Review on Exhaust Back Pressure (EBP) and its Effects on CI Engine

Transcription

1 Review on Exhaust Back Pressure (EBP) and its Effects on CI Engine Mr. Prashant D. Dabhade 1,Prof. P. R.Kulkarni 2,Prof. R. S. Powar 3 1 PG research student, M.E.(Heat power Engg.) Dr.J. J. Magdum College of Engg. Jaysingpur 2 Head, Department of Mechanical Engg., Dr.J. J. Magdum College Of Engg., Jaysingpur 3 Associate Professor & Dean Academics,Department of Mechanical Engg.,Dr.J. J. Magdum College of Engg., Jaysingpur I. INTRODUCTION The survey of literature for diesel, CI Engines applications and there challenges to face emission control problems for respective fuel motivated to work for exhaust back pressure arising from emission control techniques. As we know that CI Engines are better power source due to higher compression ratio, higher efficiency, performance and reliability than SI Engines. Hence, in most of on-road transportation and off- road stationary applications, CI Engines are widely used [1]. However, all these versatile applications face a common and major challenge which is to meet present and future emission norms. The emissions from CI Engines have adverse effects on human health, living organisms, and environment. The major emission concerns for diesel engine are: unburned hydrocarbon (UHC), oxides of carbon (CO X ), oxides of nitrogen (NO X ), oxides of sulphur (SO X ), and solid carbon particulate matter (PM). Similarly, for biodiesel it was observed that HC, CO, CO 2 were lowered, while NO X remains still higher [5, 8-10]. II. Emissions from CI Engines To meet stringent emissions norms it is very important to know kinds of emissions exhausted from CI Engines, causes for emissions and their effective control technique for diesel, biodiesel CI Engines. Emissions may be divided into two group 1) Invisible emission and 2) Visible emission. Major emissions in exhaust gas are as follows 1. Invisible emission. a) Un-burnt hydro-carbon (HC) b) Oxides of carbon (CO X ) c) Oxides of sulphur. (SO X ) d) Oxides of nitrogen. (NO X ) 2. Visible emission a) Soot and Smoke (carbon particles) b) Particulates Major causes of emission are non-stichometric combustion, dissociation of nitrogen, and impurities/changes in fuel and air, of our concern last two causes are very important. The dissociation of nitrogen is due to nitrogen molecule present in atmosphere (fresh air), and in fuel. The dissociation takes place at higher temperature in combustion chamber. Mechanism of NOx formation we have discussed in next subtitle kinetics of NOx formation. The impurities from fuel, air, and their mixture lead to increase particulate matter. Also, invariable change in fuel and air ratio causes smoke [4]. Some of techniques for improving combustion efficiency and emission control comprises of direct injection, air to air inter cooling, swirl support, multivalve cylinder head, advanced high pressure injection system (split injection or rate shaping), electronic management system (EMS), lube oil consumption control and late injection of fuel [3].In order to reduce emissions after-treatment of exhaust gas as well as in-cylinder reduction of emissions are very important. In case of after treatment it consists mainly of thermal or Catalytic converters and particulate traps. For in-cylinder reduction of emission exhaust gas recirculation (EGR) and some fuel additives are effective for CI Engines [1]. Caution: Diesel engine causes emissions in the environment; some of them are harmful for human being. Further, Exhaust systems including catalytic converter, muffler and resonator in diesel engine reduce the engine emissions. Increase in exhaust back pressure decreases nitric oxide, due to the increased exhaust gas remaining in the cylinder. IJIRT INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 167

2 Hydrocarbon emissions are also reduced as exhaust back pressure is increased. However, long term application of the system causes significant effect on engine performance and emissions. Particulate matter and other exhaust product adhere with flow passage of exhaust systems and the passage is reduced and backpressure is building up on the engine. However, exhaustive study of back pressure in IC engine in view of merits and limitations is vital [9]. Publicly available literature on the effect of back pressure on diesel engines is limited, and it seems that there has been little work on addressing the problem. Still through review sheds light on causes and effects of EBP as discussed in next section 3 III. CAUSE AND EFFECT OF EBP Agrawal A. K., et al. [4] worked out an experimental investigation to observe effect of EGR on exhaust gas temperature and exhaust opacity in CI Engines. Matrix of experiments were conducted on two cylinders, DI, air cooled CI Engines. It was observed that, as EGR rate increases exhaust gas temperature decreases significantly. However, this result surely concludes that NOx can be decreased by increasing EGR rate. On other hand, BSFC and brake thermal efficiency were unaffected at part load and EGR rate of 15%. Peter Hield [7] examined the effect of increased back pressure on a turbocharged diesel engine using the Ricardo Wave engine modeling software, to gain understanding of the problem and provide a good base for future work on methods of improving engine performance. As the back pressure increases, the engine must work harder to pump the gases out of the cylinder against the higher pressure. The pressure ratios across the turbocharger compressor and turbine decrease, reducing the mass flow of air through these components and thus the air available to the engine. At the same time, the fuel flow must increase to provide the extra power necessary to overcome the increased pumping losses while maintaining a constant brake power output. As a result the brake specific fuel consumption increases above that for an engine operating in atmospheric conditions. Murari Mohon Roy, et al., [8] their study had investigated the effect of engine backpressure on the performance and emissions of a CI engine under different speed and load conditions. A 4-stroke single cylinder naturally aspirated direct injection (DI) diesel engine was used for the investigation with the backpressure of 0, 40, 60 and 80 mm of Hg at engine speed of 600, 950 and 1200 rpm. Two parameters were measured during the engine operation: one is engine performance (brake thermal efficiency and brake specific fuel consumption), and the other is the exhaust emissions (NOx, CO and odor). NOx and CO emission were measured by flue gas analyzer (IMR1400). The engine backpressure produced by the flow regulating valve in the exhaust line was measured by Hg (mercury) manometer. Domkundwar V.M., [9] Backpressure usually refers to the pressure exerted on a moving fluid by obstructions against its direction of flow. The average pressure in the exhaust pipe during the exhaust stroke is called the mean exhaust pressure and the atmospheric pressure is called the ambient pressure. The difference between these two pressures is defined as backpressure. Rabia S. M et al., (2010) [10] have put forth the effect of changing exhaust back pressure with variable intake valve timing on the engine performance fueled with gasoline. It was found that the fuel consumption decreased and engine performance improved. The validity of the simulation technique was checked by comparing its results with those from experimental results. The experiments were conducted on four cylinders, four stroke, 1300 cc gasoline engine. The engine modified to allow for controlling load by either LIVC or throttle. The effect of these parameters on fuel saving, residual gas, and volumetric efficiency was studied. The exhaust back pressure EBP 1.0, 0.8, 0.6, 0.4 bar was maintained for experimentation. Mohammad Joardder, et al., (2011) [12] investigated the effect of engine backpressure on the performance and emissions of a CI engine under different speed and load conditions. A single cylinder, 4-stroke, naturally aspirated, direct injection (DI) diesel engine was used. The backpressure of 0, 40, 60 and 80 mm of Hg were operated at engine speed of 600, 950 and 1200 rpm. The performance and emission characteristics were noted. The engine backpressure produced by the flow regulating valve in the exhaust line was measured by Hg (mercury) manometer. Deva Kumar., et al., [13] performed experimentation with the fuel injection pressure (160 bar to 200 bar in step of 20 bar variation) and different inclinations of intake manifold (300, 600, IJIRT INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 168

3 900 & normal,) were test conditions. The Kirloskar make, 5Hp, Single cylinder, DI, water cooled, 16.5:1 CR, Injection timing 280 btdc, was used for experimentations. It was observed that the better mechanical & volumertic efficiency at 600 manifold inclination at 160 bar. However, best indicated thermal efficiency of inlet Manifold with inclination of 900 at 180 bar. Also, very less emissions at intake manifold with inclination of 300 at 200 bar. Besides, very less NOx & CO2emissions at intake manifold with inclination of 600 at 180 bar. Felipe Castillo et al., [14] studied the exhaust manifold pressure estimation method for a Diesel engine equipped with a variable geometry turbine (VGT) turbocharger. Extrapolated VGT data-maps was directly used for the estimation of the exhaust pressure using a non-iterative Newton-Raphson based method suitable for real-time applications. It was quite differ from conventional methods & takes into account the turbine speed effect on the turbine mass flow rate. The results show the good agreement of the estimator with respect to the reference model. Karuppusamy P. et al., [15] discussed with the catalytic converter design and through CFD (Star CCM+ software) analysis. A compromise between two parameters namely, more filtration efficiency with limited back pressure was at focus of study. In CFD analysis, various models with different wire mesh grid size combinations were simulated using the appropriate boundary conditions and fluid properties specified to the system with suitable assumptions. The back pressure variations in various models and the flow of the gas in the substrate were discussed. Pangavhane S. D. et al., [16] explained that, backpressure is essential for the performance of a silencer. Pressure drop of exhaust system includes losses due to piping, silencer, and termination. The most critical component regarding backpressure of any commercial muffler is cross flow perforated tube in which the diameter of the perforated tube hole and porosity of the perforations are most critical. The effect of change in dimensions of perforation diameter and change in porosity of internal tube was investigated using CFD analysis and the simulated data was compared with experimental results. It was found that the porosity of the muffler has pronounced effect on the Backpressure. The Backpressure reduced almost by 75% if the porosity was doubled. Also, if the diameter of the hole increases the backpressure decreases sharply by 40%. The change in diameter of holes has remarkable effect on back pressure. It can be seen that the backpressure varies nonlinearly and it cannot be predicted by any equation. Desale S, et al., [17] experimentally investigated effect of back pressure on four cylinder CI engine. It was reported that, the excess exhaust back pressure increases fuel flow rate to meet constant speed requirement. Also, brake thermal efficiency was reported lower at higher backpressure rate. Further, volumetric efficiency was reported to lower due to increase in backpressure. This may be due to increase in intake throttle and resulting in increased pumping work reducing amount of fresh air. Patil Atul A., et al., [18] deals with the exhaust system designed and through CFD (Fluent) analysis, a compromise between two parameters namely, more maximization of brake thermal efficiency with limited back pressure was at focus. In CFD analysis, two exhaust diffuser system (EDS) models with different angels are simulated using the appropriate boundary conditions and fluid properties specified to the system with suitable assumptions. The back pressure variations in two models and the flow of the gas in the substrate are discussed. Finally, the model with limited backpressure was fabricated and Experiments are carried out on single cylinder four stroke diesel engine test rig with rope brake dynamometer. The performance of the engine and the exhaust diffuser systems are discussed. The increase in inlet cone angle increases the pressure of the flow which leads to reduce the recirculation zones. Installation of the EDS II increases the brake thermal efficiency and decreases the backpressure. Bornare Prashant et al., [19] studied backpressure phenomenon in case of compression ignition engines. The effective after treatment techniques utilization specifically for C.I. engines, was reported as requirement of critical analysis of the complete exhaust system employed. Search on After Treatment Devices (ATD) as a modern technology was noted as very crucial because particulate matter is designated as a major cancer material. The Backpressure acting on engine is most important factor which basically deteriorates the engine techniques in new technology, but also the older technology engines which are still on the road. IJIRT INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 169

4 Umesh K.S, et al., [20] conducted CFD analysis and experimental performance of exhaust manifold to study effect on volumetric efficiency of exhaust backpressure. From CFD analysis it was found that manifold geometry has a significant impact on the volumetric efficiency of the engine. It was concluded that the modified design gives better volumetric efficiency. The results of CFD analysis were subsequently proved by experimental analysis. Vivekanand Navadagi et al., [21] reported that, exhaust manifold is one of the critical components of IC engine for improving the volumetric efficiency. The volumetric efficiency of the engine can be increased by reducing the backpressure in the exhaust manifold. This work analyzes the flow through two different models of exhaust manifold using CFD. The design of exhaust manifold is modified to get optimal geometry. The analysis results of two models are compared for back pressure. By comparing the results of two models the decrease in back pressure is found which ensure improvement in volumetric efficiency of the engine. Rajesh Bisane, et al., [22] each after treatment system design should be done in such a way that considering the complete system objectives. Energy efficient exhaust system development requires minimum fuel consumption and maximum utilization of exhaust energy for reduction of the exhaust emissions and also for effective waste energy recovery system such as in turbocharger, heat pipe etc. from C.I. engine. Traditional manifold optimization has been based on tests on Exhaust system. Dipak D. Patil, et al., [23] exhaust system plays a vital role in reducing harmful gases, but the presence of after treatment systems increases the exhaust back pressure. To reduce the exhaust emissions from C.I. engines, it is very important to understand the overall effects of Devices installed in the exhaust system. Back pressure on engine is found as an important parameter having a strong influence on engine efficiency and it need to be minimized for maximum fuel efficiency. D. Tutunea et al., [24] The exhaust pollution has become one of the important problems of environment pollution with applications in automobile industry, and the exhausted muffler has been paid attention to improve the performance of engines. The author simulated the field by numerical method with Cosmos Flow and analyzed the effect which the internal flow field has on the performance of the muffler, which may be a credible guidance of the muffler structural design. With this method the pressure distribution in the muffler is simulated and the pressure loss is predicted for the structure modification. The experiment results verify that the assembly performance of the muffler modified is better than the original muffler. Ch. Indira Priyadarsini, [25] The paper deals with the fundamental understanding of complex processes taking place involving fluid flow, pressure, velocity profiles in the catalytic converter. The study of pressure contours and velocity vectors of fluid flow inside the catalytic converter are explained using numerical model. ANSYS Workbench 14.5 is been used for geometric modelling of catalytic converter. Domain discretization and analysis was carried out in Fluid Flow (Fluent). The substrate is modelled as porous. S.Rajadurai et al., [26] The paper summarizes a candid methodology of simulating a precise pressure drop analysis using computational fluid dynamics (CFD) for an exhaust muffler assembly having glass wool. The traditional CFD methodology does not consider glass wool because the pressure drop simulation with glass wool gives a deviation of 20-40% with experimental data due to inconsistent structure. A novel modeling approach is presented which includes the glass wool region as POROUS DOMAIN in exhaust muffler. Coefficient of porosity in glass wool is calculated from one dimensional gas simulation software - WAVE by Ricardo. Analysis is simulated using CFD code via Star CCM+ by CDAdapco. The simulated pressure drop results using CFD with glass wool are compared with those of the experimental data which are in very good agreement. IV. CONCLUSION The exhaustive review of literature on research for essentials of effects on engine back pressure, summarized below. It was noticed that, numerous work has been done on single cylinder, twin cylinder and multi cylinder CI Engines with CR: 16.5:1 max., rated power 7.5 kw and above, for engine speed rpm. Exhaust gas recirculation, emission control techniques have shed light on study of engine back pressure. However, very little work on same IJIRT INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 170

5 were found to be promising one. Further, most of work encompasses engine characteristics for repeated fuel (diesel) at single operating parameters of engine. REFERENCES [1] Mathur M. L., Sharma R. P., A course in internal combustion engines Dhanpat-Rai publications, ND, 15 th ed., (2005), pg. 3-9, [2] Ganesan V., Engine emission and their control, Internal combustion engines, McGraw Hill, ND, 3 rd ed., (2008), pg [3] Heywood J. B. Fundamental of Internal Combustion Engines McGraw Hill International Editions, Automotive Technology series, (1988) [4] Agrawal A. K., Singh S. K., Sinha S., Shukla M. K., Effect of EGR on exhaust gas temperature and exhaust opacity in CI engines, Sadhana vol. 29, part 3, (2004), pg [5] hp [6] Mayer, A., Number-based Emission Limits, VERT-DPF-Verification Procedure and Experience with 8,000 Retrofits, VERT, Switzerland, pg [7] Peter Hield et al., The effect of back pressure on the operation of a diesel engine, Defence Science & Technology Organization, DSTO- TR- 2011, Feb [8] Murari Mohon Roy, et al., Effect of Engine Backpressure on the Performance and Emissions of a CI Engine, The 7th Jordanian International Mechanical Engineering Conference (JIMEC 7) (2010), [9] Domkundwar, V.M., A Course in Internal Combustion Engine, Dhanpat Rai and CO. (P) Ltd., Pg NO. edition etc. [10] Rabia S. M., and M. Abd-El-Halim., Effect of valve timing and exhaust back pressure on the performance of gasoline engine, Journal of Engineering Sciences, Assiut University, Vol. 38, No. 3, (2010) [11] #q=exhaust+pressure+valve+removal [12] Mohammad Joardder, Md. Shazib Uddin and Murari Mohon Roy., Effect of engine backpressure on the performance and emissions of a ci engine, Proceedings of the International Conference on Mechanical Engineering, Dhaka, Bangladesh, ICME11-TH-013 (ICME2011), [13] Deva Kumar, Drakshayani S., Vijaya Kumar Reddy., Effect of fuel injection pressure on performance of single cylinder diesel engine at different intake manifold inclinations, International Journal of Engineering and Innovative Technology (IJEIT) Volume 2, Issue 4, (2012) [14] Felipe Castillo, Emmanuel Witrant, Vincent Talon, Exhaust Manifold Pressure Estimation Diesel Equipped with a VGT Turbocharger, SAE , (2013) 1-7. [15] Karuppusamy P., Dr. Senthil R. Design, analysis of flow characteristics of catalytic converter and effects of backpressure on engine performance, IJREAT International Journal of Research in Engineering & Advanced Technology, Volume 1, Issue 1, March, 2013 ISSN: [16] Pangavhane Sudarshan Dilip, Ubale Amol Bhimrao, Tandon Vikram A, Pangavhane Dilip R, Experimental and CFD Analysis of a Perforated Inner Pipe Muffler for the Prediction of Backpressure, International Journal of Engineering and Technology (IJET), ISSN : , Vol 5, No 5, Oct-Nov 2013, [17] Desale S, Patil Dipak, Arakerimath R. R., Effect of engine back pressure on performance of four cylinder engine, Int. Journal of Renewable Energy Development, IJRED ISSN: [18] Patil Atul A., Navale L.G., Patil V.S., Design, Analysis of Flow Characteristics of Exhaust System and Effect of Back Pressure on Engine Performance, International Journal of Engineering, Business and Enterprise Applications (IJEBEA), IJEBEA , 2014, [19] Bornare Prashant P. Dr. D. S. Deshmukh Prof. R.Y. Patil Experimental Investigation of Backpressure Variation on a Single Cylinder C. I. Engine System Performance, Pratibha: international journal of science, spirituality, business and technology (IJSSBT), Vol. 2, No. 2, May 2014, ISSN, [20] Umesh K.S, Pravin V.K, Rajagopal, CFD analysis and experimental verification of effect of IJIRT INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 171

6 manifold geometry on volumetric efficiency and back pressure for multi-cylinder SI engine, IJESR, July 2013, Vol-3, Issue-7, [21] Vivekanand Navadagi, Siddaveer Sangamad CFD Analysis of Exhaust Manifold of Multi- Cylinder Petrol Engine for Optimal Geometry to Reduce Back Pressure, International Journal of Engineering Research & Technology (IJERT), ISSN: , Vol. 3 Issue 3, March 2014 [22] Rajesh Bisane, Dhananjay katpatal, Experimental investigation & CFD analysis of single cylinder four stroke C.I. engine exhaust system, Volume: 03 Issue: 06, Jun-2014, IJRET: International Journal of Research in Engineering and Technology, ISSN: , [23] Dipak D. Patil, Sanjay Kumbhare, K. K. Thakur, CFD Analysis of Exhaust System and Effect of Back Pressure on Engine Performance, International Journal for Mechanical Engineering, VOL 1 ISSUE 1 September 2015 Paper 1 to 09. [24] Tutunea D., M.X. Calbureanu and M. Lungu, The computational fluid dynamics (CFD) study of fluid dynamics performances of a resistance muffler, International journal of mechanics, Issue 4, Volume 7, 2013, [25] Ch. Indira Priyadarsini, Flow in Catalytic Converter of Spark Ignition Engine with Air Box, International Journal of Scientific Engineering and Technology, ISSN : [26] S.Rajadurai, Suraj Sukumaran, P.Madhusudhanan, CFD Analysis for Flow through Glass Wool as Porous Domain in Exhaust Muffler, IJISET - International Journal of Innovative Science, Engineering & Technology, ISSN , Vol. 1 Issue 7, September IJIRT INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 172