Development of In-Line Coldstart Emission Adsorber System (CSEAS) for Reducing Cold Start Emissions in 2 Stroke SI Engine Wing Commander M. Sekaran M.E. Professor, Department of Aeronautical Engineering, Vel Tech Dr RR & Dr SR Technical University, Avadi, Chennai 600062, INDIA. E-mail: sekaran.muthu@gmail.com Dr. S.Mohanamurugan M.E.,Ph.D Professor, Department of Mech Engineering, Velammal Engineering College, Ambattur, Chennai 600066, INDIA. E mail: sivallakshmi@yahoo.co.uk Abstract- Under normal operating conditions, catalytic converters appear to be the most effective means of reducing air pollution from SI engines. The conversion efficiency, however, declines very steeply for temperatures below about 350 C and is practically zero during the starting and warming-up period. Improving the conversion efficiency under these conditions is important, where the number of starting per vehicle per day tends to be high. An Cold-Start Emissions Adsorber System (CSEAS) for reducing cold-start emission (HC, NOx and CO) have been developed by combining existing catalyst technologies with a zeolite based Adsorber. The series flow in-line concept offers a passive and simplified alternative to other technologies by incorporating one additional existing converter with additional valving, purging lines and secondary air. The CSEAS reduced up to 100% of cold-start emissions beyond the three-way catalyst only base line system. The in-line CSEAS could be one of the potential technologies to meet EURO-V and future regulations without the need for ancillary electrically and its associated costs. Keywords- CO, Cold Start Emission, CSEAS, NOx I. INTRODUCTION As per the statistics available on hand, the volume of emission discharged per day is in the order of 43,000 tons of pollutants per day. 2 stroke engines are widely used than a 4 stroke engine because of the inherent advantages of better power to weight ratio. The serious disadvantage of two stroke engines is that it emit considerably high levels of unburned HC emissions.in addition the rate of post flame oxidation and exhaust oxidation are lower for 2 stroke engines due to low oxygen concentrations. The lower level of NOX emission is ascribed to the fact that the twostroke engine with carburetor runs on a very rich mixture. Catalytic converters are conducive for innocuous emissions. The catalytic technology is a proven and cost effective approach for reducing HC/CO emissions from 2 stroke and 4 stroke while maintaining the performance of the engine.the emission norms to be met by two wheelers are 2gm/Km for CO and 1.5gm/Km for HC and NO X. A. Formation of carbonmonoxide In principle the concentration of carbon monoxide contained in exhaust products represented by the water gas equation. 47.1
Wing Commander M. Sekaran and Dr. S. Mohanamurugan H 2 O + CO = H 2 + CO 2. At maximum flame temperature this equilibrium yields significant quantities of CO relative to CO 2 even for fuel lean mixture ratios. Thus, for fuel-lean or chemically correct mixture ratios however, due to the simple insufficiency of oxygen, significant concentrations of carbonmonoxide persist even in cool exhaust products. B. Formation of hydrocarbon emissions HC emissions rise rapidly as the mixture becomes substantially richer than stochiometric. When combustion quality deteriorates e.g. with very lean mixtures, HC emissions can rise rapidly due to incomplete combustion or misfire in a fraction of the engines operating cycles. II. CATALYTIC TECHNOLOGIES A. Oxidation catalysts There are two forms of catalyst placing namely, mesh type and the pellet type. The pellet type consists of a baffle container filled with the catalyst. As the exhaust gases pass through the pallets, they come in contact with the catalytic material. The pellets can often be changed without replacing the converter housing. The mesh type is cool that it occupies the entire converter volume. Carbonmonoxide in exhaust gases is combined with free atoms of oxygen to create to carbondioxide. Hydrocarbons are separated in to hydrogen and carbon and combined with oxygen to yield water and carbondioxide. The oxidation process is represented by the following chemical expression: Hydrocarbons: HC +O 2 CO 2 +H 2 O Carbondioxide: CO + O 2 CO 2. This chemical reaction explains why two gas emission analyzers cannot be used for tuning catalyst equipped engines. III. NECCESSITY OF NEW DESIGN In the existing catalytic converter very little diffusion takes place because of the flow separation at the interface of the pipe and catalytic converter. The term inlet header refers to the transition piece connecting the inlet pipe to the substrate cross section. The function of the inlet header is to diffuse the inlet flow, decreasing the dynamic head and converting as much of the jet kinetic energy as possible elevated pressure. A. Design calculations Diameter of the bend pipe = D 1 mm. Diameter of the converter = D 2 mm. Diffuser half angle = 30 degree. Space velocity = Exhaust gas flow rate / converter volume. The optimum value [3] of space velocity for two stroke engines ranges 73,000 per hour to 9,87,000 per hour. Adopt 1,20,000 per hour. Stroke of the engine (L) = 44 mm Diameter of the engine bore (D) = 47 mm. Maximum speed = 6000 rpm. Displacement of the engine= ( xdxdx L)/4 = 76.34 x10 6 m 3 Exhaust gas flow rate=displacementx V = 27.48 m 3 / hr. Converter volum = Exhaust gas flow rate / Space velocity. = 27.48 / 1,20,000. = 2.29 x 10 4 m 3 Converter volume = ( x D 2 2 x L 2 ) / 4 = 2.29 x 10 4 m 3 Put D 2 = 2D 1 We know that, D 1 = 30 mm. Length of the converter chamber = L 2 = 0.08099 m 8 cm. Diameter of the converter Chamber = D 2 = 6 cm. Thus the dimensions of the catalytic converter was obtained, as shown in Fig1. Special Issue of the International Journal of the Computer, the Internet and Management, Vol. 19 No. SP1, June, 2011 47.2
IV.EXPERIMENTAL INVESTIGATION The test engine consists of a throttling device using which the speed of the engine can be adjusted. The solex carburetor has been incorporated in the engine there is a provision for measuring the speed of the engine using a tachometer. Fig. 1 Exhaust Gas Pipe with Catalytic Converter There is a provision for measuring the outlet cooling water of the engine. An ambassador car catalytic converter is used. A battery is used to start the engine. An air compressor is used to provide secondary air injection during the experiment. A pressure gauge has been provided along with this. Fig. 2 Variation of CO vs. Time during Idling coated with. 47.3
Wing Commander M. Sekaran and Dr. S. Mohanamurugan Fig. 3 Variation of HC vs. Time during Idling coated with. Fig. 4 Variation of CO vs. Time during Full throttling coated with. Special Issue of the International Journal of the Computer, the Internet and Management, Vol. 19 No. SP1, June, 2011 47.4
Development of In-Line Coldstart Emission Adsorber System (CSEAS) for Reducing Cold Start Emissions in 2 Stroke SI Engine Fig. 5 Variation of HC vs. Time during Full throttling coated with. V. RESULTS AND DISCUSSIONS Experiments have been conducted with a catalytic converter using different metal oxides and results are discussed below: From Fig 2 and 3 variations of CO and HC Vs. time during idling are shown for different metallic oxides respectively. The emission increases gradually from zero and remains steady after few seconds. Regarding HC emissions Silver Oxide had a reduction of 25.69% and chromium oxide 17.31%, Nickel Chromium oxide and Nickel Oxide regarded a reduction of 22.9 and 18.43% respectively. In carbon monoxide emission tests Silver oxide has a good performance of 50% followed by Zinc with 41.66% while Nickel Oxide had a lowest conversion efficiency of 19.44% Fig 4 and 5 shows the deviations CO and HC during full throttling operations of the engine. The rate of emissions was more in full throttling. The maximum reduction of 16.31% was exhibited by silver oxide at the end of 30 seconds. Nickel Oxide has a low efficiency of 10.5%. With regards to CO emissions, it was reduced to a maximum of 1 % volume by Silver Oxide at the end of 27 th second. The lowest conversion efficiency of 10.9% was reported by Nickel chromium Oxide. 47.5