International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 3, March 2013)

Effect Of Multiple Injections On The Performance And Emission Of Diesel Engine-A Review Study Nirav M. Bhatt1, Dr. Pravin P. Rathod2, Arvind S. Sorathiya3, Ramesh Patel4 1

PG-Student, Mechanical Engineering Department, Government Engineering College-Bhuj Associate professor Mechanical Engineering Department, Government Engineering College-Bhuj 4 Senior Manager-R&D Department, P.M. DIESELS PVT. LTD-Rajkot, Government Engineering College Bhuj (India) 1 Corresponding Author 2,3

There are several solutions that have been implemented in recent years to achieve this goal. Pollutant emissions and performance were continuously optimized by following methods,

Abstract— The effect of the fuel injection profile on diesel engine performance by using different multiple injection strategies have been described. Modern internal combustion engines must meet high emission standard including better performance and fuel economy. The combustion process in diesel engines is under constant analysis, and during the past decade has drawn increased interest, particularly due to the use of electronically controlled fuel injection systems that enable improved control of combustion in the engine. The effect of multiple injections on the performance and exhaust emissions in a diesel engine research results shows that, it is possible to increase the combustion efficiency, fuel economy under limiting value of exhaust emission and decreasing the combustion noise by multiple injection. This affects results from the enhanced heat release rate of the pilot injection fuel and lowering delay period in combustion cycle. The results show the reduction in emission of diesel engine, reduction in combustion noise, lower specific fuel consumption, increase in thermal efficiency and power.

1) Directly by improving diesel combustion A Exhaust gas recirculation(EGR) B By improving the injection system C By modifying the combustion chamber and piston head design 2) By implementing exhaust gas after treatment systems A Diesel particulate filters B Diesel oxidation catalysts or selective catalytic reduction systems 3) By combination thereof. Multiple injection of fuel find important stand in improvement of combustion process. This technique is used in modern I.C. engine through electronically operated fuel injection system. This paper will shows a comparative study of different researchers work on the bases of techniques, type of engine used, and operating point taken for test, type of fuel injection system used and finally result discussion of each investigation work.

Keywords— combustion noise, diesel engine, exhaust emissions, fuel injection system, heat release rate, multiple injection, pilot injection.

I. INTRODUCTION Nowadays, the reduction of emissions in Diesel engines by keeping or even improving their performance and fuel consumption is one of the most important challenges that designers are facing. A present conventional engine suffers from high degree of exhaust emissions, low specific power output and relatively high combustion noise.

II. LITERATURE REVIEW Following are the research works have been investigated in the field of multiple injection techniques in I.C engine. A review of fuel injection system of C.I. engine has been described in following chronological orders.

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Ye ar

Technique

Engine type and operating point

Fuel Injection system (1)Electroni cally controlled Common rail fuel injection system used for experiment.

Results

Tow al.

et

199 4

(1)Reducing particulate and NOx emissions in a heavy-duty directinjection engine. (2)A comparison was made between single injection, double injection and triple injection.

(1)Caterpillar 3406 Heavy-duty DI diesel engine. (2)The experiments were conducted at (a)1600 rpm with 75% load. (b)1600 rpm with 25% load.

Han al.

et

199 6

(1)The mechanisms of soot and NOx emission reduction investigated numerically by Han et al. (2)The combustion process was simulated with the KIVA-II code.

(1)Multipleinjection combustion predictions were obtained using a RNG k-ε turbulence model.

(1)Turbulen t combustion modal is made of experimenta l obtained data.

(1)Multiple injections break the soot-producing rich regions at the spray tip. The result is leaner combustion during the next injections. (2)It was found that NOx reduction with multiple injections is similar to retarded single injection.

Ikegami et al.

199 7

(1)An innovative fuel injection system design to study the effect of fuel injection rate shaping on exhaust emissions. (2)Ikegami demonstrated that the fuel injection rate has a significant influence in determining the quality of exhaust emissions.

(1)HSDI single cylinder diesel engine having a high-swirl deepbowl combustion chamber with displacement of 0.857 liters. (2)Experiments were carried out under two engine speeds: 900 and 1800 rpm under equivalence ratios: 0.64 (medium load), and 0.84 (high load.)

(1)A highpressure injection system with variable injection rate that relies on spool acceleration and oilhammering in the injection pipeline used.

(1)At 900 rpm: The lowest injection rate presents the highest smoke and HC values. The lowest NOx concentration is at the smallest pilot quantity and at a long injection interval. (2)At 1800prm: Present the same low rpm results and every factor changes drastically. (3)Pilot injection increases the smoke concentration due to a longer combustion period than with medium load (4)The results shows reduction of initial injection rate and pilot injection lowers both the exhaust NOx concentration and the noise emission, and that smoke is significantly reduced by increasing the average injection rate.

Nishimur a et al.

199 8

(1)The effect of fuel injection rate on combustion, emissions,

(1)Single cylinder naturally

(1)Common rail type

(1)The rate of heat release in pilot injection is smoother in

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(1)Double injection: - Particulate reduction by a factor of three, with no increase in NOx and only 2.5% increase in BSFC compared to single injection, were found at a 75% load. (2)Triple injection: {a} Particulate reduction by a factor of two with no increase in NOx and only a 1.5% increase in BSFC was found at a 75% load. {b}A 40% reduction in particulate, 16% reduction in NOx, lower rate of pressure rise, and 1% increase in BSFC were found at 25% load.

International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 3, March 2013) combustion noise and fuel consumption was studied by means of pilot injection and injection rate shaping, focusing on the start of combustion.

aspirated D.I. diesel engine.

fuel injection equipment was used in these experiments .

comparison to regular injection due to better ignition control with pilot ignition. (2)Pilot injection is a good strategy for reducing NOx and noise, but it can and should be optimized for better performance. (3)Injection pressure control is effective in reducing NOx and combustion noise, but it increases smoke due to poor mixture creation caused by slow initial combustion.

Schomm ers et al.

200 0

(1)DaimlerChrysler evaluate the potential of multiple injection systems, by distributor pump, unit injection system and Common Rail system. (2)The main objective of this study to analysis the effect of increased common rail pressure with different nozzle geometries on performance of engine.

(1)Singlecylinder diesel engine with EGR fitment used for testing. (2)Experiment is taken at full load condition, partial load conditions and low engine speed.

(1)Multiple injections done with use of common rail injection systems.

(1)At part load conditions significant benefits in NOx and smoke reduction with high EGR rate. (2)The smoke intensity decreases with high rail pressure and less hydraulic flow rate of the nozzle with no effect with NOx. (3)At high rail pressure there was a potential to reduce smoke emissions by 40 - 60 %.

M. Badami, F. Millo et al.

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(1)The main objective of investigation is to define effect of pilot injection timing and quantity on soot, NOx, combustion noise and fuel consumption has been analyzed on a passenger car.

(1)Four cylinders DI Diesel engine with EGR fitment used for test. (2)Operating points were 1500/5, 2000/2, 2500/8 rpm/bar For each operating conditions, the pilot injection quantity was varied up to 15% of the total quantity and the pilot injection timing was varied between 32° and 1° crank angle degrees.

(1)Engine test rig equipped with a common rail fuel injection system.

(1)If the combustion energy of the pilot injection is increased with higher quantities result into high pressure and temperature in the combustion chamber before the main injection which result into NOx production increases. (2)Soot increases and combustion noise is reduced due to the reduction of the premixed phase.

Benajes, Molina et al.

200 1

(1)The main objective of study on the influence of pre and postinjection on the development of the combustion process and on engine efficiency and pollutant

(1)Experiment tests were performed with a heavy-duty 1.8 litre single-

(1) Electrically operated common rail

(1)By a pre-injection strategy it has been possible to reduce the fuel consumption with little soot penalty but causing an increase in NOx levels in most engine

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International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 3, March 2013) emissions. (2)The investigation combines study of performance and emissions measurements together with heat release analysis. (3)For each cycle, the fuel quantity of the pre- and postinjection has been varied between 12 and 20 mg/stroke, and the delay between pre- and post-injection respect to the main injection has been also modified.

cylinder diesel engine. (2)The experiments were conducted under four engineoperating conditions from the European Steady state test Cycle (ESC).

injection system used for multiple injections.

modes. (2)With post-injection have been shows to be efficient in soot reduction without NOx emission and fuel consumption penalty. (3)For low loads, pre-injection timing and quantity have a great impact on NOx and soot concentration. (4)For post-injection, deterioration in fuel consumption is observed when post-injection fuel quantities increase. (5)Soot concentration drops when post-injection are implemented

F. Millo, M. Badami et al.

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(1)The objective of this study is to find out the potential of the application of the Common Rail system to a small non-road Diesel engine. (2)There are four strategy are tested on DI engine as main injection, single pilot injection, double pilot injection and after injection.

(1)Four stroke two cylinders DI diesel with Common Rail system used for test. (2)In this test 1st and the 5th modes of the ISO 8178 – C1 cycle were considered during the experimental tests.

(1)Electroni cally operated common rail injection system used for test. (2) Common rail pressure was limited to 700 bar.

(1)This study found that the use of multiple injections can be very effective in reducing PM and combustion noise without increasing fuel consumption. (2)The main effect of the single pilot and double pilot injections proved to be a reduction in combustion noise because the rise in pressure during the main combustion is slower and also NOx is lower. (3)The After injection was found to be very useful in completing the oxidation processes which result reducing the particulate emissions.

Badami, Mallamo et al.

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(1)The aim of this study is to develop a better understanding of multiple injection strategies, the combustion and emission formation process. (2)In this study pilot-pilot-main and pilot-main-after multiple injection strategies have been analyzed to display their effect on the soot, NOx combustion noise and brake specific fuel consumption of a passenger car. (3)Different pilot injection advances and after injection quantities and positions were studied.

(1)Passenger car DI diesel engine used for test. (2)There are two strategies were investigated, the pilot-pilot-main and the pilotmain-after at three different engine operating points.

(1)Electroni cally operated common rail injection system used for multiple injections.

(1)The pilot-pilot-main strategy can be more effective in reducing combustion noise and fuel consumption than double injection strategy, but there is increasing values of emissions. (2)The pilot-main-after strategy can be most effective in decreasing soot, but the timing must be carefully selected. (3) Effect of pressure waves in the rail and the injection pipes can change the characteristics of the multiple injections showed by rail pressure analysis.

Hotta, Inayoshi

200 5

(1)This shows

(1) cylinder

(1)Common rail fuel

(1)For medium load conditions, dividing the early injection into a

experimental study effect of multiple

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Single high

International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 3, March 2013) et al.

injections on exhaust emission and performance in HSDI diesel engine. (2)The research was conducted on a single-cylinder engine coupled with a supercharger and EGR system. (3)This study investigated the following injection strategies: early pilot injection, close pilot injection and after-injection.

speed direct injection diesel engine used for test. (2) This study performed on low, medium and high load with different engine speed and pilot fuel quantity.

injection system used for multiple injections.

series of smaller injections can decrease combustion noise. (2)Dividing the early injection reduces the amount of fuel adhering to the cylinder wall (3)Under light load and low speed conditions, early pilot injection increases HC significantly with decrease in smoke emission. (4)Result shows quantity of the pilot injection must be less than 1 mm3/stroke in order to suppress NOx increase. (5)In case of After-injection reduction in smoke, HC and fuel consumption is observed.

Hardy and Reitz

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(1)This study investigated partially premixed combustion strategies using multiple injections in a heavy-duty diesel engine. (2)The investigated parameters were: start of pilot injection, pilot duration, start of main injection, pilot main and afterinjection strategy and double pilot with main and after injection strategy. (3)Multiple injection strategies in this study changed the combustion mode in the cylinder by means of increasing the premix combustion phase and decreasing the diffusive combustion phase.

(1)Singlecylinder heavyduty Caterpillar SCOTE 3401E engine coupled with intake boost pressure, exhaust back pressure and EGR systems used for tests. (2)The engine was operated at a medium load (57%) and high speed (1737 rpm) operation point.

(1)The engine was equipped with an electronicall y operated caterpillar 300B HEUI fuel injection system which capable of up to four injections.

(1)Earlier pilot injection results in a decrease in NOx and HC and increase with particulates, carbon monoxide and bsfc. (2)Increased pilot duration shows decrease in bsfc, and no significant change in CO, particulates, NOx, or HC. (3)Earlier main injection results in a decrease in CO, bsfc and particulates with increase in NOx and HC. (4)Pilot main and after-injection strategy compared to the pilot main strategy shows decrease in emissions.

Carrlucci et al.

200 6

(1)This study investigated early injection strategies as a tool for changing combustion in diesel engines. (2)This study main focused on the pilot and main, early and main, early pilot and main injection strategies.

(1)4-cylinder DI diesel engine with a supercharger used for tests. (2)Operating conditions are low load 5 Nm and speed 900 rpm, medium load 32 Nm and speed 1400 rpm and high load 80 Nm and speed 2000 rpm.

(1)Common rail fuel injection system with solenoid injectors used.

(1)For medium load the early pilot main strategy with the longest injection interval and retarded main injection gives NOx emissions are lowest, bsfc is slightly higher, and opacity values are very close to the lowest achieved value. (2)For high load, the pilot main strategy showed the best result, and for the low load conditions the early main strategy showed the best results.

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International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 3, March 2013) Ehleskog et al.

200 7

(1)This study investigates effects of multiple injections on exhaust emissions from HSDI diesel engine. (2)In this study the main injection was split into two, three and four pulses were tested and emissions of NOx, CO, HC and PM along with torque and cylinder pressures were compared with single injections data. (3)Investigation performs also with the number of injections, the effects of varying the dwell time.

(1)Single cylinder high speed direct injection research engine used for experiment.

(1)Electroni cally operated fuel injection system used for multiple injection.

(1)It was found that dividing the main injection into two parts lowered the PM and CO emissions and increased fuel efficiency and NOx emissions. (2)By using double injection strategies reduced the peak rate of heat release and increased heat release in the later stages of the combustion without changing the combustion duration. (3) When the number of injections was increased to three or four, NOx emissions was reduced but increases emissions of particulate matter, CO and HC.

F. Payri et al.

201 0

(1)This investigation relates to better understanding of the behavior and stability of the combustion in a low compression ratio (15:1) DI Diesel engine, when multiple injection strategies are applied for idling conditions (900 rpm) just after starting the engine at low temperature. (2)In this work first study was focused on combustion characterization and the second on combustion stability.

(1)4 stroke single cylinder DI Diesel engine with a swept volume of 0.365 used for test. (2)Two injection strategies were used: strategy A (one pilot + main injection) and strategy B (two pilots and main injection).

(1)High pressure two common rail fuel injection systems and a very short hp pipe used.

(1)Multiple injections improve the combustion stability after start was evident. (2)This study found total heat released increased, when a larger pilot injection mass (5 mg/st) was divide in two medium pilot injections. (3)Pre-combustion due the second pilot improved the conversion efficiency, the total heat release increased and, imep increased as well.

T. Thurnhe er et al.

201 1

(1)This research was carried out to investigate different injection strategies on a heavy-duty diesel engine with specific pilot/main, post/main and single main injection strategies were considered. (2)In this study engine speed, load, EGR rate and relative air/fuel ratio were held constant, whereas pilot and post injection fuel masses and injection timings were varied.

(1)Four stroke six cylinder heavy duty diesel engines with EGR and turbo charger fitment used for test.

(1)Common rail injection system with pressureamplified attachment used for experiments .

(1)Results shows fuel conversion efficiency is decreased with increasing pilot injection advance. (2)NOx emissions are increased with pilot injection compared to the reference point. (3)With the smaller amount of pilot fuel mass both soot and PM decreased below the reference level. (4)The 19 crank angle BTDC main injection timing leads to the most optimal centre of combustion. (5) Post injection timing and mass does not affects the centre of combustion and the peak HRR. (6)The exhaust temperature is increased with post injection.

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International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 3, March 2013) REFERENCES

III. CONCLUSION

[1 ] Tow, T. C., D. A. Pierpont, et al. (1994). ―Reducing Particulate and Nox emissions by using multiple injections in a heavy duty D.I. diesel engine.‖ SAE paper 940897: 201-215. [2 ] Han, Z., A. Uludogan, et al. (1996). ―Mechanism of soot and NOx emission reduction using multiple-injection in diesel engine.‖ SAE paper 960633: 87-102. [3 ] Ikegami, M., K. Nakatani, et al. (1997). ―Fuel injection rate shaping and its effect on exhaust emissions in a direct-injection diesel engine using a spool acceleration type injection system.‖ SAE paper 970347: 524-535. [4 ] Nishimura, T., K. Satoh, et al. (1998). ―Effects of fuel injection rate on combustion and emission in a DI diesel engine.‖ SAE paper 981929: 1894-1900. [5 ] Schommers, J., F. Duvinage, et al. (2000). ―Potential of common rail injection system for passenger car DI diesel engines.‖ SAE paper 2000-01-0944: 1030-1036. [6 ] Badami, M., F. Mallamo, et al. (2003). ―Experimental investigation on the effect of multiple injection strategies on emissions, noise and brake specific fuel consumption of an automotive direct injection common-rail diesel engine.‖ International journal of engine research 4(4): 299-314. [7 ] Desantes, J. M., J. Benajes, et al. (2004). ―The modification of the fuel injection rate in heavy-duty diesel engines. Part 2: Effects on combustion.‖ Applied Thermal Engineering 24(17-18): 27012714. [8 ] Hotta, Y., M. Inayoshi, et al. (2005). ―Achieving lower exhaust emissions and better performance in a HSDI diesel engine with multiple injections.‖ SAE paper 2005-01-0928: 883-897. [9 ] Hardy, W. and Reitz, R., ―An Experimental Investigation of Partially Premixed Combustion Strategies Using Multiple Injections in a Heavy-Duty Diesel Engine‖ SAE Technical Paper 2006-01-0917, 2006, doi: 10.4271/2006-01-0917. [10 ] Carlucci, A.P, A. Ficarela, and D. Laforgia (2006) ―Control of the combustion behavior in a diesel engine using early injection and gas addition‖. Applied Thermal Engineering 26(17-18): 22792286 [11 ] Ehleskog, R, R, Ochoterena, et al. (2007). ―Effects of Multiple Injections on Engine-Out Emission Levels Including Particulate Mass from an HSDI Diesel Engine‖ SAE paper 2007-01-0910 [12 ] F. Payri, A. Broatch, J.M. Salavert, J. Martín, ―Investigation of Diesel combustion using multiple injection strategies for idling after cold start of passenger-car engines‖, Experimental Thermal and Fluid Science 34 (2010) 857–865 [13 ] T. Thurnheer, D. Edenhauser, P. Soltic, D. Schreiber, P. Kirchen, A. Sankowski ―Experimental investigation on different injection strategies in a heavy-duty diesel engine: Emissions and loss analysis‖,Energy Conversion and Management 52 (2011) 457– 467 [14 ] Desantes, J. M., J. Benajes, et al. (2004). ―The modification of the fuel injection rate in heavy-duty diesel engines. Part 1: Effects on engine performance and emissions.‖ Applied Thermal Engineering 24(17-18): 2701-2714.

From the study of multiple injection system in C.I. engine it is found that,  Split injection technique may decrease exhaust NOx considerably, providing the ability to divide heat release into several sections, decrease flame temperature and thus decrease NOx formation.  Proper dwell time must be maintained between the two successive injections to ensure proper combustion process.  Proper use of fuel amount and dwell time of first injection would enable better control over the ignition delay time and the heat release rate of the successive combustion event.  Large first injection may result in high temperatures, which enhance soot formation. The second injection should be large enough to enable proper oxidation.  Time between injections should be adjusted in order to enable proper ignition delay time for the second injection and to enable vaporization and mixing of the fuel.  Larger first injection and higher fuel injection pressure increase mean cylinder pressure and engine efficiency. ABBREVIATION BMEP BSEC BSFC BTHE CA CI ENGINE CO CO2 HC NOX NO2 DI ENGINE HC HSDI ECM CC PPM RPM TDC BDC ATDC BTDC CR EGR

Brake mean effective pressure Brake Specific Energy Consumption Brake Specific Fuel Consumption Brake Thermal Efficiency Crank Angle Compression Ignition Engine Carbon Monoxide Carbon Dioxide Hydrocarbons Oxides of Nitrogen Nitrogen Dioxide Direct Injection Engine Hydrocarbon High speed direct injection Electronic Control Module Cubic Centimeter Particles Per Million Revolutions per Minute Top Dead Center Bottom Dead Center After Top Dead Center Before Top Dead Center Compression Ratio Exhaust Gas Recirculation

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