Research Article EXPERIMENTAL INVESTIGATION ON VARYING ENGINE TORQUE OF SI ENGINE WORKING UNDER GASOLINE BLENDED WITH OXYGENATED ORGANIC COMPOUNDS D.Balaji¹*, Dr.P.Govindarajan², J.Venkatesan³ Address for Correspondence ¹Research scholar, Anna University Coimbatore, Department of Mechanical Engineering, Panimalar institute of Technology, Chennai-602103 ²Principal, Sona College of technology, Salem-5 ³Department of Mechanical Engineering, Sri Venkateswara College Engineering Chennai-602105 E mail balsnaga2002@yahoo.com.doc ABSTRACT This paper investigates the effect of using unleaded gasoline and additives blends on spark ignition engine (SI engine) performance, combustion and exhaust emission. A four stroke, single cylinder SI engine was used for conducting this study. Performance tests were conducted for fuel consumption, volumetric efficiency, brake thermal efficiency, brake power, engine torque and brake specific fuel consumption, while exhaust emissions were analysed for carbon monoxide (CO), Hydrocarbon (HC), and Oxides of nitrogen (NOx) using unleaded gasoline and additives blends with different percentages of fuel at varying engine torque condition and constant engine speed. The result showed that blending unleaded gasoline with additives increases the brake power, volumetric and brake thermal efficiencies and fuel consumption. The CO and HC emissions concentrations in the engine exhaust decreases while the NOx concentration increases. KEYWORDS: Fuel additive; Gasoline-Additives blend; Exhaust emissions 1. INTRODUCTION the atmosphere and become hazardous to health It is the dream of engineers and scientists to develop engines and fuels such that very few quantity of harmful emissions are generated, and these could be let into the surroundings without a major impact on the environment. Air pollution is predominately emitted through the exhaust of motor vehicles and the combustion of fossil fuels. Government around the world has set forth many regulatory laws to control the emissions. One of the serious problems facing the modern technological society is the drastic increase in environmental pollution by internal combustion engines (IC engines). All transport vehicles with SI and CI (compression ignition) engines are equally responsible for the emitting different kinds of pollutants. Some of these are primary kinds having direct hazardous effect such as carbon monoxide, hydrocarbons, nitrogen oxides etc, while others are secondary pollutants such as ozone, etc., which undergo a series of reactions in [3]. The emissions exhausted into the surroundings pollute the atmosphere and cause global warming, acid rain, smog, odours, respiratory and other health hazards. The urgent need for alternative fuel is essential to replace the supplement conventional fuels. A pollutant is a component which changes the balance of environment and nature under normal condition. Carbon dioxide is not considered as pollutant as nature recycles it and produces oxygen but in a confined area if CO 2 exceeds 5000 ppm then it becomes a potential health hazard [7],[9]. The root cause for these emissions is non-stoichiometric combustion, dissociation of nitrogen and impurities in the fuel and air. The transportation which uses IC engines is the major sector for the economic growth. The major exhaust emissions HC, CO, NOx, SO 2, solid particles etc are and performance is increased by adding the suitable additives to the fuel reduced with the present technology. Additives are integral
part of today s fuel. Together with carefully formulated base fuel composition they contribute to efficiency and long life. They are chemicals, which are added in small quantities either to enhance fuel performance, or to correct a deficiency as desired by the current legislation. They can have surprisingly large effects even when added in little amount [10]. Additives are blended into fuel by refineries or end users. However use of metallic additives was subsequently discontinued mainly because of concern about the toxicity of the barium compounds in the exhaust emission. But the interest is revised recently to verify the possible use of additives to reduce emission level. Alcohol has been used as a fuel for Auto-engines since 19 th century; it is not widely used because of its high price. Alcohol is one of the fuel additive (Methanol, Ethanol) has some advantage over gasoline such as better antiknock characteristics and the reduction of CO and HC emissions. Houghton-Alico D [1] has made a study on alcohol production and potential. Several additives (oxygenated organic compounds) such as methanol, ethanol, tertiary butyl alcohol and methyl tertiary butyl ether are used as fuel additives. Although having these advantages, due to limitations in technology, economic and regional considerations alcohol fuel still cannot be used extensively. Since ethanol can be fermented and distilled from biomasses, it can be considered as renewable energy under the environmental consideration, using ethanol blended with gasoline is better than methanol because of its renewability and less toxicity. Many researchers have worked on the emission control and performance enhancement of SI engines. Winnington and Siddique [4] Hamdan, Jurban [5] and El-Kassaby [6] have studied the effect of using ethanolgasoline blends. They used maximum of 15 % of ethanol in ATd 34 engine. Palmer F H [2] has conducted a test on gasoline engine containing oxygenates. The effect of oxygenate in gasoline on exhaust emission and performance in a single cylinder, four stroke SI engine was studied by Taljaard et al [8]. Based on the economic and environmental considerations, an attempt has been made in this work to study the effects of ethanol contents in the ethanol-gasoline blended fuel on the engine performance and pollutant emission of a commercial SI engine. In the present work, to reduce the emissions and to improve the performance of petrol engine, the modification technique is used. Two fuel additives were mixed for this purpose. Various proportions of these fuel additives were mixed with the gasoline. The engine performance analysis and emission levels were measured, running the engine at varying load and constant speed. Encouraging results were obtained and the work carried out is presented. The objective of the present work is to investigate the effect of varying engine torque on the engine performance and exhaust emission working with different ethanol fuel blends. 2. Experimental set up and method The engine is a 100 cc 4 stroke, single cylinder SI engine loaded by an eddy current dynamometer. Table 1 lists some of the important specification of the engine under test. The schematic layout of the experimental set up is shown in fig 1. The engine was coupled to a eddy current dynamometer which is quipped with an instrument cabinet fitted with a torque gauge, electric tachometer and switches for the
load remote control. Fuel consumption was measured by using a calibrated burette and a stopwatch with an accuracy of 0.2s. The concentration of exhaust emission (CO, HC, NOx) and air fuel ratio were measured using a Sun glass Analyser MGA 1200. The analyser has a non-dispersive infrared molecule for CO, HC and NOx. The engine was started and allowed to warm up for a period of 20-30 min. The air fuel ratio was adjusted to yield maximum power on unleaded gasoline. Engine test were performed at constant engine speed at 3/4 th throttle opening position by varying engine torque. The speed can be maintained constant by speed sensor. Before running the engine to a new fuel blend, it was allowed to run for sufficient time to consume the remaining fuel from the previous experiment. 1. Engine 10. Moisture separator 2. Eddy current dynamometer 11. Exhaust gas analyzer 3. Electric pressure pickup 12. Carburetor 4. Personal computer 13. Air filter 5. Printer 14. Air box 6. Load sensor 15. Orifice meter 7. RPM Counter 16. Exhaust pipe 8. Dynamometer control Panel 17. Shaft 9. Exhaust gas temperature 18. Fuel measuring unit Fig 1 Experimental setup Table 1 Engine specifications Engine make and model Bajaj engine Engine type Four stroke, Single cylinder air cooled engine Bore 70 mm Stroke 90 mm Cubic capacity 100 cc Compression ratio 7.4:1 Rated power 5.2 kw Rated speed 6500 rpm Fuel Petrol
For each experiment, three runs were performed to obtain an average value of the experimental data. The variables that were continuously measured include engine speed (constant), torque, time required to consume 100 cc of fuel blend, CO, HC, NOx emission and exhaust gas temperature. The parameters such as fuel consumption rate, volumetric efficiency, brake power, brake thermal efficiency were estimated by standard equations. Table 1 shows the engine specification. 3. Result and Discussion The effect of ethanol addition to unleaded gasoline on SI engine performance and exhaust emissions at 3/4 th throttle opening at various engine torque were investigated. 3.1Fuel consumption The effect of ethanol-unleaded gasoline blends on the fuel consumption is shown in Fig 2. From Fig 2, the fuel consumption increases on the engine torque increases at constant engine speed. This behaviour is attributed to the LHV per unit mass of the ethanol fuel, which is distinctly lower than that of the unleaded gasoline fuel. Therefore the amount of fuel introduced in to the engine cylinder for a given desired fuel energy input has to be greater with the ethanol fuel. 3.2 Volumetric efficiency The effect of ethanol and unleaded gasoline fuel blends on the volumetric efficiency is shown in Fig 3. Fig 3 clearly indicates an increase of volumetric efficiency with the engine torque upto 0.9 Nm. This is due to decrease of the charge temperature at the end of the induction process and the increase of the amount of air introduced in the engine cylinder. This decrease in charge temperature is attributed by an amount as a result of the heat transfer from hot engine parts and the residual gases in the charge. At the same time, the charge temperature drops by an amount due to vaporization of the fuel blend in the inlet manifold and engine cylinder. Further increase in engine torque results in a decreasing volumetric efficiency, where the amount of air decreases as a result of choking in the induction system Fig 2 Engine torque Fuel consumption chart
. Fig 3 Engine torque Volumetric efficiency chart 3.3 Brake thermal efficiency Fig 4 presents the effect of ethanol-unleaded gasoline blends on brake thermal efficiency. As shown in the figure break thermal efficiency increases as the engine torque increases. The maximum brake thermal efficiency is recorded with 10% ethanol in the fuel blend at constant engine speed. 3.4 Specific fuel consumption The effect of using ethanol-unleaded gasoline blends on brake specific fuel consumption (BSFC) is shown in Fig 5. As shown in the figure SFC decreases as the engine torque increases. This is normal consequence of the behaviour of the engine brake thermal efficiency. Fig 4 Engine torque Brake thermal efficiency chart
Fig 5 Engine torque Specific fuel consumption chart 3.5 Exhaust emissions emission increases as compared with gasoline The effect of the Ethanol percentage in the fuel fuel for various blends. Fig 8 shows that HC blend on the CO, HC, and NOx is shown in Fig emission decreases as compared with petrol fuel 6-8. Fig 6 shows that the CO emission for various blends. It can be seen that as the decreases as compared with petrol fuel for ethanol percentage increases to 20%, the CO and various blends. Due to better combustion these HC concentration decrease for all engine torque emissions are decreased. Fig 7 shows that NOx values. Fig 6 Engine torque CO emission chart
Fig 7 Engine torque NOx emission chart Fig 7 Engine torque HC emission chart The fuel specification (density, RVP (reid vapour pressure), heating value, etc) is shown in Appendix A. Appendix A Fuel Specification Property E0 E10 E20 E30 Density (kg/l) 0.7575 0.7608 0.7645 0.7682 RON (Octane number) 95.4 98.1 100.7 102.4 RVP (kpa) 53.7 59.6 58.3 56.8 Heating value (cal/g) 10176 9511 9316 8680 Carbon (Wt %) 86.60 86.70 87.60 86 Hydrogen (Wt %) 13.3 13.2 12.3 13.9 Residue 1.7 1.5 1.5 1.5 Colour Yellow Yellow Yellow Yellow
4. CONCLUSION 1. Using ethanol as a fuel additive to unleaded gasoline causes an improvement in engine performance and exhaust emissions. 2. Ethanol addition results in an increase in brake power, brake thermal efficiency, volumetric efficiency, and fuel consumption by about 8.2%, 9%, 7% and 5.7% mean average values respectively. In addition, the brake specific fuel consumption decreases by about 2.4% mean average value. 3. Using ethanol-unleaded gasoline blend leads to a significant reduction in exhaust emissions by about 46.5% and 24.3% of the mean average values of CO and HC emission respectively for all engine torque, on the other hand NOx emissions increases for all engine torque values. 4. The addition of 30% ethanol to the unleaded gasoline is achieved on our experiments without any problems during engine operation. ACKNOWLEDGEMENT The author would like to thank the technical staff of the ICE laboratory at the Mechanical Engineering Department of Sona College of Technology. REFERENCES [1] Houghton-Alico D (1982), Alcohol fuels production and potential, Colorado. [2] Palmer F H (1986), Vehicle performance of gasoline containing oxygenates, paper C319/86, International conference on petroleum based fuels and automotive applications, London, I. Mech. E. Conference, pp. 36-46. [3] Goddger E M (1975), Hydrocarbon fuel, London, Macmillan. [4] Winnington T L and Siddiqui KM (1983), Engine performance on gasohol-the Kenyan experience, Automotive engineering. [5] Hamdan M A, Jubran BA (1986),.The effect of ethanol performance of diesel and petrol engines, Dirasat, XIII(10), pp. 229-244. [6] EL-Kassaby M M (1993), Effect of using differential ethanol-gasoline blends at different compression ratio on SI engine, Alexandria Engineering, pp.135-145. [7] Bata R V, Roan V P (1989), Effects of ethanol and methanol in alcohol-gasoline blends on exhaust emission, J. Engineering, Gas Turbine Power, ASME, pp.432-438. [8] Taljaard H C, Jaardaan CFP, Both JJ (1991), The effect of oxygen content in different oxygenates gasoline blends on performarence and emission in a single cylinder spark ignition engine, SAE 91037. [9] Unzelman J B (1991), US Clean Air Act expand role for oxygenates; oxygenates for the future, Oil and Gas Journal, pp.44-48. [10] Gulder L O (1979), Technical aspect of ethanol and ethanol gasoline blends as automotive fuel, The scientific and Technical Research Council of Turkey, Project No. 526.