coefficient (NTC) duration of the ignition.

The increasingly stringent emission regulations will mandate the retrofit of after-treatment devices for in-use diesel vehicles, in order to reduce their substantial particulate matter and nitrogen oxides (NOX) emissions. In this paper, a combination of DOC (diesel oxidation catalyst), CDPF (catalytic diesel particulate filter) and SCR (selective catalytic reduction) retrofit for a heavy-duty diesel engine was employed to perform experiment on the engine test bench to evaluate the effects on the particulate matter emissions including particle number (PN), particle mass (PM), particle size distributions and nitrogenous compounds emissions including NOX, nitrogen dioxide (NO2)/NOX, nitrous oxide (N2O) and ammonia (NH3) slip. In addition, the urea injection was also of our concern. The results showed that the DOC+CDPF+SCR retrofit almost had no adverse effect on the engine power and fuel consumption. Under the test loads, the upstream DOC and CDPF reduced the PN and PM by an average of 91.6% and 90.9%, respectively. While the downstream SCR brought about an average decrease of 85% NOX. Both PM and NOX emission factors based on this retrofit were lower than China-Ⅳ limits (ESC), and even lower than China-Ⅴ limits (ESC) at medium and high loads. The DOC and CDPF changed the particle size distributions, leading to the increase in the proportion of accumulation mode particles and the decrease in the percentage of nuclear mode particles. This indicates that the effect of DOC and CDPF on nuclear mode particles was better than that of accumulation mode ones. The upstream DOC could increase the NO2/NOX ratio to 40%, higher NO2/NOX ratio improved the efficiency of CDPF and SCR. Besides, the N2O emission increased by an average of 2.58 times after the retrofit and NH3 slip occurred with the average of 26.7 ppm. The rate of urea injection was roughly equal to 8% of the fuel consumption rate. The DOC+CDPF+SCR retrofit was proved a feasible and effective measurement in terms of reducing particulate emissions and NOX simultaneously for in-use engine. However, it also resulted in higher N2O emission, NH3 slip as well as urea injecting strategy problem which should be of further concern.

Exhaust particle emissions from a heavy duty diesel engine using B20 biodiesel (20% biodiesel blend with 80% diesel by volume) were investigated, and the engine was equipped with three kinds of exhaust aftertreatment devices: DOC (diesel oxidation catalyst), DOC + DPF (diesel particle filter), and DOC + CDPF (catalyzed diesel particle filter). Particle mass, particle number and size distribution, and PAHs (polycyclic aromatic hydrocarbons) and inorganic ions in the particle emissions from the engine were studied. Compared with the engine without exhaust aftertreatments, DOC decreased nucleation mode particle number by 19.83%, while accumulation mode particles exhibited slight changes. The DOC + DPF reduced the total particle number by 82.54%, while the DOC + CDPF reduced it by 91.71%. Compared with the engine without exhaust aftertreatments, the three aftertreatments were shown to reduce total PAH emissions. DOC + DPF and DOC + CDPF can decrease total TEQ (toxicity equivalent quantity) effectively with a sharp decrease in PAH mass. The DOC increased the TEQ of particles by 46.9%. The catalyst in the DOC increased some high molecular weight PAHs such as BaA, BbF + BkF, and BaP, which led to the increase in TEQ. The DOC increased the total inorganic ions by 2%, while the DOC + DPF and DOC + CDPF decreased inorganic ions by 89.5% and 82.9%, respectively. Catalysts in DOC and CDPF promotes the formation of SO 4 2− and NO 3 − , which leads to higher inorganic ion emissions with DOC than no aftertreatments and higher inorganic ion emissions with a DOC + CDPF than with a DOC + DPF.

In recent years, horticultural plants have frequently suffered significant heat damage due to excessive temperatures. In this study, a horticultural spray cooling system was designed, consisting mainly of a jet fan and spraying system. CFD simulation technology and response surface methodology were used to optimize the design of the jet fan, which improved the thrust of the fan. The length of the inlet section was 300 mm, the length of the outlet section was 300 mm, the length of the cone section was 450 mm, and the diameter of the outlet was 950 mm, where the thrust of the jet fan was 225.06 N. By establishing the CFD model of spray cooling in a tea field and designing a L9 (34) orthogonal experiment, the effect of the spray parameters on the maximum temperature drop and effective cooling distance was studied, and the best parameters were selected. The simulation results show that the optimum parameters are a spray flow rate of 4.5 kg/s, a droplet diameter of 15–45 μm, a droplet temperature of 298.15 K, and a nozzle double circle layout. Based on the simulation results of the optimized jet fan and spray parameters selected, a spray cooling test bench was established. Field test results show that when the initial ambient temperature was 310.05 K–310.95 K, the maximum temperature drop of the spray cooling fan was 9.1 K, and the cooling distance was approximately 36.0 m. The temperature drop decreased with increasing distance from the fan. This study is of great significance to protect horticultural plants from extremely high temperatures.

Nitrogen oxides (NOx) and particle emissions from a light-duty diesel car with B10 (10% biodiesel from cooking oil +90% diesel, v/v) and G10 (10% GTL fuel +90% diesel, v/v) were investigated under the New European Driving Cycle (NEDC). The car was equipped with a high-pressure common rail system, cooled exhaust gas recirculation (EGR), and diesel oxidation catalyst (DOC). Results show that G10 has the lowest fuel consumption and B10 has the highest fuel consumption among the three fuels. B10 can increase the NOx emissions, and the G10 NOx emission is lower than diesel. The number-weighted particle size distribution shows that B10 and G10 can decrease the particle number at almost a full size range. In the four urban driving cycles (UDC), the geometric mean diameter (GMD) of B10 and G10 are both smaller than diesel. For the extra urban driving cycle (EUDC), the particle number concentration and emission rate are far higher than UDC cycle. The acceleration phase has a higher particle number emission rate and nucleation particle number than deceleration for the three fuels. Particle number emission is reduced when using B10 and G10 regardless of acceleration or deceleration. Number-weighted particle size distribution in acceleration and deceleration shows that the nucleation particle number in deceleration is far higher than acceleration, whereas accumulation particle shows the opposite tendency.

Altitude has a significant effect on combustion of heavy-duty diesel engines, especially during cold start. An experimental study on a heavy-duty diesel engine operating at different altitudes was conducted. Tests were based on a direct injection (DI) turbocharged diesel engine with intake and exhaust pressure controlled by the plateau simulation test system to stimulate altitude conditions including 0 m, 1000 m, 2000 m, 3000 m and 4000 m. Results indicated that the compression and expansion resistance moment reduced and the speed increased during the cranking period. The peak pressure of several cycles was increased during the start-up period; however, the expansion pressure dropped more and the indicated mean effective pressure (IMEP) reduced as the altitude rose. While at an altitude of over 2000 m, the peak pressure fluctuated obviously during the start-up period. The higher the altitude was, the more the fluctuation amplitude and cycle number increased and combustion instability enhanced, which resulted the start-up period time increasing at high altitude. When the altitude rose, the cycle-to-cycle variation of the peak pressure and speed fluctuation increased during the idle, the ignition and CA50 were delayed and the combustion duration was shortened. The effect of altitude on combustion characteristics of the diesel engine was more significant during the start-up period than during its idle period.

One of the ways to meet future emission standards for cars and to limit the peak pressure of a heavy-duty, highly supercharged diesel engine is to reduce the compression ratio. Nevertheless, complications appear because stringent limitations to a reduction in the diesel compression ratio are the start-up requirements, in particular at high altitudes. An experimental study was conducted on the effect of the altitude on the combustion characteristics during the start-up process of a direct-injection midspeed intercooled turbocharged diesel engine with a compression ratio of 14.25:1. Specialized testing was conducted on the low-compression-ratio diesel engine, the intake pressure and the exhaust pressure of which were controlled by a plateau simulation test system to simulate the conditions at altitudes of 0 m, 1000 m, 2000 m, 3000 m, 3750 m and 4500 m. The results indicated that the pressure in the cylinder was lower during the cranking period as the altitude increased and that this caused the ignition operation to become difficult at altitudes above 3000 m. The combustion characteristics are significantly impacted by altitudes above 2000 m. At an altitude of 0–1000 m, the curve pattern of the cycle cylinder pressure had mainly a single peak during the start-up period. When the altitude increased to 2000 m, twin peaks and afterburn appeared in the cycles. Misfire appeared during the start-up period when the altitude increased to 3000 m, the combustion instability increased and the average indicated mean effective pressure decreased rapidly. When the altitude increases, the cycle-to-cycle variations in the peak pressure increased during idle, the ignition and the crank angle position at 50% of the cumulative heat release rate were delayed and the combustion duration was extended.

With increasingly stringent emission regulations, the cold start emissions have become more important than ever. Using a low compression ratio is a feasible way to improve a heavy-duty engine&rsquo, s efficiency and emissions. However, cold start performance restricts the development of this technology, especially at high altitudes. In response, we conducted a study of the emissions of a heavy-duty low-compression-ratio diesel engine during start-up process at different altitudes. A plateau simulation system controlled the inlet and exhaust pressure to create altitude environments of 0 m, 1000 m, 2000 m, 3000 m, 3750 m and 4500 m. The gas, particulate and volatile organic compound (VOC) emissions were analyzed with speed and cycle during the start-up process. The results indicated that cold start performance and combustion characteristics became worse as altitudes increased. The gas and particulate emissions of carbon monoxide (CO), carbon dioxide (CO2), total hydrocarbon (THC) and nitrous oxide (NOX) almost all increased as the engine speed and altitude increased, and was much higher than in idle conditions. The PN and PM emissions in each particle diameter also increased as the altitude increased, which was the same as the nucleation mode and the accumulation mode particles. VOC emissions were also measured, which increased during the start-up process as altitudes increased.

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.

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.

Accurate estimation of soot loading in DPF is an important basis for the efficient application of diesel exhaust aftertreatment system. However, some prediction methods need to be equipped with additional equipment, which increases the cost and does not significantly improve the accuracy of soot loading prediction. Moreover, the previous soot loading prediction models rarely consider the ash deposition and particle collection rules from the perspective of collection mechanism. In this study, a novel soot loading prediction model based on collection mechanism and multilayer equivalent permeability considering the deep bed and filter cake collection stage is proposed. The prediction model is based on theory of packed beds of spherical particles. The wall and cake are divided into four different layers: particulate layer, ash layer, wall layer, and clean wall layer, respectively. Finally, the overall soot loading equation is established and the numerical solution is solved by Taylor’s formula. The model is verified by bench test, which can ensure high prediction accuracy without increasing the cost of regeneration. The maximum prediction error is less than 5%, and the average error is 2.72%. Based on the model, effects of the key structural parameters such as DPF diameter, length, cell density and wall thickness, as well as the engine operating parameters such as exhaust mass flow and temperature on the pressure drop and soot loading characteristics were further researched. The research results can provide important guidance for accurate triggering of regeneration, formulation of active regeneration control strategy and improvement of DPF durability.

This study proposes an extended filtration model for diesel particulate filter based on diesel particulate matter morphology characteristics. This model introduces the parameter of variable effective density to modify the filtration model and develops the global filtration correction coefficient ϑp to consider the changes of PM morphological parameters. The specific calculation formulas of these two parameters are given in the paper. The filtration model proposed in this paper is based on the theory of spherical particles packed bed. Results show that the prediction error of the extended model can be as low as 0.66%, the average prediction error is 1.17%, and the prediction accuracy is improved by 34.08% compared with the former model. Filtration efficiency growth coefficient E gro exhibits a bimodal distribution, and the PM in the two particle size ranges of 110–140 nm and greater than 500 nm is more sensitive to the micro-changes in parameters caused by PM deposition in the porous substrate. In addition, the filtration time interval has the greatest influence on the growth rate, especially for the small and medium particle sizes ranging between 166.5 and 294.3 nm.

When the active regeneration of a diesel particulate filter (DPF) occurs during a drop to idle (DTI) process, a massive amount of heat accumulates in the DPF, leading to a rather high peak temperature and a large temperature gradient, which can damage the DPF. Therefore, this study focuses on the temperature characteristics of a DPF in DTI active regeneration, so as to avoid the DPF damage at high temperature and large temperature gradient. The effects of particulate matter (PM) load, target regeneration temperature, and mass flow of exhaust gas on the temperature characteristics were investigated in this study. The peak temperature was found in the center of the outlet section of the DPF, the temperature gradient in the radial direction was much larger than that in the axial direction, and the maximum temperature gradient appeared near the outer surface of the DPF, that’s where the cracks are most likely to occur. In general, with the increase of PM load and target regeneration temperature, the peak temperature and the maximum temperature gradient of the DPF both increased, whereas they declined with the increase of mass flow of exhaust gas. Especially, decreasing PM load and increasing mass flow were very effective to decrease the maximum temperature gradient. Based on the experiments, two linear models were established to predict the peak temperature and the maximum temperature gradient of the DPF in DTI active regeneration respectively. Furthermore, the soot mass limit (SML) of the DPF was determined based on a series of DTI active regeneration experiments.

Catalyzed diesel particulate filters (CDPFs) are crucial technologies to control the particulate emissions from diesel engines. While obvious drops in filtration efficiencies (FEs) for particle number (PN) occur during the passive regeneration of CDPFs, which can lead to the deterioration of transient emissions. Therefore, in this study, a quasi-2-D model, including a fluid dynamic model, a back-diffusion model, a global kinetic model and a basic filtration model, was established for describing the PN-filtration-behavior of a CDPF. An extended filtration model was developed based on the soot fragmentation hypothesis, considering the effects of the particle diameter, soot load, exhaust gas temperature and flow velocity. An 8.8L, heavy duty diesel engine equipped with a commercial DOC and a CDPF was employed. The particle number and size distributions before and after the CDPF were determined with an engine exhaust particle sizer (EEPS) under eight operating conditions. The extended filtration model was calibrated with the test data, and the model results aligned with those of experiments with a maximal error less than 5% and an average error less than 1%. Then, the undetermined parameters in the extended filtration model were evaluated under the eight working conditions, and distinct regularities were observed among these parameters. The time-dependent PN-filtration-behavior of the tested CDPF was also explored based on the model. According to the model predictions, it was found that the PN-filtration-behavior of a CDPF was different from that of a DPF, and the PN-FE of a CDPF might be still unsatisfactory under the high-soot-load conditions.

The paper describes a calibration for a differential phase measurement system frequency from 5 Hz to 1 MHz based on two dual-channel high-speed digitizers controlled by National Instrument multiple instruments synchronization technology. The measurements compared single-end sampling mode and differential mode, and extra phase calibration experimental for differential phase measurement system. Phase measurement jitters are observed on differential mode. The results indicate the differential phase measurement is accuracy enough for calibration.

PubMed: 31209238, The effectiveness of most cancer targeted therapies is short-lived. Tumors often develop resistance that might be overcome with drug combinations. However, the number of possible combinations is vast, necessitating data-driven approaches to find optimal patient-specific treatments. Here we report AstraZeneca’s large drug combination dataset, consisting of 11,576 experiments from 910 combinations across 85 molecularly characterized cancer cell lines, and results of a DREAM Challenge to evaluate computational strategies for predicting synergistic drug pairs and biomarkers. 160 teams participated to provide a comprehensive methodological development and benchmarking. Winning methods incorporate prior knowledge of drug-target interactions. Synergy is predicted with an accuracy matching biological replicates for >60% of combinations. However, 20% of drug combinations are poorly predicted by all methods. Genomic rationale for synergy predictions are identified, including ADAM17 inhibitor antagonism when combined with PIK3CB/D inhibition contrasting to synergy when combined with other PI3K-pathway inhibitors in PIK3CA mutant cells. © 2019, The Author(s)., National Institute for Health Research, NIHR Wellcome Trust, WT: 102696, 206194 Magyar Tudományos Akadémia, MTA Bayer 668858 PrECISE AstraZeneca, We thank the Genomics of Drug Sensitivity in Cancer and COSMIC teams at the Wellcome Trust Sanger Institute for help with the preparation of the molecular data, Denes Turei for help with Omnipath, and Katjusa Koler for help with matching drug names across combination screens. We thank AstraZeneca for funding and provision of data to the DREAM Consortium to run the challenge, and funding from the European Union Horizon 2020 research (under grant agreement No 668858 PrECISE to J.S.R.), the Joint Research Center for Computational Biomedicine (which is partially funded by Bayer AG) to J.S.R., National Institute for Health Research (NIHR) Sheffield Biomedical Research Center, Premium Postdoctoral Fellowship Program of the Hungarian Academy of Sciences. M.G lab is supported by Wellcome Trust (102696 and 206194)., Competing interests: K.C.B., Z.G., G.Y.D., E.K.Y.T., S.F., and J.R.D. are AstraZeneca employees. K.C.B., Z.G., E.K.Y.T., S.F., and J.R.D. are AstraZeneca shareholders. Y.G. receives personal compensation from Eli Lilly and Company, is a shareholder of Cleerly, Inc., and Ann Arbor Algorithms, Inc. M.G. receives research funding from AstraZeneca and has performed consultancy for Sanofi. The remaining authors declare no competing interests.