IJSRD - International Journal for Scientific Research & Development| Vol. 4, Issue 05, 2016 | ISSN (online): 2321-0613
Prediction of Exhaust Products from a Diesel Engine with Recirculated Exhaust Gas Cooled through CFD Simulated EGR Cooler Mr. Ibrahim Hussain Shah1 Dimpesh Silarpuriya2 1 Assistant Professor 2PG Student 1,2 Department of Mechanical Engineering 1,2 IET DAVV Indore Abstract— Demand of energy increases day by day and the major part of human life is depended on the energy, is fulfilled by non-renewable sources of energy. Fossil fuel like petrol and diesel are the major energy producer. When the combustion of this takes place than higher amount of energy is generated but we have to compromise with our health and our nature because of the major amount of hazardous gases and other matters produced which have negative impact on life cycle of human being and nature. So the key point is that we should try to overcome that problem with our great technological development and researches. In this paper an effort applied which is related with the diesel engine with Exhaust gas recirculation cooler and controls the particulate matter entitled due to the combustion of diesel fuel and affect of the particulate matter on Human concerns include effects on breathing and the respiratory system, damage to lung tissue, and premature death. Small particles penetrate deeply into sensitive parts of the lungs and can cause or worsen respiratory disease such as emphysema and bronchitis, and aggravate existing heart disease. In this work an experimental analysis is done on the diesel engine test rig attached with Exhaust gas recirculation cooler and some experimental data were collected. On the basis of that experimental Data models of EGR cooler were designed with their different Shell and tube geometry. And simulation is done on ANSYS 15.0. Key words: Exhaust Gas Recirculation Cooler (EGR), Number of Transfer Unit Method (NTU), Computation Fluid Dynamics (CFD), Heat Transfer (HT) I. INTRODUCTION The main objective of this paper is to predict NO X and soot deposition in the tubes of EGR cooler. Exhaust gas recirculation is an effective method for NOX control. The exhaust gases mainly consist of inert carbon dioxide, nitrogen and possess high specific heat. When recalculated to engine inlet, it can reduce oxygen concentration and act as a heat sink, this process reduces oxygen concentration and peak combustion temperature, which results in reduced NOX. EGR is one of the most effective techniques currently available for reducing NOX emissions in internal combustion engines [1]. The methods of soot deposition are Particle inception, Surface growth and Coalescence and agglomeration. Soot fouling is defined as the accumulation of particles on a heat transfer surface forming an insulating powdery layer on the tube surface of EGR cooler. Particle inception process probably consists of radical additions of small, probably aliphatic, hydrocarbons to larger aromatic molecules [8]. Surface growth is the process of adding mass to the surface of a nucleated soot particle, during surface growth, the hot reactive surface of the soot particles readily accepts gas-phase hydrocarbons, which appear to be mostly acetylenes [8]. This leads to an increase in soot mass, while
the number of particles remains constant. Surface growth continues as the particles move away from the primary reaction zone into cooler and less reactive regions, even where hydrocarbon concentrations are below the soot inception limit. Coalescence and agglomeration are both processes by which particles combine. Coalescence (sometimes called coagulation) occurs when particles collide and coalesce, thereby decreasing the number of particles and holding the combined mass of the two soot particles constant. During coalescence, two roughly spherically shaped particles combine to form a single spherically shaped particle. There is no specific method to control the formation of soot deposition but through the EGR technique we approach the tradeoff for NOX and soot formation [8]. We developed different models of EGR cooler on ANSYS 15.0. And through CFD simulation and combustion stoichiometry, prediction of different exhaust product especially NOx and soot for different models are predicted. [6] II. ENGINE SPECIFICATION Twin cylinder four stroke, vertical, water cooled diesel engine developing 10 H.P. (7.5 K W) at 1500 rpm. Lubricating oil – 20 w / 40. Lubricating Oil quantity required – 7 Litres [4] Dynamo meter swinging field alternator 230 V (1 ph) 6 KVA capacity coupled to the engine. [4] Type Four Stroke Injection Direct Dynamic engineering Engine manufacture equipment Cylinder 2 BoreĂ— stroke 200mm* 300mm Power/Engine Speed 7.5/1500 r.p.m (Rev/Minute) Compression ratio 16.5:1 Table 1: Engine Specification Form above data we calculate the mass flow rate and temperature of exhaust gas Mass flow rate = 0.002 kg/s Hot gases inlet temperature = 639 k Hot gases outlet temperature = 423 k III. DESIGN OF EGR COOLER A. Heat transfer rate from tubes of EGR Cooler đ?‘ž = 0.00749 ∗ 1.082 [340 − 115] =1.742 Kj/S
B. Mass Flow Rate of Gases đ?‘šđ?‘“ = đ?›ź ∗ đ??´đ?‘† ∗ đ?‘‰ [1] đ?‘šđ?‘“ = 1.194118 ∗ 2 ∗ 3.14 ∗ .005 ∗ .2 ∗ 1 = 0.00749 đ?‘˜đ?‘”/đ?‘
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Prediction of Exhaust Products from a Diesel Engine with Recirculated Exhaust Gas Cooled through CFD Simulated EGR Cooler (IJSRD/Vol. 4/Issue 05/2016/243)
C. Logarithmic Mean Temperature Difference LMTD = LMTD =
[(T3 −T1 )−(T4 −T2 )] (T −T1 ) } 4 −T2 )
Ln{(T3
[(340−38)−(115−79.9)] (340−38)
Ln{(115−79.9)}
[2] = 141[2]
D. Thermal Resistance đ?‘…đ?‘“ = đ??´đ?‘† ∗
đ??żđ?‘€đ?‘‡đ??ˇ đ?‘ž
= 6.28 ∗ 10−4 ∗ (
141 1.742
) = 0.051[2]
Both above model of EGR cooler prepared by CAD software solid works 15.0. And the solution of model 1 and model 2 determined by CFD simulation on ANSYS 15.0. V. SOLUTION WITH FLUENT A. Solution for Simple shell and tube with rectangular cross section fin EGR Cooler (Model 1) 1) Step -1 Import Geometry
E. Effectiveness of Exhaust Gas Recirculation Cooler đ?œ– = đ?‘ž/đ?‘?đ?‘šđ?‘–đ?‘› ∗ (đ?‘‡3 − đ?‘‡1 )= 0.719[1]
6. Thickness of soot layer
đ?œ•đ?‘“ = đ??ž ∗ đ?‘… = 0.024560 mm [9] Design parameter obtain from kern’s method and TEMA data book [3] S. Parameters Values No. 1 Number of transfer unit 1.67 2 Tube outer diameter d0 12.7 mm 3 Tube outer diameter di 10.3 mm 4 Tube thickness 1.2 mm Total Surface area of 5 1.1086 ∗ 10−3 đ?‘š2 tubes (A) 6 Numbers of tubes 6 7 Pitch of tubes 16 mm 8 Bundle diameter 49.97mm 9 Shell diameter 50.00 mm Table 2: Design Parameter
Fig. 3: Import geometry of Simple shell and tube with rectangular cross section fin EGR Cooler (Model 1) 2) Step - 2 Generation of Mesh
IV. MODELING OF EGR WITH PROPOSED RESULTS Modeling done with proposed results in the following ways ď€ Simple shell and tube with rectangular cross section fin EGR Cooler (Model 1) ď€ Simple stack with rectangular cross section wavy fin EGR Cooler (Model 2)
Fig. 4: Meshing of Simple shell and tube with rectangular cross section fin EGR Cooler (Model 1) 3) Step - 3 setup geometry and solution
A. Simple shell and tube with rectangular cross section fin EGR Cooler (Model 1)
Fig. 1: Exploded View of Simple shell and tube with rectangular cross section fin EGR Cooler (Model 1) B. Simple stack with Rectangular Cross Section Wavy fin EGR Cooler (Model 2)
Fig. 5: Temperature gradient of Simple shell and tube with rectangular cross section fin EGR Cooler (Model 1) S.no Parameters Temperatures 1 Gas inlet temperature 642 2 Gas outlet temperature 421 3 Water inlet temperature 318 4 Water outlet temperature 387 Table 3: Results of Model 1 4) Effectiveness for model 1 642−421 đ?œ–= = 68 % 642−318
Fig. 2: Simple stack with rectangular cross section wavy fin EGR Cooler (Model 2)
B. Simple stack with rectangular cross section wavy fin EGR Cooler (Model 2) Similarly above steps follow for model 2 and obtained following results
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Prediction of Exhaust Products from a Diesel Engine with Recirculated Exhaust Gas Cooled through CFD Simulated EGR Cooler (IJSRD/Vol. 4/Issue 05/2016/243)
2 3 4
Gas outlet temperature 410 Water inlet temperature 318 Water outlet temperature 438 Table 4: Results of Model 2 1) Effectiveness of Model 2 642−410 đ?œ–= = 71 % 642−318
VI. RESULTS AND COMPARISONS For above models applying chemical stoichiometry to determine different exhaust products and energy equation for flame temperature respectively for different percentage of EGR. Fig. 6: Temperature gradient of Simple stack with đ?‘š1đ?‘” đ?‘?đ?‘?1đ?‘” đ?‘‡1đ?‘” + đ?‘š2đ?‘Ž đ?‘?đ?‘?2đ?‘Ž đ?‘‡2đ?‘Ž = đ?‘š3đ?‘” đ?‘?đ?‘?3đ?‘” đ?‘‡3đ?‘” [5] rectangular cross section wavy fin EGR Cooler (Model 2) Following results obtained for respective models as s.no. Parameters Temperature shown in below table 1 Gas inlet temperature 642 Percentage of Flame Temperature CO2 CO NO PM EGR in (k) (Mole Fraction) (Mole Fraction) (Mole Fraction) (Mole Fraction) 10 1698 1.14*10-1 5.0*10-5 9.06*10-4 2.10*10-2 -1 -5 -4 20 1680 1.14*10 4.4*10 8.46*10 2.11*10-2 -1 -5 -4 30 1657 1.14*10 3.3*10 7.44*10 2.22*10-2 -1 -5 -4 40 1628 1.14*10 2.3*10 6.89*10 2.27*10-2 -1 -5 -4 50 1593 1.14*10 1.4*10 5.96*10 2.28*10-2 Table 5: Exhaust products for Model 1 Percentage of Flame temperature CO2 CO NO PM EGR in (k) (Mole Fraction) (mole fraction) (mole fraction) (mole fraction) 10 1692 1.14 *10-1 5.1 *10-5 8.86 *10-4 2.10 *10-2 -1 -5 -4 20 1669 1.14 *10 3.8 *10 8.11 *10 2.11 *10-2 -1 -5 30 1641 1.14 *10 2.7 *10 7.27 *10-4 2.12 *10-2 -1 -5 -4 40 1607 1.14 *10 1.7 *10 6.32 *10 2.13 *10-2 -1 -5 -4 50 1568 1.14 *10 1.0 *10 5.35 *10 2.14 *10-2 Table 6: Exhaust products for Model 2 Flame temperature with respect to percentage of Flame temperature and NOX formation curve for EGR curve shows that for these two models as below. Model 1 and Model 2 as follows
Fig. 7: EGR Curve It is clear from above curve minimum flame temperature obtained for Model 2. From Soot formation and percentage of EGR curve it is clear that formation of soot for model 2 is very less than the model 1
Fig. 8: EGR Curve
Fig. 9: EGR curve
Fig. 10: EGR curve It is clear that from above two curves the NOX generation in Model 2 is very less than Model 1. Above two models analyzed through combustion stoichiometric and we found that the exhaust products and
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Prediction of Exhaust Products from a Diesel Engine with Recirculated Exhaust Gas Cooled through CFD Simulated EGR Cooler (IJSRD/Vol. 4/Issue 05/2016/243)
different flame temperatures for simple shell and tube with rectangular fin type of EGR Cooler with 10 % EGR up to 50 % EGR with respect to reducing flame temperatures (1698 K to 1593 K). In this way exhaust products particularly NO and PM where in the range 9.60*10-4 mole fraction and 2.10*10-2 mole fraction at 10% of EGR similarly at 50% EGR it is going to 5.96 *10-4 mole fraction and 2.28 *10-2 mole fraction. It shows that with excessive EGR up to 50% Recirculation, PM Deposition increasing and NO production were decreasing. This calculation were done by taking the temperature of gas which is cooled in EGR cooler with simple shell and tube of geometry from temperature 642 K to 421 K. While using stack and rectangular wavy finned type of EGR cooler the gas temperature was reduced to 410 K. So the flame temperature inside the cylinder ranges (1692 K to 1568 K) In this way exhaust products particularly NO and PM where in the range 8.86*10-4 mole fraction and 2.10*10-2 mole fraction at 10% of EGR. Similarly at 50% EGR it is going to 5.35 *10 -4 mole fraction and 2.14 *10-2 mole fraction. It shows that with excessive EGR up to 50% Recirculation PM Deposition increasing and NO production were decreasing.
[9] HelgiFridriksson, BengtSund´en, Shahrokh Hajireza, Martin Tun´er “CFD Investigation of Heat Transfer in a Diesel Engine with Diesel and PPC Combustion Modes” Society of Automotive Engineers of Japan, vol.9,No.3 pp 175-177 Inc. JSAE 20119177, SAE 2011-01-1838, (2011) [10] Tarek M. Belal1, El Sayed et al. Investigating Diesel Engine Performance and Emissions Using CFD, Energy and Power Engineering, 2013, 5, 171-180
VII. CONCLUSION This calculation show that the. analysis for this twin cylinder four stroke direct injection type diesel engine the simple shell and tube rectangular cross section type of EGR cooler give only 68 % effectives whereas the stack type rectangular wavy fined type of EGR cooler give 71 % effectiveness with low amount of NO and PM production so these EGR cooler should be suggested for these engine. REFERENCES [1] J.B. Heywood, Internal Combustion Engine Fundamentals. McGraw-Hill, New York, 2011 [2] Mahesh M. Rathore, Engineering heat and mass transfer, University science press 2012 [3] TEMA, standards of the tubular Exchanger Manufacturer’s Association (TEMA), 8 th Edition, Section 1-5 pp 7-10, tubular Exchanger Manufacturers Association, Inc. New York, 1999. [4] User manuals of ‘Diesel Engine Test Rig’, provided by their manufacturer. [5] T. J. Wallington, E. W. Kaiser and J. T. Farrell Automotive fuels and internal combustion engines: a chemical perspective published as an Advance Article on the web 23rd January 2006 DOI: 10.1039/b410469 [6] Arjun Krishnan1, Vinay C. Sekar2 “Prediction of NOx reduction with Exhaust Gas Recirculation using the Flame Temperature Correlation Technique" Proceedings of the National Conference on Advances in Mechanical Engineering March 18–19, 2006 [7] Y.LIU,Y-T. ZHANG, T. QIU, X, DING Optimization research for a high pressure common rail diesel engine based on simulation International Journal of Automotive Technology, Vol. 11 No. 5 pp 625-636 (2010) [8] M.R. Malayeri,T-zornek, deposition of nano sized soot particle in various EGR cooler under thermophortic and isothermal condition, proceeding of international conference heat exchanger fouling and cleaning,(2011)
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