International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 13, December 2018, pp. 192 202, Article ID: IJMET_09_13_020 Available online at http://www.iaeme.com/ijmet/issues.asp?jtype=ijmet&vtype=9&itype=13 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 IAEME Publication Scopus Indexed EXPERIMENTAL INVESTIGATION OF EMISSION CONTROL USING AG CATALYTIC CONVERTER IN A FOUR STOKE DIESEL ENGINE A. Dhanalakshmi and M.Suresh Faculty, Department of Mechanical Engineering, Sri Sairam Engineering College, West Tambaram, Chennai-600 044, India ABSTRACT Catalytic converters play a major role in automobiles which reduce the harmful gasses from engine exhaust significantly. The three way catalysts (TWCs) are widely used in automobiles for the past 25 years and are more successful (20). The aim of our work is to reduce the harmful gasses, by replacing conventionally used noble materials by comparatively cheaper and economically viable Silver (Ag). CATIA V5R15 software is used to create geometric model of our catalytic converter. To oxidise HC and CO, at a higher rate atmospheric air is injected inside the catalytic converter at constant pressure. The presence of oxygen in the exhaust gas helps to increase the oxidation process (13). This work is aimed to reduce harmful gases from diesel engine exhaust. Key Words: Diesel Engine, catalytic Convertor, Emission Cite this Article: A. Dhanalakshmi and M.Suresh, Experimental Investigation of Emission Control Using Ag Catalytic Converter in a Four Stoke Diesel Engine, International Journal of Mechanical Engineering and Technology, 9(13), 2018, pp. 192 202 http://www.iaeme.com/ijmet/issues.asp?jtype=ijmet&vtype=9&itype=13 1. INTRODUCTION Automotive catalyst technology to meet ultra-low emission vehicle (ULEV) emission levels for conventional diesel engine vehicles requires major improvements in catalytic activity and reactor engineering(6). A major challenge is in reducing vehicle cold-start emissions. ULEV emission levels can be exceeded in the first minute of the Federal Test Procedure (FTP) cold-start if the catalyst does not achieve its light-off temperature (9). To achieve these cold-start emission reductions, several approaches are actively being evaluated including electrically heated catalysts (1,3), fuel burners( 4,5) and hydrocarbon absorbers(6). Some of these techniques have demonstrated the ability to substantially reduce cold-start emissions; however, they also add substantial complexity and cost to the emission control system. Additional work has concentrated on the development of advanced catalyst technology based on high loading of palladium (7,8). These palladium catalysts have demonstrated improved warmed-up hydrocarbon activity and lower light- off temperatures compared to conventional platinum/rhodium catalysts. It must be http://www.iaeme.com/ijmet/index.asp 192 editor@iaeme.com
A. Dhanalakshmi and M.Suresh recognized; however, that automotive catalyst light-off during vehicle cold-start is a dynamic process dependent not only on catalyst activity but the transfer of exhaust gas heat to the catalyst surface and the thermal mass of the catalyst / substrate combination(9). A major limitation of conventional ceramic or metal monolithic automotive catalyst technology is the large thermal mass associated with the catalyst substrate (11). This results in a major delay in cold-start catalyst light-off times due to the large amount of exhaust energy required to heat the catalyst to reaction temperatures (10). The development of alternate catalyst/substrate technology with reduced thermal mass, high heat transfer rates and high catalyst activity could result in significant advancements in achieving emission levels at and below the ULEV standard. Conventional monolithic catalysts consist of metal or ceramic substrates having long flow channels, typically three to six inches in length, coated with a ceramic slip coat (wash coat) and a formulation containing precious metal catalysts. Automotive catalytic converter light-off occurs in a kinetically-limited regime, where catalyst surface temperature has an exponential effect upon reaction rate (9, 10). After full light-off, conventional catalytic converters operate at temperature conditions where the actual catalytic reaction rate is faster than the rate at which reactants can be transported to the surface, i.e. the reaction is mass transfer limited(12). The reduced reaction rates of conventional monolith reactors is the result of the development of a boundary layer along the walls in the monolith channels, which limits the rate of mass transfer. Such boundary layers become fully developed within five to ten channel diameters of the entrance (16, 17). The Microlith converter avoids such boundary layer limitation by replacing the long channels of a conventional converter with a series of short substrates, each short enough to avoid substantial boundary layer build-up. As a result, Microlith conversion rates as a function of converter length are much higher than conventional converters. The Microlith conversion rate is further enhanced through the use of high cell densities ( 388 cells per sq. cm), allowing a much higher catalyst geometric surface area (GSA) per unit volume up to four times that of a 62 cells per sq. cm ceramic monolith(18). The result is much higher conversion efficiencies than conventional monolithic catalysts with a smaller converter size. The smaller catalyst volume required for a given conversion also requires less precious metal alternatively, the same metal loading can be utilized to extend catalyst life. Use of less substrate material and less precious metal allow total costs to be below those of conventional designs. 2. EXPERIMENTAL SETUP AND METHODOLOGY 2.1. DESIGN ANALYSIS http://www.iaeme.com/ijmet/index.asp 193 editor@iaeme.com
Experimental Investigation of Emission Control Using Ag Catalytic Converter in a Four Stoke Diesel Engine 2.2. FABRICATION OF CATALYTIC CONVERTER 2.2.1. Fabrication of catalyst-1 Silver (Ag): A newly developed catalytic converter coated with silver (Ag) has a property to reduce the oxides of nitrogen (NOx) was fabricated. The surface of sheet metal was etched with the help of wood Nickel solution to get more efficient catalytic property. Silver (Ag) cannot be directly on stainless steel sheet directly. The flash coat was given which is electrolytic nickel, then over the flash coat silver coating was given for 2 microns thickness (19). http://www.iaeme.com/ijmet/index.asp 194 editor@iaeme.com
A. Dhanalakshmi and M.Suresh Chemical Reaction Figure 3 Silver Coated Catalyst 2NOX=N2+O2 2.2.2. Fabrication of catalyst-2 Platinum (Pt) & Palladium (Pd) The existing two way catalytic converter is coated with catalysts Platinum and Palladium (6). When the exhaust gasses sent through this catalyst, it oxidises the hydrocarbons and carbon monoxide to carbon dioxide and water (11). The picture of this catalyst has shown below. The reactions which are as follows, Figure 4 Existing Ceramic Substrate Chemical reaction CO+O=CO2 HC+O2=H2O+CO2 The outer shell was fabricated using 3mm thickness sheet and the welding was done by arc welding. The catalyst 1 shown in Fig. 3. Was fabricated by stainless steel sheet metal thickness of 0.1mm. One of the two sheets was punched in a zigzag design (7). The catalysts 2 was taken from the existing device of two way catalytic converter which has coating on the ceramic monolith. The air is supplied between the two substrates. By injecting air into the device, which helps to reduce the NOx and CO (14). http://www.iaeme.com/ijmet/index.asp 195 editor@iaeme.com
Experimental Investigation of Emission Control Using Ag Catalytic Converter in a Four Stoke Diesel Engine 2.3. ENGINE SETUP Specifications for the engine are listed below: Figure 5 Fabricated Catalytic Converter Table.1. Engine details http://www.iaeme.com/ijmet/index.asp 196 editor@iaeme.com
A. Dhanalakshmi and M.Suresh Figure 6 Experimental Setup The engine is equipped with a single 96 in.3 close-coupled catalytic converter with the inlet face of the catalyst 4 inches from the exhaust manifold flange. Prior to instrumentation and baseline testing, the engine was driven to stabilize the operation (6). The engine was fitted with a three-stage electronic air pump to provide air injection into the exhaust manifold during cold-start to provide an overall lean (excess air) environment to the catalyst during the engine rich cold-start condition for faster catalyst light-off(12). The pump is operated at 12 volts and a maximum current of 40 amperes. The maximum flow rate of the pump is 622 liter/min. A series of tests were conducted varying the air injection rate and injection time during cold-start (9). An injection rate of approximately 370 liters/min for 45-55 seconds was found to give optimum cold-start hydrocarbon (HC) and CO performance with a minimal negative impact on NOx emissions. The air pump and air distribution system is presented in Figure 1. Air is distributed to the exhaust manifold through a 2.54 cm diameter air rail. The air rail has four 6.35 mm diameter injection tubes. One injection tube is inserted into each of the four exhaust ports. AVL GAS ANALYSER The prototype converters prepared for testing are described below: Standard ceramic monolith catalytic converter for baseline testing - 1.6 liter 62 cells per cm 2 ceramic monolith Pd only formulation with 11.14 gm of Pd (11) Microlith /Monolith (cascade) in a single catalytic converter - 0.11 liter Microlith - 5.3/4.6/0.2 Pt/Pd/Rh formulation with 3.85 gm of platinum group metals - 1.6 liter 62 cells per cm 2 ceramic monolith Pd only formulation with 11.14 gm of Pd. The Microlith is mounted in the inlet of the catalytic converter. The monolith is mounted ½ inch behind the Microlith. http://www.iaeme.com/ijmet/index.asp 197 editor@iaeme.com
Experimental Investigation of Emission Control Using Ag Catalytic Converter in a Four Stoke Diesel Engine 3. RESULTS AND DISCUSSIONS Figure 7 AVL Gas Analyser 3.1 CARBON MONOXIDE The result of carbon monoxide has shown in figure 8. It is found that the catalytic converter which we designed has controlled the Carbon Monoxide better than the normal exhaust. Figure 8 Comparison of CO http://www.iaeme.com/ijmet/index.asp 198 editor@iaeme.com
A. Dhanalakshmi and M.Suresh 3.2. HYDRO CARBONS The result of HC has shown in Fig.9. It is found that the presence of HC in our developed catalytic converter has higher than the normal exhaust. But in 0% load, by supplying air in to the device reduced the HC level than the normal exhaust. Figure 9 Comparison of HC 3.3. OXIDES OF NITROGEN The result of NOX has shown in Fig.3. The newly developed catalytic converter reduces the NOX than the normal exhaust. Especially in full load condition, by supplying additional air which reduces the harmful gasses from the exhaust. Figure 10 Comparison of NOx http://www.iaeme.com/ijmet/index.asp 199 editor@iaeme.com
Experimental Investigation of Emission Control Using Ag Catalytic Converter in a Four Stoke Diesel Engine 3.4. CARBON DIOXIDE The result of CO2 analysis has shown in Fig.11. The presence of CO2 in the developed catalytic converter is less than the existing one. But without supplying air the presence is almost same as the existing device. Figure 11 Comparison of CO 2 3.5. SMOKE EMISSIONS The result of smoke test has shown in Fig. 12. The percentage of smoke in the newly developed catalytic converter is little more than the existing one. Figure 12 Comparison of smoke http://www.iaeme.com/ijmet/index.asp 200 editor@iaeme.com
A. Dhanalakshmi and M.Suresh 4. CONCLUSION The newly designed and fabricated Ag catalytic converter has been investigated. It is found that the carbon monoxide gets reduced from 0.08% to 0.01% in newly designed catalytic converter. The presence of HC in our device is higher than the existing device. But when supplying additional air into the device which reduces the HC level comparatively. It is found that the NOx has reduced from 1448 to 1167 ppm in full load condition. The percentage of oxygen has increased from our newly designed device s exhaust, by injecting constant pressure air into the device. By injecting air into the device, the presence of CO2 gets reduced. Without injecting air in to the device it is almost as same as the normal exhaust. The smoke percentage of our device is little more than the existing device. But the difference is very negligible. REFERENCES [1] Ammann, M -The three-way catalytic converter (TWC) -IEEE-6788999 - vol.3-2000pp1561-1566 [2] McKinley - Selective catalytic reduction (SCR)- SAE International Journal of Fuels and Lubricants- vol. 3-2011 [3] K Hirata - Pressure-loss reduction and velocity-profile improvement in a catalytic converter by a flow deflector- IJSME International Journal Series- - 2006-pp1206-1211 [4] S F Benjamin - Phosphorus deposition on a three-way catalyst under accelerated ageing conditions - Journal of Automobile Engineering-954407011414480-2012 [5] G Konstantas J. - Modelling three-way catalytic converters: An effort to predict the effect of precious metal loading-journal of Engg. Gas Turbines Power- 1.1787506-2004 [6] S Samuel - Real-world performance of catalytic converters- Journal of Automobile Engineering, Proceedings -2005 pp881-888 [7] S.J. Jeong - A three-dimensional numerical study of the effect of pulsating flow on conversion efficiency inside a catalytic converter- Journal of Automobile Engineering 09544070-2001 [8] I. P. Kandylas - Mathematical modelling of precious metals catalytic converters for diesel NOx reduction- Journal of Automobile Engineering - 279 292-1999 pp 279-292 [9] A N Karkanis - Emission reduction during cold start via catalyst surface control- Journal of Automotive Eng-2004 pp 1333-1340 [10] A. M. Stamatelos- Computer aided engineering in diesel exhaust after treatment systems design -Journal of Automobile Engineering - 09544070-1999. [11] M I Soumelidis- A chemically informed, control-oriented model of a three-way catalytic converter-journal of Automobile Engineering - 09544070JAUTO259-2007. [12] E.Korin - Reducing cold-start emission from internal combustion engines by means of a catalytic converter embedded in a phase-change material- Journal of Automobile Engineering-1999 pp 575-583. [13] PLS Muthaiah, Dr.M.Senthil Kumar, Dr.S.Sendilvelan - CFD Analysis of catalytic converter to reduce Particulate matter and achieve limited back pressure in Diesel Engine- Global journal of researches in Engineering- Vol 10-issue 5- Oct 2010. [14] Sivanandi Rajadurai et al - Wiremesh Substrates for Oxidation, TWC and SCR converters - ACS Industries Advanced Propulsion and Emission- 2006 http://www.iaeme.com/ijmet/index.asp 201 editor@iaeme.com
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