Ethanol-gasoline Blends Research Articles

Alcohol fuels for spark-ignition engines: Performance, efficiency and emission effects at mid to high blend rates for binary mixtures and pure components

The paper evaluates the results of tests performed using mid- and high-level blends of the low-carbon alcohols, methanol and ethanol, in admixture with gasoline, conducted in a variety of test engines to investigate octane response, efficiency and exhaust emissions, including those for particulate matter. In addition, pure alcohols are tested in two of the engines, to show the maximum response that can be expected in terms of knock limit and efficiency as a result of the beneficial properties of the two alcohols investigated. All of the test work has been conducted with blending of the alcohols and gasoline taking place outside the combustion system, that is, the two components are mixed homogeneously before introduction to the fuel system, and so the results represent what would happen if the alcohols were introduced into the fuel pool through a conventional single-fuel-pump (dispenser) approach. While much has been written on the effect of blending the light alcohols with gasoline in this way, the results present significant new findings with regard to the effect of the enthalpy of vaporization of the alcohols in terms of particulate exhaust emissions. Also, in one of the tests, two mid-level blends are tested in a highly downsized prototype engine – these blends being matched for stoichiometry, enthalpy of vaporization and volumetric energy content. The consequences of this are discussed and the results show that this approach to blend formulation creates fuels which behave in the same manner in a given combustion system; the reasons for this are discussed. One set of tests using pure methanol alternately with cooled exhaust gas recirculation and with excess air shows a significant increase in thermal efficiency that can be expected as the blend level is increased. The effect on nitrous oxide emissions is shown to be similarly beneficial, this being primarily a result of the enthalpy of vaporization of the alcohol cooling the charge coupled with the lower adiabatic flame temperature of the alcohol. Whereas it is normally a beneficial characteristic in spark-ignition combustion systems, one disadvantage of a high value of enthalpy of vaporization is shown in another series of tests in that, in admixture with gasoline, it is a driver on flash boiling of the hydrocarbon component in the blend in direct injection combustion systems. In turn, this causes the particulate emissions of the engine to increase quite markedly over those of ethanol–gasoline blends at the same stoichiometry. The paper shows for the first time the dichotomy of the potential efficiency improvement with the challenge of particulate control. This effect poses a challenge for the future introduction and use of such high blend rate fuels in engines without particulate filters. Although it must be stated that the overall particulate emissions of the methanol–gasoline blend are lower than for gasoline, the effect is only present at extremely low load, and that there is a likelihood that particulate filters will be adopted in production vehicle anyway, nullifying this issue.

An experimental and modeling study to investigate effects of different injection parameters on a direct injection HCCI combustion fueled with ethanol–gasoline fuel blends

In this study, Stochastic Reactor Model (SRM) was used to simulate a direct injection homogenous charge compression ignition (DI-HCCI) engine fueled with ethanol–gasoline blends by two stage direct injection (TSDI) strategies. Performance of the DI-HCCI engine was examined at constant engine speed and high equivalence ratio conditions. TSDI strategies were applied during the intake stroke (first injections) and at the end of the compression stroke (second injections) by using different injection ratios (IR) of E10 and E20 blends. SRM results were compared and validated with the experimental results. Experimental and SRM results showed that the first injection variation does not have significant effect on controlling HCCI combustion while variation of the second injection timing and IR change peak pressure significantly. Therefore, this strategy can be used to control the HCCI combustion.

A consequential assessment of changes in greenhouse gas emissions due to the introduction of wheat straw ethanol in the context of European legislation

Until today, first generation (1G) biofuels dominate the market for alternative fuels. The European Commission decided to cap 1G biofuels and promote second generation (2G) biofuels with the intention to reduce greenhouse gas (GHG) emissions, to limit the competition of food, feed and biofuels, as well as to improve societal approval. The assessment of consequences entailed to a shift from 1G to 2G biofuels is required to judge whether such a shift is advisable or not. According to the renewable energy directive (RED), GHG savings, need to be determined for all biofuels. By the end of 2020, fuel blends need to achieve a GHG reduction of 6%. Thus, GHG savings will determine the quantity of biofuel to be blended with fossil fuels and thereby eventually define the demand for biofuels. In this paper, the consequences of a shift from a 1G to a 2G biofuel is assessed by the example of bioethanol from wheat grains and straw. In total, three concepts of 2G ethanol production from wheat straw are considered: fermentation of C6-sugars with (1) co-production of feed, (2) coupled with biogas production and (3) co-fermentation of C5- and C6-sugars with co-production of feed. To determine the effect of the introduction of 2G ethanol, GHG savings according to RED are calculated first, and, in a second step, consequences of the shift from 1G to 2G ethanol are assessed by accounting for substitution mechanisms and emissions from direct and indirect land-use change (LUC). GHG savings of these 2G concepts according to RED methodology range from 103 to 105%. The shift from 1G ethanol to these 2G concepts is assessed by two scenarios: (1) additional production of 2G ethanol and (2) the replacement of 1G ethanol by 2G ethanol. Results indicate that GHG emissions decrease in scenario 1 if all surplus ethanol replaces fossil fuels. Under the given assumptions, the reduction in emissions ranges from 9.0 to 12.1 kg CO2-eq./GJ ethanol-gasoline blend. If 1G ethanol is replaced by 2G ethanol, GHG emission increase in a range from 7.5 to 16.5 kg CO2-eq./GJ fuel blend. This is mainly due to the provision of feed that needs to be supplied as a consequence of the shift in production: 1G ethanol production provides a high protein feed that needs to be provided by other means. Hence, the main driver for an increase in emissions is the provision of soybean meal and entailed emissions from LUC. A sensitivity analysis shows that these results are robust regarding input parameters and LUC assumptions. These findings point out that it is of utmost importance to assess changes induced by the introduction of novel fuels rather than assessing them isolated from market conditions. Based on these findings, it can be concluded that current and proposed legislation might trigger effects opposed to those intended.

Prediction of engine performance and exhaust emissions with different proportions of ethanol–gasoline blends using artificial neural networks

ABSTRACTThe main purpose of this study is to experimentally investigate the use of ANNs (artificial neural networks) modelling to predict engine power, torque and exhaust emissions of a spark ignition engine which operates with gasoline and methanol blends. For the ANN modelling, the standard back-propagation algorithm was found to be the optimal choice for training the model. Afterwards, the performance of the ANN predictions was evaluated with the experimental results by comparing the predictions. Fuel type and engine speed have been used as the input layer, while engine torque, power, exhaust emissions, Tex and BSFC have also been used separately as the output layer. It was found that the ANN model is able to predict the engine performance, exhaust emissions, Tex and BSFC with a correlation coefficient of 0.9991887425, 0.9990868573, 0.9986749623, 0.9988624137, 0.9976761492, 0.9992943894 and 0.9978899033 for the Power, Torque, CO, CO2, HC, Tex and BSFC for testing data, respectively.

The Application of Artificial Neural Network in Prediction of the Performance of Spark Ignition Engine Running on Ethanol-Petrol Blends

The performance analysis of a single cylinder spark ignition engine fuelled with ethanol – petrol blends were carried out successfully at constant load conditions. E0 (Petrol), E10 (10% Ethanol, 90% Petrol), E20 (20% Ethanol, 80% Petrol) and E30 (30% Ethanol, 70% Petrol) were used as fuel. The Engine speed, mass flow rate, combustion efficiency, maximum pressure developed, brake specific fuel consumption and Exhaust gas temperature values were measured during the experiment. Using the experimental data, a Levenberg Marquardt Artificial Neural Network algorithm and Logistic sigmoid activation transfer function with a 4–10–2 model was developed to predict the brake specific fuel consumption, maximum pressure and combustion efficiency of G200 IMEX spark ignition engine using the recorded engine speed, mass flow rate, biofuels ratio and exhaust gas temperature as input variables. The performance of the Artificial Neural Network was validated by comparing the predicted data with the experimental results. The results showed that the training algorithm of Levenberg Marquardt was sufficient enough in predicting the brake specific fuel consumption, combustion pressure and combustion efficiency of the test engine. Correlation coefficient values of 0.974, 0.996 and 0.995 were obtained for brake specific fuel consumption, combustion efficiency and pressure respectively. These correlation coefficient obtained for the output parameters are very close to one (1) showing good correlation between the Artificial Neural Network predicted results and the experimental data while the Mean Square Errors were found to be very low (0.00018825 @ epoch 10 for brake specific fuel consumption, 1.0023 @ epoch 3 for combustion efficiency and 0.0013284@ epoch 5 for in-cylinder pressure). Therefore, Artificial Neural Network toolbox called up from MATLAB proved to be a useful tool for simulation of engine parameters. Artificial Neural Network model provided accurate analysis of these complex problems and has been found to be very useful for predicting the performance of the spark ignition engine. Thus, this has proved that Artificial Neural Network model could be used for predicting performance values in internal combustion engines, in this way it would be possible to conduct time and cost efficient studies instead of long experimental ones.

Effect of ethyl acetate addition on phase stability, octane number and volatility criteria of ethanol-gasoline blends

Blending ethanol in gasoline causes problems related to volatility and phase stability of the fuel blends. Ethanol is completely miscible with water so it has high affinity to water that may be present in storage tanks or that formed due to humidity. Drop in ambient temperature influences the stability of ethanol-gasoline blends and causes phase separation to the blend. This phase separation cause disadvantages like: poor quality fuel, loss in cost, and damage to storage tanks and engine parts due to corrosion. In this work, Ethanol-blended gasolines E5, E10, E15, E20 and ethanol-free gasoline (E0) were formulated to study the effects of ethyl acetate addition on these fuels. The obtained results revealed that the addition of ethyl acetate to ethanol-gasoline blends has many advantages such as enhancing the stability of the fuel blends and improving octane number with no adverse impacts on the volatility criteria of the investigated fuel blends.

The Application of Artificial Neural Network in Prediction of the Performance of Spark Ignition Engine Running on Ethanol-Petrol Blends

The performance analysis of a single cylinder spark ignition engine fuelled with ethanol – petrol blends were carried out successfully at constant load conditions. E0 (Petrol), E10 (10% Ethanol, 90% Petrol), E20 (20% Ethanol, 80% Petrol) and E30 (30% Ethanol, 70% Petrol) were used as fuel. The Engine speed, mass flow rate, combustion efficiency, maximum pressure developed, brake specific fuel consumption and Exhaust gas temperature values were measured during the experiment. Using the experimental data, a Levenberg Marquardt Artificial Neural Network algorithm and Logistic sigmoid activation transfer function with a 4–10–2 model was developed to predict the brake specific fuel consumption, maximum pressure and combustion efficiency of G200 IMEX spark ignition engine using the recorded engine speed, mass flow rate, biofuels ratio and exhaust gas temperature as input variables. The performance of the Artificial Neural Network was validated by comparing the predicted data with the experimental results. The results showed that the training algorithm of Levenberg Marquardt was sufficient enough in predicting the brake specific fuel consumption, combustion pressure and combustion efficiency of the test engine. Correlation coefficient values of 0.974, 0.996 and 0.995 were obtained for brake specific fuel consumption, combustion efficiency and pressure respectively. These correlation coefficient obtained for the output parameters are very close to one (1) showing good correlation between the Artificial Neural Network predicted results and the experimental data while the Mean Square Errors were found to be very low (0.00018825 @ epoch 10 for brake specific fuel consumption, 1.0023 @ epoch 3 for combustion efficiency and 0.0013284@ epoch 5 for in-cylinder pressure). Therefore, Artificial Neural Network toolbox called up from MATLAB proved to be a useful tool for simulation of engine parameters. Artificial Neural Network model provided accurate analysis of these complex problems and has been found to be very useful for predicting the performance of the spark ignition engine. Thus, this has proved that Artificial Neural Network model could be used for predicting performance values in internal combustion engines, in this way it would be possible to conduct time and cost efficient studies instead of long experimental ones.

Study of Corrosion of Metallic Materials in Ethanol–Gasoline Blends: Application of Electrochemical Methods

Ethanol–gasoline blends (EGBs) can easily absorb large amounts of water because of the presence of ethanol. Acidic compounds and ions can be dissolved in water, and these substances can have corrosive effects on metallic construction materials. With the increasing content of ethanol in fuels, the conductivity and ability of fuel to absorb water increases, and the resulting fuel is becoming more corrosive. In this work, we tested E10, E40, E60, E85, and E100 fuels that were prepared in the laboratory. These fuels were purposely contaminated with water and trace amounts of ions and acidic substances. The aim of the contamination was to simulate the pollution of fuels, which can arise from the raw materials or from the failure to comply with good manufacturing, storage, and transportation conditions. The corrosion properties of these fuels were tested on steel, copper, aluminum, and brass using electrochemical impedance spectroscopy and Tafel curve analysis. For comparison, static immersion tests on steel we...

Ethanol-Blended Gasoline Policy and Ozone Pollution in Sao Paulo

We examine four discontinuities in the ethanol content in blended gasoline fuel, mandated by Brazil’s central government over the period 2010–13, to test the joint hypotheses that (1) atmospheric ozone production in the Sao Paulo metropolitan area is limited by the volume and reactivity of volatile organic compounds (VOC-limited) and (2) increased ethanol use in the gasoline-ethanol vehicle fleet leads to higher ozone concentrations in urban Sao Paulo’s ambient air. We adopt a regression discontinuity design (RDD) and flexibly test each discontinuity separately. Our finding that ozone levels actually increased with ethanol penetration on each of the four occasions is consistent with a recent empirical study that used different identifying variation and contrasts with a modeling study of Sao Paulo’s atmosphere that predicted significant ozone abatement from hypothetical ethanol use. We find no significant relationship between ethanol versus gasoline use and PM2.5 levels. Current tailpipe emissions standards prescribe the exclusion of the mass of unburned ethanol that is emitted—our results suggest that this standard be reviewed. Following decades of VOC emissions control, urban areas in the United States and elsewhere that are currently VOC-limited may see ozone levels rise if and when they adopt mid-level ethanol gasoline blends, whether to meet the Renewable Fuel Standard or Intended Nationally Determined Contributions to abating fossil fuel emissions agreed upon at COP21 in Paris.

Particulate Matter and Gaseous Emission of Hydrous Ethanol Gasoline Blends Fuel in a Port Injection Gasoline Engine

The industrialization that increases day by day needs more and more power/fuel sources that are commonly available, abundant, renewable, and environmentally friendly. Recently, nearly all of the cities in China (PRC) have been influenced by haze. However, the pollutants from automobiles have always been seriously considered to be the main contamination causes of the haze and that influence human health. This study concerns the impact of hydrous ethanol on in-cylinder pressure, particulate matter (PM), and gaseous emissions (oxides of nitrogen (NOx) and unburned hydrocarbon (HC)) from a port fuel injection (PFI) gasoline engine. Tests were conducted on a four-cylinder port injection gasoline engine at different engine loads at an engine speed of 2000 rev/min for commercial gasoline, hydrous ethanol-gasoline blends (10% and 20% hydrous ethanol by volume), and an anhydrous ethanol-gasoline blend (20% anhydrous ethanol by volume). The results show that the peak in-cylinder pressure with the use of gasoline was the highest compared with the hydrous ethanol and anhydrous ethanol blends. Compared with the anhydrous ethanol blend, the hydrous ethanol blends performed well at a high load condition, equivalent to a low load. In addition, the total particulate number (PN) declines with an increase in engine operating loads for all of the fuels tested. The outcome of this study is an important reduction in PM number, mass emissions, and mean diameters of particles as the use of hydrous ethanol blends increases, while the form of the particulate size distribution remains the same. Furthermore, the NOx emission is raised with a rise in engine load, and NOx and HC emissions are reduced with the use of hydrous ethanol and anhydrous ethanol blend as equated with pure gasoline. Moreover, the correlation between the total particle number against NOx and HC has been found; the number of particles increases when the NOx emission decreases, and the opposite trend is exhibited for the HC emission. Therefore, it can be concluded that hydrous ethanol blends look to be a good selection for PM, NOx, and HC reduction for gasoline engines.

The impact of various ethanol-gasoline blends on particulates and unregulated gaseous emissions characteristics from a spark ignition direct injection (SIDI) passenger vehicle

This study investigated the effects of various ethanol-gasoline blends on the hazardous air pollutants (HAPs) emissions from a wall-guided direct injection passenger vehicle. The fuel economy (FE) as well as regulated and unregulated gaseous emissions was evaluated on a chassis dynamometer using the federal test procedure (FTP-75) mode. Five fuels with varying ethanol contents of E0, E10, E30, E50, and E85 were prepared by blending ethanol into commercial gasoline on a volumetric basis and were analyzed each fuel specification. The engine control schemes of fuel injection quantity for various ethanol blends were adjusted to optimize the engine starting capability, vehicle drivability and emissions performance. The FE of the E85 fueled vehicle decreased by 29% relative to gasoline fuel due to the low energy content of ethanol. Blending ethanol into gasoline produced a dramatic decrease of particulate emission, because pure ethanol has no aromatic compounds and carbon content lower than that of gasoline. As a result, nano-particles were rarely emitted in the vehicle tests of fuels with more than 30% ethanol. Carbonyl compounds emissions, which originate from partial oxidization or incomplete combustion of ethanol, also rose sharply as the ethanol content increased, while volatile organic compound (VOC) emissions were reduced considerably with medium- and high-ethanol formulations due to the lower proportion of aromatic components in these fuels.

An experimental study on soot distribution characteristics of ethanol-gasoline blends in laminar diffusion flames

In view of the potential of bio-ethanol as an alternative fuel and the particulate matter (PM) issues during gasoline combustion, the soot distribution characteristics of ethanol-gasoline blends in laminar diffusion flames were studied on a Gülder liquid burner using the two-color laser induced incandescence (TC-LII) technique. During the experiments, the ethanol ratio in the blends was varied from 20% to 80% by volume in order to investigate quantitatively the soot reduction potential of ethanol. In order to study the effect of reduction in carbon content due to ethanol addition on soot formation, the experiments were performed under a fixed fuel mass flow rate and a fixed carbon mass flow rate. It was found that both peak and average soot volume fraction in the flame reduced significantly with increasing ethanol content under both fuel supplying modes, however, this effect was progressively less pronounced as ethanol content increased. By comparing the two fueling modes, it was found that the reduction in carbon content due to ethanol addition has little impact on soot reduction. For a given ethanol blending ratio, the soot reduction under the same carbon mass flow rate was only slightly smaller than that under the same fuel mass flow rate. In terms of flame characteristics, the initial height of soot formation increases with increasing ethanol content under both fuel supply modes mainly due to the increased fuel outlet velocity. Radially, the peak soot location moves from the outside towards the center gradually as height increases. However, along the center line of the flame, the initial height of soot formation decreases with increasing ethanol content under the same fuel flow rate, whereas the trend remained similar to that in the whole flame under the same carbon flow rate.

Performance, emission and combustion characteristics of a single cylinder spark ignition engine using ethanol–petrol-blended fuels

ABSTRACTThe performance, exhaust emission and combustion analyses of a single cylinder spark ignition engine fuelled with extended range of ethanol–petrol blends were carried out successfully at full load conditions. Ethanol produced from raffia trunks was blended with petrol at different proportions by volume. In order to establish a baseline for comparison, the engine was first run on neat petrol. The engine performance parameters (engine torque, brake power, brake specific fuel consumption, brake mean effective pressure and brake thermal efficiency), exhaust emission parameters (CO, HC, CO2 and O2 emissions) and combustion parameters were determined for each blend of fuel at different engine speeds. The test results interestingly revealed that the addition of ethanol to petrol causes an improvement in combustion characteristics and significant reduction in exhaust emissions which in turn improved engine performance. In all, ethanol and its blends with petrol exhibited performance characteristics trends similar to that of petrol thus confirming them as suitable alternative fuels for spark ignition engines.

The policy recommendations on cassava ethanol in China: Analyzed from the perspective of life cycle “2E&W”

The Chinese government has been implementing the policy of encouraging to use ethanol-blended gasoline as fuels. However, the actual application is still facing lots of challenges. In this study, a well-operated cassava ethanol system in China was chosen as the case study to investigate energy consumption, GHGs emission, and water footprints (“2E&W”) from the life cycle perspective. The status quo and the evolution of China’s policies on bioethanol were also reviewed. Positive net energy value of 13.64MJ/L ethanol and net GHGs emission of 1473gCO2-eq/L ethanol were found for cassava ethanol, which indicates that it could be an excellent substitute for gasoline. Compared with gasoline, using E10 and E85 could have the potential reduce fossil energy usage and GHG emissions. During its life cycle, ethanol conversion is the most energy-intensive and GHGs-intensive stage. The water footprint of cassava ethanol is 2998m3/tonne. Unlike energy consumption and GHGs, the cassava planting stage is the most water-footprint-intensive stage due to the grey water caused by the fertilizer. The life cycle results of cassava ethanol are sensitive to many factors, such as cassava yield, energy input. Finally, some policy recommendations are provided.

Experimental study of gasoline-ethanol-hydrogen blends combustion in an SI engine

This study presents experimental results of engine performance, combustion and emissions in an SI engine fueled by gasoline-ethanol-hydrogen blends. In the experimental studies, engine performance and emission values were analyzed fueled by gasoline, gasoline-ethanol and gasoline-ethanol-hydrogen blends, respectively. When ethanol has been added volumetrically to gasoline 20% of ethanol (G80E20), engine performance and emissions have been worsened. However, the engine performance and emission values have been improved with the adding of hydrogen to blend. The results showed that the addition of hydrogen to the gasoline-ethanol blend improved the combustion process and improved the combustion efficiency, expanded the combustibility range of the gasoline-ethanol blend, reduced emissions. But, nitrogen oxide emission values increased with the adding of hydrogen.

A comprehensive experimental study on nucleate boiling in gasoline and gasoline-ethanol blends

Recent advances in fuel research have identified many benefits associated with heating fuels before they are injected into internal combustion engines, including improved cold starting and reduced greenhouse gas emissions. Extensive research has also been carried out into alternative, renewable biofuels. Of these, ethanol, which is normally used in ethanol-gasoline blends, is one of the most promising. However, although the characteristics and uses of heated fuel have been much discussed in the literature, it is important to improve our understanding of the fuel-heating process, which frequently involves nucleate boiling. This paper describes a comprehensive, novel experimental study of nucleate boiling in pure gasoline, ethanol and gasoline-ethanol blends. The heat transfer coefficient, critical heat flux and hysteresis effect are analyzed for each test fluid, and some considerations on the pressure effect are presented. For all the gasoline-ethanol blends, the heat transfer coefficient and critical heat flux increased with increasing pressure. Addition of ethanol to gasoline did not significantly change the heat transfer coefficient until the mole fraction exceeded 35%. The behavior of the heat transfer coefficient and critical heat flux indicates the existence of an azeotrope close to an ethanol mole fraction of 20%. Finally, gasoline exhibited partial nucleation during increasing heat flux at pressures greater than 202kPa. Addition of ethanol to pure gasoline gradually eliminated this behavior until total nucleation was achieved.

Optimizing Blendstock Composition and Ethanol Feedstock to Reduce Gasoline Well-to-Pump CO2 Emission

Lifecycle CO2 emission of ethanol blended gasoline was simulated to investigate how fuel properties and composition affect overall emission. Fuel research octane number (RON), octane sensitivity and ethanol content (derived from sugarcane and corn) were varied in the simulations to formulate blended fuels that economically achieve target specifications. The well-to-pump (WTP) simulation results were then analyzed to understand the effects of fuel composition on emission. Elevated ethanol content displaces aromatics and olefins required in gasoline blendstock to reach a target fuel specification. The addition of greater sugarcane-based ethanol percentage in constant aromatics and olefins fuel reduces its WTP CO2 emission. Corn-based ethanol blending does not offer CO2 emission offset due to its high production emissions. The mixing of sugarcane-based with corn-based ethanol is shown to be a potentially effective method for achieving a blended fuel with a lower lifecycle CO2 emission. Besides CO2 emission, the total greenhouse gas (GHG) emission from land-use conversions (LUC), CH4, and N2O are also significant in determining the optimal fuel blend. Herein, we present preliminary results showing that total GHG emissions significantly increase when either corn or sugarcane ethanol is blended at even small percentages; detailed results will be addressed in future communications.

Assessment of environmentally friendly fuel emissions from in-use vehicle exhaust: low-blend iso-stoichiometric GEM mixture as example.

Gasoline-ethanol-methanol fuel blends were formulated with the same stoichiometric air-to-fuel ratio and volumetric energy concentration as any binary ethanol-gasoline blend. When the stoichiometric blends operated in a vehicle, the time period, injector voltage, and pressure for each fuel injection event in the engine corresponded to a given stoichiometric air-to-fuel ratio, and the load was essentially constant. Three low oxygen content iso-stoichiometric ternary gasoline-ethanol-methanol fuel blends were prepared, and the properties were compared with regular-type fuel without added oxygen. One of the ternary fuels was tested using a fleet of in-use vehicles for15weeks and compared to neat gasoline without oxygenated compounds as a reference. Only a small number of publications have compared these ternary fuels in the same engine, and little data exist on the performance and emissions of in-use spark-ignition engines. The total hydrocarbon emissions observed was similar in both fuels, in addition to the calculated ozone forming potential of the tailpipe and evaporative emissions. In ozone non-attainment areas, the original purpose for oxygenate gasolines was to decrease carbon monoxide emissions. The results suggest that the strategy is less effective than expected because there still exist a great number of vehicles that have suffered the progressive deterioration of emissions and do not react to oxygenation, while new vehicles are equipped with sophisticated air/fuel control systems, and oxygenation does not improve combustion because the systems adjust the stoichiometric point, making it insensitive to the origin of the added excess oxygen (fuel or excess air). Graphical abstract Low level ternary blend of gasoline-ethanol-methanol were prepared with the same stoichiometric air-fuel ratio and volumetric energy concentration, based on the volumetric energy density of the pre-blended components. Exhaust and evaporative emissions was compared with a blend having no oxygen in a fleet of 12 in-use vehicles. Vehicles that had suffer a normal deterioration of emissions and do not react to oxygenation, and new vehicles with more sophisticated air/fuel control systems do not improve combustion.

The Stress Corrosion Cracking Susceptibility in Ethanol-Gasoline Blends

The interest in terms of fuels who are based on ethanol, as a total or partial substitute for fossil fuels. In this research, three concentrations of water (0.5%, 5% and 10%) by volume were evaluated, in ethanol-gasoline blends at 95% by volume of ethanol, using cyclic polarization curves (CPC) on API-5L X52. As a complementary technique, weight loss (WL) was monitored with exposures of 30, 60 and 90 days of immersion. The objective of this investigation is to determine the mechanism of corrosion and the measurement of the effect of the water related to the WL of steel, regardless to the ethanolic mixtures. The result obtained from the mass loss was increased when the water concentration was less than 5% by volume. The CPC showed that blends with low water content there is a tendency to the formation of corrosion by pitting, which was corroborated by scanning electron microscope (SEM).

Susceptibility Evaluation to the Stress Corrosion Cracking in Biofuels

The objective of this research is to evaluate the susceptibility of stress corrosion cracking (SCC) to the effect of adding water in different concentrations of 0.5, 5 and 10% in ethanol-gasoline blends up to 95 and 85% of ethanol, in addition to an inert media for API 5L-X52 steel, commonly used in the transport of hydrocarbons, by constant extension rate test (CERT). Extension rate range was 10-6 s-1, simultaneously, the potential and current noise were examined by the Electrochemical Noise technique where the registered fluctuations have correspondence with the dissolution of the material. Additionally, it was observed that tests with low content in % (V) of water present the less satisfactory results, as well as secondary cracks in the samples analyzed by SCC.