An experimental study on the impact of biodiesel origin on the regulated and PAH emissions from a Euro 4 light-duty vehicle

This study investigates the impact of mid-high biodiesel blends on the criteria and PAH emissions from a pick-up diesel vehicle. The vehicle was a Euro 4 (category N1, subclass III) compliant common rail light duty vehicle fitted with a diesel oxidation catalyst. Emission and fuel consumption measurements were performed on a chassis dynamometer using constant volume sampling (CVS) technique, following the European regulations. All measurements were conducted over the NEDC and Artemis driving cycles. Aiming to evaluate the fuel impact on emissions, a soy-based biodiesel, a palm-based biodiesel, and an oxidized biodiesel obtained from used frying oils were blended with an ultra low sulfur diesel at proportions of 30%, 50% and 80% by volume. CO₂ emissions and fuel consumption exhibited increases with biodiesel over all driving conditions which ranged up to 5%. NO_x emissions were found to be above the Euro 4 limit and increased with biodiesel between 5% and 10% except for the blends prepared with the palm-based methyl ester. The emissions of PM, HC, and CO decreased with the addition of biodiesel reaching maximum reductions in the order of 10%, 30% and 20% respectively; however, some increases were observed over the NEDC which may be attributed to cold-start. Sharp increases in most PAH, nitro-PAH and oxy-PAH compounds were observed with the application of biodiesel. These increases were particularly noticeable with the use of the oxidized blends, a phenomenon that it is related with the type and quality of this fuel. The emissions were also affected by the operating conditions of the engine. It was found that most PAH compounds were decreased as the mean speed and load of the driving cycle increased.     

Oxygenated transportation fuels. Evaluation of properties and emission performance in light-duty vehicles in Mexico

Recently a “Biofuels Promotion and Development Law” was approved in Mexico that requires increasing volumes of renewable to blend into the transportation fuel pool, much of which is likely to be ethanol. Emissions data under the three different driving conditions of the United States FTP-75 certification cycle were obtained for regulated, toxic and carbonyl compounds using recent model year vehicles representing 61% of the typical fleet available in Mexico. Ozone-forming potential and specific reactivity of tailpipe and evaporative emissions were also calculated. Comparison were performed using the traditional methyl-tertiary butyl ether employed in Mexico with an ethanol fuel at the same level of oxygen content, taking into account the current fuel specifications and the stream stocks available at the Mexican refineries. The results suggest that the contribution of cold start to regulated emissions range from 37% to 40% whiles those of toxic from 40% to 47% in both fuels. Results also indicate an increase in the rates of evaporative emissions of higher Specific Reactivy with the ethanol fuel. Estimation of the percent reduction of pollutants using the Complex Model of the USA Environmental Protection Agency suggests that volatile organic compounds will exceeds the limits imposed by the model if vapour pressure of the ethanol gasoline is not properly adjusted.     

Engine performance and exhaust gas emissions of methanol and ethanol-diesel blends

In this study, the effects of methanol-diesel (M5, M10) and ethanol-diesel (E5, E10) fuel blends on the performance and exhaust emissions were experimentally investigated. For this work, a single cylinder, four-stroke, direct injection, naturally aspirated diesel engine was used. The tests were performed by varying the engine speed between 1000 and 1800 rpm while keeping the engine torque at 30 Nm. The results showed that brake specific fuel consumption and emissions of nitrogen oxides increased while brake thermal efficiency, smoke opacity, emissions of carbon monoxide and total hydrocarbon decreased with methanol-diesel and ethanol-diesel fuel blends.     

Effects of ethyl tert-butyl ether addition to diesel fuel on characteristics of combustion and exhaust emissions of diesel engines

The effects of ethyl tert-butyl ether (ETBE) addition to diesel fuel on the characteristics of combustion and exhaust emissions of a common rail direct injection diesel engine with high rates of cooled exhaust gas recirculation (EGR) were investigated. Test fuels were prepared by blending 0, 10, 20, 30 and 40 vol% ETBE to a commercial diesel fuel. Increasing ETBE fraction in the fuel helps to suppress the smoke emission increasing with EGR, but a too high fraction of ETBE leads to misfiring at higher EGR rates. While the combustion noise and NO_x emissions increase with increases in ETBE fraction at relatively low EGR rates, they can be suppressed to low levels by increasing EGR. Though there are no significant increases in THC and CO emissions due to ETBE addition to diesel fuel in a wide range of EGR rates, the ETBE blended fuel results in higher aldehyde emissions than the pure diesel fuel at relatively low EGR rates. With the 30% ETBE blended fuel, the operating load range of smokeless, ultra-low NO_x (<0.5 g/kWi h), and efficient diesel combustion with high rates of cooled EGR is extended to higher loads than with the pure diesel fuel.     

Perspectives on the utilization of waste fat from beef cattle and fowl for biodiesel production in Mexico

The purpose of this research was to perform a preliminary inventory of the waste fat generated from beef cattle and fowl in Mexico that could be used for biodiesel production. Additionally, the CO₂ emissions reduction that could be achieved by using the potential biodiesel to replace an energy‐equivalent amount of fossil diesel was assessed. Based on national reports for the year 2014, it was estimated that the non‐edible fat from beef cattle and fowl annually generated in Mexico is sufficient to produce 216.0 kt of biodiesel, which would furnish 8379 TJ. This amount is equivalent to 1.5% of the energy annually consumed in Mexico as fossil diesel for road transport. The potential 216.0 kt of animal fat‐based biodiesel that can be produced annually could replace 198.3 kt of fossil diesel and thus allow a reduction in the WTW (well to wheels) emissions of 592.3 kt CO₂, which represents 1.5% of the WTW CO2 emitted from the combustion of the fossil diesel used for road transportation in Mexico in the year 2014. © 2016 Society of Chemical Industry     

Comparison of emissions of a direct injection diesel engine operating on biodiesel with emulsified and fumigated methanol

Biodiesel is an alternative fuel for internal combustion engines. It can reduce carbon monoxide (CO), hydrocarbon (HC) and particulate matter (PM) emissions, compared with diesel fuel, but there is also an increase in nitrogen oxides (NO_x) emission. This study is aimed to compare the effect of applying a biodiesel with either 10% blended methanol or 10% fumigation methanol. The biodiesel used in this study was converted from waste cooking oil. Experiments were performed on a 4-cylinder naturally aspirated direct injection diesel engine operating at a constant speed of 1800 rev/min with five different engine loads. The results indicate a reduction of CO₂, NO_x, and particulate mass emissions and a reduction in mean particle diameter, in both cases, compared with diesel fuel. It is of interest to compare the two modes of fueling with methanol in combination with biodiesel. For the blended mode, there is a slightly higher brake thermal efficiency at low engine load while the fumigation mode gives slightly higher brake thermal efficiency at medium and high engine loads. In the fumigation mode, an extra fuel injection control system is required, and there is also an increase in CO, HC and NO₂ (nitrogen dioxide) and particulate emissions in the engine exhaust, which are disadvantages compared with the blended mode.     

An analysis for effect of cetane number on exhaust emissions from engine with the neural network

Decoupling cetane number from the other compositions and properties of diesel fuel, the individual effect of cetane number on the exhaust emissions from an engine may be researched. This paper has presented a back-propagation neural network model predicting the exhaust emissions from an engine with the inputs of total cetane number, base cetane number and cetane improver, total cetane number and nitrogen content in the diesel fuel; as well as the output of the exhaust emissions of hydrocarbon (HC), carbon oxide (CO), particulate matter (PM) and nitrogen oxide (NO_x). An optimal design has been completed for the number of hidden layers, the number of hidden neurons, the activation function, and the goal errors, along with the initial weights and biases in the back-propagation neural network model. HC, CO, PM and NO_x have been predicted with the model, the effects of cetane improver and nitrogen content on them have also been analyzed, and better results have been achieved.     

The influence of oxygenated fuels on emissions of aldehydes and ketones from a two-stroke spark ignition engine

A spark-ignited two-stroke chainsaw engine was used to study the influence of pure oxygenated fuels on exhaust emissions of carbonyls (aldehydes and ketones) and regulated emissions, i.e. hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NO_x). Three fuels—methanol, methyl tert-butylether (MTBE), and ethyl tert-butylether (ETBE)—were used in the tests, each at three air/fuel ratios (λ) and the generated emissions were compared to those observed in previous tests with ethanol, aliphatic gasoline, and regular gasoline. Use of all four oxygenated fuels (ETBE, ethanol, methanol and MTBE) resulted in substantially higher total carbonyl emissions (11, 11, 8.9 and 7.8 g/kWh, respectively) than use of both aliphatic and regular gasoline (2.1 and 2.6 g/kWh, respectively). Further, up to 44-fold higher levels of specific carbonyls were generated from the oxygenated fuels than from regular gasoline: significant amounts of formaldehyde were produced from all of the oxygenated fuels, but they were especially high from methanol and MTBE; acetaldehyde was formed in high amounts from ethanol and ETBE; while acetone and methacrolein were formed from both MTBE and ETBE. In addition, increases in λ increased exhaust emissions of formaldehyde, acetaldehyde, acetone, and methacrolein in cases where these were the main carbonyls formed. Increasing λ also variously increased, reduced or had no significant effect on emissions of other measured carbonyls. Lower amounts of CO and NO_x emissions were formed from all oxygenates (especially methanol) than from regular gasoline.     

Experimental study of the effects of vegetable oil methyl ester on DI diesel engine performance characteristics and pollutant emissions

Vegetable oil methyl ester (VOME) is produced through the transesterification of vegetable oil and can be used as biodiesel in diesel engines as a renewable, nontoxic, and potentially environmentally friendly fossil fuel alternative in light of growing concerns regarding global warming and increasing oil prices. This study used VOME fuels produced from eight commonly seen oil bases to conduct a series of engine tests to investigate the effects of VOME on the engine performance, exhaust emissions, and combustion characteristics. The experimental results showed that using VOME in an unmodified direct injection (DI) diesel engine yielded a higher brake specific fuel consumption (BSFC) due to the VOME fuel’s lower calorific value. The high cetane number of VOME also imparted a better ignition quality and the high intrinsic oxygen content advanced the combustion process. The earlier start of combustion and the rapid combustion rate led to a drastic increase in the heat release rate (HRR) and the in-cylinder combustion pressure (ICCP) during the premixed combustion phase. A higher combustion rate resulted in higher peaks of HRR and ICCP as well as near the top dead center (TDC) position. Thus, it was found that a diesel engine fueled with VOME could potentially produce the same engine power as one fueled with petroleum diesel (PD), but with a reduction in the exhaust gas temperature (EGT), smoke and total hydrocarbon (THC) emissions, albeit with a slight increase in nitrogen oxides (NO_x) emissions. In addition, the VOME which possesses shorter carbon chains, more saturated bonds, and a higher oxygen content also yields a lower EGT as well as reduced smoke, NO_x, and THC emissions. However, this is obtained at the detriment of an increased BSFC.     

Rôles of catalytic oxidation in control of vehicle exhaust emissions

Catalytic oxidation was initially associated with the early development of catalysis and it subsequently became a part of many industrial processes, so it is not surprising it was used to remove hydrocarbons and CO when it became necessary to control these emissions from cars. Later NOx was reduced in a process involving reduction over a Pt/Rh catalyst followed by air injection in front of a Pt-based oxidation catalyst. If over-reduction of NO to NH₃ took place, or if H₂S was produced, it was important these undesirable species were converted to NOx and SOx in the catalytic oxidation stage. When exhaust gas composition could be kept stoichiometric hydrocarbons, CO and NOx were simultaneously converted over a single Pt/Rh three-way catalyst (TWC). With modern TWCs car tailpipe emissions can be exceptionally low. NO is not catalytically dissociated to O₂ and N₂ in the presence of O₂, it can only be reduced to N₂. Its control from lean-burn gasoline engines involves catalytic oxidation to NO₂ and thence nitrate that is stored and periodically reduced to N₂ by exhaust gas enrichment. This method is being modified for diesel engines. These engines produce soot, and filtration is being introduced to remove it. The exhaust temperature of heavy-duty diesels is sufficient (250–400 °C) for NO to be catalytically oxidised to NO₂ over an upstream platinum catalyst that smoothly oxidises soot in the filter. The exhaust gas temperature of passenger car diesels is too low for this to take place all of the time, so trapped soot is periodically burnt in O₂ above 550 °C. Catalytic oxidation of higher than normal amounts of hydrocarbon and CO over an upstream catalyst is used to give sufficient temperature for soot combustion with O₂ to take place.     

Effects of volumetric efficiency on the performance and emissions characteristics of a dual fueled (gasoline and LPG) spark ignition engine

In this study, effects of variation in volumetric efficiency on the engine emissions characteristics with different LPG usage levels (25%, 50%, 75%, and 100%), on an engine operated with new generation closed loop, multi-point, and sequential gas injection system were investigated. For this purpose, experiments were carried out under constant engine speed (3800 rpm) and different load (5%, 30%, 60%, 90%) conditions. The variations in volumetric efficiency, air-fuel ratio, brake thermal efficiency, brake specific fuel consumption, brake specific energy consumption, and exhaust gasses were examined. The volumetric efficiency decreased considerably at the use of 25% LPG level. As for the 50%, 75% and 100% LPG usage, volumetric efficiency decreased in proportion to LPG usage level. Air-fuel ratio decreases with the increase in LPG usage level and the minimum air-fuel ratio value was obtained at 100% LPG usage. At the use of mixture containing 25% LPG, brake specific fuel and energy consumption decreased while the brake thermal efficiency was maintained. Positive results were obtained at all LPG usage levels in terms of exhaust emissions. Best results were achieved at using 100% LPG for exhaust emissions.     

A vehicle testing programme for calibration and validation of an evaporative emissions model

A vehicle testing programme has been designed in order to calibrate and validate an empirical evaporative emissions model developed in previous work. To this aim, a large number of “targeted” tests have been performed on four vehicles covering a wide range of the model input parameters such as fuel volatility, ambient temperature, fuel tank and carbon canister size, fuel system materials. The fair agreement between modelled and measured values demonstrates that “bottom-up” modelling work and “top-down” vehicle testing may be combined to predict evaporative emissions on a vehicle level.     

The impact of soy-based biodiesel on PAH, nitro-PAH and oxy-PAH emissions from a passenger car operated over regulated and nonregulated driving cycles

This study explores the impact of neat soy-based methyl ester and its 50% v/v blend with low sulphur automotive diesel on PAH, nitro-PAH and oxy-PAH emissions of a Euro 2 compliant diesel passenger car tested on a chassis dynamometer. Emission measurements were evaluated for the certification NEDC, a hot-start UDC (urban part of NEDC) and the non-legislated Artemis driving cycles which simulate urban, rural and highway driving conditions in Europe. Overall, 16 PAHs, 4 nitro-PAHs and 6 oxy-PAHs were determined in the exhaust. The results obtained, showed that PAH emissions decreased with the addition of biodiesel during all driving modes. However, their nitrated and oxygenated products were found to increase with biodiesel compared to diesel fuel. The use of pure biodiesel led in some increases in PAH emissions when compared to its 50% blend. PAH emissions were also found to be adversely influenced by cold-start conditions and certain fuel properties.     

Calculation of mass emissions, oxygen mass fraction and thermal capacity of the inducted charge in SI and diesel engines from exhaust and intake gas analysis

New computational procedures are proposed for experimentally evaluating air-fuel ratio and mass fractions of exhaust emissions as well as EGR rate, oxygen mass fraction and thermal capacity of the inducted charge in IC engines running with diesel oil, gasoline or any alternative liquid or gaseous fuel, such as LPG or CNG. Starting from the chemical reaction of fuel with air, from gaseous and smoke level measurements in the raw gases, the procedures calculate the volume fractions of oxygen in the combustion air and of compounds in the exhaust gases, including those that are not usually measured, such as water, nitrogen and hydrogen. The methods also take the effects of various fuel and combustion air compositions into account, as well as to the presence of water vapor, CO₂, Ar and He in the combustion air.The algorithms are applied to four different automotive engines under wide ranges of steady-state operating conditions: three turbocharged diesel engines featuring high-pressure cooled EGR systems, and an SI naturally aspirated bi-fuel engine running on either gasoline or CNG. The computed air-fuel ratios are compared to those obtained from directly measured air and fuel mass-flow rates as well as from more conventional UEGO sensor data. The mass emissions are worked out in terms of both brake specific mass emissions and emission indexes of each pollutant species, and the results are compared to those obtained by applying SAE and ISO recommended practices. The computed oxygen mass fraction of the inducted charge was then compared to that derived from direct measurement of O₂ concentration in inlet manifold. Finally, the sensitivity of results to the main engine working parameters, the influence of environmental conditions (in particular the effect of air humidity on NO_x formation) and the experimental uncertainties are determined.     

Influence of two-stage injection and exhaust gas recirculation on the emissions reduction in an ethanol-blended diesel-fueled four-cylinder diesel engine

The purpose of this study is to investigate the effects of two-stage injection and exhaust gas recirculation (EGR) on the spray behavior and exhaust emission characteristics in diesel-ethanol fuel blends fueled four-cylinder diesel engine. The spray behavior is analyzed from the spray development process, spray tip penetration, and spray cone angle, which are obtained from the spray images. The combustion and exhaust emission characteristics are measured from the four-cylinder diesel engine with a common-rail injection system.The experimental results revealed that the increase of the pilot injection amount causes the fast development of the injected pilot spray, and the penetration difference among the main sprays is less than that among the pilot sprays. An increase in the ethanol blending ratio causes an increase in the ignition delay in the pilot combustion, but the main combustion is little influenced by the ethanol blending. The increase in the pilot injection amount shows the reduction effects of NO_x emissions when the pilot injection timing is advanced beyond BTDC 20°. The concentration of soot emissions shows a decreasing pattern according to the advance of the pilot injection and the decrease in the pilot injection amount. The CO emissions increase with the advance of the pilot injection timing, the increase in the pilot injection amount, and the ethanol blending ratio. In addition, the increase in the ethanol blending ratio and the advance of the pilot injection timing induce an increase in the HC emissions. The increase in the pilot injection amount induces a slight increase in the HC emissions.     

Influence of fuel and air/fuel equivalence ratio on the emission of hydrocarbons from a SI engine. 1. Experimental findings

A spark ignition engine was used to study the impact of fuel composition and of the air/fuel equivalence ratio on exhaust emissions of specific hydrocarbons. The fuel blends used contained eight main hydrocarbons and four oxygenated compounds. The fuel components that produce each exhaust pollutant are identified. The emissions of all HC generally decrease with the addition of oxygenated compounds, except sometimes in the case of methane, ethane and cyclohexane. Under rich conditions, the relative increase of exhaust methane and benzene is more important than the other saturated HC. Some HC are correlated with the physical properties of the fuel and other exhaust pollutants.     

Air quality assessment in a highly industrialized area of Mexico: Concentrations and sources of volatile organic compounds

Parallel to the economical benefits brought by the oil industry in Mexico, there have been some negative environmental effects due to emission of pollutants to the atmosphere. Salamanca, a city located inside one of the most important industrial corridors of the country, has been frequently affected by elevated concentrations of sulfur dioxide and particle matter. However, little is known about volatile organic compounds (VOCs), which in this study are analyzed along with criteria pollutants and meteorological parameters during February–March 2003 at urban, suburban and rural sites. Although sulfur dioxide average levels were ∼0.017 ppm, a high concentration event (∼0.600 ppm), attributable to emissions from the oil refinery and the thermoelectric power plant, was observed at the urban site at night time. The VOCs concentration varied from 170 ± 50 ppbC (rural) to 699 ± 212 (urban) and were constituted by 40% alkanes, 13% aromatics, 11% olefins and 11% of halogenated. The most abundant species were propane (167 ± 40 ppbC), n-butane (91 ± 23 ppbC), toluene (51 ± 10 ppbC) and i-pentane (44 ± 7 ppbC), that are related to combustion processes. Freon-114, methyl bromide and 1,2-dichloroethane which are likely emitted by application of pesticides, soil fumigation and fabrication of chemicals, showed high concentrations (48 ± 10, 50 ± 10 and 32 ± 6 ppbC respectively) in the rural sites, highlighting the importance of control measurements implementation for these species, as they represent a potential hazard for public health. Moreover, these halocarbons showed similar ratios regardless the monitoring site, suggesting same source. Modeling results indicated that meteorological conditions generally transport air masses to the northeast rural areas where the highest concentrations of ozone were calculated.     

Experimental and numerical study on the combustion characteristics of partially premixed charge compression ignition engine with dual fuel

The objective of this work is to investigate the effect of premixed fuel ratio on the combustion and emission characteristics in diesel engine by the experimental and numerical method. In order to investigate the effect of various factors such as the premixed ratio, EGR rate, and equivalence ratio on the exhaust gas from the premixed charge compression ignition diesel engine, the injection amount of premixed fuel is controlled by electronic port injection system. The range of premixed ratio between dual fuels used in this study is between 0 and 0.85, and the exhaust gas is recirclulated up to 30 percent of EGR rate.     

汽油含硫量对排放的影响研究

随着我国国民生活水平的提高和汽车工业的发展,汽车逐渐的在我国普及开来,本文针对汽油这种汽车燃料的含硫量对排放量的影响进行了一定的实验,并且得出了相关的实验数据和实验结果。     

Exhaust emissions and fuel properties of partially hydrogenated soybean oil methyl esters blended with ultra low sulfur diesel fuel

Important fuel properties and emission characteristics of blends (20 vol.%) of soybean oil methyl esters (SME) and partially hydrogenated SME (PHSME) in ultra low sulfur diesel fuel (ULSD) were determined and compared with neat ULSD. The following changes were observed for B20 blends of SME and PHSME versus neat ULSD: improved lubricity, higher kinematic viscosity and cetane number, lower sulfur content, and inferior low-temperature properties and oxidative stability. With respect to exhaust emissions, B20 blends of PHSME and SME exhibited lower PM and CO emissions in comparison to those of neat ULSD. The PHSME blend also showed a significant reduction in THC emissions. Both SME and PHSME B20 blends yielded small increases in NO_x emissions. The reduction in double bond content of PHSME did not result in a statistically significant difference in NO_x emissions versus SME at the B20 blend level. The test engine consumed a greater amount of fuel operating on the SME and PHSME blends than on neat ULSD, but the increase was smaller for the PHSME blend.