A study and analysis on hcci engines


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A study and analysis on hcci engines

  1. 1. INTERNATIONAL JOURNAL OF Issue 3, Sep- Dec (2012) © IAEME 0976 – International Journal of Mechanical Engineering and Technology (IJMET), ISSN 6340(Print), ISSN 0976 – 6359(Online) Volume 3, MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET)ISSN 0976 – 6340 (Print)ISSN 0976 – 6359 (Online) IJMETVolume 3, Issue 3, September - December (2012), pp.545-554© IAEME: www.iaeme.com/ijmet.aspJournal Impact Factor (2012): 3.8071 (Calculated by GISI) ©IAEMEwww.jifactor.com A STUDY AND ANALYSIS ON HCCI ENGINES INLET VALVE Chitthaarth.M.R (1), Charles DhonyNaveen.I.A (2), Sunil Kumar.G (3),Dr.K.Manivannan(4) School of mechanical and building science, VIT university, Vellore-632014, TamilNadu, India. Chitthaarth.m.r@gmail.com: +919677915050 ABSTRACT The paper deals with the redesigning of the typical inlet valve in the HCCI**engine , which involves innovative designing and new material composition. We have done the analysis of this redesigned inlet valve using advanced CAD packages and the results proves the improvement in overall performance of the component, its working life and its capacity of efficient thermal conductivity. KEYWORDS: Inlet valve, HCCI engine **Homogeneous charge compression ignition engine INTRODUCTION: At present everyone needs their automotive is to be fuel efficient and exit lessemission now. This has led to the surface of an old idea as a new one. HCCI (homogeneous charged compression ignition). Earlier this technology had lot of hindrance but now with advance sophisticated computer improvement this has been made possible and the problem solved for the betterment of the world. So HCCI as stated above its acronym means homogeneous charged compression ignition. It’s the combination of both conventional spark-ignition and diesel compression ignition technology. The engine has a high compression ratio than the other two types of engines. As the HCCI engine is concept engine, we have selected the inlet valve component as our study and analysis. We have views in the component hopping to develop the existing material composition and some design factors which could help in increasing the efficiency and the performance of the engine, and also the component’s life. So through this study, we brought a brief explanation of the development of the inlet valve, which could be more efficient and have a better life time by reducing the wear and tear in the valve contacting surface. 545
  2. 2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEMELITERATURE SURVEY: The Homogeneous Charge Compression Ignition (HCCI) engine has attracted much interestin recent years because it can simultaneously achieve high efficiency and low emissions. However, itis difficult to control the ignition timing with this type of engine because it has no physical ignitionmechanism. Varying the amount of fuel supplied changes the operating load and the ignition timingalso changes simultaneously. The HCCI combustion process also has the problem that combustionproceeds too rapidly. This study examined the possibility of separating ignition timing control andload control using an HCCI engine that was operated on blended test fuels of dimethyl ether (DME)and methane, which have vastly different ignition characteristics. The influence of the mixing ratiosof these two test fuels on the rapidity of combustion was also investigated. Moreover, as a basicresearch subject, the behaviour of formaldehyde (HCHO), an intermediate that is produced by coolflame reactions, was observed by spectroscopic techniques. The experimental results revealed that,within the range of the experimental conditions used in this study, the quantity of DME suppliedsubstantially influenced the ignition timing, whereas it was little affected by the quantity of methanesupplied. This indicates that the ignition timing can be controlled by the quantity of DME suppliedand that the load can be adjusted by the quantity of methane supplied. Spectroscopic measurements ofthe behaviour of a substance corresponding to HCHO also indicated that the quantity of DMEsupplied significantly influenced the cool flame. [1] We propose a model based control strategy to adapt the injection Settings according to the airpath dynamics on a Diesel HCCI Engine. This approach complements existing air path and fuel pathcontrollers, and aims at accurately controlling the start of combustion. For that purpose, start ofinjection is adjusted based on a Knock Integral Model and intake manifold conditions .Experimentalresults are presented, which stress the relevance of the approach. [2] Homogenous-charge-compression-ignition (HCCI) engines have the benefit of highefficiency with low emissions of NO and particulates. These benefits are due to the autoignitionprocess of the dilute mixture of fuel and air during compression. However, because there is no direct-ignition trigger, control of ignition is inherently more difficult than in standard internal combustionengines. This difficulty necessitates that a feedback controller be used to keep the engine at a desired(efficient) setpoint in the face of disturbances. Because of the nonlinear autoignition process, thesensitivity of ignition changes with the operating point. Thus, gain scheduling is required to cover theentire operating range of the engine. Controller tuning can therefore be a time-intensive process. Withthe goal of reducing the time to tune the controller, we use extremum seeking (ES) to tune theparameters of various forms of combustion-timing controllers. In addition, in this paper, wedemonstrate how ES can be used for the determination of an optimal combustion-timing setpoint onan experimental HCCI engine. The use of ES has the benefit of achieving both optimal setpoint (formaximizing the engine efficiency) and controller-parameter tuning tasks quickly.[3] In the limit of homogeneous reactants and adiabatic combustion, ignition timing and pollutantemissions in homogeneous-charge compression-ignition (HCCI) engines would be governed solely bychemical kinetics. As one moves away from this idealization, turbulence and turbulence/chemistryinteractions (TCI) play increasingly important roles. Here the influence of TCI on autoignition andemissions of CO and unburned hydrocarbon (UHC) is examined using a three-dimensional time-dependent computational fluid dynamics (CFD) model that includes detailed chemical kinetics. TCI isaccounted for using a hybrid probability density function (PDF) method. Variations in globalequivalence ratio, wall temperature, swirl level, degree of mixture inhomogeneity (premixed versusdirect injection, and start of-injection timing for direct-injection cases), and a top-ring-landcrevice (TRLC) are investigated. In addition to providing new insight into HCCI combustionprocesses, this work also demonstrates the feasibility of bringing transported PDF methods tobear in modeling a geometrically complex three dimensional time-dependent turbulentcombustion system. [4] 546
  3. 3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEMEABOUT THE HCCI ENGINE: HCCI (Homogeneous charge compression ignition engine) engine is a hybrid enginewhich works the compression ignition method. The working of the SI engine is that the airfuel mixture is sent into the engine and the ignition is done using the spark plug. Thus in theCI engine the air sent in separately and the fuel is been injected during the compressionstroke and the ignition takes place by the compression process. The method used in the HCCIengine is that the air fuel mixture is sent inside the combustion chamber and during thecompression stroke the mixture reaches the auto ignition point, it is that the combustion takesplace without any ignition system. HCCI is an alternative engine which works on the high compression process. It giveshigh efficiencies as the CI engines, it operates on the principle of the premixed fuel is burntwith high volumetric compression achieved by the piston. It has the features of the both theSI and CI engine. The difference in the engine is been shown in the figure. In the fuel mixtureis well mixed in the compression process, which leads to low emission and no throttle losswhich leads to high working efficiency. Figure 1.Showsthe differenceof the diesel engine, gasoline engine, HCCI engine. However, it is same like the other engine at present, the combustion occurs for thecomplete fuel mixture rather than first in the hot spot. The main advantage is that HCCI isthat combustion takes place at very low temperature which will reduce the emission of thetoxic gases. The HCCI in date has the dual mode of operation, for the initial cold start the SItype working is been used, then in running it is been shifted to the HCCI mode. This HCCImode is used for the ideal running and the mid-load operation, for high load condition it isagain shifted to the normal SI mode this is achieved by using computer control in cars. 547
  4. 4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME Considering the environmental restriction and the pollution standards for the HCCIengine, it has very low pollution rates. It is because that the fuel get well mixed and fullyburnt in the power stroke, its operation is similar to the diesel engine working. The pressure isvery high when the stoichiometric or rich mixture is used. The figure shows the pressurereadings of the SI and HCCI engines. The HCCI auto ignition is achieved with the lean fuelmixture, comparably lesser than the SI engine. There should be an obvious that there is noexplicit timing for the HCCI engine combustion.CHALLENGES FACED IN HCCI ENGINES: HCCI operation is achieved by controlling the process temperature and air fuelmixture composition so that the auto ignition is achieved in TDC . achieving this is verydifficult than using some spark plugs for ignition. This is the only engine which uses the fullelectronic engine controls for achieving a good combustion in the HCCI engine. Some of thetechnical barriers must be overcome before it is production, The factors mention below. 1. IGNITION TIMING: Controlling the speed and load of the HCCI engine in various conditions is thedifficulty faced at present. The combustion or the ignition in the HCCI engine fully dependson the charge mixture composition, the temperature present and pressure.The out ratio of theHCCI engine varies according to the input of the fuel mixture ratio. For proper combustiontiming the temperature plays a major role, several methods were proposed to meet the variousload and the speed factors. By using the EGR unit the inlet temperature is been maintained, toachieve a constant inlet temperature andusing a VCR mechanism to alter TDC temperatures,to obtain a better compression ratio VVT technology is used. 548
  5. 5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME 2. OPERATING RANGES We know that the HCCI engines operates at low and medium loads, it is difficult tomake it operate at high load conditions. It leads to more noise and causing more emissionproblems, and engine damage. Thus some experiments prove that it can be achieved byincrease the partially stratifying the charge at high load operating conditions. More no ofequipment’s are available for achieving the partially stratifying the charge to be achieved athigh load conditions. 3. COLD-START: In the cold start the compressed gas will be cooled due to the cold temperature in thecylinder walls. The compressed gas must having the normal temperature for the firing processand some ideas must be implemented for maintain the temperature. Considering cold startingvarious process have been carried out, the solution is that starting the engine in SI mode andwarming up it and again changing it to HCCI mode. Using the VVT, we can reduce thewarming up cycles and time. 4. ENGINE EMISSIONS: HCCI engines have low emissions of NOx, but have high emissions of HC(hydrocarbons) andCO(carbon monoxide). Mostly controlling HC and CO emissions forHCCI engines will require the exhaust emission control devices. Catalyst technology for HCand CO removal is the popular device used in automobiles for many years. The low tempexhaust gas which enters the catalyst will reduce the performance of the device. Consideringthe factor the catalyst must be developed for low temperature to meet its purpose.STUDY ON INLET VALVE: In present days we are comfortable with high performance and maintenance freevehicle. This fact lead to usage of more advanced material composition to achieve, a betteradvantage than the exiting one and having a best design structure for each and everycomponent in the engine which leads to best performance. In thisstudy we have study andanalysis of the inlet valve in the HCCI engine. The inlet valve plays a major role in havingthe required quantity of mixture for the combustion process. It has arapid cooling during thesuction of the air inside of the combustion chamber, and rapid heating during the powerstroke. This factor is considered as the major problem in the inlet valve for all the engine, sowe considered in having a good and better solution for such factor and observing the presentvalve material composition and the design of it, through this we have come across the factthat we can control the rapid cooling and rapid heating by making some changes in the designand in the material composition. Through this changes we can achieve the requiredconditions. We absorbed that the nickel chromium alloy and the silicon chromium alloy aremajorly used as the valve material. In our study we have selectedthe titanium alloy as a valvematerial and decided to analysis its material composition and analysing the temperature flowin the material. To improve the material strength and the material conductivity,wearimplementing the titanium alloy for its lighter weight and more efficient in hightemperatures. Also we have planned to maintain a constant temperature in the valve the 549
  6. 6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEMEsodium liquid metal is filled inside for this higher performance valve. It is very efficient intransferring the heat from one place to another.The titanium alloy has the maximum temp of1700o c this melting point is 200oc above the steel. Titanium very light weight compared tosteel and other alloys. It has the tensile of 210-1380 mpa, this is the strength which is beenequivalent to the steel alloys. The ductile strength of titanium is 56% greater than steel. It haslow thermal conductivity so it has high dissipation of heat from the component and it hasbetter life.DESIGN PARAMAMETERS Overall length of the valve: 110 mm Diameter of the stem: 8 mm Diameter of the head: 300mm Diameter of the seat: 250mm Seat angle: 45o Head diameter: 300 mm Ground length: 850mm Height of head rim: 1mm Stepped stem end length: 20mm Tip chamfer: 1mm Height of the seat: 2mm Overall thickness of the head: 10mmThe material of the present valve is nickel chromium and we have upgraded to titanium alloy,and the detail analysis is explained below.Design models Fig. a: This the prototype model of the valve assembly in the engine head, which consists of the timing gear, cam shaft, valve guide, springs. 550
  7. 7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME Fig. b: the actual valve designed in PRO-E Fig. C: the new designed valve using PRO-E Fig.d: the new designed valve with the hollow path inside 551
  8. 8. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEME Here is the design of the valve the existing design (fig.c) and the change of the design(fig.d),which has the hollow hole in the centre of the valve in where the sodium liquid metal is filled tomaintain the constant temperature and below is the analysed results fig. Fig.1 this is the designed valve pressure analysis Fig.2 this is the actual valve pressure analysis Fig.3temperature analysis in designed valve Fig.4 temperature analysis in the actual valveDESIGN STEPS: • First we have to develop the model after the design parameters using the cad package, PRO-E is our working CAD package for using work • For importing the file to the ANSYS for analysing, we have to change the pro-e format to PARASOLID. • Now open the ANSYS and go to files, import, Para. • The design will appear in the ANSYS window, check model for any data losses. • Goto preferences and select the structural. • Goto post processor –element type-add-solid-brick 185 • Goto material- prop-material model-structural-linerar-elastic-isentropic, then enter the values. • Goto meshing-size cntrl-manual size-global-size,enter the values. • Goto mesh-mesh-pick all-ok. • All the areas of the object will be meshed with respect to the entered value • Goto loads-define loads-apply-structural-areas, and select the areas to be defined. • Then loads-define loads-apply-pressure-areas, and select the areas in which the pressure acts. • Goto solutions-solve-current LS-solution done. • Goto general postprocessor-plot results-condor plot-nodal solution, you will get the deformed results. • Goto read results-condor plot-nodal solution, you will get the results for the deformed solutions. 552
  9. 9. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEMEDISCUSSION AND RESULTS Through the analysis and the results we arrived that the new material composition and thedesign parameters has more efficiency and high strength, then the exiting one. The results areshown below.Theresult for the actual valve pressure analysisMAXIMUM ABSOLUTE VALUES NODE 1526 2941 1519 2941 VALUE -0.12585E-04 0.60067E-04 0.13121E-04 0.60071E-04Through this table, we found that the maximum deflection acting is 0. 60071E-04 at the midface of the valve at node 2941 and the minimum value is -0.12585E-04 at the node 1526. It isabsorbed that the pressure is acting at a moderate rate of 0.13121E-04 this leads to worn outof the material soon.The result for the designed valve pressure analysisMAXIMUM ABSOLUTE VALUES NODE 21 42 23 42 VALUE 0.12470E-04 0.55310E-04-0.12278E-04 0.55394E-0Through this table, we found that the maximum deflection acting is 0.5539E-04 at the midface of the valve at node 42 and the minimum value is 0.12470E-04 at the node 21. It isabsorbed that the pressure acting on the material of the valve is comparatively low than thepressure acting on the actual valve design.The result for the (existing) actual valve temperature analysisMAXIMUM ABSOLUTEVALUES NODE 5950 VALUE 1280.0Through this table, we found that the maximum temp acting on the node 5950 at a temp of1280, and it has a moderate temperature flow throughout the valve. This leads to a fastcracking in the material, and elongation.The result for the designed valve temperature analysisMAXIMUM ABSOLUTEVALUES NODE 1 VALUE 1280.0Through this table, we found that the maximum temp acting on the node 1 at a temp of 1280,and it has a less temperature flow throughout the valve compared to the existing valve design.This result compared to the above temp analysis gives a better material life of the component.By comparing all the results we can conclude that our new design and the new materialcomposition gives best result than the exiting one. 553
  10. 10. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 3, Sep- Dec (2012) © IAEMEREFERCENCES:1. [1] Analysis of the Combustion Characteristics of a HCCI Engine Operating on DME andMethane Yujiro TSUTSUMI, Katsuhiro HOSHINA, Akira IIJIMA, Hideo SHOJI NihonUniversity Graduate School, Nihon University2. [2] Active Combustion Control of Diesel HCCI Engine: CombustionTiming M. Hillion, J.Chauvin and O. Grondin IFP, France.N. PetitEcole des Mines de Paris, France3. [3] HCCI Engine Combustion-Timing Control: Optimizing Gains and Fuel ConsumptionVia Extremum Seeking Nick J. Killingsworth, Member, IEEE, Salvador M. Aceves, DanielL. Flowers, Francisco Espinosa-Loza, and MiroslavKrstic´, Fellow, IEEE4. [4] A PDF Method for Multidimensional Modeling of HCCI Engine Combustion: Effectsof Turbulence/Chemistry Interactions on Ignition Timing and Emissions Y.Z. Zhang, E.H.Kung, and D.C. Haworth Department of Mechanical & Nuclear Engineering, ThePennsylvania State University, University Park, PA, USA• http://www.isrj.net/publishArticles/1250.pdf• http://www.enginebuildermag.com/Article/1171/valve_selection_hot_valve_materials_fo r_hot_engines.aspx• http://www.journalamme.org/papers_vol23_2/1122.pdf• http://www.lexairinc.com/valves/learning/poppet.html• http://en.wikipedia.org/wiki/Superalloy• http://www.reade.com/home/619• http://www.supraalloys.com/specs.php• http://www.azom.com/article.aspx?ArticleID=1341• http://www.alloysino.com/Nichrome_resistance_heating_alloy.html• http://www.google.co.in/search?oq=(KJ%2Fm%C2%B7h&sugexp=chrome,mod=0&sou rceid=chrome&ie=UTF8&q=(KJ%2Fm%C2%B7h#hl=en&sclient=psyab&q=KJ%2Fm %C2%B7h+full+form&oq=KJ%2Fm%C2%B7h+full+form&gs_l=serp.3...15489.21935. 0.22111. 1&bav=on.2,or.r_gc.r_pw.r_qf.&fp=7a2bc1bd829fb614&bpcl=35277026&biw=1241&b ih=584• http://www.technologyreview.in/news/416667/new-diesel-engine-emits-cleaner-fumes/• http://www.nickel-alloys.net/nickel_chrome_alloys.html• http://www.ndt-ed.org/GeneralResources/MaterialProperties/ET/Conductivity_Iron.pdf• http://www.reade.com/home/619• http://www.goodfellow.com/E/Nickel-Chromium-Alloy.html• http://www.google.com/patents/US4191601• http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html• http://www.kayelaby.npl.co.uk/general_physics/2_3/2_3_7.html 554