Role of Altitude in Influencing the Spray Combustion Characteristics of a Heavy-Duty Diesel Engine in a Constant Volume Combustion Chamber. Part II: Impinging Diesel Jet.

Wall impingement, particularly liquid-wall impingement, has been demonstrated to be one of the critical causes of combustion deterioration in plateau diesel engines. Obviously, the complexity of wall impingement is exacerbated by the plateau scenario. However, fundamental studies specifically dedicated to this phenomenon are still inconclusive and insufficiently detailed, obviating the feasibility of the targeted design and optimization of diesel engines operating in regions with different altitudes. Consequently, the second part of this investigation, presented in this work, focused on the detailed physical and chemical processes of impinging spray combustion under different altitude conditions. A wall impingement system was designed to generate an impinging spray flame. The impingement distance was varied from 77 to 37 mm to cover different situations of wall impingement. The liquid spray, ignition, and combustion processes were visualized in detail by using different optical diagnostics. The results showed that the variation of the liquid length with the impingement distance was mainly dependent on the liquid impingement under the same altitude condition. The effect of the impingement distance on the ignition distance was more sensitive to the altitude. The quantitative analysis of the flame natural luminosity confirmed the decisive effect of the impinging flame morphology on the ambient entrainment and fuel-air mixing under different altitude conditions, and it also revealed that there was an optimal impingement distance under identical altitude conditions to achieve minimum soot emissions. And interestingly, the optimal impingement distance increased with altitude. Finally, the spray combustion processes of an impinging diesel jet were determined to occur in four typical regions, upon which a schematic diagram depicting the flame structure of an impinging diesel jet was proposed to phenomenologically describe the role of altitude in impinging spray combustion processes. Based on this, an attempt was made to explore some new perspectives beyond the popular solutions to recover and improve the performance of plateau diesel engines.

Emission Characteristics of Particulate and Gaseous Pollutants from a Light-Duty Diesel Engine with SDPF.

Due to the inherent combustion characteristics of diesel engines, particulate matter (PM) and nitrogen oxides (NOx) are the main pollutants of diesel engines. NOx emissions under low load and low temperature are the focus of future regulation. Selective catalytic reduction coated on diesel particulate filter (SDPF) can reduce NOx and PM emissions of diesel engines at the same time, especially improving the emission characteristics of NOx under low load and low temperature. In this paper, a light-duty diesel engine with diesel oxidation catalyst (DOC) and SDPF was studied, and emission of particulate and gaseous pollutants of the engine before DOC, after DOC, and after SDPF was measured under 10 steady-state operating conditions. The effects of SDPF on particulate size distribution, the filtration efficiency of particulate, and the conversion efficiency of gaseous pollutants were analyzed. The results show that DOC + SDPF can trap PM with particle sizes between 10 and 23 nm by 1-2 orders of magnitude, and the conversion and filtration efficiency of DOC + SDPF for both gaseous pollutants and PM exceeds 90% under low-temperature and low-load conditions. The filtration efficiency of SDPF is 94.37% for PM and 90.36% for PN, and the conversion efficiency is 91.43% for NOx.

Study on the Catalytic Characteristics of Precious Metal Catalysts with Different Pt/Pd Ratios for Soot Combustion.

Soot particles in engine exhaust seriously pollute the atmosphere and endanger human health. For soot oxidation, Pt and Pd precious metal catalysts are widely used and are effective. In this paper, the catalytic characteristics of catalysts with different Pt/Pd mass ratios for soot combustion were studied through X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller analysis, scanning electron microscopy, transmission electron microscopy, the temperature-programmed oxidation reaction, and thermogravimetry. Besides, the adsorption characteristics of soot and O2 on the catalyst surface were explored by density functional theory (DFT) calculations. The research results showed that the activity of catalysts for soot oxidation from strong to weak is Pt/Pd = 10:1, Pt/Pd = 5:1, Pt/Pd = 1:0, and Pt/Pd = 1:1. XPS results showed that the concentration of oxygen vacancies in the catalyst is the highest when the Pt/Pd ratio is 10:1. The specific surface area of the catalyst increases first and then decreases with the increase of Pd content. When the Pt/Pd ratio is 10:1, the specific surface area and pore volume of the catalyst reach the maximum. The following are the DFT calculation results. With the increase of Pd content, the adsorption energy of particles on the catalyst surface decreases first and then increases. When the Pt/Pd ratio is 10:1, the adsorption of C on the catalyst surface is the strongest, and the adsorption of O2 is also strong. In addition, this surface has a strong ability to donate electrons. The theoretical simulation results are consistent with the activity test results. The research results have a guiding significance for optimizing the Pt/Pd ratio and improving the soot oxidation performance of the catalyst.

Effect of catalyzed diesel particulate filter and its catalyst loading on emission characteristics of a non-road diesel engine.

In this study, the effects of a diesel oxidation catalyst (DOC) coupled with a catalyzed diesel particulate filter (CDPF) with different catalyst loadings on the power, fuel consumption, gaseous and particulate emissions from a non-road diesel engine were investigated. Results showed that the after-treatment had a negligible effect on the power and fuel consumption. The reduction effect of the DOC on the CO and hydrocarbon (HC) increased with the engine load. Further reductions occurred coupling with the CDPF. Increasing the catalyst loading resulted in a more significant reduction in the HC emissions than CO emissions. The DOC could increase the NO2 proportion to 37.9%, and more NO2 was produced when coupled with the CDPF below 250°C; above 250°C, more NO2 was consumed. The after-treatment could reduce more than 99% of the particle number (PN) and 98% of the particle mass (PM). Further reductions in the PN and PM occurred with a higher CDPF catalyst loading. The DOC had a better reduction effect on the nucleation particles than the accumulation ones, but the trend reversed with the CDPF. The DOC shifted the particle size distribution (PSD) to larger particles with an accumulation particle proportion increasing from 13% to 20%, and the geometric mean diameter (GMD) increased from 18.2 to 26.0 nm. The trend reversed with the CDPF and the accumulation particle proportion declined to less than 10%. A lower catalyst loading on the CDPF led to a higher proportion of nucleation particles and a smaller GMD.

Experimental investigation on the effects of DPF Cs-V-based non-precious metal catalysts and their coating forms on non-road diesel engine emission characteristics.

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 Cs2V4O11 (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.

Study on the real-world emission characteristics of gaseous and particulate pollutants from an inland ship using a portable emission measurement system.

The emissions of pollutants from inland ships endanger the urban environment and human health, deserving quantitative study to make reduction measurements to achieve clean emissions. In this study, the real-world gaseous emissions (CO, THC, SO2, NOx) and particulate emissions including particle mass (PM) and particle number (PN) as well as the particle size distribution and particle compositions from an inland ship were investigated using a portable emission measurement system (PEMS) method. The results showed that the emission concentrations of CO, THC, PM and PN at departure and idling conditions were significantly higher than those at other conditions, while the emission concentrations of NOx and SO2 at cruising condition were the highest. The particle size distribution always presented a bimodal distribution ranged at 40 nm and 200 nm respectively at different conditions and engine loads. The proportion of nucleation mode particles was the highest at departure condition, and a larger engine load resulted in a declined proportion of nucleation mode particles. The anions of the emitted particles mainly included nitrite ion (NO2-), nitrate ion (NO3-), sulfate ion (SO42-), and cations mainly included ammonium ion (NH4+), sodium ion (Na+) and potassium ion (K+). The main components of organic carbon (OC) in soot were OC1 and OC2, accounting for more than 80 %, while the main component of elemental carbon (EC) was EC2, accounting for 83.9 %. The emission factors based on fuel consumption of CO and THC were significantly higher at idling conditions than other conditions, and the emission factor of NOx was higher at cruising conditions, while the emission factors of PM and PN were higher at departure and idling conditions than other conditions.

Experimental evaluation of DPF performance loaded over Pt and sulfur-resisting material for marine diesel engines.

Different from vehicle engines, Diesel Particulate Filter (DPF) inactivation is an unavoidable issue for low-speed marine diesel engines fueled with Heavy Fuel Oil (HFO). This paper introduced a sulfur resisting material in Silicon Carbide (SiC)-DPF to improve DPF performance. The results of bench-scale experiments showed that the Balance Point Temperature of the modified DPF module was 300°C and DPF modules had a good filtration performance, with Particulate Matters (PMs) residual being less than 0.6 g per cycle. In pilot-scale tests, PMs emissions of unit power decreased with engine load going up, filtration efficiency of nucleation mode PMs being only 36% under 100% load, while DPF still had a good performance in accumulation mode PMs control, being 94.2% under the same load. DPF modules showed excellent regeneration durability in the 205h endurance test, with a regeneration period of 1.5-2h under 380°C. There was no obvious degeneration in the DPF module structure, with no cracks or breakage. Besides, the DPF module could also control gaseous emissions, total emissions decreased by 10.53% for NO and 57.19% for CO, respectively. The results suggested that introducing sulfur-resisting material in DPF could greatly improve the DPF performance of low-speed marine diesel engines fueled with HFO.

Investigation of sniffer technique on remote measurement of ship emissions: A case study in Shanghai, China.

Shipping emissions have aroused wide concern in the world. In order to promote the implementation of emission regulations, this study develop a ship based sniffing technique to perform remote measurement of the SO2, NOx and CO2 from ships entering and leaving Shanghai port at the open sea. The ship emission prediction model, Smoke diffusion model and source identification model were developed to automatically analyze the emission data and screen the object ship source based on Automatic Identification System (AIS) system. The fueling documents of the detected ship were obtained from maritime sector and the results precision of the sniffer technique was evaluated by comparing the measured Fuel sulfur content (FSC) with actual value deduced from fueling documents. The influences of wind speed and direction, object ship parameters and monitoring distance on the identification of object ship and accuracy of the calculated FSC were thoroughly investigated and the corresponding correction factors under different conditions were deduced. The modified emission factor ratio of CO2 to NOx were proposed in order to improve the accuracy. It is demonstrated that with wind speed higher than 2 m/s and test distance shorter than 400m, the sniffer technique exhibit high efficiency and accuracy for the remote emissions measurement of ship upwind with detection rate higher than 90% and test error of FSC below 15%. To reduce the influence of the wind direction, at least two sniffer systems were required to guarantee that at least one station is in the downwind of the ship lane. Based on the results and discussion, a novel sniffer monitoring system with two buoy based sniffing stations placed close to each side of the ship lane far off shore was proposed to realize the remote monitoring of ship emissions.

Effect of Exhaust Gas Recirculation Combined with Selective Catalytic Reduction on NO x Emission Characteristics and Their Matching Optimization of a Heavy-Duty Diesel Engine.

Exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) have become important technologies to reduce the NO x emission of heavy-duty diesel engines and meet the increasingly stringent emission regulations. This paper studied the effect of EGR combined with SCR on the NO x emission characteristics of a heavy-duty diesel engine based on the engine bench test. The results showed that the NO reduction rate of EGR-coupled SCR increased with the increase of engine load, and the effect was no longer significant when the NO reduction rate exceeded a certain limit under the same working conditions. EGR combined with SCR has little effect on NO2 emission reduction, and the increase of engine speed can significantly improve the efficiency of the NO2 reduction rate at 75 and 100% load. 25% opening of the EGR valve (OEV) and 50% OEV have very similar effects on the NO x reduction rate when the engine speed is at a low level. Compared with low engine speeds, increased OEV or ammonia NO x molar ratio (ANR) had a more obvious effect on the NO x reduction rate at high engine speeds. SCR combined with low valve-opening EGR had a more significant effect on the NO x reduction rate. The increase of OEV led to the increase of fuel consumption rate, but the effect on the fuel consumption rate decreased gradually with the increase of diesel engine speed. Meanwhile, this study optimized the matching relationship between OEV and ANR based on the data of the genetic algorithm, which provides a theoretical research method and application basis for diesel engine-matching of EGR and SCR.

Study on the Emission Characteristics of Urban Buses at Different Emission Standards Fueled with Biodiesel Blends.

Biodiesel is a promising clean and alternative fuel that can meet the demand of energy saving and environmental protection. In this study, the effects of biodiesel blends on the gaseous and particulate emission characteristics of China-III, IV, and V urban buses were investigated based on a heavy chassis dynamometer. The results showed that the biodiesel blend resulted in a reduction in CO, THC, PN, and PM emission but an increase in the NOx and CO2 emission, and the effects were enhanced with the biodiesel ratio, which also depended on the bus speed. Simultaneously, the emission standards of buses had an obvious effect on the emissions and changed the effect of biodiesel on the emissions. A higher emission standard of the bus highlighted the effect of biodiesel on the emission. From China-III to China-IV to China-V buses, the comprehensive changes produced by B5 in the emissions increased from 5.57 to 6.78 to 6.83%, while for B10, a significant increase in the changes was obtained, reaching 12.98, 14.68, and 15.02%, respectively, for the three emission stage buses.

Experimental Study on Diesel Engine Emission Characteristics Based on Different Exhaust Pipe Coating Schemes.

The thermal insulation performance of exhaust pipes coated with various materials (basalt and glass fiber materials) under different braiding forms (sleeve, winding and felt types) and the effects on the emission characteristics of diesel engines were experimentally studied through engine bench tests. The results indicated that the thermal insulation performance of basalt fiber was higher than that of glass fiber, and more notably advantageous at the early stage of the diesel engine idle cold phase. The average temperature drop during the first 600 s of the basalt felt (BF) pipe was 2.6 °C smaller than that of the glass fiber felt (GF) pipe. Comparing the different braiding forms, the temperature decrease in the felt-type braided material was 2.6 °C and 2.9 °C smaller than that in the sleeve- and winding-type braided materials, respectively. The basalt material was better than the glass fiber material regarding the gaseous pollutant emission reduction performance, especially in the idling cold phase of diesel engines. The NOx conversion rate of the BF pipe was 7.4% higher than that of the GF pipe, and the hydrocarbon (HC) conversion rate was 2.3% higher than that of the GF pipe, while the CO conversion rate during the first 100 s was 24.5% higher than that of the GF pipe. However, the particulate matter emissions were not notably different.

Fuel Consumption Modeling of a Turbocharged Gasoline Engine Based on a Partially Shared Neural Network.

Fuel consumption is the most important parameter that characterizes the fuel economy of the engines. Instead of manual fuel consumption calibration based on the experience of engineers, the establishment of a fuel consumption model greatly reduces the time and cost of multiparameter calibration and optimization of modern engines and realizes the further exploration of the engine fuel economy potential. Based on the bench test, one-dimensional engine simulation, and design of experiment, a partially shared neural network with its sampling and training method to establish the engine fuel consumption model is proposed in this paper in view of the lack of discrete working conditions in the traditional neural network model. The results show that the proposed partially shared neural network applying Gauss distribution sampling and the frozen training method, after an analysis of the number of hidden neurons and epochs, showed optimal prediction accuracy and excellent robustness in full coverage over the whole load region on the test data set obtained through the bench test. Eighty-seven percent of the prediction errors are less than 3%, all prediction errors are less than 10%, and the R 2 value is improved to 0.954 on the test data set.

Interactions between Used Cooking Oil Biodiesel Blends and Elastomer Materials in the Diesel Engine.

Used cooking oil (UCO) biodiesel may be one of the most potential alternative fuels in China to lower the dependency on crude oil for transportation. An experimental study has been conducted to assess the interactions between biodiesel produced from UCO in Shanghai and elastomer materials on high-speed marine diesel engines by immersing elastomer materials into conventional fossil diesel, 5, 10, and 20%, of a volumetric blending ratio of UCO biodiesel and pure UCO biodiesel. The test duration is 168 h at different temperatures of 25, 50, and 70 °C. Meanwhile, the effects of the mixing ratio of UCO biodiesel and the immersion temperature on the compatibility of elastomer materials with UCO biodiesel were analyzed. The results revealed that elastomer materials such as nitrile butadiene rubber (NBR), ethylene propylene diene monomer (EPDM), fluororubber (FKM), and silicone rubber (SR) exposed to biodiesel blends would reveal worse but acceptable changes than those exposed to petroleum diesel, including the slight increase of mass and volume and decline of tensile strength and hardness. FKM, NBR, and SR represented better compatibility with pure UCO biodiesel than diesel, and EPDM showed worse compatibility with UCO biodiesel as the blend ratio rises. In general, the recommended volumetric mixing ratio of UCO biodiesel should be no larger than 20%. The present study could be helpful for the investigation of UCO biodiesel blends as a potential fuel to satisfy the energy demand.

Study of spatial and temporal aging characteristic of catalyzed diesel particulate filter catalytic performance used for diesel vehicle.

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.

Study on the Effects of EGR and Spark Timing on the Combustion, Performance, and Emissions of a Stoichiometric Natural Gas Engine.

This paper involved conducting an experimental investigation on the effects of exhaust gas recirculation (EGR) and spark timing on the combustion, performance, and emission characteristics of a China-VI heavy-duty, natural gas engine fueled with high-methane content. The results showed that increasing the EGR rate extends the spark timing range and slows the combustion. This then increases ignition delay, prolongs combustion duration, and decreases heat release rate. Peak in-cylinder pressure (PCP) and indicated thermal efficiency (ITE) initially increase because of higher boost pressure with increasing EGR rate. However, as EGR rate increases further, PCP and ITE begin to decrease because of the deviation of combustion phasing. Lower in-cylinder temperature caused by higher EGR rate may cause nitrogen oxide (NOx) emissions to reduce significantly, while total hydrocarbon (THC) and carbon monoxide (CO) emissions increase, and THC emissions could increase exponentially at high EGR rates. In-cylinder pressure, temperature, and heat release rate increase with early spark timing, but the rate of increase is reduced at higher engine speeds. Early spark timing causes THC and CO emissions to increase at part-load conditions, whereas there is little change at full-load conditions. NOx emissions also increase with early spark timing because of the higher in-cylinder temperature.

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.

Experimental study on the emission characteristics of a non-road diesel engine equipped with different after-treatment devices.

A comparative experiment was conducted based on a non-road diesel engine to investigate the effects of two after-treatment devices on the engine's emission characteristics as well as their power and fuel consumption performances. The first after-treatment device is a combination of a diesel oxidation catalyst (DOC) and a catalytic diesel particulate filter (CDPF). The second device is a single CDPF-coated improved noble metal catalyst. Results showed that the two after-treatment devices had almost no effect on the power and fuel consumption performance. The gaseous and particulate emissions of the engine depended on the operation conditions including the speed and load. However, the dual DOC+CDPF system and the single CDPF reduced more than 81% of the carbon monoxide (CO) and 73% of the hydrocarbon (HC) emissions. Notably, the reduction efficiency by the single CDPF was higher than that of the DOC+CDPF system. In terms of the particulate emissions, both after-treatment devices achieved more than 96% reduction of the particle number (PN) and up to 88% reduction of the particulate mass (PM). Similarly, the single CDPF outperformed the dual DOC+CDPF system in reducing particle emissions. Although no changes occurred in the bimodal particle size distribution of the engine after the installation of the two after-treatment devices, they performed differently in reducing particles with different sizes. The particles reduction efficiency of the DOC+CDPF system was higher than that of the single CDPF for the particles smaller than 14.3 nm, and this trend converted for particles larger than 14.3 nm. Improving the noble metal catalyst load in the CDPF ensured a performance that rivaled the DOC+CDPF system. Apart from the NOx emissions, the installation of a single CDPF with an improved noble metal catalyst load can make the non-road diesel engine meet the limits of the China IV emission regulations.

A phenomenological model for particle number and size distributions of a diesel engine with a diesel oxidation catalyst.

Particle number is a key index for evaluating particulate emissions, and diesel oxidation catalysts (DOCs) are one of the most important technologies for controlling the particulate emissions of a diesel engine. In this paper, a novel phenomenological one-dimensional model was established to predict particle number and size distributions at a DOC outlet with the aim of investigating the effects of DOC on particle number emissions. The phenomenological model consisted of two submodels: submodel-1, a global kinetic model for calculating particle size in particle number and size distributions after particles had passed through the DOC, and submodel-2, an original global parametric model for calculating the particle number at the DOC outlet. The effects of the sampling process, fuel properties, and the engine operating condition were considered in submodel-2. An 8.8 L, direct-injection, heavy-duty diesel engine was tested. The particle number and size distributions at the DOC inlet and outlet were determined using an engine exhaust particle sizer. The test data, coupled with literature results, were used to calibrate and validate the phenomenological model. This model was then applied to investigate the influence of various factors on particle number and size distributions at the DOC outlet. It was found that dilution temperature, fuel sulfur content, exhaust gas temperature, and gas hourly space velocity (GHSV) played a key role in the particle number after DOC oxidation. The particle number concentration at the DOC outlet increased as fuel sulfur content and exhaust gas temperature increased and decreased as GHSV and dilution temperature increased. In general, results proved that this phenomenological model was accurate enough to predict particle number and size distributions at a DOC outlet under most operating conditions. It may serve as a useful tool for research and development focusing on PM reduction of diesel engines and air pollution control.

Emission factors of particulate and gaseous compounds from a large cargo vessel operated under real-world conditions.

On-board emissions measurements were performed on a Handysize-class bulk carrier operating under real-world conditions. Emission factors (EFs) were determined for criteria pollutants such as NOx, CO, total hydrocarbons (THC), and PM; PM composition, including organic and elemental carbon (OC and EC), inorganic species, and a variety of organic compounds and VOC species (including alkanes, alkenes, single-ring aromatics, and oxygenated VOCs) were also analyzed. To investigate the impacts of engine type, fuel, and operating conditions on emissions, measurements were conducted on one main and one auxiliary engines using low- and high-sulfur fuels (LSF and HSF) under actual operating conditions, including at-berth, maneuvering, and cruising at different engine loads. OC was the most abundant PM component (contributing 45-65%), followed by sulfate (2-15%) and EC (1-20%). Compounds with 3 or 4 aromatic rings, including phenanthrene, fluoranthene, pyrene, and benzo[b+k]fluoranthene, dominated the particulate polycyclic aromatic hydrocarbons (PAHs) emitted from the ship, accounting for 69-89% of the total PAHs. Single-ring aromatics constituted 50-78% of the emitted VOCs and were dominated by toluene. In this study, switching from HSF (1.12% S) to LSF (0.38% S) reduced emitted PM by 12%, OC by 20%, sulfate by 71%, and particulate PAHs by 94%, but caused an increase in single-ring aromatics. The power-based EFs generally decreased with increasing engine loads. However, decreasing the ship engine load also reduced the vessel speed and, thus, decreased emissions over a given voyage distance. Herein, a Vessel Speed Reduction (VSR) from 11 to 8-9 knots decreased NOx and PM emissions by approximately 33% and 36%, respectively, and OC, EC, sulfate, and particulate PAHs in PM emissions by 34%, 83%, 29%, and 11%. These data can be used to minimize uncertainty in the emission factors used in ship emissions calculations.

[Pollutant Emissions from Diesel Buses Fueled with Waste Cooking Oil Based Biodiesel].

Two diesel buses respectively certified to meet China Ⅲ and China Ⅴ emission standards were used as prototype vehicles, fixed on a heavy-duty chassis dynamometer and driven according to a typical city bus driving cycle to analyze the pollutant emissions and volatile organic compounds (VOCs). The buses were fueled with diesel and waste cooking oil based biodiesel with 10 vol% blend ratio (B10). The emissions of total hydrocarbon(THC), CO, particulate matter (PM), and the number of solid particles with a diameter of 23 nm to 2.5 µm (referred to as "solid particulate number of PM2.5") from the bus certified to meet China Ⅴ (referred to as "China V bus") were 39.3%, 19.9%, 77.4%, and 28.4% lower than those from the other bus certified to meet China Ⅲ (referred to as "China Ⅲ bus"), while NOx emissions were 31.7% higher. Moreover, alkanes, alkenes, aromatic hydrocarbons, and oxygenated compounds in VOCs emitted from the China V bus were lower than those emitted from the China Ⅲ bus, suggesting lower atmospheric reactivity and smaller potential of secondary organic aerosol formation. Compared with the emission results of two diesel-fueled buses, the B10-fueled buses emitted smaller amounts of THC, CO, PM, and solid particulate number of PM2.5, lower oxygenated compounds but higher alkenes; slightly higher NOx emissions than China Ⅲ but slightly lower NOx emissions than China V. Consequently, the atmospheric reactivity of VOCs in exhaust gas from the bus fueled with B10 was higher than that from the diesel-powered bus.