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Propulsion and Power Research

Propulsion and Power Research 2013;2(4):276–283

2212-540X & 2013 Nhttp://dx.doi.org/10.10

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Peer review under rand Astronautics, Chin

ORGINAL ARTICLE

Experimental investigation of performanceimproving and emissions reducing in a two strokeSI engine by using ethanol additives

Mohsen Ghazikhania, Mohammad Hatamib,c,n, Behrouz Safaria,Davood Domiri Ganjic

aFerdowsi University of Mashhad, Engineering Faculty, Mechanical Engineering Department, IranbEsfarayen University, Engineering and Technical College, Mechanical Engineering Department, Esfarayen, North Khorasan, IrancBabol University of Technology, Mechanical Engineering Department, Mazandaran, Babol, Iran

Received 3 August 2013; accepted 14 October 2013Available online 13 December 2013

KEYWORDS

Two stroke engine;Ethanol additives;Delivery ratio;Scavenging efficiency;Emissions

ational Laboratory f16/j.jppr.2013.10.00

hor: Tel.: þ98 511 8

.hatami2010@gmail

esponsibility of Natia.

Abstract In present study, the operational parameters for a two stroke gasoline engine such asdelivery ratio, scavenging efficiency, trapping efficiency, etc. have been investigated experimentallywhen its fuel is blended with ethanol additives. Also the amounts of emitted pollutants (HC, CO,CO2 and NOX) from this engine are measured in various engine velocity and loads. In experiments,ethanol is combined with gasoline in different percentages of 5%, 10% and 15%. The experimentshave been done for 2500, 3000, 3500 and 4500 rpm. The results show that in most test cases, whenalcoholic fuel is used, scavenging efficiency and delivery ratio increased due to rapid evaporation ofethanol, but fuel converging efficiency and brake specific fuel consumption (BSFC) decreased. Themost outstanding result of using ethanol additive is significant reduction in pollutions emitted fromengine and CO with 35% reduction has the most reduction percentage among other pollutants.& 2013 National Laboratory for Aeronautics and Astronautics. Production and hosting by Elsevier B.V.

All rights reserved.

or Aeronautics and Astronautics. Pro2

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.com (Mohammad Hatami).

onal Laboratory for Aeronautics

1. Introduction

Development of alcohol fuel would be of great sig-nificance in many aspects. For instance, it can protectenvironments by reducing the emissions. Alternative fuelssuch as biodiesel and ethanol can satisfy the demand forrenewable energy sources with low environmentalimpacts. Now ethanol has been used as a total or partial

duction and hosting by Elsevier B.V. All rights reserved.

Experimental investigation of performance improving and emissions reducing in a two stroke SI engine by using ethanol additives 277

substitute fuel for gasoline in many countries. Some applica-tions of ethanol as a fuel are introduced in the following. Anew and simple strategy for the simultaneous determination ofethanol and methanol in fuel ethanol using cyclic voltamm-etery at a gold electrode is reported by Pereira et al. [1]. Theeffects of the use of ethanol as an additive to diesel oil-soybean biodiesel blends on fuel consumption is furtherinvestigated by Randazzo et al. [2]. They found that the coldstart time increased with increasing ethanol content in the fuelblend but specific fuel consumption was not affected byincreasing biodiesel concentration in the blend or by the use of2% of ethanol as an additive. However, the use of 5% ofethanol concentration in the B20 blend resulted in increasedspecific fuel consumption. Zhang et al. [3] focused ondecreasing brake specific fuel consumption (BSFC) of dieselengine by introducing dimethyl ether (DME) or ethanol intoair intake and fueling emulsified fuel to diesel engine together.Boretti [4] observed a better fuel conversion efficiency for adual fuel ethanol-diesel than the diesel only over the full rangeof speeds and loads with all the advantages of the renewableethanol in terms of environment and energy security. Emissioncharacteristics from a four-stroke motorcycle engine using10% ethanol-gasoline blended fuel (E10) were investigated byJia et al. [5]. Their results indicate that CO and HC emissionsin the engine exhaust are lower with the operation of E10 ascompared to the use of unleaded gasoline. According to Heet al. [6], using ethanol as an additive to diesel fuel can reduceparticular matter (PM) emission and increase the flexibility ofNOX emissions control under different engine operatingconditions. Increased fuel consumption and low ignitionquality are pointed out as the main barriers for ethanolapplication in diesel engines.

Because ethanol or ethylic alcohol (C2H5OH) can beproduced from herbaceous seeds, beets and potatoes, it canbe a suitable alternative fuel for oil categories fuels [7,8].Ethanol has blended to gasoline for increasing octane numberand its non-detonation properties. Eyidogan et al. [9]investigated the effect of ethanol-gasoline (E5, E10) andmethanol-gasoline (M5, M10) fuel blends on the performance

Figure 1 Schematic of th

and combustion characteristics of a SI engine. They showedusing ethanol lead to an increase in BSFC and octane number.These results were expected because the heating values of thealcohols are 37%–53% lower than that of pure gasoline.Xiaolu Li et al. [10] used ethanol fuel, which benefits from alow cetane number, in a two stroke diesel engine with exhaustgas recirculation (EGR). They showed ethanol makes lowersoot and NOX, and also causes 2%–3% increase in thermalefficiency. The effects of ethanol addition (10% and 15% involume) on the performance and emissions of a four cylinderturbocharged indirect injection diesel engine having differentfuel injection pressures (150, 200 and 250 bar) at full loadwere investigated by Can et al. [11]. Their results showed thatthe ethanol addition reduces CO, soot and SO2 emissions,although it caused an increase in NOX emission and approxi-mately 12.5% (for 10% ethanol addition) and 20% (for 15%ethanol addition) power reductions. Recently ethanol is widelyused as a fuel additive in different engines, some of theserecently works are introduced in [12–14].

In the present work, effects of adding ethanol to gasolineon performance and emissions in a two stroke SI engine areinvestigated. Outcomes reveal that using ethanol improvesthe scavenging efficiency and delivery ratio of the engine.Results also show that in the all conditions, emissions(HC, CO2, CO and NOX) have been significantly reduced.Schematic of the experimental setup is shown in Figure 1.

2. Mathematical formulation of operatingparameters

In this section all the requirement equations andoperating parameters for a two stroke engine are presented[15].

2.1. Delivery ratio

Delivery ratio is a parameter for describing the scaven-ging process in two stroke engines. It can be defined as

e experimental set up.

Table 1 Specifications of the test engine.

Engine model 2-stroke JAP-J34

Bore 35 mmNumber of cylinder 1Stroke 35 mmDisplacement volume 34 mlCompression ratio 6Nominal output power 0.5 kW, 4000 rpmMaximum speed 6000 rpmCorporation Plint & Partners LTD

M. Ghazikhani et al.278

following for experimental purposes,

Λ¼ mass of delivered mixture per cyclerefrence mass

¼ mass of delivered mixture per cycledisplacement� ambientdensity

ð1Þ

2.2. Scavenging efficiency

Scavenging efficiency indicates to what extent theresidual gases in the cylinder have been replaced with freshair as follows definition,

ηsc ¼mass of delivered mixture retainedmass of trapped cylinder charge

ð2Þ

a useful and applicable equation for experimental purposesfor scavenging efficiency is presented by Ganesan [16].

ηsc ¼m�aðkg=minÞ

NðrpmÞ � ρsc � Vtotal¼ m

�aðkg=minÞ

NðrpmÞ � pexh287�T0

� Vd � rr�1

ð3Þ

2.3. Fuel conversion efficiency

The measure of an engines efficiency which will becalled fuel conversion efficiency is given by:

ηf ¼Wc

mfQLHV¼ Pb

m�f QLHV

ð4Þ

It means the output work per every cycle on input energyto the engine so m

�f is the mass of fuel inducted per cycle.

2.4. Brake specific fuel consumption (BSFC)

A more useful parameter for showing the fuel consump-tion of two stroke engines is brake specific fuel consump-tion or BSFC which it means the fuel flow rate per unitbrake power output.

BSFC¼ mf

Pbð5Þ

2.5. Trapping efficiency

Trapping efficiency indicates what fraction of the mixturesupplied to the cylinder is retained in the cylinder.

ηtr ¼mass of delivered mixture retained

mass of delivered mixtureð6Þ

By using exhaust gas analyze, trapping efficiency can becalculated by following equation [15].

ηtr ¼ 1� ½O2�exh½O2�atm

ð7Þ

3. Experimental apparatus

3.1. Experiment setup

The experimental setup consists of a two stroke, onecylinder SI engine, an engine test bed and an exhaust analyzer.The schematic of the experimental set up is shown in Figure 1.The engine model is JAP-J34 and the cooling fluid is water.Specifications of the engine are given in Table 1. Formeasuring the fuel consumption, the time of 1 cc fuelconsumption was measured with a digital chronometer witha definition rate of 70.01 s. The exhaust temperature, inletand outlet cooling water temperature were measured withPT100 sensors and their values were shown on a screen.

3.2. Exhaust gas analyzer

The DELTA 1600S analyzer is used to measure exhaustgases. It is a small and lightweight (800 g) analyzer. Itsresponse time is 15 s and flow rate approximate 1.2 l/min.This analyzer can measure Carbon monoxide (CO), Carbondioxide (CO2), Hydrocarbons (HC), Oxygen (O2) and Nitricoxide (NOX). The excess air (lambda) calculated fromBrettschneider formula can also be determined by thisanalyzer. Using lambda and stoichiometric air to fuel ratio,we are able to calculate the actual air to fuel ratio.

4. Tests procedure

All the tests were done in three general steps. First of allfor obtaining performance map, after that for determiningthe specification of blended fuels and finally running theengine in various speed with using blended fuels. All thetests were done in internal combustion engine laboratoryof Ferdowsi university of Mashhad, Iran. For obtainingthe performance map, we started engine with gasoline, andengine was stabilized awhile to reach stable state. In thisstate we set engine in full throttle and apply maximumpower to it. We have done these all for 2500, 3000, 3500and 4500 rpm and recorded 1 cc fuel consumption time andtorque.

Experiments were performed with four different fuels at25%, 50% and 75% of full load. Fuels were pure gasoline,95% gasolineþ5% ethanol, 90% gasolineþ10% ethanol

Experimental investigation of performance improving and emissions reducing in a two stroke SI engine by using ethanol additives 279

and 85% gasolineþ15% ethanol. Some properties ofdescribed fuels are presented in Table 2.

The testing procedure is as follows. As mentioned, experi-ments were performed with four different fuels at 50% of fullload and 2500, 3000, 3500 and 4500 rpm. After completion of

Table 2 Some properties of the test fuels.

Properties Gasoline Ethanol Gasoline with 5% etha

Typical formula C7.93H14.83 C2H5OH C7.63H14.39O0.05

Density/(kg/lit) 0.7378 0.7987 0.7408Heating value/(MJ/kg) 44.4 26.8 43.45Molecular weight 110 46 106.75Stoichiometric air/fuel 14.5 8.97 14.43

Figure 2 (a) Delivery ratio, (b) scavenging efficiency, (c) trapping efficien

Figure 3 (a) Delivery ratio, (b) scavenging efficiency, (c) trapping efficien

a standard warm up procedure, the engine speed was increasedfrom 2500 to 4500 rpm at 50% of maximum torque. At eachpoint, the engine was stabilized for 2 min, and then, the mea-surement parameters (temperatures, exhaust gases, water massflow, fuel consumption time, torque and speed) were recorded.

nol Gasoline with 10% ethanol Gasoline with 15% ethanol

C7.34H13.95O0.1 C7.04H13.51O0.15

0.7439 0.746942.51 41.58103.63 100.3914.31 14.17

cy and (d) combustion temperature for four type fuels in 50% full load.

cy and (d) combustion temperature for four type fuels in 75% full load.

M. Ghazikhani et al.280

5. Results and discussion

5.1. Operating parameters

Figures 2 and 3 show operation parameters and engineefficiencies for different fuels for 50% and 75% full loadrespectively. As shown in Figures 3(a) and (b), 10% and15% ethanol addition caused an increase in delivery ratioand subsequently scavenging efficiency improves approxi-mately 40%. Better scavenging is due to rapid ethanolevaporation wherein burned gases are better scavenged. Asseen in Figure 2(b) when the ethanol percentage is low(5%), its effect is not very clear, but for 15% ethanol

Figure 4 (a) BSFC and (b) fuel conversion efficiency in 50% full lo

Figure 5 Carbon monoxide (CO) versus engine speed in (a) 25% full ltemperature.

increasing in scavenging efficiency completely is evident.Figure 3(c) shows trapping efficiency, as seen in this figure,using ethanol (in all percentages blended with gasoline)causes reduction in trapping efficiency. Since rapid eva-poration of ethanol makes lower air pressure in comparisonto total manifold pressure and obstruct the air inlet path, sothe result is trapping efficiency reduction. Because ofexistence oxygen in ethanol structure, blended ethanol withgasoline makes lower combustion temperature, which isshown in Figure 2(d). Figure 3 reveals that using ethanol asan additive fuel in gasoline make increases in delivery ratioand scavenging efficiency but it reduces the trapping efficiencyand combustion temperature. The effect of ethanol additives

ad, (c) BSFC and (d) fuel conversion efficiency in 75% full load.

oad, (b) 50% full load, (c) 75% full load and (d) CO versus exhaust

Experimental investigation of performance improving and emissions reducing in a two stroke SI engine by using ethanol additives 281

on BSFC and fuel conversion efficiency is presented inFigure 4 for 50% and 75% full load in various engines speeds.Because using ethanol have two different opposite aspects.Having lower heating value than pure gasoline is a drawbackaspect, while lower flash point and lower ignition delay areadvantages. As shown in Figures 4(a) and (b) (for 50% fullload), 4(c) and 4(d) (for 75% full load) by using 10% and 15%ethanol, the negative aspect is dominated to the positive aspect,so BSFC is increased. But for 5% ethanol in more speeds(2500, 3000 and 4500 rpm), the positive aspect has dominatedand BSFC has been reduced but for 3500 rpm the treatment is

Figure 6 Carbon dioxide (CO2) versus engine speed in (a) 25% full lotemperature.

Figure 7 Hydrocarbons (HC) versus engine speed in (a) 25% full loatemperature.

as the same as 10% and 15% ethanol. So using 5% ethanolmay be an advantage from BSFC reduction perspective.

5.2. Emissions (CO, CO2, HC and NOX)

Carbon monoxide (CO) is produced from the partialoxidation of carbon-containing compounds; it forms whenthere is not enough oxygen to produce carbon dioxide (CO2),such as when operating a stove or an internal combustionengine in an enclosed space. In the presence of oxygen, carbonmonoxide burns with a blue flame, producing carbon dioxide.

ad, (b) 50% full load, (c) 75% full load and (d) CO2 versus exhaust

d, (b) 50% full load, (c) 75% full load and (d) HC versus exhaust

Figure 8 Nitric oxide (NOX) versus engine speed in (a) 25% full load, (b) 50% full load, (c) 75% full load and (d) NOX versus exhausttemperature.

M. Ghazikhani et al.282

Figure 5 illustrates the CO emitted from engine in differentloads and speeds. As seen in this figure increasing in ethanolpercentage makes significant decrease in CO, for instance in25% full load and 4500 rpm, CO decreased approximately71% when 15% ethanol added to gasoline. For other speedsand loads CO decreased averagely 35%.Carbon dioxide (CO2) is a naturally occurring chemical

compound composed of two oxygen atoms covalently bondedto a single carbon atom. When ethanol or extra oxygenappears in gasoline fuel, due to rapid evaporation and bettermixing between air and fuel and excellent combustion, CO2'sintensity, like other emissions, will decrease. Figure 6 showsthe CO2 exhausted from the engine. For large loads and lowspeeds, engine emitted lower CO2 than the other situations andby each 5% increasing the ethanol to the fuel, CO2 decreasedabout 6.3%.Hydrocarbons (HC) is an organic compound consisting

entirely of hydrogen and carbon. Unburned hydrocarbons(UHCs) are the hydrocarbons emitted after petroleum isburned in an engine. In piston engines some of the fuel-airmixture “hides” from the flame in the crevices provided by thepiston ring grooves. Also, some regions of the combustionchamber may have a very weak flame and low combustiontemperature. Thus, when unburned fuel is emitted from acombustor HC is formed. HC emitted from the test engines indifferent velocities and loads in presented in Figure 7. Thesefigures confirm that using ethanol reduces HC level in all casesand for each 5% ethanol, HC approximately 6% decreased.Nitric oxide (NOX) is a generic term for mono-nitrogen

oxides NO and NO2. They are produced from the reaction ofnitrogen and oxygen gases in the air during combustion,especially at high temperatures. As seen in Figure 8 the ethanoladditives has most influence on NOX emissions and it can bethe biggest advantage of ethanol because it reduced NOX about83% when it is used in high percentages (15%) and high speedengines also it averagely 38% reduced. Because ethanolchemical formula contains an oxygen molecule, when it's added

to gasoline a better combustion occurred and NOX amountreduced.

6. Conclusion

In this paper ethanol is blended with gasoline in threedifferent percentages 5%, 10% and 15% for a two strokeSI engine. This paper investigates the effects of ethanoladditives and engine speed on the engine combustion,operating parameters, efficiencies and emissions. Followingconclusions can be drawn from the present study:

(1)

Due to ethanol evaporation in 10% and 15% ethanoladdition an increase in delivery ratio and subsequentlyscavenging efficiency (approximately 40%) is observed.But trapping efficiency has been decreased about 15%.

(2)

For 5% ethanol the positive aspect of adding ethanol(having lower flash point and ignition delay) dominatedthe negative aspect (having lower heating value) andBSFC reduced which is an advantage for this state.

(3)

CO decreased approximately 71% when 15% ethanoladded to gasoline. Generally for different speeds andloads, CO decreased averagely 35% and by each 5%increasing the ethanol to the fuel, CO2 decreasedabout 6.3%.

(4)

Using ethanol reduced HC level in all cases and foreach 5% ethanol, HC approximately 6% decreased.

(5)

The most advantage of ethanol additives is NOX

reduction which is reduced about 83% when it is usedin high percentages of ethanol (15%) and averagely38% for other cases.

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