REDUCTION EMISSIONS BY OPTIMIZING THE CYLINDER PROCESSES USING ETHANOL AND GASOLINE ETHANOL BLEND INTO SI 2-STROKE ENGINE

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1 REDUCTION EMISSIONS BY OPTIMIZING THE CYLINDER PROCESSES USING ETHANOL AND GASOLINE ETHANOL BLEND INTO SI 2-STROKE ENGINE C. COFARU 1, N. ISPAS 1 AND M. ALEONTE 2 1 Department of Automotive and Transportation, Transilvania University of Brasov, Eroilor Blvd., 29, 536, Brasov, Romania 2 Karlsruhe Institute of Technology (KIT) Institut für Kolbenmaschinen (IFKM), Karlsruhe, Germany ABSTRACT Ethanol (CH 3 CH 2 OH) is a colorless and clear liquid. It is also known as ethyl alcohol or grain alcohol. Ethanol has the same chemical formula if it is produced from starch and sugar-based feedstock, such as corn grain, sugar cane, or from cellulose feedstock (such as crop residues or wood chips). Ethanol has many positive features as an alternative liquid fuel, such as: - Ethanol is a renewable, relatively safe fuel that can be used with few engine modifications; - The energy density is higher than that of other alternative fuels, as methanol; - The third benefit of ethanol is that it can improve agricultural economies; - By using ethanol, countries energy security increases; - Using ethanol might decrease emissions of HC, CO, NO x, and CO 2. Ground level ozone-forming compounds are emitted during the combustion of gasoline, such as aromatics, olefins, and hydrocarbons and they would be eliminated with the use of ethanol. Carbon dioxide emissions might be improved, depending on the choice of material for the ethanol production and the energy source used in its production. Then, a well to wheel analysis is necessary. Two-stroke engines have a low importance for automotive applications being used for light vehicle, motorbike, motor-boat and motor-tools. The paper presents the results of experimental tests by using a spark ignition-2-stroke engines with different configurations, as fuelling systems and compression ratio. During the experimental work, pure gasoline, pure ethanol and E 85 were used as fuels. The measured data were energetic parameters (power, torque, and fuel consumption), emissions (HC, CO, NO x, and CO 2 ) and operational temperatures and pressures. The tests results were discussed taking into account the influences on air fuel mixing process and combustion. The main conclusion of this research is that the ethanol can be promoted as engine fuel according to environmental, oil dependence and social benefits. INTRODUCTION The history of obtaining ethanol is very long; the fermentation of sugar into ethanol is one of the earliest organic reactions that humanity learned to carry out, the obtained products being beer and wine used as beverages (the content of alcohol not exceeding 15%). A higher concentration of ethanol was obtained by applying the process of distillation discovered by Greek alchemists in Alexandria during the first century A.D. The processes of distillation become a large development in the world during the Middle Ages. Pure ethanol was obtained in 1796 by Johann Tobias Lowitz who applied the filtering of distilled ethanol through activated charcoal. Some years later, other chemists (Antoine Lavoisier, Nicolas- Théodore de Saussure) made several studies on ethanol establishing its chemical formula and properties (9). Nowadays, the technologies used to produce ethanol follow two ways: one to produce bioethanol, the other to produce synthetic ethanol. Most of the world's ethanol production is obtained through the method of fermentation of crops (93%) and only 7% represents synthetic ethanol. Ethanol (ethyl alcohol, grain alcohol, ETOH) is a clear, colorless liquid alcohol with characteristic odor and alcohol is a group of chemical compounds whose molecules contain a hydroxyl group (OH), bonded to a carbon atom. Bioethanol is produced through the fermentation of agricultural products such as corn, barley, sugar cane, sugar beet or wood. The production of bioethanol from cellulose biomass such as, corn leaves and stalks, has the potential to raise the feedstock in the existing industry and become the future technology for fuel ethanol production. The main advantage being that that the carbon removed from the atmosphere by photosynthesis and stored in biomass will serve as row material for bioethanol production, which will be burned in engines that emit CO2 and the process is closed. In conclusion, the net income, in terms of CO2 emission, is zero. Synthetic ethanol is produced through the syntheses from natural gas, coal, and ethylene, and used as fuel, it presents the same disadvantage as any fossil fuel, burn it, releases carbon stored over millions of years into the atmosphere. There are advantages and disadvantages associated with the use of ethanol as an alternative fuel to petroleumbased fuels: a) The advantages are the following: o Ethanol is produced by using renewable resources;

2 o Combustion of ethanol is cleaner in the air than the petroleum products, releasing less carbon (soot) and carbon monoxide; o The use of ethanol as engine fuel could reduce carbon dioxide emissions, because a renewable energy resource is used to produce crops required to obtain ethanol and to distil fermented ethanol. b) The disadvantages are as follows: o Ethanol has a lower heat of combustion (per mole, per unit of volume, and per unit of mass) that petroleum-based fuels; o Producing crops to obtain ethanol requires large surface of arable land, leading to problems, such as soil erosion, deforestation, fertilizer run-off and salinity; o The disposal of waste fermentation liquor results in various environmental problems ; o The use of high ethanol concentrations requires modifications of typical internal combustion engines. The properties of gasoline and ethanol are presented in Table 1. Table 1. Fuel s properties Characteristics Ethanol Chemical formula C 8 H 18 CH 3 CH 2 OH Density (kg/m 3 ) 748 to Boiling point ( o C) 3 to 19 78,3 Reid vapors pressure.7 to (dan/cm 2 ) Low heating value (kj/kg) Latent heat (kj/kg) 29 to AFR Stoich Compositions (%) C H O ~85 ~ Octane no (COR) 9 to Auto-ignition Temperature ( o C) Some ethanol properties can be exploited for replacing gasoline used as fuel in spark ignition engines, as: - Higher octane number of ethanol reduces the knock tendency and improves combustion phasing. By using ethanol the compression ratio may increase up to five units compared to gasoline operation which determines the improvement of engine thermal efficiency. - Combustion of air-ethanol mixtures presents faster laminar flame speed. In the lambda range from.9 to 1., ethanol presents around 45% higher laminar flame speed than gasoline. This advantage reduces the knock probability while the residence time of the endgas prior to the flame front arrival is shortened. - The combustion of ethanol results in a larger volume of burnt gases and hence, a greater pressure. The combustion products from ethanol have 3% higher content of water than gasoline, which increases the burnt gas heat capacity and reduces the combustion temperature. The lower combustion temperature has a positive effect on heat losses and improves the thermal efficiency of the cycle, (3,4,5,6,8). In Europe, the first engine fueled by alcohol was an engine developed by Nicolaus Otto. In USA, the first series car having an flexible engine capable of using ethanol, gasoline or kerosene was used on the Ford Model T.This car was manufactured between 198 and The demand of ethanol as an engine fuel increased after the oil embargoes in 197 s. In the United States, in 1992, the Energy Policy Act was released.the Act defines the gasoline- ethanol blends with at least 85% ethanol, as alternative fuel. Tax deductions are given to promote the sales of vehicles capable of running on alternative fuel, and the conversion of old vehicles into such vehicles. E85 is a fuel made of a blend of 85% ethanol and 15% unleaded gasoline. E85 was created for flexible fuel vehicles, or vehicles that can run on any blend of ethanol up to 85%. Today, the increasing costs of climate change related to the use fossil fuels require a major perspective of the energy production; a great attention is given for the use of biomass to produce fuels, especially for transport as alternative to petrol. Biofuels production becomes extremely interesting when obtained from alternative sources, in particular from waste or renewable source. The use of bioethanol in the transport sector can contribute to decrease the greenhouse gas emissions from vehicles. Other attractive properties include increased octane rating and enthalpy of vaporization compared to standard gasoline, which allow for the use of increased compression ratios and the possibility of more favorable spark timings, increasing engine efficiency. The heat of ethanol s vaporization is 846 kj/kg; this value is higher than that for gasoline, which is between 29 kj/kg and 38 kj/kg. This property of ethanol can contribute to the increase of engine s power and efficiency due to the cooling effect of air fuel mixture. Instead, at a lower engine load, this effect can cause ignition difficulties due to the cylinder s lower temperatures. The ethanol s lower heating value is smaller than that of gasoline, but this difference is compensated by the difference between the stoichiometric values of the air. Under these conditions, the chemical energy of the airfuel-mixture mass unity is practically the same (stoichiometric mixture air-ethanol presents 2975 kj/kg, and 2925 kj/kg for stoichiometric air-gasoline mixture) (7). Ethanol-gasoline blends work well in automobile s engines and in other four-stroke engines, as well. However, problems arise when ethanol-gasoline blends are used in two-stroke engines. Two-stroke engine is used for ultra- light vehicles, motor scooters, motor-cycles, snowmobiles and boats, as well as, on lawn and garden equipment, such as: lawn movers, weed trimmers, chainsaws, power blowers and sprayers. For these applications, the two-stroke engines require a oil-fuel mixture for lubrication, and this is the only source of lubrication of these types of engines.

3 As for as the two-stroke engines, the ethanol-gasoline blends pose three major problems: o Lubrication alcohol and oil do not mix well. The oil additives tend to separate from mixture in presence of alcohol; o Deterioration - rubber and plastic parts can suffer under the influence of ethanol; o Water and corrosion alcohol attracts water, absorbing the moisture from the air into the fuel system. Making some minor modifications on the engine, the mentioned problems can be avoided. The physical properties of ethanol provide important benefits when added to gasoline. Ethanol has both a higher octane rating and a higher heat of vaporization than typical gasoline. A content of oxygen of 7.36 wt% in ethanol promotes combustion efficiency as well as high combustion temperature; the idea to use ethanol was superimposing oxidation reaction over pyrolysis reactions. Reasons for using ethanol to fuel two-stroke engines: 1. Ethanol can reduce country s dependence on imported oil, should foreign supplies be interrupted. 2. Farmers have an increased demand of grain, which helps to stabilize prices. 3. The ethanol improves the quality of the environment. It reduces carbon monoxide emissions, lead and other carcinogens (cancer causing agents) when removed from gasoline. 4. Ethanol-blended fuels can clean the fuel system and also absorb moisture. EXPERIMENTAL SETUP A single cylinder two stroke engine was used to collect the experimental data in this research. The engine having the specification presented in Table 2 was connected to an Eddy Current Dynamometer type Schenk W4. Table 2. Experimental engine characteristics Engine type Parameter Two stroke, Spark ignition engine (SI) No of cylinders 1 Compression ratio 8:1, 9:1 Swept volume (cm 3 ) 7.7 Bore (mm) 5 Stroke (mm) 36 Connecting rod length 75 (mm) Fuel delivery Carburetor, Direct injection air assisted Fuels E; E85, E1 Crankcase scavenging Schnürle full loop Engine cooling Air The fuels used on the experimental work were gasoline, E85 and E1. The properties of these fuels are presented in the Table 3. Table 3. Properties of the tested fuels Properties E85 E1 Chemical 85 /14/ 57/13/3 52/13/35 composition C/H/O (%) Lower heating value (kj/kg) Stoichiometric A/F ratio Density at 15 C (kg/m 3 ) In Table 4, the matrix of experimental research is presented: Table 4. Engine and fuel testing matrix Fuels E85 E1 Engine configuration Carburetor, ε=8 - - Carburetor, ε=9 - - ADI, ε=8 ADI, ε=9 ADI- air assisted fuel direct The fuel consumption was measured using an AVL fuel mass flow meter. The cylinder pressure data was obtained with an AVL GH12D piezoelectric transducer. The data regarding crankshaft position were obtained using a Heidenhain transducer type ROD 426A, Data acquisition, including cylinder pressure and various other critical pressures and temperatures, is achieved using a combination of hardware and software. The Morphee platform (for recording of power, torque, temperatures, pollutant emissions, mixture quality λ) and Combi SmeTec (for pressures, air flow, spark timing injection duration) were used. To record engine control parameters such as intake manifold pressure, air flow rate, spark timing, fuel injection pressure, injection duration, equivalence ratio, etc., calibration tools were also used (1,2). The equipment needed for pollutant measurements are presented in Table 5. Table 5. Equipment for pollutant measurement Equipment type Pollutant Hartmann & Braun Magnos 16 (%Vol) O 2 /N 2 Hartmann & Braun Uras 14 (%Vol) CO 2 Hartmann & Braun Uras 14 (%Vol) CO ECO Physics CLD 7 EL (ppm) NO/NO x Testa FID HC (ppm) HC The engine test incorporated a full electronic control of the spark, fueling rate, and throttle. Several modifications were incorporated. During the experimental tests, the compression ratio of the engine was increased from 8:1 to 9:1, in order to operate efficiently with ethanol. For fuelling systems, one of the options was the direct injection-air-assisted system in order to exploit the

4 vaporization properties of the fuels used. Air-assisted fuel injectors are used to permit the fuel to enter the combustion chamber in small droplets so, the fuel could atomize quickly and mix with the freshly scavenged air. It lessens the effects of charge and exhaust-gas mixing, significantly reduces short-circuiting, and offers precise air/fuel ratio control. Depending on the injection timing the homogenous mixture or stratified mixture may be organized in the combustion chamber. For early injection timing, when the intake ports are open, the air and the fuel have time to homogenize; simultaneously, a part of the mixture can escape through the exhaust ports. On the contrary, when the injection timing is set after the exhaust ports have been closed, there is no fuel lost to the exhaust. This second case may be able to promote mixture s stratified charge combustion at part loads, which greatly improves combustion stability especially at high levels of residual gas being trapped. One main change comprises the location of the Strata TM air-assisted fuel injector (Figure 1.) in the cylinder to realize a direct fuel injection. Air-assisted direct injection is applied to a range of 2-stroke engines, from 5 to 5 cc/cylinder displacements. The air-assisted injector operates in the following manner: the fuel pumped into the air-fuel mixture formation chamber contained in the airassisted DI system had a pressure of.6.7 MPa. The air pressure was induced into the air-fuel mixture formation chamber in the air assisted direct injection system with a pressure of MPa. In order to have a constant compressed air pressure, an air regulator was mounted on the air inlet system. The main advantage of air-assisted fuel injector is a good atomization of fuel; droplets size having less than 6 SMD on the condition of air-assist pressure. EXPERIMENTAL RESULTS AND DISCUSSIONS The results of experimental tests are presented and discussed in two subsections: combustion and emissions. Therefore, the effects of increasing of compression ratio and fuel used (E, E85 and E1) on the engine performance are described and discussed below. Combustion The two-stroke engine having a compression ratio of ε=8:1 was selected for the test. It was provided with a carburetor, under these conditions, the process of air-fuel mixing takes place outside the engine. The air-fuel mixture at the spark time will be homogenized. The exchange gas process is called scavenging process and presents the same timings for all operation range of the engine. For this configuration, the value of compression ratio was increased at ε=9. The engine provided with carburetor was tested by using gasoline (E) and the experimental data were used as a base line for comparison with the results obtained on a new version of the same engine where an air-assisted fuel direct had been equipped. This new two-stroke engine version was tested for previous values of compression ratio (ε=8:1and ε=9). In case of replacing the carburetor system with a direct injection air-assisted system, the mixing air-fuel process takes place in the cylinder. By controlling the injection timing and the fuel spray characteristics, the mixture can be controlled in a stratified way in the combustion chamber. The brake power is one of the important factors that determine the performance of an engine, and the variation of brake power with speed was obtained at full load conditions for the engine having a compression ratio of ε=8:1 and ε=9:1, provided with carburetor or air-assisted fuel direct operating with gasoline E85 and E1. The results of the brake power are presented in Figure 2 and Figure 3. Figure 1. The air-assisted DI fuel injector In case of a direct fuel injection, the crank train lubrication and durability remain a problem to be solved. Because of this reason the lubricant oil needs to be added to the intake air charge. The engine lubrication was achieved by fitting an oil pump, as the oil cannot be mixed with the fuel, the pump delivering the oil into the intake air flow. The oil pump frequencies were controlled by taking in account the engine operating parameters. During the experimental test the engine was cooled by using a Viking BE 6 fan. P [kw] 4 3,5 3 2,5 2 1,5 1,5 E 85 E 1 Figure 2. The brake power of the engine using different fuelling systems and fuels for ε=8:1 For typical gasoline engines, power output can be improved with a higher compression ratio unless excessive knock problems predominate. The results of experimental tests show that, by using gasoline, the increasing of compression ratio by an unit (from 8:1 to 9:1) representing 12.5 %, the brake power rise on all range of operating speed (55-75 rpm). The maximum

5 power at 75 rpm rises from 3.16 kw to 3.27 kw (+3.48%). Heat release rate peak of (kj/m 3 CA) is located at about 2 degrees ATDC. At the end of combustion process in combustion chamber, 98 (kj/m 3 ) is accumulated. P [kw] 4 3,5 3 2,5 2 1,5 1,5 E 85 E 1 Figure 3. The brake power of the engine using different fuelling systems and fuels for ε=9:1 Analyzing the cylinder pressure for engine speed corresponding at maximum torque, the increase from 2.94 MPa at 7 crank angle degrees ATDC to 3.54 MPa at 6 crank angle degrees ATDC, (+2.4%) can be noticed. In case of the engines with compression ratios of ε=8 and ε=9, provided with air-assisted, when using E 85, the increase of maximum cylinder pressure determined by rising of compression ratio to 3.47 MPa at 4.7 crank angle degrees ATDC to 4.8 MPa at 4.2 crank angle degrees ATDC, (Figure 4). As for E1, the pressure increases from 3.41 MPa at 5.3 crank angle degrees ATDC to 4.54 MPa at 5.4 crank angle degrees ATDC, (Figure 5). Figure 5. Cylinder pressure using E1 as fuel Figure 6. Heat released and cumulative heat per cycle for engine ε=9:1 Figure 4. Cylinder pressure using E85 as fuel The combustion process can be better analyzed on basis of measurements of the cylinder pressure which are used to calculate net heat release rates during the combustion of the engine cycle. Studying the graph of heat released, the point at which net heat release rate becomes positive determines the location of start of combustion. Figure 6 presents the rate of heat released and cumulative heat of the engine having ε=9:1, for a cycle corresponding with the engine s speed, maximum torque at full load. The start of combustion is located at 16 CA BTDC and the combustion process ends at 25 CA ATDC. The increasing value of compression ratio determines greatly influence on temperature of the cylinder. Figure 7 shows the evolution of cylinder s temperature for the engine equipped with carburetor, for cycle corresponding to maximum torque. The maximum cylinder s temperature increases from 1581 K for the engine having ε = 8 to 1843 K for the engine having ε = 9, representing + 19%. Using direct fuel injection, the air mixing and combustion were improved; in consequence, the maximum value of cylinder temperature rose from 1581K, in case of carburetor, to 1869 K for the case of air-assisted direct injection, representing 16 %, for the engine having ε = 8. The research conducted on the two-stroke engine provided with air-assisted direct using E85 and E1 as fuel presents increased values for rated power over the operating range of the engine in both engines (ε = 8, ε = 9). The obtained values for rated maximum power for the engine having a compression ratio ε = 9 were: 3.27 kw (carburetor and gasoline), 3.35 kw (air-assisted direct injection and gasoline) and 3.48 kw (air-assisted direct injection and E85 and E1).

6 The gas temperature in the cylinder increases with the increase of engine load. In case of full load, using the research fuels (E, E85 and E1) in the engine ( ε = 9) equipped with air-assisted direct injection engines for the cycle corresponding to maximum torque, the maximum temperature varies with the concentration of ethanol and gasoline, as it is shown in Figure 9. the same variations, lower levels being for the engine having ε=9:1. Figure 9. Cylinder s temperatures for engine with airassisted direct injection (ADI) 6 5 Figure 7. Cylinder s temperature for engine with carburetor BSFC [g/kwh] E 85 1 E 1 Figure 1. The brake specific fuel consumption of the engine using different fueling systems and fuels for ε=9:1 Figure 8. Cylinder s temperature for engine with carburetor and air-assisted direct injection (ADI) The peak temperature of cylinder decreases from 2478 K, when gasoline (E) is used, to 1869 K for pure ethanol (E1), representing -32%. Figure 1 shows the chart plotted for gasoline, ethanol blends and pure ethanol showing brake specific fuel consumption at various engine speed conditions at full load. It presents that the fuel specific consumption values of E85 and E1 were lower than in the engine using gasoline and carburetor and higher than in case of direct injection of gasoline. Emissions The emission tests were made for two version of compression ratio (ε=8:1, ε=9:1) and for two fuelling systems, carburetor and air-assisted direct fuel injection, using as fuels: gasoline, E85 and E1. Examining the chart of HC emissions (Figure 11) for the engines versions presented above, the emissions follow The magnitude of reductions of HC emissions for engine fueled with carburetor and direct injection and gasoline versions, were the following: the HC levels decrease from ppm to 3652 ppm (-74.4%) at 55 rpm and ppm to 3284 ppm (-73.8%) at 75 rpm, see Figure 11. Increasing the engine compression ratio, the combustion process in the cylinder was improved and it resulted in a higher cycle temperature which determined level of HC oxidation. The decreasing of HC emissions for these two compression versions fuelled with gasoline were: carburetor -3.4% at 55 rpm and -6.5% at 75 rpm; direct injection % at and -6.5%. Replacing the carburetor with an air-assisted direct fuel resulted in a great reduction (> 7%) of HC emissions. These lower values of HC emission can be explained by taking in account: reduction of air-fuel mixture loss by short-circuit, diminishing the influence of crevices, improved combustion process due to air-fuel mixture and state of cylinder gases. Interesting results of HC emissions can be observed for these two versions of engines when fuelled with E85 an E1. Because the E85 and E1 were tested using only the, the results could be compared with those obtained by using gasoline provided with the same fuelling system.

7 For the engine version with ε = 8:1, in case of E85, the HC emissions were higher than in case of gasoline over on entire range of engine speeds varying between % and 88.76%. In case of the same engine fueled with E1, the HC emissions decreased linearly with the increasing of engine speed from +34.3% to -27.9%. Increasing the compression ratio to ε = 9:1, the HC emissions decreased in comparison with previous engine and for both fuels E85 and E1 decreased linearly with rising of engine speed, ( Figure 12). This evolution can be explained taking info account the level of the exhaust gases which contribute to the late oxidation of HC and CO. Greater emissions at lower engine speed can be determined by the advanced spark timing which influences the hydrocarbon emissions to increase. This increase is caused by two mechanisms. The first being determined by an increased in-cylinder pressure (from advanced combustion) which causes a greater mass of hydrocarbons to be trapped in the crevice volumes. The second mechanism being determined by the lower exhaust temperature (resulting from advanced combustion) causes less oxidation of hydrocarbons released from crevices. Later, the engine speed was increased; the heat loss diminished and the exhaust gas temperatures were higher and caused oxidation of hydrocarbons. of CO emissions. Comparing the peak of CO emissions for these two fuelling system the measured values decreased from 7.56 (%) to 4.29 (%) which represents %. Fuelling the engine with direct with E 85 and E1 and comparing the measured values for CO emissions with those obtained by using gasoline considered as baseline two situations can be encountered: the first one, for E85, the emissions of CO increase for a speed range rpm, and these increased comprised between +75.8% and +4.69%, (Figure 14). The second test is represented by CO emission by using E1. In this case the emission was lower than in case of using gasoline, the reduction being of -5.24% and %. The increase of CO for E85 can be attributed to the reduction in fuel volatility and the expected increase in fuel impingement on the piston crown caused by the very early first injection. The reduction for pure ethanol (E1) is thought to be caused by the removal of all high boiling point fractions present in gasoline. Another reason for the increase in CO for the higher ethanol blends could be the reduced mixing leading to a reduced homogeneity associated with the longer injection duration. The combustion of rich regions and flame quenching in overly lean regions is expected to increase CO levels. HC [ppm] E 85 E 1 CO [%] E 85 E Figure 13. CO emissions for the engine with ε=9:1 HC emissions repoted to gasoline [%] Figure 11. HC emissions for the engine with ε=9:1 6, 4, 2,, -2, -4, E 85 47,18 28,43 18,76 11,87 4,29 E 1 34,72 2,21 2,52-11,75-24,21 E 85 E 1 Figure 12. HC emissions of E85 and E1 compared with gasoline (ε=9:1) The engine provided with carburetor presents higher CO emissions (Figure 13). When the carburetor was replaced by direct the combustion process was improved, as a consequence there were the reductions CO emissions reported to gasoline [%] 1, 5,, -5, -1, E 85 75,58 2,48 24,89 4,69-9,9 E 1-15,21-5,24-41,35-5, -71,1 E 85 E 1 Figure 14. CO emissions of E85 and E1 compared with gasoline (ε=9:1) The level of NO X emissions is highly dependant on the in-cylinder temperature, as the in-cylinder temperature increases, the rate of NOx formation also increases. Increasing by a unit the engine compression ratio (+12.5%), the peak of emissions rise from 124 ppm to 34 ppm ( %). In case of the engine with direct

8 injection of gasoline, for both values of compression the emissions of NOx increased dramatically due to the improvement of combustion process, the peak of emissions being 93 ppm and 586 ppm for version ε = 9:1 (+92.76%). Fuelling the direct injection engine with E 85 and E1, for both cases, there was also a general reduction in NO X for an engine speed range 55-7 rpm. For maximum engine speed a small NOx peak of increasing occurs, (Figure 15 and Figure 16). The NO X level, then, increases slightly at lower engine speed for pure ethanol and this is due to the combustion s advanced leading to a higher in-cylinder pressure and temperature compared to that of E85 ethanol. NOx [ppm] E 85 E 1 Figure 15. NOx emissions for the engine with ε=9:1 NOx emissions reported to gasoline [%] 15, 1, 5,, -5, -1, E 85-42,91-57,9-59,4-1,68 125,3 E 1 17,73-34,33-58,87-34,92 27,71 E 85 E 1 Figure 16. NOx emissions of E85 and E1 compared with gasoline (ε=9:1) CONCLUSIONS In this study, engine performance and pollutant emissions from different engine configurations and fuels have been experimentally investigated. Based on the experimental research on two-stroke engines with carburetor and direct fuel s using E, E85 and E1, the following conclusions are drawn: - The effect of compression ratio when changed from 8:1 to 9:1 with gasoline for both engine versions carburetor and direct fuel s, there were an increases of energetic parameters (power, torque) and a decrease of brake fuel consumption. Regarding HC and CO emissions for all tests, the results shown lower values, while the NOx level was found to be higher, with higher compression ratios due to a faster combustion and thus higher in-cylinder pressure because of a combination of advanced combustion and higher flame speeds. - The use of E85 and E1 engine with direct injection presents higher energetic parameter, better fuel consumption due to improved combustion and stability. This effect resulting in advanced and faster combustion, improved combustion efficiency as a result of better evaporation (reduction of heavy fractions) and mixing coupled with the presence of oxygen within the fuel molecule. The pollutant emissions of HC, CO and NOx present lower values compared with those of the engine with carburetor and gasoline. - The main conclusion of this reserch is that the E85 and E1 are suitable as alternative fuels for two-stoke S.I. engine. Combustion duration decreases due to its higher laminar burning rate, much higher research octane number value, higher flame velocity allowing the improvement of engine performance by using higher compression ratios. REFERENCES (1) Aleonte, M., Cosgarea, R., Jelenschi, L., Cofaru, C., 211 "Technical Solutions for Improving the Efficiency of a Two Stroke SI Engine," Bulletin of the Transilvania University of Braşov. Series I: Engineering Sciences, Vol. 4 (53), p. 6. (2) Aleonte, M., Cofaru, C., Cosgarea, R., Scutaru, M.L., Jelenschi, L., Sandu, G., 211 "Experimental Researches of Fuelling Systems and Alcohol Blends on Combustion and Emissions in a Two Stroke SI Engine " Recent Researches in Neural Networks, Fuzzy Systems, Evolutionary Computing & Automation, U. "Transilvania", Brasov, pp ISBN (3) Gupta, S. K., Dubey, N.216 Experimental investigation of two stroke petrol engine operating on blends of methanol, ethanol and gasoline International Journal of Engineering Technology and Applied Science. ISSN: , Vol. 2 Issue 2. (4) Mithaiwala, K, A., Gosai, D.C Performance improvement of IC engine using blends of ethanol fuel: a review International Research Journal of Engineering and Technology ISSN: Volume: 4 Issue: 4. pp (5) Narasimha Kumar, S. 214 Effect of ethanol gasoline blends on engine performance parameters in copper coated two stroke spark ignition engine. International Journal of Scientific Engineering and Technolog.y ISSN: Volume No.3 Issue No.4, pp (6) Oliverio, N., Stefanopoulou, A., Jiang, L., Yilmaz, H. 21. Ethanol detection in flex-fuel direct injection engines using in-cylinder pressure measurements SAE Int. J. Fuels Lubr. Volume 2. Issue 1. pp (7) Radu, Al. Pana, C., Negurescu, N. 214 An experimental study on performance and emission characteristics of a bioethanol fueled S.I. engine. U.P.B. Sci. Bull. ISSN , Series D, Vol. 76, Issue 1. pp (8) Turner,D., Xu, H., Cracknell, R., F., Natarajan, V., Chen,X. 211 Combustion performance of bio-ethanol at various blend ratios in a gasoline direct injection engine Fuel journal homepage: (9)