Experimental Investigation on Ceramic Hot Surface Ignition C.I Engine using Methanol Fuel * P Sreenivasulu 1, B Durga Prasad 2 1 Department of Mechanical Engineering, BVSR Engineering College, Chimakurthy, Prakasam- 523226, AP, India. 2 Depatment of Mechanical Engineering, J.N.T.U.A College of Engineering, Anantapur-515002, A.P, India. *sreenupothula@gmail.com, +919866408481 ABSTRACT The concept of using alcohol fuels as an alternative to diesel fuel in diesel engines is one of the recent developments. The scarcity of petroleum fuels due to the fast depletion of petroleum deposits and frequent rise in their costs in the international market have spurred many efforts to find alternatives. Alcohols are quickly recognized as prime candidates to displace or replace high octane petroleum fuels. However, alternatives for the large demand of diesel fuels in many countries were not so evident. Innovative thinking led to the finding of various techniques by which alcohol can be used as a fuel in diesel engines. Amongst the fuel alternatives proposed, the most favourite ones are methanol and ethanol. So far no established method is available to run a normal diesel engine with a compression ratio from 14:1 to 20:1 by using alcohol as a fuel. This is because, the properties of diesel engine fuels differ from the properties of diesel fuels. The specific tendency of alcohols to ignite easily from a hot surface makes it suitable for ignition in a diesel engine. The advantage of this property of alcohols enables to design and construct a new type of engine called surface ignition engine. In this type of engine, the injected fuel ignites not by compression ignition but by contact with a hot surface maintained with in the engine. Since methanol and ethanol are very susceptible to surface ignition, this method is very suitable for these fuels. The hot surface which can be used in surface ignition engine is a ceramic heater with hot surface flush. Hence the present research work carries the experimental investigation on ceramic hot surface ignition engine with methanol as the fuel and with catalytic coatings with an objective to find the best one in terms of performance, emissions and combustion parameters. Keywords: Ceramic hot surface ignition, Partially stabilized zirconia, Methanol, Copper coating, Chromium coating, Nickel Coating 1. INTRODUCTION During the mid and late 1980 s research on alcohol fuels undertaken in the United States, Japan, and Europe expanded greatly. The research covered the entire alcohol production, distribution and utilization process from the section of high-yield cultivators as feed stocks for the production process to the performance of neat alcohol fuels and blends in production passenger vehicles. The major focus of this paper is the primary alcohol fuel i.e methanol (methyl alcohol). Methanol (CH 3 OH) is originally produced by the destructive distillation of wood. Methanol can also be manufactured from a variety of carbon based feed stock such as natural gas, coal [1, 2]. On the other hand, alcohols do have a few disadvantages compared to diesel fuel [1]. They have low calorific value and so they require more fuel mass to release the same amount of energy. In addition to it they have higher heats of vaporization. Hence they require more energy to convert the same mass of liquid fuel to vapour state. Alongwith this the lower (67% by volume) flammability limits of methanol and ethanol are higher than that of diesel. As a result a larger concentration (by volume) of the alcohol fuel vapour must be present for the mixture to ignite compared to diesel fuel [3]. The low vapour pressure the high heat of vaporization and the higher lean flammability limit of alcohol fuels make them inherently difficult to ignite under cold ambient conditions. Another disadvantage is doi:10.18831/james.in/2015031001 1
the low cetane number compared to diesel fuel [3,4]. To overcome these disadvantages, some modifications are proposed for an engine i.e., hot surface ignition for easy ignition. Table A1 refers to the comparison of properties of fuels studied in this work. 2. EXPERIMENTAL WORK The two most commonly known methods of combustion in an I.C engine are compression ignition and spark ignition. In C.I engines, the working medium, air is first compressed to high pressure and temperature. Then fuel is injected into the combustion chamber where the jet disintegrates into a core of fuel surrounded by an envelope of air and fuel particles created by the automation and vaporization of the fuel and turbulence inside the combustion chamber. During the delay period, the fuel atomize, vaporize and get mixed with air. Its temperature increase leads to a chemical reaction which accelerates until inflammation[5].the experimental setup is shown in figure B1. A constant speed stationary four stroke surface ignition ceramic heater C.I engine is selected for the experiment. Partially Stabilized Zirconia (PSZ) ceramic heater is fitted inside the cylinder head and connected by a 12 volts D.C battery to ignite the fuel methyl alcohol in the combustion chamber. Because of its very high fracture toughness, it has one of the highest maximum service temperature (2000 0 C) among ceramics. PSZ ceramic heater is used in diesel engines owing to two very notable properties, one is high temperature capability and the other is low thermal conductivity[6]. This means that engine made with zirconia would retain much of the heat generated in the combustion chamber instead of loosing it to the surroundings. Therefore combustion of fuels gets complete resulting in an increase in combustion efficiency and reduction in pollution[7, 8]. The relevant parameters such as performance parameters, emission parameters, combustion parameters are calculated for methanol fuel. The engine is run to gain uniform speed after which it is gradually loaded.the experiments are conducted at different loads. The engine is run for at least 10 minutes after which data is collected. The experiment is repeated three times and the average value is taken. Experiments are conducted by using three different catalytic coatings on the same engine and the results are compared. 2.1. Catalytic coatings Catalytic coating is done to speed up the reaction rates during combustion. Like catalysts, various catalytic surfaces enhances the chemical reaction and speed up the chemical reaction rates during combustion. In this work we used copper, chromium and nickel as the catalyst coating [8,9,10,11]. Table 1 shows the engine specifications. Table 1.Engine specifications MAKE Kirlosker MODEL No.of cylinder 1 Bore X stroke(mm) Rated output power Rated speed AV-1 80X110 3.84kW(5H.P) 1500 RPM Compression ratio 16.5:1 Injection pressure Cooling system Lubrication system Attachment Direct Injection Water cooled Force feed Ceramic heater 3. RESULTS AND DISCUSSIONS The experimental tests are carried out on the ceramic hot surface ignition four- stroke CI engine using methanol and the performance parameters, combustion parameters and emission parameters are calculated. The experimental tests are also conducted on the same engine with different catalytic coatings on combustion chamber and compared with plain engine i.e without coating.the results are shown below. 3.1. Performance parameters 3.1.1. Brake thermal efficiency The brake thermal efficiency with brake power for three different coatings coated on the combustion chamber with CHSI engine is explained diagrammatically in figure B2. It is found that, the brake thermal efficiency for all catalytic coatings to CHSI engine are higher as compared to plain CHSI engine with methanol as fuel over a wide range of operations. The brake thermal efficiency of plain CHSI engine, copper coating, chromium coating and nickel coating at maximum load 2
are 29.5%, 31%, 30.7%, 30.2% respectively. This is due to the positive ignition of injected methanol sprayed under all conditions by copper coated CHSI engine.the brake thermal efficiency is maximum for copper coating compared to all other coatings and is 31%. 3.1.2. Volumetric efficiency The difference in volumetric efficiency between the brake power output and the three types of catalytic coatings along with the CHSI engine is visualized in the figure B3 The volumetric efficiency of plain CHSI engine, copper coating, chromium coating and nickel coating at maximum load is 87%, 86.2%, 86.8 and 86.5% respectively. It is observed that, drop in volumetric efficiency is more for copper coatings in CHSI engines. The drop in volumetric efficiency for other coatings varies depending upon the degree of insulation with which they are coated. The combustion chamber surface temperature is very high during the suction stroke such that the transfer to the incoming air is high which tends to a decrease in the volumetric efficiency. The drop in volumetric efficiency affects combustion by reducing the amount of air available for combustion. 3.1.3. Exhaust gas temperature The variation of exhaust gas temperature with brake power for different catalytic coatings on CHSI engine is illustrated in figure B4. By using catalytic coating in combustion chamber, the exhaust temperature increases. The plain CHSI engine exhibits lower exhaust temperature among all the fuel tested i.e 360 0 C, when compared to other coatings at rated load condition. The exhaust temperature for copper coating, chromium and nickel at maximum load is 410 0 C, 400 0 C and 390 0 C respectively. 3.2. Emission parameters 3.2.1. Hydro carbon emissions The variation in HC emission levels with brake power output is detailed in figure B5. The copper coated CHSI engine shows lowest HC emissions. The HC emissions level is lower for copper coated CHSI engine, which is about 110ppm at maximum load. The hydrocarbon emission for plain CHSI engine, chromium and Nickel at maximum load is 145ppm, 115ppm, and 120ppm respectively. It is observed that the HC emissions are almost equal at lower loads. By increasing the load HC emissions are also increased. The HC emission level for all the other coated CHSI engines are in between the plain CHSI engine and the copper coated CHSI engine with methanol as fuel. 3.2.2. Carbon monoxide emission Figure B6 illustrates the variation of CO emissions with brake power output for different coatings on CHSI engines. The copper coating CHSI engine indicates lower level of CO emissions when compared to that of other two coatings. In CHSI engine, the variation of CO emission at lower output is negligible. The CO emission for plain CHSI engine, copper coating, Chromium coating and nickel at maximum load are 0.16%, 0.13%, 0.14%, and 0.145% respectively. 3.2.3. Nitrogen oxide emission Figure B7 shows the variation of NO X emission levels with brake power for various coatings of a CHSI engine. Complete combustion takes place, due to higher combustion chamber temperature in the catalytic coated CHSI engine and the oxidation rate of NO X is also improved. The plain CHSI engine gives the lowest NO X emission and is about 2290ppm at rated load. The NO X emission for copper coating, chromium coating and nickel coating at maximum load are 2520ppm, 2450ppm and 2350ppm respectively. Out of all the coatings which are experimented, NO X emission is higher with copper coated CHSI engine when compared to that of the other coatings on the CHSI engine. 3.2.4. Exhaust smoke emissions The study of exhaust smoke emission for different coatings on CHSI engine with brake power is shown in figure B8. The copper coated CHSI engine gives the lowest smoke emission almost over the entire operating range. The exhaust smoke emission of plain CHSI engine, copper coating, chromium coating and nickel coating at maximum load are 2.3 BSU, 1.35 BSU, 1.7 BSU, and 2.00 BSU respectively. Chromium and nickel coatings can be taken into account 3
in the reduction of smoke emission. At the maximum load, the maximum reduction in smoke emission is noted to be 1.35 BOSCH UNITS for copper coated CHSI engine. 3.3. Combustion parameters 3.3.1. Cylinder peak pressure The variation of cylinder peak pressure with brake power output for different coatings on CHSI engine is illustrated in figure B9. The peak pressure is higher with all coatings particularly at high output, where the gas temperature accelerates the combustion process. It is observed that the cylinder peak pressures for all the catalytic coated CHSI engines are higher than plain CHSI engine. The copper coated CHSI engine shows high cylinder peak pressure as compared to other coated CHSI engine which is about 88 bar. The cylinder peak pressure of plain CHSI engine, chromium, and nickel at maximum load are 79 bar, 85 bar, and 83 bar respectively. 3.3.2. Ignition delay Figure B10 exhibits the variation of ignition delay with brake power output for different coatings on CHSI engine. The copper coated CHSI engine performs the lowest ignition delay and plain CHSI engine shows the highest ignition delay period. This is due to the hotter combustion chamber in copper coated CHSI engine.the ignition delay for plain CHSI engine, copper coating, chromium coating, nickel coating at maximum load is 12 0 CA, 6 0 CA, 7 0 CA, and 8 0 CA respectively. Because of the lower ignition delay in the catalytic coated CHSI engine, the operation of catalytic coated CHSI engine is smoother compared to plain CHSI engine. 3.3.3. Combustion duration The variation of combustion duration with brake power for the three different catalytic coated CHSI engine is illustrated in figure B11. The copper coated CHSI engine performs for a slightly shorter duration of combustion when compared to other coatings on CHSI engine due to the hotter combustion chamber. The combustion duration for plain CHSI engine, copper coating, chromium coating and nickel coating at maximum load are 33 0 CA, 26 0 CA, 27 0 CA, and 28 0 CA respectively. Generally, combustion duration is proportional to amount of fuel in combustion chamber. Therefore combustion duration is smaller at lower loads and larger at higher loads. The plain and other coated CHSI engine indicates slightly longer combustion duration than copper coated CHSI engine. 3.3.4. Maximum rate of pressure rise The difference in maximum rate of pressure rise considering brake power output for three different types of catalytic coatings on CHSI engine is visualized in figure B12. The maximum rate of pressure rise is minimum for copper coated CHSI engine and it is maximum for plain CHSI engine with methanol as fuel. The rated pressure rise with methanol in the low output ranges is due to sluggish combustion. The maximum rate of pressure rise for plain CHSI engine, copper coating, chromium coating and nickel coating at maximum load are 5.4 bar/ 0 CA, 5.10 bar/ 0 CA, 5.2 bar/ 0 CA and 5.3 bar/ 0 CA respectively. 4. CONCLUSION Out of three coatings coated on the combustion chamber of the CHSI engine being tested, the copper coating on the CHSI engine is proved to be good in terms of performance and emission as compared to plain CHSI engine. 1.The brake thermal efficiency for copper coated CHSI engine is 31%. 2.The volumetric efficiency is 87% for plain CHSI engine. 3.The exhaust gas temperature for plain CHSI engine is 360 0 C and is the lowest when compared to other coatings. 4.It is found that the minimum smoke emission is noted as 1.35 BOSCH UNITS for copper coated CHSI engine. 5.The copper coated CHSI engine shows the lowest HC emission of 110ppm. 6.The copper coated CHSI engine gives the lowest level of CO emissions of 0.125%. 7.The plain CHSI engine gives the lowest NOx emission of 2290ppm. 8.The cylinder peak pressure for copper coated CHSI engine is 88 bar and is the highest. 9.The maximum rate of pressure rise is lower for copper coated CHSI engine and is 5.1 bar/ 0 CA. 10.The ignition delay is lower for copper coated CHSI engine and is 6 0 CA. 4
11.The combustion duration is lower for copper coated CHSI engine and is 26 0 CA. REFERENCES [1] A.J.Markel and B.K.Bailey, Modelling and Cold Start in Alcohol-Fueled Engines, Report No. NRELflP-540-24180, National Renewable Energy Laboratory, 1998. [2] R.K.Green, Developments in the use of Methanol as a substitute for Diesel Oil, University of Canterbury, New Zealand, 1993. [3] D.N Assanis, The effect of Thin Ceramic Coatings on Petrol Engine Performance and Emissions, International Journal of Vehicle Design, Vol. 13, No. 4, pp. 378-387, 1992. [4] R.B. Poola, B.Nagalingam and K.V.Goplakrishnan, The Effect of Thermal Insulation and In-Cylinder Catalyst on the Performance of a Twostroke SI Engine with Methanol as Fuel, Proc. of the Tenth International Symposium on Alcohol fuels, USA, 1993, pp.888-896. [5] Gholamhassan Najafi and T.F.Yusaf, Experimental Investigation of using Methanol-Diesel Blended Fuels in Diesel Engine, Proc. of the fourth International Conference on Thermal Engineering:Theory and Applications, UAE, 2009, pp. 1-5. [6] R.Poola, B.Nagalingam and K.Gopalakrishnan, Performance of Thin-Ceramic-Coated Combustion Chamber with Gasoline and Methanol as Fuels in a Two-Stroke SI Engine, SAE Technical Paper, 1994, http://dx.doi.org/10.4271/941911 [7] K.Bro and P.S.Pederson, Alternative Diesel Engine Fuels: An Experimental Investigation of Methanol, Ethanol, Methane and Ammonia in a D.I Diesel Engine with Pilot Injection, SAE Technical Paper, 1977, http://dx.doi.org/10.4271/770794 [8] D.Cipolat, Improvement in Performance of a Methanol Fuelled Compression Ignition Engine, Proc. of XII International Symposium on Alcohol Fuels, Beijing, 1998, pp.133-138. [9] R.Rama Udaya Marthandan, N.Siva Kumar and B.Durga Prasad, Experimental Investigation on Four Stroke Ceramic Heater Surface Ignition C.I Engine using Different Blends of Ethyl Alcohol, International Journal of Advances in Engineering and Technology, Vol. 2, No. 1, 2012, pp. 249-257. [10] C. Mishra, N. Kumar, B.S.Chauhan, H.C Lim and M. Padhy, Some Experimental Investigation on use of Methanol and Diesel Blends in a Single Cylinder Diesel Engine, International Journal of Renewable Energy Technology Research, Vol. 2, No. 1, 2013, pp. 01-16 [11] Ambarish Datta, Suhail Dutta, Bijan Kumar Mandal, Effect of Methanol Addition to Diesel on the Performance and Emission Characteristics of a CI Engine, Journal of Basic and Applied Engineering Research, Vol. 1, No. 3, 2014, pp. 8-13. 5
APPENDIX A Table A1.Properties of fuels Fuel\chara cteristics chemist ry Viscosit y(mpasec) Surface tension( mn/m) Boil ing poi nt 0 C Calorif ic value( kj/kg) Density (kg/l) Autoig nition temp( 0 C) Flash point ( 0 C) Oct ane num ber Cet ane num ber Stoi chio air/f uel Rati o Diesel Mixtur e of hydroc arbons 2 23.8 170-340 44500 0.84 180-240 52-50- 55 14.7 :1 Methanol CH 3 OH 0.54 22.07 64.5 23800 0.792 464 11 92 3 6.4: 1 6
APPENDIX B Figure B1.Experimental setup Figure B2.Variation of brake thermal efficiency with brake power for different coatings on CHSI engine. 7
Figure B3.Variation of volumetric efficiency with Brake power for different coatings on CHSI engine Figure B4.Variation of exhaust gas temperature with brake power for different coatings on CHSI engine 8
Figure B5.Variation of HC emission with brake power for different coatings on CHSI engine Figure B6.Variation of carbon monoxide emissions with brake power for different coatings on CHSI engine. 9
Figure B7.Variation of NO X emissions with brake power for different coatings on CHSI engine Figure B8.Variation of smoke emissions with brake power for different coatings on CHSI engine 10
Figure B9.Variation of cylinder peak pressure with brake power for different coatings on CHSI engine Figure B10.Variation of ignition delay with brake power for different coatings on CHSI engine 11
Figure B11.Variation of combustion duration with brake power for different coatings on CHSI engine Figure B12.Variation of max.rate of pressure rise with brake power for different coatings on CHSI engine 12
APPENDIX C Nomenclature CHSI-Ceramic Hot Surface Ignition PSZ-Partially Stabilized Zirconia 13