Sebuah Kajian Pustaka: JEMMME, Vol.2, No. 1, May 2017 ISSN 2541-6332 e-ISSN 2548-4281 JEMMME | Journal of Energy, Mechanical, Material, and Manufacturing Engineering 41 Spider Web Shape of Brass Catalytic Converter for Reducing Exhaust Gas Emission Roro Heni Hendaryatia and Ali Mokhtarb a,bDepartment of Mechanical Engineering, Faculty Of Engineering, University of Muhammadiyah Malang Jl. Raya Tlogomas No. 246, Malang, Indonesia Telp. (0341) 464318-128 Fax. (0341) 460782 e-mail: heni@umm.ac.id Abstract The rapid increase of the number of motor vehicles, especially motorcycles, makes serious problem caused by the pollution from gas emission of fossil fuel combustion. The problems related to human health and the erosion on ozone layer is credited to its gas emission. Several dangerous and toxic gasses such as Hydrocarbon (HC), Carbon Monoxide (CO), and Nitrogen Oxide (NOx), Sulphur Dioxide (SO2), and Lead (Pb) are emitted during IC engine operation. To manage those dangerous gasses, catalytic converter which converts the gasses into more eco-friendly CO2H2O and N2 may be employed. In this research, a specially designed catalytic converter made from brass (CuZn) wire in the form of spider web pattern was fitted into exhaust system of a standard motorcycle. The performance of the converter for several engine rotation speeds was examined by measuring CO and HC of exhaust by using Gas Analyzer. By comparing the exhaust of a standard exhaust system and modified exhaust system (fitted with converter), it can be concluded that the converter was able to decrease the exhaust emission gas. For HC content, the percentage of decrease was as much as 36,88 % for converter fitted exhaust system compared to 61.12% for standard one. For CO content, the decrease percentage was 19.90% compared to 80.10% for standard one. Keywords: spider web, brass, catalytic converter, gas emission 1. INTRODUCTION Motor vehicles are the main transportation mode in the modern era. In line with the more efficient of automotive industries make the production volume of motor vehicle becomes higher with cheaper prices. This condition makes motor vehicles become more affordable to the most people. As the results, the pollution caused by exhaust gas emission becomes dangerously higher. An internal combustion (IC) engine produce exhaust gas which typically comprised of Hydrocarbon (HC), Carbon Monoxide (CO), and Nitrogen Oxide (NOx), Sulphur Dioxide (SO2), and Lead (Pb). The most dangerous gas from the exhaust is CO as product of imperfect combustion which fatal to human when inhaled [1]. To reduce the risk of this dangerous gas, Environmental Sustainable Transportation (EST) program offered 12 programs or approaches to reduce the problem of air pollution, especially caused by transportation sector. One of the programs is to modify the exhaust system of motor vehicle by adding catalytic converter. The converter work is based on converting gas (such as CO) by oxidation process to friendlier CO2 by chemical reaction in a medium which has catalyst property [2]. For reducing gas pollution from exhaust gas mailto:heni@umm.ac.id JEMMME, Vol.2, No. 1, May 2017 ISSN 2541-6332 e-ISSN 2548-4281 JEMMME | Journal of Energy, Mechanical, Material, and Manufacturing Engineering 42 of IC engine, especially gasoline one, catalytic converter has also found its application [3]. Other techniques to reduce gas pollution in IC engine are modification of the IC Engine, fuels or combustion system, other than modification on the exhaust system [4]. Previous researches, showed that catalyst from Copper (Cu) and Brass (CuZn) could be employed to reduce the content of CO and HC from exhaust gas for range of engine rpm and number of catalyst cells. The several configuration of catalyst such as 12 (twelve) inline catalyst cells [5], perforated pipe of brass [6], and catalytic converter in shape of spider web made of Copper applied to Supra-X 125 motorcycle [7]. In other research, the effectiveness of substrate materials of catalyst, i.e. Brass, in reducing NOx for gasoline IC engine has been shown [8]. In this research, cheaper material (CuZn) was employed to filter the exhaust gas rather than using more expensive one such as Platinum (Pt) and Rhodium (Rh). CuZn is effective as converter as shown in above previous research. The solid CuZn in form of wire was employed as catalyst because its availability and versatility to employ for different shape. The spider web shape was employed with the consideration of good strength and filtering capability of the shape. 2. METHODOLOGY Specially designed catalytic converter as shown in Figure 2.1 was examined for its effectiveness in reducing dangerous gasses in exhaust of IC engine. The casing was designed in accordance with the shape of standard exhaust system of motorcycle. Also the inner diameter and thickness of casing wall followed the standard to maintain the functions of exhaust system as effective as standard one to dissipate heat and flow the exhaust. (a) (b) Figure 2.1 Casing of catalytic converter, a. Drawing, b. Actual. The catalytic converter was assembled from Brass (CuZn) wire with diameter of 0.8 mm and Copper (Cu) wire with diameter of 0.4 mm and takes the shape of spider web with 13 row of converter as depicted in Figure 2.2. (a) (b) Figure 2.2 Design of catalytic converter, a. Drawing, b. Actual. JEMMME, Vol.2, No. 1, May 2017 ISSN 2541-6332 e-ISSN 2548-4281 JEMMME | Journal of Energy, Mechanical, Material, and Manufacturing Engineering 43 The research has been carried out by employing experimental methods. The catalytic converter then was installed in motorcycle exhaust system. The contents of HC and CO were measured using Gas Analyser for standard exhaust system and catalytic converter installed one. The variables for the experiment were given in Table 2.1 below. The fuel for the research was PertaliteTM, and the research was executed by varying the engine rpm to several values. Variable response for the research was the content of exhaust gasses as measured by Gas Analyser. The flowchart of the research was given in Figure 2.3. Figure 2.3 Flowchart of the experiment of catalytic converter To execute the research, the experimental design was given in Table 2.1 below. It compared two exhaust systems, the standard one and catalytic converter installed one. The fuel for the experiment was PertaliteTM from Pertamina with 5 replications per cell. Start Finish Design of Catalytic Converter Preparation (Materials and Equipment) Manufacturing of Catalytic Converter Test of Catalytic Converter Installation of Gas Analyser Test of Standard Exhaust System Test of Catalytic Converter Exhaust System Data Extraction of Exhaust Gas Data Analysis Is Data Good? Conclusions JEMMME, Vol.2, No. 1, May 2017 ISSN 2541-6332 e-ISSN 2548-4281 JEMMME | Journal of Energy, Mechanical, Material, and Manufacturing Engineering 44 Table 2.1 Variables for the experiment Exhaust System Fuel Engine rpm 1500 2000 2500 3500 Standard Pertalite D111 D112 D113 D114 D115 D121 D122 D123 D124 D125 D131 D132 D133 D134 D135 D141 D142 D143 D144 D145 Spider web converter Pertalite D211 D212 D213 D214 D215 D221 D222 D223 D224 D225 D231 D232 D233 D234 D235 D241 D242 D243 D244 D245 The experimental runs were depicted in Figure 2.3 below and were taken on 9 January 2017 in Automotive Engineering Laboratory, State University of Malang. (a) (b) Figure 2.3 Experimental runs, a. Test stand, b. Gas analyser. The data measured for the experiment were content of HC, CO, CO2, and O2. 3. RESULT AND DISCUSSION The data of exhaust system content was depicted in Table 3.1 and Table 3.2 below. Table 3.1 Content of exhaust gas for standard exhaust system Engine rpm Data HC (ppm) CO (%) CO2 (%) O2 (%) 1500 average 214.4 2.978 3.66 14.84 2000 average 228.0 2.874 3.40 15.52 2500 average 251.8 2.430 2.86 16.28 3500 average 260.6 3.330 3.68 14.22 JEMMME, Vol.2, No. 1, May 2017 ISSN 2541-6332 e-ISSN 2548-4281 JEMMME | Journal of Energy, Mechanical, Material, and Manufacturing Engineering 45 Table 3.2 Content of exhaust gas for catalytic converter installed exhaust system Engine rpm Data HC (ppm) CO (%) CO2 (%) O2 (%) 1500 average 162.8 2.254 3.34 16.32 2000 average 263.2 1.448 1.94 18.12 2500 average 260.6 2.192 2.58 16.06 3500 average 265.8 2.950 3.28 14.90 After data on the contents of gasses have been acquired, the next step was to count the percentage of emission and percentage of emission reduction according to the Equation 1 and Equation 2. ๐‘ƒ๐‘’๐‘Ÿ๐‘๐‘’๐‘›๐‘ก๐‘Ž๐‘”๐‘’ ๐‘œ๐‘“ ๐‘’๐‘š๐‘–๐‘ ๐‘ ๐‘–๐‘œ๐‘› = ๐‘’๐‘š๐‘–๐‘ ๐‘ ๐‘–๐‘œ๐‘› ๐‘Ž๐‘ฃ๐‘’๐‘Ÿ๐‘Ž๐‘”๐‘’ ๐‘ค๐‘–๐‘กโ„Ž ๐‘๐‘Ž๐‘ก๐‘Ž๐‘™๐‘ฆ๐‘ ๐‘ก ๐‘’๐‘š๐‘–๐‘ ๐‘ ๐‘–๐‘œ๐‘› ๐‘Ž๐‘ฃ๐‘’๐‘Ÿ๐‘Ž๐‘”๐‘’ ๐‘ค๐‘–๐‘กโ„Ž ๐‘๐‘Ž๐‘ก๐‘Ž๐‘™๐‘ฆ๐‘ ๐‘ก ร— 100 % (1) and ๐‘ƒ๐‘’๐‘Ÿ๐‘๐‘’๐‘›๐‘ก๐‘Ž๐‘”๐‘’ ๐‘œ๐‘“ ๐‘’๐‘š๐‘–๐‘ ๐‘ ๐‘–๐‘œ๐‘› ๐‘Ÿ๐‘’๐‘‘๐‘ข๐‘๐‘ก๐‘–๐‘œ๐‘› = 100 โˆ’ ๐‘ƒ๐‘’๐‘Ÿ๐‘๐‘’๐‘›๐‘ก๐‘Ž๐‘”๐‘’ ๐‘œ๐‘“ ๐‘’๐‘š๐‘–๐‘ ๐‘ ๐‘–๐‘œ๐‘› (2) The results were presented in Table 3.3, Table 3.4, and Table 3.5 below. Table 3.3 Percentage of emission Exhaust System HC (ppm) CO (%) CO2 (%) O2 (%) Standard 238.7 2.903 3.400 15.215 Catalytic Converter 238.1 2.211 2.785 16.350 Value 99.75 76.16 81.91 107.00 Table 3.4 Percentage of emission reduction HC (ppm) CO (%) CO2 (%) O2 (%) 99.75 76.162 81.912 107 Value 0.25 23.837 18.088 -7 Table 3.5 Comparison of percentage of emission reduction Materials HC (ppm) CO (%) Brass 0.25 23.837 Copper 18.24 38.696 4. CONCLUSION From the research, the relationship between HC and engine rpm was depicted in Graphic 4.1. Graphic 4.1 Relationship between emission of HC and engine rpm JEMMME, Vol.2, No. 1, May 2017 ISSN 2541-6332 e-ISSN 2548-4281 JEMMME | Journal of Energy, Mechanical, Material, and Manufacturing Engineering 46 Reduction in HC emission for catalytic converter could be considered insignificant since only 0.25 ppm of reduction was achieved. This trend may be caused by the mechanism of combustion which unable to combust all available fuel (imperfect combustion) in combustion chamber or maybe misfire. Another cause may be there was failure/trouble in firing system such as bad plug or its wire, early combustion or low compression pressure. Also, from Graphic 4.1 it was shown that reduction of HC emission is not consistent since for 1500 rpm it decreased significantly from 214.4 ppm for standard exhaust system to 162.6 ppm for catalytic converter installed exhaust system. But, in higher rpm the trend of HC emission was always above the standard emission. In general, the catalytic converter converts HC into water (H2O) and carbon dioxide (CO2) thru oxidation process as follows: CH + C2 โ†’ H2O + CO2 (3) The surface contact of the catalyst gives activation energy to oxidate HC (hydrocarbon) into H2O (water) and CO2 so that reduction of CH is achieved. In this research, even though the content of CO2 of catalytic converter installed exhaust system is always lower than standard one but the measurement of HC showed the contradictions. It is an interesting one to be examined more in the next experiment. Graphic 4.2 Relationship between emission of CO and engine rpm Graphic 4.3 Relationship between emission of CO2 and engine rpm JEMMME, Vol.2, No. 1, May 2017 ISSN 2541-6332 e-ISSN 2548-4281 JEMMME | Journal of Energy, Mechanical, Material, and Manufacturing Engineering 47 The reduction of CO emission could be considered good with percentage of reduction reached 23.837%. The mechanism of CO reduction is as follows: 2 CO + O2 โ†’ 2 CO2 (4) The trend of reduction in CO was not following the smooth with lowest emission on 2000 rpm. This trend may be caused by non-homogenous mixture of fuel and air in IC engine test bed. The reduction of CO2 emission could be considered good with percentage of reduction reached 18.088%. The result also shows that the catalytic converter was able to convert CO into CO2 so that the emission of CO2 was better for every rpm. Graphic 4.4 Relationship between emission of O2 and engine rpm The reduction of O2 emission could be considered well with percentage of reduction reached -7.0% which means there was increase of O2 emission. This result was contrary to the theory of catalytic converter in which the oxidation process of HC (Equation 3) and CO (Equation 4) and there was a big possibility that the casing of exhaust system supply more O2 thru some unsealed surface (leaked). In general, the research has proven that the designed catalytic converter was able to reduce the dangerous gas such as CO in all rpm and to some extent the content of HC (on 1500 rpm). REFERENCES [1] Wardhana, W.A. Dampak Pencemaran Lingkungan. Yogyakarta: Penerbit Andi. 2004. [2] Dowden, D.A. et.al. Catalytic Hand Book. New York: Verlag, Inc. 1970. [3] Heisler, H. Advanced Engine Technology. London: Hodder Headline Group. 1995. [4] Mathur, S.L. Internal Combustion Engine. Second Edition. New York: McGraw-Hill Book Company, Inc. 1975. [5] Refkiandi, R. and Mokhtar, A. Catalytic Converter Jenis Tembaga dan Kuningan Berbentuk Plat Sejajar Susunan 12 Sel. Final Project. Malang: Undergraduate Program of Department of Mechanical Engineering UMM 2010. [6] Mokhtar, A. Catalytic Converter Jenis Katalis Pipa Kuningan Berlubang untuk Mengurangi Emisi Kendaraan Bermotor. Laporan Penelitian, Universitas Muhammadiyah Malang. 2012. JEMMME, Vol.2, No. 1, May 2017 ISSN 2541-6332 e-ISSN 2548-4281 JEMMME | Journal of Energy, Mechanical, Material, and Manufacturing Engineering 48 [7] Hafid, L. Catalytic Converter Berbahan Tembaga Berbentuk Sarang Laba-laba Pada Knalpot Supra-X 125 Untuk Mengurangi Emisi Gas Buang. Final Project. Malang: Undergraduate Program of Department of Mechanical Engineering UMM. 2016. [8] Irawan, B. and Subri, M. 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