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NumericalEmissionAnalysesofaDieselEngineFuelledwithHHOCNG

ConferencePaper·March2016

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BahattinTanç

MustafaKemalUniversity

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MustafaKaanBaltacioglu

iskenderuntechnicaluniversity

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HüseyinTuranArat

İskenderunTechnicalUniversity16PUBLICATIONS7CITATIONS

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International Conference on Natural Science and Engineering (ICNASE’16)March 19-20, 2016, Kilis

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ICNASE’16

Numerical Emission Analyses of a Diesel Engine Fuelled withHHOCNG

Bahattin TANÇFaculty of Mechanical Engineering, Iskenderun Technical University

Raif KENANOĞLUFaculty of Mechanical Engineering, Iskenderun Technical University

Ertuğrul BALTACIOĞLUFaculty of Mechanical Engineering, Iskenderun Technical University

Mustafa Kaan BALTACIOĞLU*Faculty of Mechanical Engineering, Iskenderun Technical University

HüseyinTuran ARATFaculty of Mechanical Engineering, Iskenderun Technical University

Corresponding Author e-mail: kaanbaltacioglu@gmail.com

ABSTRACTIn this numerical study, a 6L, six cylinder, turbocharged, air cooled diesel enginewas run under

three different cases with AVL-Boost v2013 for simulated the exhaust emission parameters. In numericalanalyses; first case is considered as neat diesel fuel and second one is substituted diesel fuel and the thirdone is substituted diesel fuel + HHOCNG (Hydroxy-Compressed Natural Gas) fuel mixture. Both caseshave playing an important role for dual fuelled diesel engines. Substitution of diesel quantity is used assimilar to pilot diesel injection phenomenon. Model engine was operated between 1000-3000 rpms andemission parameters were listed as; NOx, CO, CO2 and EGT. As a general result, HHOCNG+ substituteddiesel fuel mixture was environmental emission outputs.

Keywords: Exhaust Emissions, AVL Boost, HHOCNG, Diesel Substitution

1 INTRODUCTIONDiesel engines provide important fuel economy and durability advantages for large heavy-duty

trucks, buses, non-road equipment and passenger cars. They are often the power plant of choice for heavyand light-duty applications. While they have many advantages, they also have the disadvantage ofemitting significant amounts of particulate matter (PM),NOx, hydrocarbon (HC), carbon monoxide (CO),and toxic air pollutants [1]. In order to reduce toxic emissions as well as GHG (greenhouse gas), naturalgas are widely used on taxis, buses and light-duty trucks as an additive or main fuel. With thedevelopment of natural gas combustion technology, utilization of natural gas engines has also beenextended to heavy-duty trucks and marine main impellers, where good power performance is in greatdemand. The methods of improving combustion and emission characteristics of engines fuelled withnatural gas and pilot diesel have been extensively studied in recent years, however, most of them arefocused on pilot-ignited premixed natural gas engines.[2,-10]. Beside, author’s previous works could beuseful for more understandable knowledge.

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Additionally, natural gas has been mixed with hydrogen and hydrogenated blending fuels forpreventing the performance outputs and playing an important role in reducing the CO and CO2 emissions.Hydroxy gas (HHO) is an electrolyzing phase of water decomposition with suitable ion-conducting. Intheoretically H-H-O atomic bonds were occurred from this decomposition [3].

In this study, model diesel engine were simulated with turbocharged equipment and fuelled withthree cases. Normal diesel operation; substitution of diesel fuel amount (50%) operation and substituteddiesel and 25HHOCNG (vol/vol with 25HHO/75CNG) fuel mixture operation; cases were simulated andexhaust emissions of model engine were examined and results were mentioned detailed.

2 SIMULATON MODEL

BOOST simulates a wide variety of engines, 4-stroke or 2-stroke, spark or auto-ignited.Applications range from small capacity engines for motorcycles or industrial purposes up to large enginesfor marine propulsion. A symbolic model of a diesel engine used for experimental research on a test bedwas thus created. All these components need design and operational data corresponding to the operationcondition [11]. Simulation model is illustrated in figure 1[11].

Figure 1: AVL BOOST System Model

In the model systems component occur eight types main elements. First one is system boundary(SB1), the beginning of the model conditions were defined in this point. Secondly, Turbocharger (TC1)unit was used for conditioning of intake air and the cooler (CO1) unit was also used for conditioning ofintake air to prepare for combustion process. Next element is plenum 1 (P1), collects enough conditionedair for all cylinders and it was used for intake manifold. In this simulation, the engine consists of sixcylinders. Cylinders were numbered in the figure 1 (C1,C2,..,C6). Plenum 2 and Plenum 3 (PL2, PL3)used for exhaust manifold, after cylinders. Engine, is used for defining of engine specification such asengine speed, stroke type and friction, was represented E1. Pipes were used as the connection elements

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Additionally, natural gas has been mixed with hydrogen and hydrogenated blending fuels forpreventing the performance outputs and playing an important role in reducing the CO and CO2 emissions.Hydroxy gas (HHO) is an electrolyzing phase of water decomposition with suitable ion-conducting. Intheoretically H-H-O atomic bonds were occurred from this decomposition [3].

In this study, model diesel engine were simulated with turbocharged equipment and fuelled withthree cases. Normal diesel operation; substitution of diesel fuel amount (50%) operation and substituteddiesel and 25HHOCNG (vol/vol with 25HHO/75CNG) fuel mixture operation; cases were simulated andexhaust emissions of model engine were examined and results were mentioned detailed.

2 SIMULATON MODEL

BOOST simulates a wide variety of engines, 4-stroke or 2-stroke, spark or auto-ignited.Applications range from small capacity engines for motorcycles or industrial purposes up to large enginesfor marine propulsion. A symbolic model of a diesel engine used for experimental research on a test bedwas thus created. All these components need design and operational data corresponding to the operationcondition [11]. Simulation model is illustrated in figure 1[11].

Figure 1: AVL BOOST System Model

In the model systems component occur eight types main elements. First one is system boundary(SB1), the beginning of the model conditions were defined in this point. Secondly, Turbocharger (TC1)unit was used for conditioning of intake air and the cooler (CO1) unit was also used for conditioning ofintake air to prepare for combustion process. Next element is plenum 1 (P1), collects enough conditionedair for all cylinders and it was used for intake manifold. In this simulation, the engine consists of sixcylinders. Cylinders were numbered in the figure 1 (C1,C2,..,C6). Plenum 2 and Plenum 3 (PL2, PL3)used for exhaust manifold, after cylinders. Engine, is used for defining of engine specification such asengine speed, stroke type and friction, was represented E1. Pipes were used as the connection elements

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Additionally, natural gas has been mixed with hydrogen and hydrogenated blending fuels forpreventing the performance outputs and playing an important role in reducing the CO and CO2 emissions.Hydroxy gas (HHO) is an electrolyzing phase of water decomposition with suitable ion-conducting. Intheoretically H-H-O atomic bonds were occurred from this decomposition [3].

In this study, model diesel engine were simulated with turbocharged equipment and fuelled withthree cases. Normal diesel operation; substitution of diesel fuel amount (50%) operation and substituteddiesel and 25HHOCNG (vol/vol with 25HHO/75CNG) fuel mixture operation; cases were simulated andexhaust emissions of model engine were examined and results were mentioned detailed.

2 SIMULATON MODEL

BOOST simulates a wide variety of engines, 4-stroke or 2-stroke, spark or auto-ignited.Applications range from small capacity engines for motorcycles or industrial purposes up to large enginesfor marine propulsion. A symbolic model of a diesel engine used for experimental research on a test bedwas thus created. All these components need design and operational data corresponding to the operationcondition [11]. Simulation model is illustrated in figure 1[11].

Figure 1: AVL BOOST System Model

In the model systems component occur eight types main elements. First one is system boundary(SB1), the beginning of the model conditions were defined in this point. Secondly, Turbocharger (TC1)unit was used for conditioning of intake air and the cooler (CO1) unit was also used for conditioning ofintake air to prepare for combustion process. Next element is plenum 1 (P1), collects enough conditionedair for all cylinders and it was used for intake manifold. In this simulation, the engine consists of sixcylinders. Cylinders were numbered in the figure 1 (C1,C2,..,C6). Plenum 2 and Plenum 3 (PL2, PL3)used for exhaust manifold, after cylinders. Engine, is used for defining of engine specification such asengine speed, stroke type and friction, was represented E1. Pipes were used as the connection elements

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are also numbered from 1 to 18. Lastly, Measuring Points (MP) were used to see the stability of thesystem. The sample model of programme is used in this programme and effects of HHOCNG fuelmixtures on exhaust emissions were analysed.

The simulation has calculated the whole systems with the helped of some empirical equations. TheNOx formation model implemented in BOOST is based on Pattas and Häfner [11].

rNO= CPostProcMult *CKineticMult*2.0(1-α2) r1/(1+AK2)(r4/(1+AK4)) (1)α= (cNO,act / cNO,eq) * (1/CPostProcMult) ; AK2= r1/(r2 + r3), AK4= r4/(r5 + r6), (2)

Also the formation of CO model applied in BOOST is based on Onorrati et.al. [11]

rco= Cconst*(r1 + r2) * (1-α) (3)

In equaiton 1 and 2; c is molar concentraiton in equilibrium, ri is reactions rates of Zeldovichmechanism for NO and reaction rates of based on the model for CO.

3 RESULTS

The emission results of a non-modified pilot injected diesel engine operated with substitution ofdiesel amount and HHOCNG mixture were given in this sub-section. The emissions of NOx, CO, CO2 andEGT outputs were illustrated with graphs and mentioned detailed.

Figure 2 shows the variation between engine speed and NOx formation. As known; NOx formationis a function of temperature. It means that the temperature is starting increasing, NOx formation decreases.It can be clearly seen from the figure; that 25HHOCNG with substituted diesel fuel mixture have resultedwith better NOx than neat diesel. Numerically, mean reduction values of25HHOCNG with substituteddiesel fuel 5.24%.CNG mixture was minimized this effect and decreased the values under standard dieseloperation.

Figure 2: NOx – Engine Speed

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CO2 versus Engine Speed of 25HHOCNG with substituted diesel fuel mixture, substituted dieselfuel and normal diesel operation are illustrated in Figure 3. Significant reduction of CO2 emissions mostlydepends on the amount of hydrocarbon fuel inducted into the cylinders. When using alternative gas fuelsin a non-modified diesel engine, it is the most important unforgettable thing that; while these gas fuelsimprove the engine performance, they have to be balanced the harmful exhaust emissions values. When itcompared the diesel and 25 HHOCNG with substituted pilot quantities operated it was generated the CO2values differences with 21,72%.

Figure 3: CO2 – Engine Speed

Figure 4 illustrates CO emissions as a function of engine speed for normal diesel operation and25HHOCNG mixture with substituted diesel operation. There are minor decreases on CO emissions withdual-fuel compared to standard diesel results. Especially at higher engine speeds, the difference betweenfuel mixtures and diesel fuel is increasing. The reason of this could be explained with incompletecombustion of CNG due to insufficient ignition sources as well as higher fuel–air equivalence ratio. It iswell known that the rate of CO formation is a function of the available amount of unburned gaseous fuelas well as the mixture temperature, both of which control the rate of fuel decomposition and oxidation.Numerically; CO emission values were decreased 11.5% for 25HHOCNG with substituted diesel fuelmixture and 4,5% for substituted diesel fuel with respect to standard diesel operation.

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Figure 4: CO – Engine Speed

The Exhaust Gas Temperature – Engine Speed graph is shown in Figure 5.It is clearly seen that, inlow speeds, the reduction of the exhaust temperature as a result of the HO that is a clear indication ofbetter combustion and cleaner gases. Low speeds occurred the exhaust gas temperature tends to belowered as the concentration of hydrogen is increased. This is a reflection of the combined effects of thereduction in the total energy released and the faster combustion rates producing higher quashing rates [2].At higher speeds, increase of burning velocity of the mixture by hydrogen addition which shortens thecombustion duration and increases the cylinder gas temperature and exhaust gas temperature [3]. For thisstudy, the maximum EGTs 25HHOCNG + pilot diesel and neat diesel fuel are 484,27oC, 411,33oC,492,94oC respectively.

Figure 5: EGT – Engine Speed

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4 CONCLUSION

The main goal of this work was to find out the emission characteristics of diesel engineenriched with HHO-CNG mixture at the point of use without making any modification to theengine with numerical simulation approach. The following conclusions can be drawn on thebasis of numerical results;

• The one of the important results can be added that; the numerical simulation can be usefulfor measuring the exhaust emissions in ICE area.

• Mixtures of HHO with CNG compensate each other’s disadvantages and provide apromising gaseous fuel mixture with several advantages. Combination of Hydroxy (HHO)and CNG as fuel mixture for internal combustion reduced the harmful exhaust emission.

• HHOCNG fuel mixture provides decreasing emission parameters such as CO, CO2, NOxoutputs.

• As a result of EGT values show that, HHOCNG fuel mixture has better combustioncharacteristic at higher engine speed.

5 ACKNOWLEDGEMENTS

This study was conducted with AVL BOOST simulation program. We are grateful to AVL-AST,Graz, Austria to provide us this program within the scope of UPP (University Partnership Program)

REFERENCES

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[4] Baltacıoğlu K.M., “Hydroxy (HHO) and Hydrogen (H2) Enriched Compressed Natural Gas(CNG) usage in Biodiesel Fuelled Compression Ignition (CI) engines” PhD Thesis, ÇukurovaUniversity, 2016.

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