IMPACT OF SPARK IGNITION TIMING ON POLLUTANTS OF MODIFIED COMBUSTION CHAMBER OF SI ENGINE

International Journal of Mechanical and Production Engineering Research and Development (IJMPERD) ISSN (P): 2249–6890; ISSN (E): 2249–8001 Vol. 10, Issue 3, Jun 2020, 1131-1138 © TJPR Pvt. Ltd.

IMPACT OF SPARK IGNITION TIMING ON POLLUTANTS OF MODIFIED COMBUSTION CHAMBER OF SI ENGINE NAGINI YARRAMSETTY1, MADDALI VS MURALIKRISHNA2 & S. NAGASARADA3 1

Assistant Professor, Chaitanya Bharathi Institute of Technology, Hyderabad, India 2

Professor, Chaitanya Bharathi Institute of Technology, Hyderabad, India

3

Professor, Jawaharlal Nehru Technological University Hyderabad, India

ABSTRACT The most important and prominent pollutants from Spark ignition engines are carbon monoxide (CO), un-burnt hydro carbon (UBHC) and nitrogen oxide levels (NOx). Inhalation of these pollutants from atmospheric air cause serious health disorders. To control these pollutants effectively and efficiently is the need of the automobile industry. Alcohols support in reducing the pollutants as their physical properties and chemical properties are nearer to neat gasoline. Experimentation is done on four stroke variable compression engine with copper coating (300 μ , thickness) on top surface of the piston, inside of the liner and cylinder head with gasohol (20% ethanol and 80% gasoline, by vol) as fuel and with varying ignition timing and found the pollution levels of CO, UBHC and NO x. CO and UBHC are controlled with Catalytic

reduced at optimum ignition timing in comparison with conventional engine with recommended ignition timing.

KEYWORDS: CE, CCE, Pollutants, Modified Catalytic Converter, Selective Catalytic Reduction Technique, Air Injection, Optimum Ignition Timing, Recommended Ignition Timing

Received: May 26, 2020; Accepted: Jun 16, 2020; Published: Jun 25, 2020; Paper Id.: IJMPERDJUN202097

Original Article

converter and NOx levels are controlled with selective catalytic reduction (SCR) technique. Pollution levels in CCE

INTRODUCTION In this world of enormous emerging developments in automobile industry, there is a great requirement to modify conventional spark ignition engine such that human, animal and plant life are protected from the large amounts of harmful pollutants released to atmosphere. The major contributing pollutants effecting the atmosphere are CO, UBHC and NOx, released from the SI engine. In order to reduce carbon monoxide (CO), Unburnt Hydrocarbons and Nitrogen Oxides (NOx) pollutants more effectively and efficiently many methods are tried like, combustion chamber modification, alcohols blended with neat gasoline and using modified catalytic converter attachment. Alcohols are found to be the best alternative fuel to neat gasoline as their properties are comparable to gasoline. Octane number for alcohols are higher than that of gasoline fuels.[1-3].Blending alcohol with neat gasoline has potential to decrease pollutants with a minimum modification of the engine.[4].Ethanol blended gasoline [neat gasoline blended with ethanol, 20%, by vol) showed considerable decrease in pollution levels when compared with neat gasoline on CE. [5-6]. Formation of carbon dioxide is due to incomplete combustion and UBHC is due to settlement of fuel in the crevices and comes out during exhaust stroke without participating in combustion which is called as quenching effect. They cause human health disorders like asthma, vomiting sensation, etc and effect the environment. Due to high temperatures and availability of oxygen, NOx is produced which also effect animal and plant life.[2,7 ].Catalytic converter supports potentially in effectively reducing pollutants in SI engines. [8-11].Combustion

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chamber modification with copper coating on the top surface of the piston, cylinder head and inside surface of liner showed considerable reduction in pollution.[12-13].In addition to blending of alcohols with neat gasoline, modification of combustion chamber and attaching of catalytic converter, advancing spark plug timing results in slowing down the generation of pollutants.[14-15].The control of NOx has been achieved by the improvements in the engine design and combustion chamber modification, such as retarded injection timing, turbo charging with inter cooling and exhaust gas recirculation. But most of these modifications resulted in increase of pollution by particulate emissions and deterioration of fuel economy. However, the selective catalytic reduction technique was recognized as most effective in reduction of NOx levels. The modified zeolites like lanthanum ion exchanged zeolites are cheaper and can reduce NOx over wide range of air-fuel ratios and temperatures.[16-17 ].

Little information is available on CCE with gasohol, coating on inside of liner of water cooled SI engine, with varied ignition timings, so author has made an attempt in this direction. Present paper presents pollutant levels of CO, UBHC with catalytic converter with sponge iron as catalyst and NOx levels with selective catalyst technique at optimum ignition timing on CCE using gasohol as fuel and compared with conventional engine at recommended ignition timing.

MATERIALS AND METHODS The schematic diagram shown in figure-1 is used for the experimental work. Gasoline and Gasohol are used as fuels in a four-stroke, single cylinder, water cooled variable compression ratio engine(3to9) connected with an eddy current dynamometer and an iron- constantan thermocouple is used to find exhaust gas temperature. Mass flow rates of air and fuel are measured with air-box and burette methods respectively. Speed of the engine varying from 2400 to 3000 rpm. In copper coated engine, top surface of the piston, cylinder head and inner surface of liner are coated with (300 μ thickness) copper by plasma spray gun. The coating strength can with stand for more than 50 h of operation [13]. CO and UBHC emissions in engine exhaust are measured with Netel Chromatograph analyzer. Nitrogen oxide levels were measured with NOx Analyzer. The catalyst was prepared by using zeolite and lanthanum ion salt. Ion exchange was done by stirring 500 grams of zeolite in a 2N solution of lanthanum (III) salt for 5-6 hours at 70-80oC. [18-19]. Ion exchanged zeolite was recovered by filtration and activated by calcinations in an oven at 400oC for 3 hours and was furnace cooled to retain mechanical properties. Modified zeolite (Catalyst-A) so obtained was placed in catalytic chamber which had a cylindrical shape with a diameter of 120 mm and length 600 mm. Infusion of urea on lanthanum exchanged zeolite (catalyst-B) was made by gravity feed dosing system. A nozzle was used to generate fine spray of urea solution into exhaust gas before it entered into catalytic chamber containing lanthanum exchanged zeolite. NOx emissions were controlled with use of different catalysts in both versions of the engine at peak load operation of the engine.

The manufacturer’s recommended ignition timing is 25obTDC. (before top dead centre). Ignition timing was varied by sensor method. The test fuels used in the experiment were neat gasoline and gasoline blended with 20% ethanol by volume.

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1. Engine 2. Power Measuring Device 3. Rheostat 4. Measuring Device of Discharge. 5. Pressure Measuring Device, 6. Chamber of Air, 7. Fuel Storage Facility, 8. Directional Valve, 9. Burette, 10. Temperature Sensor 11 Multi-Gas Analyzer, 12. Pressure Boost up Device, 13. Temperature Sensor for Coolant, 14. Flow Meter for Coolant 15.Ball Valve, 16. Rotometer 17. Chamber for Air and 18. Chamber with Oxidizer.

Figure 1: Experimental Set Up. The exhaust gas from the engine is made to pass through catalytic converter (figure-2) provided at exit of the engine. It is designed such that desired amount of air enters into it maintaining backpressure as constant. For three different operating conditions on a catalytic converter, experiments are done. First condition is not using catalytic converter (Set-A), second is using only catalytic converter (Set-B) and third is using both catalytic converter and extra air supply (Set-C).

Note: All dimensions are in mm.

1. Air Chamber, 2. Inlet for Air Chamber from the Engine, 3. Inlet for Air Chamber from the Compressor, 4.

Outlet for air Chamber, 5. Catalytic Chamber, 6. Intermediate-Cylinder, 7. Inner-Cylinder, 8.Outer Sheet, 9.Intermediate Sheet, 10. Inner Sheet, 11. Outlet for Exhaust Gases, 12. Provision to Deposit the Catalyst, and 13.

Insulation.

Figure 2: Details of Catalytic Converter.

RESULTS AND DISCUSSIONS Table 1 shows the optimum ignition timing with test fuels with different versions of the engine.

Table 1: Data of Optimum Ignition Timing Manufacturer’s Recommended Ignition Timing–25obTDC with Gasoline as Fuel Engine Fuel Optimum Ignition Timing in Version Degrees before Top Dead Centre CE Gasoline 28 CCE Gasoline 27 CE Gasohol 28 CCE Gasohol 27 www.tjprc.org

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Figure-3, presents bar chart showing the variation of carbon mono oxide (CO) emissions at full load with different versions of the engine at RIT and OIT with gasoline and gasohol. Assuming test fuel (gasoline) same and configuration of engine different, CCE with gasoline operation decreased CO emissions at full load by 19% at recommended injection timing (RIT) and 9% at optimum injection timing (OIT) in comparison with CE with gasoline operation. It is because copper acted as catalyst in combustion chamber, whereby facilitated effective combustion of fuel leading to formation of CO2 instead of CO. Similarly assuming test fuel (gasohol) same with varying configuration, CCE with gasohol operation decreased CO emissions at full load by 23% at RIT and 17% at OIT in comparison with CE with gasohol operation. This is because gasohol decreased CO emissions at full load when compared to neat gasoline operation, as fuel-cracking reactions were eliminated with ethanol.

From same figure-3, it is observed that CO emissions decreased with advanced ignition timing with both version of the combustion chamber. More utilization of oxygen and with increase of combustion period with advanced ignition timing have reduced CO emissions at full load.

Figure 3: Bar Chart Showing Variation of Carbon Monoxide (CO) Emissions at full Load.

Figure-4, presents bar chart showing the variation of un-burnt hydro carbons (UBHC) at full load with different versions of the engine at RIT and OIT with gasoline and gasohol as fuels. Considering test fuel same and configuration of the engine different CCE with gasoline operation decreased UBHC emissions at full load by 36% at RIT and 15% at OIT in comparison with CE with gasoline operation. Similarly CCE with gasohol operation decreased UBHC emissions at full load by 39% at RIT and 16% at OIT in comparison with CE with gasohol operation. CCE improved combustion with pronounced activity of copper, as copper is a good conductor of heat, leading to improve combustion and causing reduction of crevice volume and hence UBHC emissions.

From same figure-4, it is observed that, UBHC emissions followed the similar trends as CO emissions in CCE and CE with both test fuels. Increase of duration of combustion and complete utilization of oxygen improved combustion and thus reducing crevice volume and hence UBHC emissions.

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Figure 4: Bar Chart Showing Variation of un–Burnt Hydrocarbons (UBHC) at Full Load.

Table 2 shows data of pollution levels with SI engine provided with catalytic converter with sponge iron as catalyst with different operating conditions , Set-A (without catalytic converter and without air injection), Set-B (With catalytic converter and without air injection), Set-C (With catalytic converter and with air injection). Void ratio was maintained as 0.6, mass of catalyst was kept as 2kg, air flow rate was kept as 60 l/minute, for achieving maximum reduction efficiency of catalyst [8]. From table 2, it can be observed that CO emissions and UBHC emissions decreased considerably with catalytic operation in set-B with ethanol blended gasoline and further decrease in CO was pronounced with air injection with the same fuel. The effective combustion of the ethanol blended gasoline itself decreased CO emissions and UBHC emissions in both configurations of the engine. Set-C reduced pollution levels effectively with increased oxidation rate of reaction.

Table 2: Data of Pollution Levels at full Load with Catalytic Converter Pollutant Set Gasoline Ethanol Blend (EB) CE CCE CE CCE CO Emissions (%) RIT Set-A 3.7 3.0 3.0 2.3 OIT 2.0 2.2 2.1 1.5 RIT Set-B 2.2 1.8 1.8 1.4 OIT 1.7 1.3 1.3 0.9 RIT Set-C 1.1 0.9 0.9 0.7 OIT 0.9 0.7 0.7 0.5 UBHC Emissions (ppm) RIT Set-A 500 320 420 255 OIT 220 190 225 270 RIT Set-B 300 195 250 155 OIT 250 145 200 105 RIT Set-C 150 95 125 75 100 45 75 25 Figure-5, presents bar chart showing the variation of nitrogen oxide (NOx) levels at full load with different versions of the engine at RIT and OIT with gasoline and gasohol.

Assuming test fuel (gasoline) same and configurations of the engine as different, CCE with gasoline operation increased NOx emissions at full load by 20% at RIT and 16% at OIT in comparison with CE with gasoline operation.

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Similarly assuming gasohol same, CCE with gasohol increased NOx emissions at full load by 12% at RIT and 20% at OIT in comparison with CE with gasohol operation. However, CCE marginally increased NO x emissions with gasoline operation at recommended ignition timing, as combustion chamber was more hot but gasoline blended with ethanol reduced overall NOx levels effectively in comparison with neat gasoline because of high latent heat of vaporization of ethanol, reduced combustion temperatures leading to decrease in NOx levels.

From same figure-5, it is noted, with advanced ignition timing, NOx emissions increased with both versions of the engine with both test fuels. This is due to increase of resident timing and more availability of oxygen leading to increase of combustion temperatures and hence NOx emisisons.

Figure 5: Bar Chart Showing the Variation of Nitrogen Oxide Levels.

Table.3 presents data of nitrogen oxide levels with different versions of the engine with test fuels at RIT and OIT with the application of catalyst-A and Catalyst-B. Catalyst-A significantly reduced nitrogen oxide levels in both versions of the engine, with test fuels while catalyst-B further reduced nitrogen oxide levels due to absorption of temperatures by zeolite as zeolite has high surface area.

Ignition Timing in Degrees before Top Dead Center RIT(25)

OIT(27)

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Table 3: Data of NOx Emissions Operating CE Condition Gasoline Gasohol of Catalyst Without 200 180 catalyst With 160 140 Catalyst–A With 120 110 Catalyst–B Without catalyst With Catalyst–A With Catalyst-B

CCE Gasoline

Gasohol

240

200

190

160

150

130

--

---

330

290

---

---

275

230

---

---

220

195

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OIT(28)

Without catalyst With Catalyst–A With Catalyst–B

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290

250

---

---

240

200

---

---

195

160

---

---

CONCLUSIONS The optimum ignition timing was obtained with CE was 28 o bTDC while it was 27o bTDC with CCE with test fuels.

Engine with copper coated combustion chamber showed reduction of pollutants over CE with test fuels at recommended ignition timing and optimum ignition timing.

Based on Fuel 20E operation showed exhaust emissions like carbon monoxide, unburnt hydro carbons and nitrogen oxides reduced when compared with CE and CCE with petrol.

With Provision of Catalyst Set-B with sponge iron as oxidizer effectively decreased pollutants at OIT with petrol and 20E in comparison with Set-A with CE and CCE. Set-C operation at OIT reduced pollutants in comparison with Set-A with petrol and 20E with CE and CCE. Based on Spark Plug Ignition Timing At optimum ignition timing (OIT) exhaust emissions, like CO and HC reduced with petrol and 20E when compared with RIT for both CE and CCE. However, nitrogen oxide levels increased with advanced ignition timing for CE as well as CCE.

ACKNOWLEDGMENT Authors are thankful to the authorities of Chaitanya Bharathi Institute of technology for supporting us, to carry out the experimental work.

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