Emissions from Copper Coated Two Stroke Spark

International Journal of Applied Engineering Research ISSN 0973-4562 Volume 6, Number 21 (2011) pp. 2507-2516 © Research India Publications http://www.ripublication.com/ijaer.htm

Emissions from Copper Coated Two Stroke Spark Ignition Engine with Methanol Blended Gasoline with Catalytic Converter M.V.S. Murali Krishna1*, K. Kishor2, P.V.K. Murthy3 and A.V.S.S.K.S. Gupta4 1,2

Mechanical Engineering Department, Chaitanya Bharathi Institute of Technology, Gandipet, Hyderabad- 500 075, India E-mail: [email protected] 3 Vivekananda Institute of Science and Information Technology, Shadnagar, Mahabubnagar-509216, India E-mail: [email protected] 5 Mechanical Engineering Department, J.N.T. University, Kukatpally, Hyderabad-500 085, India *Corresponding Author E-mail: [email protected]

Abstract This paper reports emissions of carbon monoxide (CO), un-burnt hydro carbons (UHC) and aldehydes from two-stroke, single cylinder spark ignition (SI) engine with methanol blended gasoline (80% gasoline, 20% methanol, by volume) having copper coated engine [copper-(thickness, 300 μ) coated on piston crown and inner side of cylinder head] provided with catalytic converter with sponge iron as catalyst and compared with conventional SI engine with gasoline operation. Copper-coated engine showed reduction in emissions when compared to conventional engine with both test fuels. Catalytic converter with air injection significantly reduced pollutants with both test fuels on both configurations of the engine. Keywords: SI Engine, Pollutants, Catalytic converter, Air injection

Introduction Methanol blended gasoline improved engine performance and decreased pollution levels when compared to pure gasoline on conventional engine (1-3). Carbon monoxide (CO) and un-burnt hydrocarbons (UHC), major exhaust pollutants formed due to

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incomplete combustion of fuel, cause many human health disorders4-9. Such pollutants also cause detrimental effects10 on animal and plant life, besides environmental disorders. Aldehydes11, carcinogenic in nature are intermediate compounds due to incomplete combustion. They also cause many health disorders11 Engine modification 12,13 with copper coating on piston crown and inner side of cylinder head improves engine performance, as copper is a good conductor of heat and combustion is improved with copper coating. Catalytic converter is effective 14-18 in reduction of pollutants in SI engine. The present paper reports the emissions in copper-coated engine (CCE) with catalytic converter with methanol blended gasoline and compared with conventional engine (CE) with pure gasoline operation

Materials and Methods Fig.1 shows experimental set-up used for investigations. A twostroke, singlecylinder, water-cooled, SI engine (brake power 2.2 kW at the rated speed of 3000 rpm) is coupled to an rope brake dynamometer for measuring brake power. Compression ratio of engine is 9:1

Figure 1: Experimental set up. 1. Engine, 2.Eddy current dynamometer, 3. Loading arrangement, 4. Fuel tank, 5. Fuel Sensor, 6.Exhaust temperature indicator, 7. Directional valve, 8. CO Analyzer, 9.Rotometer, 10. Heater, 11. Air compressor, 12 Air chamber, 13.Catalyst chamber, 14.Filter, 15.Rotometer, 16. Heater, 17. Roundbottom flasks containing DNPH Solution Fuel consumption and exhaust gas temperature of engine are measured with electronic sensors. In catalytic coated engine, piston crown and inner surface of cylinder head are coated with copper by plasma spraying. A bond coating of NiCoCr alloy is applied (thickness, 100 μ) using a 80 kW METCO plasma spray gun. Over

Emissions from Copper Coated Two Stroke Spark Ignition Engine

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bond coating, copper (89.5%), aluminium (9.5%) and iron (1.0%) are coated (thickness 300 μ). The coating has very high bond strength and does not wear off even after 50 h of operation12. CO and UHC emissions in engine exhaust are measured with Netel Chromatograph analyzer at various magnitudes of brake mean effective pressure (BMEP). DNPH method19 is employed for measuring aldehydes in the experimentation. The exhaust of the engine is bubbled through 2,4 dinitrophenyl hydrazine (2,4 DNPH) solution. The hydrazones formed are extracted into chloroform and are analyzed by employing high performance liquid chromatography (HPLC) to find the percentage concentration of formaldehyde and acetaldehyde in the exhaust of the engine. A catalytic converter15 (Fig.2) is fitted to exhaust pipe of engine. Provision is also made to inject a definite quantity of air into catalytic converter. Air quantity drawn from compressor and injected into converter is kept constant so that backpressure does not increase. Experiments are carried out on CE and CCE with different test fuels [pure gasoline and gasoline blended with methanol (20% by vol)] under different operating conditions of catalytic converter like set-A, without catalytic converter and without air injection; set-B, with catalytic converter and without air injection; and set-C, with catalytic converter and with air injection.

Note: All dimensions are in mm. Figure 2: Details of Catalytic converter. 1.Air chamber, 2.Inlet for air chamber from the engine, 3.Inlet for air chamber from compressor, 4.Outlet for air chamber, 5.Catalyst chamber, 6. Outer cylinder, 7. Intermediate cylinder, 8.Inner cylinder, 9. Outlet for exhaust gases, 10.Provision to deposit the catalyst and 11.Insulation

Results and Discussion Methanol blended gasoline decreased CO emissions at all loads when compared to pure gasoline operation on CCE and CE, as fuel-cracking reactions1 are eliminated with methanol (Fig.3). The combustion of alcohol produces more water vapor than free carbon atoms as methanol has lower C/H ratio of 0.25 against 0.44 of gasoline. Methanol has oxygen in its structure and hence its blends have lower stoichiometric air requirements compared to gasoline. Therefore more oxygen that is available for combustion with the blends of methanol and gasoline, leads to reduction of CO

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emissions. Methanol dissociates in the combustion chamber of the engine forming hydrogen, which helps the fuel-air mixture to burn quickly and thus increases combustion velocity, which brings about complete combustion of carbon present in the fuel to CO2 and also CO to CO2 thus makes leaner mixture more combustible, causing reduction of CO emissions. CCE reduces CO emissions in comparison with CE. Copper or its alloys acts as catalyst in combustion chamber, whereby facilitates effective combustion of fuel leading to formation of CO2 instead of CO.

Figure 3: Variation of CO emissions with BMEP in different versions of the engine with pure gasoline and methanol blended gasoline at a compression ratio of 9:1 and speed of 3000 rpm. CE- conventional engine: CCE- Copper coated engine: COCarbon monoxide emissions: BMEP-Brake mean effective pressure Table-1 shows the data of CO emissions with different test fuels with different configurations of the engine at different operating conditions of the catalytic converter.


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Table-1: Data Of ‘Co’ Emissions With Different Test Fuels With Different Configurations Of The Engine At Different Operating Conditions Of The Catalytic Converter. Set

Conventional Engine Copper coated engine Pure gasoline Methanol Pure gasoline Methanol blended gasoline blended gasoline Set-A 5.0 3.0 4.0 2.4 Set-B 3.0 1.8 2.4 1.44 Set-C 2.0 1.2 1.6 0.96 From the table, it can be observed that CO emissions deceased considerably with catalytic operation in set-B with gasohol and further decrease in CO is pronounced with air injection with the same fuel. The effective combustion of the methanol blended gasoline itself decreased CO emissions in both configurations of the engine. UHC emissions followed the same trend as CO emissions in CCE and CE with both test fuels, due to increase of flame speed with catalytic activity and reduction of quenching effect with CCE (Fig.4). Catalytic converter reduced pollutants considerably with CE and CCE and air injection into catalytic converter further reduced pollutants. In presence of catalyst, pollutants get further oxidised to give less harmful emissions like CO2.

Figure 4: Variation of UHC emissions with BMEP in different versions of the engine with pure gasoline and methanol blended gasoline at a compression ratio of 9:1 and speed of 3000 rpm. CE- conventional engine: CCE- Copper coated engine: UHC- Unburnt hydro carbons: BMEP-Brake mean effective pressure

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Table-2 shows the data of UHC emissions with different test fuels with different configurations of the engine at different operating conditions of the catalytic converter. The trend observed with UHC emissions is similar to that of CO emissions in both versions of the engine with both test fuels. Table 2: Data Of ‘UHC’ Emissions With Different Test Fuels With Different Configurations Of The Engine At Different Operating Conditions Of The Catalytic Converter. Set

Conventional Engine Copper coated engine Pure gasoline Gasohol Pure gasoline Gasohol Set-A 750 525 600 420 Set-B 450 315 360 252 Set-C 300 210 240 168 Table-3 shows the data of formaldehyde emissions with different test fuels with different configurations of the engine at different operating conditions of the catalytic converter. Formaldehyde emissions increased drastically with methanol blended gasoline in both versions of the engine in comparison with pure gasoline operation. However, the percentage increase in formaldehyde emissions is less with copper coated engine when compared with conventional engine. This shows that copper coated engine decreases formaldehyde emissions considerably. With the both test fuels, CCE drastically decreased formaldehyde emissions in comparison with conventional engine. The intermediate compounds will not be formed is the reason for decrease of formaldehyde emissions in CCE. This shows combustion is improved with catalytic activity in CCE which decreased formaldehyde emissions. Formaldehyde emissions decreased with Set-B operation and further decreased in Set-C operation in both versions of the engine with both test fuels. This is due to increase of oxidation reaction with the use of catalyst and air which caused reduction of formaldehyde contents. Table-3: Data Of Formaldehyde Emisisons Emissions With Different Test Fuels With Different Configurations Of The Engine At Different Operating Conditions Of The Catalytic Converter. Set

Conventional Engine Copper coated engine Pure gasoline Methanol Pure gasoline Methanol blended gasoline blended gasoline Set-A 9.1 23.6 6.8 13.6 Set-B 6.3 10.8 4.1 10.2 Set-C 3.5 8.0 3.2 5.5


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Table-4 shows the data of percentage deviation of formaldehyde emissions with different test fuels with different configurations of the engine in comparison with pure gasoline operation on conventional engine at different operating conditions of the catalytic converter. Table-4: Data Of Percentage Deviation Of Formaldehyde Emissions With Different Test Fuels In Different Configurations Of 2-Stroke Spark Igntion Engine In Comparison With Pure Gasoline Operation On Conventional Engine Set

Formaldehyde Emissions (%) Conventional Engine Copper coated Engine Pure Gasoline Methanol Pure Gasoline Methanol blended gasoline blended gasoline Set-A -+159% -25% +41% Set-B -30% +18.6% -55% +12% Set-C -61% -12% -65% -39% From the table it can be observed, the percentage deviations are less with both test fuels on copper coated engine, which shows the importance of CCE engine in decreasing formaldehyde emissions. However, with pure gasoline on CCE is more active in comparison with methanol blended gasoline as catalytic activity decreased with decrease of combustion temperature as latent of heat of evaporation of methanol is high which absorbs temperature from surroundings leading to decrease of catalytic activity. The percentage decease of formaldehyde emissions with catalytic converter is high with pure gasoline operation in both versions of the engine in comparison with methanol blended gasoline as combustion temperatures are high with pure gasoline operation which promotes oxidation reaction. Table-5 shows the data of acetaldehyde emissions with different test fuels with different configurations of the engine at different operating conditions of the catalytic converter. Table 5: Data Of Acetaldehyde Emisisons Emissions With Different Test Fuels With Different Configurations Of The Engine At Different Operating Conditions Of The Catalytic Converter. Set

Conventional Engine Copper coated engine Pure gasoline Methanol Pure gasoline Methanol blended gasoline blended gasoline Set-A 7.7 12.3 4.9 13.3 Set-B 4.9 6.5 3.5 7.7 Set-C 2.1 3.8 1.4 3.9

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The trend exhibited by acetaldehyde emissions is similar to that of formaldehyde emissions. However, with methanol blended gasoline the magnitude of acetaldehyde emissions are higher.Table-6 shows the data of percentage deviation of formaldehyde emissions with different test fuels with different configurations of the engine in comparison with pure gasoline operation on conventional engine at different operating conditions of the catalytic converter. Table 6: Data Of Percentage Deviation Of Formaldehyde Emissions With Different Test Fuels In Different Configurations Of 2-Stroke Spark Igntion Engine In Comparison With Pure Gasoline Operation On Conventional Engine Set

Acetaldehyde Emissions (%) Conventional Engine Copper coated Engine Pure Gasoline Methanol Pure Gasoline Methanol blended gasoline blended gasoline Set-A -+60% -36% +72% Set-B -36% -15% -54% 0% Set-C -72% -51% -81% -49% As it is noticed from the table, similar trends are observed with that of formaldehyde emissions. CCE engine decreased acetaldehyde emissions considerably with catalytic converter and air injection operation. Improved combustion with increased rate of oxidation reaction decreased acetaldehyde emissions considerably. Methanol blended gasoline operation with CCE decreased acetaldehyde emissions considerably in comparison with conventional engine as combustion is improved with gasohol operation.

Conclusions CO and UHC in exhaust decreased by 30% and 25% respectively in conventional engine with gasohol when compared to pure gasoline operation. These pollutants decreased by 20% with catalytic coated engine when compared to conventional engine with both test fuels. Set-B operation decreased CO and UHC emissions by 40%, while Set-C operation decreased these emissions by 60% with test fuels when compared to Set-A operation. Aldehyde emissions decreased considerably with methanol blended gasoline operation on CCE engine, when compared with conventional engine.

Acknowledgements Authors thank authorities of Chaitanya Bharathi Institute of Technology, Hyderabad for facilities provided. Financial assistance from Andhra Pradesh Council of Science and Technology (APCOST), Hyderabad, is greatly acknowledged.


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