Total Hydrocarbon Emissions Research Articles

Quantifying the carbon conversion efficiency and emission indices of a lab-scale natural gas flare with internal coflows of air or steam

To better understand the effect of air- and steam-assist on flaring operations on carbon conversion efficiency and pollutant emissions, a lab-scale coflow burner constructed of two concentric circular tubes was used. Natural gas at 20 SLPM flowed through the annular space and increasing amounts of air or steam were added through the inner tube until flame extinction was invoked. The combustion products were captured by an exhaust hood and analyzed using a gas chromatograph to measure the concentrations of CH4, C2H6, C3H8, C4H10, CO and CO2. A photoacoustic extinctiometer and a NOx analyzer were used to measure black carbon and NOx concentrations, respectively. A challenge associated with the experiments was to accurately resolve stark transitions in conversion efficiency and orders of magnitude change in key emissions. Results indicated that the addition of air or steam to a natural gas jet diffusion flame caused a sudden collapse in carbon conversion efficiency, occurring at a coflow-fuel gas mass flow ratio of 1.8 for steam and 5.0 for air. As was expected, the CO2 emission indices for both air and steam coflow followed their respective carbon conversion efficiency trends. Conversely, the total unburned hydrocarbon emission indices increased with the reduction in carbon conversion efficiency. NOx emission indices for air and steam coflow were shown to decrease by an order of magnitude compared to the unassisted flame. For air coflow this occurred before the collapse in carbon conversion efficiency, while for steam coflow this occurred concurrently. Black carbon emission indices decreased rapidly by three orders of magnitude for both air and steam coflow. For both these lab-scale air and steam assisted flares there was a range of mass flow rates of the assist fluid that resulted in high combustion efficiency and low pollutant emissions.

Performance and Emission Analysis of Partially Premixed Charge Compression Ignition Combustion

In order to investigate the performance and emissions behavior of a high compression ratio compression ignition (CI) engine operating in partially premixed charge compression ignition (PPCI) mode, a series of experiments were conducted using a single-cylinder engine with a high-pressure rail fuel injection system. This included a moderately advanced direct injection strategy to attempt PPCI combustion under low load conditions by varying the injection timing between 25 deg and 35 deg before top dead center (BTDC) in steps of 2.5 deg. Furthermore, during experimentation the fuel injection pressure, engine speed, and engine torque were kept constant. Performance parameters and emissions were measured and analyzed using a zero-dimensional heat release model. Compared to the baseline conventional 12.5 deg BTDC injection, in-cylinder pressure and temperature were higher at advanced timings for all load conditions considered. Additionally, NOx, PM, CO, and total hydrocarbon (THC) were higher than conventional results at the 0.5 N·m load condition. While PM emissions were lower, and CO and THC emissions were comparable to conventional injection results at the 1.5 N·m load condition between 25 deg and 30 deg BTDC, NOx emissions were relatively high. Hence, there was limited success in beating the NOx-PM trade-off. Moreover, since the start of combustion (SOC) occurred BTDC, the resulting higher peak combustion pressures restricted the operating condition to lower loads. As a result, further investigation including exhaust gas recirculation (EGR) and/or variance in fuel cetane number (CN) is required to achieve PPCI in a high compression ratio CI engine.

Experimental investigation on performance and combustion characteristics of spark-ignition dual-fuel engine fueled with methanol/natural gas

This study aims to evaluate the performance, emissions, and combustion characteristics of a methanol/natural gas dual-fuel spark-ignition engine by conducting several experiments. A heavy-duty natural gas engine is modified by adding a methanol port-injection system to accelerate the burning rate, increase the thermal efficiency, and reduce the hydrocarbon emission. The effects of the methanol energy substitution ratio (MSR) on the brake thermal efficiency, heat release rate, peak cylinder temperature, flame development period, flame propagation period, and emissions are investigated under light, medium, and heavy loads (brake mean effective pressures of 0.387, 0.775, and 1.163 MPa, respectively) at an engine speed of 1600 rpm and a relative air/fuel ratio of 1.3. The results show that the peak cylinder pressure, peak cylinder temperature, and heat release rate increase with an increase in the MSR. A larger MSR leads to a shorter flame development period and flame propagation period as well as earlier combustion phasing. In addition, the brake thermal efficiency increases and the equivalent brake specific fuel consumption decreases significantly with methanol enrichment under the three engine load conditions. For exhaust emissions, the brake specific total hydrocarbon emission decreases while the brake specific nitrogen oxide emission increases slightly with an increase in the MSR. For cycle-by-cycle variation, the coefficient of variation in the indicated mean effective pressure increases slightly with an increase in the MSR. In addition, the peak ringing/knocking intensity is found to be 2.05 MW/m2 that is much less than the critical knocking point (5 MW/m2). Therefore, there was no knocking throughout the entire experiment.

Effects of spark timing and methanol addition on combustion characteristics and emissions of dual-fuel engine fuelled with natural gas and methanol under lean-burn condition

This paper aimed to study the effects of spark timing and methanol addition on the combustion characteristics and emissions of a natural gas/methanol dual-fuel engine. The engine speed is maintained at 1600 rpm and the brake mean effective pressure (BMEP) is maintained at 0.387 MPa with an excess air/fuel ratio of 1.3. The methanol energy substitution ratio (MSR) is set to 0%, 7.5%, and 14.5%. The spark timings are varied from 18 °CA to 38 °CA before the top dead centre, in intervals of 4 °CA. The results demonstrate that for a specific spark timing, the methanol addition increases the peak cylinder pressure, the maximum of the heat release rate, and the peak cylinder mean temperature. Concurrently, it decreases the flame development period (CA0-10) and the flame propagation period (CA10-90) with an increase in the MSR. An improvement in the brake thermal efficiency (BTE), a reduction in the total hydrocarbon (THC) emission, and an increase in the nitrogen oxide (NOX) emission are achieved using methanol enrichment. In addition, the effect of these trends is more pronounced with an increase in MSR. In contrast, for a specific MSR, a spark timing advance increases the peak cylinder pressure and temperature, while decreasing the exhaust temperature under an identical BMEP. Moreover, the spark timing at the maximum BTE retards as MSR increases.

A new concept of actively controlled rate of diesel combustion (ACCORDIC): Part II—simultaneous improvements in brake thermal efficiency and heat loss with modified nozzles

A new diffusion-based combustion concept (named it as Actively Controlled Rate of Diesel Combustion) for the confirmation of brake thermal efficiency optimum heat release rate profile based on multiple fuel injectors has been investigated. The outstanding results are; it is possible to achieve desired heat release rate profile only by the independent control of injection timing and duration of three injectors installed to a cylinder. The optimum brake thermal efficiency was not achieved with the Otto-like cycle but with the Sabathe-like cycle as predicted by a zero-dimensional thermodynamic model. Furthermore, smoke emissions were concurrently reduced with NOx emissions by increasing fuel amount from the side injectors without any deterioration in CO and total hydrocarbon emissions. On the other hand, brake thermal efficiency itself was not so improved than expected, because of lower heat release in the late part of combustion and unexpected less heat loss reduction. To solve these issues, combustion visualization and numerical simulation analysis were carried out. The results suggested that the adjacent sprays with narrower angle from each side injector deteriorated air entrainment and mixture formation, which might also result in the deterioration in wall heat loss in the expansion stroke. To solve both issues simultaneously, modified nozzle to inject against the swirl from the side injectors was utilized and achieved an improvement in both brake thermal efficiency and heat loss. That is the interdependent and reciprocal control of in-cylinder flow and fuel injection will be one of the breakthrough technologies for current trade-offs by the temporal and spatial spray flame optimization. Furthermore, the nozzle having higher flow rate with less number of orifice was utilized for the side injectors. Even though the smoke emissions were not optimized yet, brake thermal efficiency was much improved with higher heat release rate in the late part of combustion.

Effect of hydrogen peroxide additive on the combustion and emission characteristics of an n-butanol homogeneous charge compression ignition engine

The homogeneous charge compression ignition (HCCI) combustion was conducted on a modified engine to investigate the effect of hydrogen peroxide (H2O2) additive on the combustion and emission characteristics, such as the indicated thermal efficiency (ηi), the total hydrocarbon (THC), the carbon monoxide (CO) and the nitrogen oxides (NOx) emissions. A simulation using CHEMKIN software was also performed to analyze the experimental data. The results indicate that the addition of H2O2 facilitates the formation of hydroxyl (OH) radical and hydroperoxyl (HO2) radical in the cylinder under HCCI mode, which greatly affects the combustion and emission characteristics of the n-butanol HCCI engine. By adding H2O2, ηi increases, NOx emission remains at an ultra-low level, but THC and CO emissions reduce at almost all the test conditions. Especially at the low intake temperature (Tin) or low load condition, the improvements are very obvious, which suggests that addition of H2O2 may extend the low Tin and low load limits of HCCI engines.

Evaluation of methyl ester derived from novel Chlorella emersonii as an alternative feedstock for DI diesel engine & its combustion, performance and tailpipe emissions

This work examines the feasibility of fueling methyl ester derived from green algae species, Chlorella emersonii in a compression ignition engine. This work also proposes Chlorella emersonii methyl ester (CEME) as a potential alternative energy source since the above species is available extensively in freshwater, marine and aquatic ecosystems throughout the world. CEME was blended with petroleum diesel fuel at various volume proportions of 10%, 20%, 30%, 40% and 100% and their properties were analyzed as per ASTM standards for its application as biofuel. The prepared test fuels were analyzed experimentally in a single cylinder diesel engine at a constant speed (1500 rev/min) for its performance, combustion and emission (regulated and unregulated) characteristics. Test results indicated that, the characteristics of 20% CEME+80% DIESEL fuel blend was in par with neat DIESEL fuel in terms of thermal efficiency, THC (total hydrocarbon), CO (carbon monoxide) and smoke emissions. However, CEME blends resulted in slightly higher levels of CO2 (carbon dioxide) and NOx (oxides of nitrogen) emissions. In terms of unregulated emissions, CEME blends in DIESEL showed lowered toluene and acetaldehyde emissions. However, acetone and formaldehyde emissions increased with higher percentage of CEME in DIESEL blend. At full load, the attained cylinder pressure and heat release rate of CEME were comparatively lower than DIESEL fuel. Overall, it can be concluded that B20 (20% CEME +80% DIESEL fuel) blend can be a positive variant feedstock and it can be utilized in an unmodified diesel engine with minimal tailpipe emissions.

Effects of dual-direct injection parameters on performance of fuel Jet Controlled Compression Ignition mode on a high-speed light duty engine

Fuel Jet Controlled Compression Ignition (JCCI) was proposed to control the combustion phasing of premixed charge. In this mode, a small quantity of jet-injection diesel fuel was used to ignite the premixed charge, which was prepared by the main pre-injection blended fuels of diesel and ethanol-gasoline. Experiments of JCCI mode combined with dual-direct injection strategy were conducted on a modified single-cylinder naturally aspirated diesel engine. Effects of jet-injection and pre-injection parameters on the combustion and emission characteristics were investigated in detail under four engine load conditions at the rated speed of 3000 r/min. Experimental results showed that the diesel fuel jet-injection could control the ignition timing and combustion phasing robustly at all the four engine load conditions. The combustion process was composed of two stages, the jet fuel spontaneous combustion stage and the pre-mixture combustion stage. Besides, sensitive analysis of the jet-injection and pre-injection parameters on the JCCI mode performance were also accomplished. Advancing the jet-injection timing could shorten the combustion duration and improve the indicated thermal efficiency (ITE), but along with an increase in the nitrogen oxides (NOx) emissions, especially at higher engine loads. As the pre-injection energy ratio was upgraded, the local equivalence ratio and the diffusion-controlled combustion could be reduced, resulting in the reduction of soot emissions. Sensitivity interval was introduced to access the effects of pre-injection timing. Beyond this interval, the pre-injection timing showed insignificant effects on the combustion characteristics and emissions. With the increase of pre-injection pressure, more pre-injection fuels penetrated into the crevice and near liner regions, and the total hydrocarbon (THC) emissions were increased. Finally, the enhanced reactivity of pre-injection fuels was demonstrated to effectively reduce THC emissions at lower engine loads.

Experimental study on the durability of biodiesel-powered engine equipped with a diesel oxidation catalyst and a selective catalytic reduction system

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.

Performance, emission and combustion characteristics of CI dual fuel engine powered by diesel/ethanol and diesel/gasoline fuels

The effects of gasoline/diesel and ethanol/diesel on combustion, fuel economies and exhaust emissions of dual fuel direct injection diesel engine were experimentally investigated. Tests were carried out based on a direct injection engine at a constant engine speed of 1500 rpm and full load. The results showed that with the fraction of gasoline and ethanol increasing, ignition delay was noticed. Operating parameters of dual fuel engine powered with gasoline were at the same level as for engine powered by pure diesel fuel. In case of powering by ethanol the values of thermal efficiency and indicated mean effective pressure increased (about 13 %) with increase of ethanol fraction up to 55 %. For maximal analyzed gasoline fraction specific NOx (nitrogen oxide) emission increased by 2.7 times, but for ethanol the increase was lower and it was by 2.5-times compared to reference values obtained for an engine powered by pure diesel fuel. Regarding THC (total hydrocarbons) emission up to 45 % of ethanol or gasoline energetic fraction no significant increase in specific THC emissions was noted. With the increase in ethanol and gasoline fraction in combustion process causes lower CO (carbon monoxide) emission. It turns out that it is possible to co-combustion of gasoline in a compression-ignition internal combustion engine.

Influence of second generation biodiesel on engine performance, emissions, energy and exergy parameters

The present study compares diesel engine performance, emissions, energy and exergy parameters of three non-edible biodiesels blends and a reference diesel. The three biodiesel blends were prepared so as to keep the blend oxygen percentage at around 3.3 wt%. Considering the economy and availability, waste cooking and macadamia (Macadamia integrifolia) biodiesels were chosen for all the engine experiments. A commercial diesel was used as a reference fuel to compare the performance and emissions with those of the biodiesel blends. To keep the oxygen percentage of the blends approximately the same as for the reference diesel, around 30% waste cooking biodiesel was added to 70% reference diesel to make the first blend. Similarly, around 30% macadamia biodiesel was mixed with 70% reference diesel to make the second blend. In addition, 10% macadamia biodiesel and 20% waste cooking biodiesel were mixed with the 70% reference diesel to make the third blend with similar oxygen content. The macadamia blend is designated as MaD, the waste cooking blend is termed WcD, and the blend with macadamia and waste cooking biodiesel is abbreviated as MaWcD. This study aimed to investigate the influence of the fuel-oxygen on engine performance, emissions, energy and exergy parameters. A well-instrumented, 4-cylinder, 4-stroke, naturally aspirated direct injection (DI) diesel engine was used for the experiments. The engine was loaded and coupled with an eddy current dynamometer. Performance, emissions, energy and exergy parameters for the three biodiesel blends were compared with those of the reference diesel. Without significant reduction in engine performance, a significant reduction in total unburnt hydrocarbon (THC), carbon monoxide (CO), and particulate matter (PM) emissions with a penalty of increased nitrogen oxides (NOx) emissions were realised with all three biodiesel blends.

Experimental studies on the co-effects of engine operating parameters and fuel functional groups on the performance and emissions of a GDI engine

The distributions of molecular functional groups in gasoline have strong effects on the in-cylinder micro-combustion, macro-heat release and emission generation mechanism. It is quite difficult to study the coupling relationship between fuel functional groups and engine performance with commercial gasoline due to its complex components. In this paper, multi-components gasoline surrogates including toluene reference fuel (TRF), n-heptane/iso-octane/toluene/cyclohexane (CTRF) and n-heptane/iso-octane/toluene/cyclohexane/diisobutylene (CDTRF) were applied to study the effects of fuel functional groups and engine control parameters (spark timing, equivalence ratio) on combustion and emissions of a gasoline direct injection (GDI) engine. Amongst the results, it is worth noting that the surrogates produce 30–40% higher nitrogen oxide (NOx) emissions than gasoline and have obvious advantages in particulate matter (PM) emissions, however, at the cost of high carbon monoxide (CO) and total hydrocarbon (THC) emissions. In addition, there are obvious differences in combustion characteristics and unregulated emissions between the surrogates due to different functional groups.

A review on the engine performance and exhaust emission characteristics of diesel engines fueled with biodiesel blends.

Biodiesels have gained much popularity because they are cleaner alternative fuels and they can be used directly in diesel engines without modifications. In this paper, a brief review of the key studies pertaining to the engine performance and exhaust emission characteristics of diesel engines fueled with biodiesel blends, exhaust aftertreatment systems, and low-temperature combustion technology is presented. In general, most biodiesel blends result in a significant decrease in carbon monoxide and total unburned hydrocarbon emissions. There is also a decrease in carbon monoxide, nitrogen oxide, and total unburned hydrocarbon emissions while the engine performance increases for diesel engines fueled with biodiesels blended with nano-additives. The development of automotive technologies, such as exhaust gas recirculation systems and low-temperature combustion technology, also improves the thermal efficiency of diesel engines and reduces nitrogen oxide and particulate matter emissions.

The dual-port fuel injection system for fuel economy improvement in an automotive spark-ignition gasoline engine

The purpose of the present study was to investigate the performance of the dual-port injection (DPI) system in an automotive spark-ignition engine. The DPI system utilizes two port fuel injection (PFI) injectors per cylinder, i.e., one injector at each intake port. An original 4-cylinder PFI engine head was modified to accommodate total 8 PFI injectors. In the present study, three spray angles and two install configurations were investigated in the intake port visualization, steady-state part-load experiments, and cold-start experiment. The intake port spray visualization experiment showed that the wider fuel spray provided better fuel distribution, but also more wall wetting. The steady-state engine experiment at the several critical part-load conditions showed that the DPI system in combination with the open-valve-injection strategy achieved the most brake specific fuel consumption (BSFC) reduction of 4.6%. The average BSFC reduction of the 9-point experiment was 2.8%. The cold-start experiment also showed a fuel economy gain by the DPI system. In the cold-start experiment the wider spray angle exhibited higher total hydrocarbon emission likely due to the greater wall wetting observed in the intake port spray images.

Application of dual-fuel combustion over the full operating map in a heavy-duty multi-cylinder engine with reduced compression ratio and diesel oxidation catalyst

This research focuses on the potential of the dual-fuel combustion engine fueled with regular gasoline and diesel to meet the Euro V emission standard over the whole operating range with a simple after-treatment system. For this purpose, a mode-switching strategy was investigated in this work. The engine maps of this strategy were obtained using a dedicated experimental procedure on a modified heavy-duty multi-cylinder engine. The switching of dual-fuel modes mainly depended on the engine load. At 25% engine load, fully premixed reactivity controlled compression ignition combustion was applied to achieve high efficiency and low emission combustion. At operating conditions higher than 50% load, homogeneous charge induced ignition combustion with up to three diesel injections (pre-, main and post-injections) was applied. Then, the effects of compression ratio on the dual-fuel combustion over the full operating map were explored and analyzed in detail. It was found that in spite of a slight increase in the fuel consumption, better combustion and emission performance over the whole operating map could be achieved in the dual-fuel combustion with a lower compression ratio. Finally, the effects of diesel oxidation catalyst were also investigated. The exhaust temperatures of this dual-fuel strategy were higher than the diesel oxidation catalyst light-off temperature, ensuring an effective conversion of the total hydrocarbon and carbon monoxide emissions. Furthermore, from the particle number-size distribution analysis, it was found that reactivity controlled compression ignition was dominated by the nucleation mode particles, while homogeneous charge induced ignition was dominated by the accumulation mode particles which tended to increase as the load increased. In addition, with a lower compression ratio of 16:1 and the application of diesel oxidation catalyst, the cycle-averaged regular emissions of the mode-switching combustion strategy could meet the Euro V emission standard simultaneously in the European Stationary Cycle test.

Variability in the primary emissions and secondary gas and particle formation from vehicles using bioethanol mixtures

ABSTRACTBioethanol for use in vehicles is becoming a substantial part of global energy infrastructure because it is renewable and some emissions are reduced. Carbon monoxide (CO) emissions and total hydrocarbons (THC) are reduced, but there is still controversy regarding emissions of nitrogen oxides (NOx), aldehydes, and ethanol; this may be a concern because all these compounds are precursors of ozone and secondary organic aerosol (SOA). The amount of emissions depends on the ethanol content, but it also may depend on the engine quality and ethanol origin. Thus, a photochemical chamber was used to study secondary gas and aerosol formation from two flex-fueled vehicles using different ethanol blends in gasoline. One vehicle and the fuel used were made in the United States, and the others were made in Brazil. Primary emissions of THC, CO, carbon dioxide (CO2), and nonmethane hydrocarbons (NMHC) from both vehicles decreased as the amount of ethanol in gasoline increased. NOx emissions in the U.S. and Brazilian cars decreased with ethanol content. However, emissions of THC, CO, and NOx from the Brazilian car were markedly higher than those from the U.S. car, showing high variability between vehicle technologies. In the Brazilian car, formation of secondary nitrogen dioxide (NO2) and ozone (O3) was lower for higher ethanol content in the fuel. In the U.S. car, NO2 and O3 had a small increase. Secondary particle (particulate matter [PM]) formation in the chamber decreased for both vehicles as the fraction of ethanol in fuel increased, consistent with previous studies. Secondary to primary PM ratios for pure gasoline is 11, also consistent with previous studies. In addition, the time required to form secondary PM is longer for higher ethanol blends. These results indicate that using higher ethanol blends may have a positive impact on air quality.Implications: The use of bioethanol can significantly reduce petroleum use and greenhouse gas emissions worldwide. Given the extent of its use, it is important to understand its effect on urban pollution. There is a controversy on whether there is a reduction or increase in PM emission when using ethanol blends. Primary emissions of THC, CO, CO2, NOx, and NMHC for both cars decreased as the fraction of ethanol in gasoline increased. Using a photochemical chamber, the authors have found a decrease in the formation of secondary particles and the time required to form secondary PM is longer when using higher ethanol blends.

Influence on Performance and Emissions of an Automotive Diesel Engine Fueled with Biodiesel and Paraffinic Fuels: GTL and Biojet Fuel Farnesane

The effects of a paraffinic biofuel (farnesane) obtained from sugar cane, a gas to liquid (GTL) fuel, and a biodiesel fuel on performance and emissions of a light duty engine were evaluated. Similar engine performance is obtained with all fuels maintaining the default electronic control unit (ECU) configuration. Clear reductions in total hydrocarbon (THC) emissions were observed with all alternative fuels, and, comparing both paraffinic fuels, farnesane was more beneficial. Reductions were also obtained with these fuels in particle emissions, with the exception of the mode G, which is not an operating mode included in the New European Driving Cycle (NEDC), where particle number concentration of paraffinic fuels was higher compared with diesel and biodiesel fuels. This behavior could be explained by the nonoptimization of ECU at this engine work condition. The benefits in terms of pollutant emission obtained with farnesane make it a potential biofuel for use in diesel engines.

From actual ethanol contents in gasoline to mid-blends and E-85 in conventional technology vehicles. Emission control issues and consequences

The study investigated the combustion and emissions of gasoline engines using four ethanol–gasoline blends ranging from 10 to 85 volume percent ethanol, and an E0 control Performance were compared in single cylinder engine and tested in a chassis dynamometer using two Tier I vehicles. The octane sensitivity of the fuels increases with the addition of ethanol from 7.8 for a non-oxygenated fuel to 23 for the 85% ethanol blend. Fuel sensitivity have a direct relationship with the latent heat of vaporization, because charge cooling is one of the way alcohols increases Research Octane Number. For the primary gaseous compounds, an increase in total hydrocarbon emissions and a decrease in aromatic BTEX compounds was detected as the amount of ethanol in the fuel increased. Both vehicles operated without engine fault code display except when the E-85 was used. The engine could be started stably with E10, E20, and E45. However, for E85 the engine idling became unstable because the air–fuel mixture was too lean making impossible the reduction reactions necessary for NOx emission control in the catalytic converter.

Effects of high bioethanol proportion in the biodiesel-diesel blends in a CRDI engine

In this experimental study, the usage of high bioethanol proportion in the different types of biodiesel-diesel blends were carried out to discover the effects of the high bioethanol proportion on the injection, combustion, performance and emission parameters of a common rail diesel injection (CRDI) engine with two stage injection (TSI) strategy under different engine loads. The TSI strategy consisted of two stage direct injection into the cylinder as a pilot and main injection. The bioethanol (BE) was produced used wastes originated from sugar production process, animal-based (AB) biodiesel was originated from waste fleshing oil and the vegetable based (VB) biodiesel was obtained from safflower-canola oil mixture. Pure diesel fuel (DF), three AB ternary blends (bioethanol-diesel-animal based biodiesel), and three VB ternary blends (bioethanol-diesel-vegetable based biodiesel) were determined as test fuels. Bioethanol ratios were 25% and 35% by mass in the AB and VB ternary blends, while biodiesel concentration was fixed to be 20% by mass. It was found that the maximum cylinder gas pressure (Pmax) of the VB ternary blends observed higher than that of AB ternary blends and DF at high loads, while the Pmax decreased by usage of AB and VB ternary blends at low and medium load conditions. Longer ignition delay (ID), higher thermal efficiency, lower maximum pressure rise rate (MPRR) values were observed by usage of the higher percentage of bioethanol (35 by mass%) in the AB and VB ternary blends at medium and high load conditions. AB ternary blends were more effective than the VB ternary blends on the reduction in total hydrocarbon (THC) emission, while carbon monoxide (CO) emissions increased with the increase in bioethanol content in the AB and VB ternary blends at low and high load conditions. Nitrogen oxides (NOx) and smoke emissions can be decreased by usage of high bioethanol proportion in the blends at high load conditions, simultaneously. The combustion and emission results showed that the usage of ternary blends with TSI strategy contributed to the elimination of the negative effects of the high bioethanol content.

Real-world fuel use and gaseous emission rates for flex fuel vehicles operated on E85 versus gasoline

ABSTRACTFlex fuel vehicles (FFVs) typically operate on gasoline or E85, an 85%/15% volume blend of ethanol and gasoline. Differences in FFV fuel use and tailpipe emission rates are quantified for E85 versus gasoline based on real-world measurements of five FFVs with a portable emissions measurement system (PEMS), supplemented chassis dynamometer data, and estimates from the Motor Vehicle Emission Simulator (MOVES) model. Because of inter-vehicle variability, an individual FFV may have higher nitrogen oxide (NOx) or carbon monoxide (CO) emission rates on E85 versus gasoline, even though average rates are lower. Based on PEMS data, the comparison of tailpipe emission rates for E85 versus gasoline is sensitive to vehicle-specific power (VSP). For example, although CO emission rates are lower for all VSP modes, they are proportionally lowest at higher VSP. Driving cycles with high power demand are more advantageous with respect to CO emissions, but less advantageous for NOx. Chassis dynamometer data are available for 121 FFVs at 50,000 useful life miles. Based on the dynamometer data, the average difference in tailpipe emissions for E85 versus gasoline is −23% for NOx, −30% for CO, and no significant difference for hydrocarbons (HC). To account for both the fuel cycle and tailpipe emissions from the vehicle, a life cycle inventory was conducted. Although tailpipe NOx emissions are lower for E85 versus gasoline for FFVs and thus benefit areas where the vehicles operate, the life cycle NOx emissions are higher because the NOx emissions generated during fuel production are higher. The fuel production emissions take place typically in rural areas. Although there are not significant differences in the total HC emissions, there are differences in HC speciation. The net effect of lower tailpipe NOx emissions and differences in HC speciation on ozone formation should be further evaluated.Implications: Reported comparisons of flex fuel vehicle (FFV) tailpipe emission rates for E85 versus gasoline have been inconsistent. To date, this is the most comprehensive evaluation of available and new data. The large range of inter-vehicle variability illustrates why prior studies based on small sample sizes led to apparently contradictory findings. E85 leads to significant reductions in tailpipe nitrogen oxide (NOx) and carbon monoxide (CO) emission rates compared with gasoline, indicating a potential benefit for ozone air quality management in NOx-limited areas. The comparison of FFV tailpipe emissions between E85 and gasoline is sensitive to power demand and driving cycles.