Your SlideShare is downloading. ×
Advanced Ic engines unit 4
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Advanced Ic engines unit 4

2,648

Published on

Framed as per anna university syllabus

Framed as per anna university syllabus

Published in: Technology, Business
0 Comments
4 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
2,648
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
258
Comments
0
Likes
4
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of Engineering• There are various problems asso-ciated with vegetable oils being used as fuel incompression ignition (C.I.) engines, mainly caused by their high viscosity.• The high viscosity is due to the large molecular mass and chemical structure of vegetableoils which in turn leads to problems in pumping, combustion and atomization in theinjector systems of a diesel engine.• Due to the high viscosity, in long term operation, vegetable oils normally introduce thedevelopment of gumming, the formation of injector deposits, ring sticking, as well asincompatibility with conventional lubricating oils .• Therefore, a reduction in viscosity is of prime importance to make vegetable oils asuitable alter-native fuel for diesel engines.• The problem of high viscosity of vegetable oils has been approached in severalways, such as preheating the oils, blending or dilution with other fuels, trans-esterificationand thermal cracking/pyrolysis.Use of jatropha curcas oil and diesel fuel blends in CI Engine
  • 2. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of Engineering• Jatropha curcas is a large shrub or tree native to the American tropics but commonlyfound and utilized throughout most of the tropical and subtropical regions of the world.• Several properties of the plant, including its hardness, rapid growth, easy propagationand wide ranging usefulness have resulted in its spread far beyond its originaldistribution.• The jatropha oil is a slow-drying oil which is odourless and colourless when fresh butbecomes yellow on standing. The oil content of jatropha seed ranges from 30 to 50% byweight and the kernel itself ranges from 45 to 60%.• The oil compares well against other vegetable oils and more importantly to diesel itselfin terms of its fuel rating per kilogram or hectare of oil produced. But the greatestdifference between jatropha oil and diesel oil is viscosity.• The high viscosity of curcas oil may contribute to the formation of carbon deposits in theengines, incomplete fuel combustion and results in reducing the life of an engine.Use of jatropha curcas oil and diesel fuel blends in CI Engine
  • 3. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringThe heating value of the vegetable oil is comparable to the diesel oil and theetane no. is slightly lower than the diesel fuel.However, the kinematic viscosity and the flash point of jatropha curcas oil areseveral times higher than the diesel oil.Use of jatropha curcas oil and diesel fuel blends in CI EngineFuel properties
  • 4. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI Engine• Dilution or blending of vegetable oil with other fuels like alcohol or diesel fuel wouldbring the viscosity close to a specification range.• Jatropha oil is blended with diesel oil in varying pro portions with the intention ofreducing its viscosity close to that of the diesel fuel.• The important physical and chemical properties of the biodiesel thus prepared are givenin Table below. The various blends were stable under normal conditions.
  • 5. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI EngineEffect of dilution on viscosity of vegetable oil and biodiesel• The high viscosity of jatropha curcas oil has been decreased drastically bypartial substitution of diesel oil.• The viscosity of the vegetable oil was decreased on increasing the dieselcontent in the blend.• Though a substantial decrease in viscosity and density was observed with70:30 jatropha/diesel (J/D) and 60:40 J/D blends, still the viscosity and densityare quite a lot higher than that of diesel.• A reduction of viscosity of 55.56% and 62.13% was obtained with 70:30 and60:40 J/D blends, respectively.• The corresponding viscosity and the density were found to be 23.447 and19.222 cSt, and 0.900 and 0.890 g/cc at 30 C.
  • 6. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI Engine• The viscosity and density of jatropha curcas oil were reduced from 52.76 and0.93292 to 17.481 cSt and 0.880 g/cc, respectively, with 50:50 J/D blend.• A reduction of viscosity of 66.86% was achieved.• The viscosity of the 40:60 J/D blend was slightly higher than diesel oil.• In this case the viscosity was found to be 13.958 cSt and the percentagereduction of viscosity was 73.55 whereas the viscosity anddensity of blendscomprising 30:70 and 20:80 J/D are close to those of diesel oil.Effect of dilution on viscosity of vegetable oil and biodiesel
  • 7. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI Engine• Viscosity of 9.848 and 6.931 cSt and density of 0.862 and 0.853 g/cc wereobserved with 30:70 and 20:80 J/D, respectively. The correspondingviscosity reductions were 81 and 86.86%.• Therefore, 70–80% of diesel may be added to jatropha oil to bring theviscosity close to diesel fuel and thus blends containing 20–30% of jatrophaoil can be used as engine fuel without preheating.Effect of dilution on viscosity of vegetable oil and biodiesel
  • 8. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI EngineEffect of temperature on viscosity of jatropha curcas oil and various blends• From the properties of the blends shown in Table, it has been observed thatbiodiesel containing more than 30% jatropha oil have high viscositycompared to diesel.• The viscosity of these blends needed to be reduced more in order to make itsuitable as biodiesel to be used in the diesel engine.• From the literature, it wasfound that heating the fuel makes its spraycharacteristics more like those of diesel oil, which is the direct result ofviscosity reduction.• Therefore, efforts have been made to decrease the viscosity by heating thebiodiesels.• For this, the viscosities of the oils as well as the blends were measured atvarying temperature in the range 25–75 C.
  • 9. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI EngineEffect of temperature on viscosity of jatropha curcas oil and various blends
  • 10. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI Engine• The results show that the viscosity of jatropha oil is higher than diesel oil atany temperature. However, the viscosity of vegetable oil was decreasedremarkably with increasing temperature and it becomes close to diesel oil attemperatures above 75 C.• Biodiesel containing 70 and 60% vegetable oil has viscosity close to diesel oilbetween 70 and 75 C, and between 60 and 65 C, respectively.• Viscosity values of 50:50 J/D and 40:60 J/D are close to diesel in the range of55–60 C and at about 45 C, respectively, whereas the blend containing30:70 J/D has viscosity close to diesel at the range of 35–40 C.• Therefore, the blends of 30:70 and 40:70 J/D may be used with slight heatingor even without heating, particularly in summer season.
  • 11. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI EngineEngine test - Effect of brake horse power on specific fuel consumption
  • 12. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI Engine• It was observed that the specific fuel consumptions of the oil as well as the blends weredecreased with increasing load from 0.77 to 3.078 and tended to increase with furtherincrease in BKW.• The fuel consumptions were also found to increase with a higher proportion of jatrophacurcas oil in the blend.• Though the blends as well as the jatropha curcas oil maintained a similar trend to that ofdiesel, the SFC in the case of the blends were higher compared to diesel oil in the entireload range.• This is mainly due to the combined effects of the relative fuel density, viscosity andheating value of the blends.• However, blends containing 30:70 and 40:60 J/D have SFC very close to that of diesel oil.• The SFC values were found to be 0.338 and 0.365 at 3.078 BKW; the correspondingvalue for diesel is 0.316.Engine test - Effect of brake horse power on specific fuel consumption
  • 13. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI Engine• The specific fuel consumption of 0.693 was observed using 50:50 J/D blend as fuelwhich is comparable to the SFC obtained with diesel oil under the same load.• The higher density of blends containing a higher percentage of jatropha curcas oil hasled to more discharge of fuel for the same displacement of the plunger in the fuelinjection pump, thereby increasing the SFC.Engine test - Effect of brake horse power on specific fuel consumption
  • 14. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI EngineEngine Test: Effect of BKW on brake thermal efficiency• Initially with increasing BKW the brake thermal efficiencies of the vegetable oil, dieseland the blends were increased and the maximum thermal efficiencies were obtained atBKW of 3.078 and then tended to decrease with further increase in BKW.• There was a considerable increase in efficiencies with the blends compared to theefficiency of jatropha oil alone, but the brake thermal efficiencies of the blends and thejatropha curcas oil were lower than that with diesel fuel throughout the entire range.• The maximum values of thermal efficiencies with 60:30 and 70:30 J/D were observedas 21.45% and 20.53%, respectively.
  • 15. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI EngineEngine Test: Effect of BKW on brake thermal efficiency• Among the blends tested, in the case of 30:70 J/D, the thermal efficiency andmaximum power output were close to the diesel values, followed by the 40:60 J/Dblend.• Corresponding maximum brake thermal efficiencies of 26.09 and 24.36% wereobserved with these blends. A reasonably good thermal efficiency of 22.44% wasalso observed with the 50:50 J/D blend.• The maximum thermal efficiency of 27.11% was achieved with diesel, whereas only18.52% thermal efficiency was observed using jatropha curcas oil.• The drop in thermal efficiency with increase in proportion of vegetable oil must beattributed to the poor combustion characteristics of the vegetable oils due to theirhigh viscosity and poor volatili ty.
  • 16. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI EngineEngine Test: Effect of BKW on brake thermal efficiency
  • 17. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI EngineEngine Test: Effect of BKW on exhaust gas temperature• The exhaust gas temperature increased with increase in BKW in all cases. Thehighest value of exhaust gas temperature of 554 C was observed with the jatrophaoil, whereas the corresponding value with diesel was found to be 425 C only.• This is due to the poor combustion characteristics of the jatropha curcas oil because ofits high viscosity. The combustion characteristics of the blends were improved byincreasing the proportion of diesel fuel in the J/D blend.• The exhaust gas temperature for 20:80 J/D was observed to be very close to diesel oiland the temperatures were comparable to those with diesel oil blends with 30:70 and40:60 J/D over the entire load.• The maximum exhaust temperature was recorded as 550 and 540 C with 70:30 and60:40 J/D blends, respectively at 3.74 BKW. With 50:50 J/D, the value was found to be535 C.
  • 18. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI EngineEngine Test: Effect of BKW on exhaust gas temperature
  • 19. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringUse of jatropha curcas oil and diesel fuel blends in CI Engine• Significant reduction in viscosity was achieved by dilution of vegetable oil with diesel invarying proportions.• Among the various blends, the blends containing up to 30% (v/v) jatropha oil haveviscosity values close to that of diesel fuel.• The blend containing 40% (v/v) vegetable oil has a viscosity slightly higher than that ofdiesel. The viscosity was further reduced by heating the blends.• The viscosity of the blends containing 70 and 60% vegetable oil became close to that ofdiesel in the temperature ranges of 70–75 and 60–65 C, respectively.• The corresponding temperatures were found to be 55–60 and 45 C for 50 and 40%blends, whereas only at 35–40 C did the viscosity of the 30:70 J/D blend become closeto the specification range.• Acceptable brake thermal efficiencies and SFCs were achieved with the blendscontaining up to 50% jatropha oil.
  • 20. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringAlcohol as Fuel in IC Engine• Alcohol is of organic origin and can be produced from a wide range of abundantly availableraw materials. Ethanol (C2H5OH) can be produced by fermentation of carbohydrates whichoccur naturally and abundantly in some plants like sugarcane and can also be producedfrom starchy materials like corn, potatoes, maize and barley.• The starchy material is first converted into sugar which is then fermented by yeast. For thelarge-scale production of methanol (CH3OH), the following methods are commonlyemployed:a) Destructive distillation of wood,b) Synthesis from water gas,c) From natural gas but it is petroleum based,d) From coal, a relatively abundant fossil fuel.• Alcohols have high antiknock characteristics which permit spark-ignition engines to run athigher compression ratios.• A lean mixture will burn and the exhaust gas temperature will be lower.• Alcohols, therefore, will reduce CO and NOx in the exhaust. The alcohol fuelled SI enginescan produce a slightly higher power output.
  • 21. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of Engineering• Methanol is considered to be one of the most likely alternative automotive fuels.However, several major technical difficulties must be resolved before 100 % methanolcan become a commercially acceptable fuel for use in vehicles.• The most commonly mentioned difficulties are cold start (no start below 15 C), safety(explosive mixture in the fuel tanks, invisible flame), and corrosion and wear of engineand fuel system materials.• In addition, the vehicle range (distance covered) will also be reducedsubstantially, unless the size of the fuel tank is greatly increased, because the volumetricenergy density of methanol is only about one-half of that of gasoline.• Most of these problems may be resolved by using a medium concentration (30-70 % byvolume) blend of methanol and gasoline. However, the use of such blends maycompromise some of methanols key NOx emissions.Alcohol as Fuel in IC Engine
  • 22. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringAlcohol as Fuel in IC EngineThe physical properties of methanol, ethanol and gasoline
  • 23. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringNatural Gas as Fuel in IC Engine• Natural gas is a mixture of several different gases. The primary constituent ismethane, which typically makes up 85-99 % of the total volume.• The other constituents include other hydrocarbons, inert gases such as nitrogen,helium and carbon dioxide, and traces of hydrogen sulphide and water.• The non-methane hydrocarbons present in natural gas consist primarily of ethane. Theremainder is made up mostly of propane and butane, with some traces of C5 andhigher species.• Natural gas is an excellent fuel for SI engines. As a gas under normal conditions, itmixes readily with air in any proportion.• Unlike liquid fuels it does not need to vaporize before burning.• Thus cold engine starting is easier especially at low temperatures, and cold-startenrichment is not required.• Cold-start enrichment is a major source of CO emissions and emissions-relatedproblems in gasoline-fuelled SI engines.• Natural gas has a high ignition temperature, and is resistant to self-ignition. It hasexcellent antiknock properties.
  • 24. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringNatural Gas as Fuel in IC Engine• Pure methane has an equivalent research octane number (RON) of 130, the highest ofany commonly used fuel.• Because of its antiknock properties, natural gas can safely be used with enginecompression ratios as high as 15:1 (compared to 8-10:1 for 91 octane gasoline).• Natural gas engines using these higher compression ratios can reach significantlyhigher efficiencies than are possible with gasoline.
  • 25. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringLPG as Fuel in IC Engine• Liquified Petroleum Gas (LPG) is a product of petroleum gases, principally propane(C3H8), propylene (C3H6) and butane (C4H10).• These gases can be liquified at normal temperatures by subjecting them to a moderatepressure. Owing to the demand from industry for butane derivatives, LPG sold as a fuelis made up largely of propane.• Liquified petroleum gases are used as fuels for stoves, trucks, buses and tractors inmany parts of the world.• The LPG has higher heating value compared to gasoline. Since propane and butane areheavier than air, the escaping gas will tend to settle and collect in pockets thus creatingan explosion hazard.• The LPG is suitable for IC engines because of its availability and low carboncontent, thus resulting in drastic reduction in exhaust emissions.• The LPG has a high self-ignition temperature and a high octane number, which makes itmore suitable for SI engines.
  • 26. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringLPG as Fuel in IC Engine• Engines with natural gas and LPG can run lean because of their better distribution andhigher misfire limits.• Also, their higher octane numbers, allow an increase in the compression ratio in SIengines, which consequently improves the thermal efficiency and reduces the exhaustemissions.
  • 27. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringHydrogen as Fuel in IC Engine• With the imposition of stringent emission standards along with the decreasing availability ofpetroleum products, it is imperative that a search for low polluting alternative fuels bemade.• Hydrogen, as an SI engine fuel acquires special significance in view of its unlimited supplypotential and almost non-polluting characteristics.• Even though with current economics hydrogen would be a costly automotive fuel, basedon long-term considerations, its relative cost standing may improve considerably.• As and when a cheaper method of hydrogen production becomes available, it could beused for aircraft, marine vessels, railways and automotive vehicles.• Hydrogen has emerged as a potential fuel for internal combustion engines. It is generallyconsidered to be non-polluting because hydrogen contains no carbon.• Species such as carbon monoxide and unburned hydrocarbons, which are normally foundin gasoline fueled engines, would be virtually eliminated in the exhaust.• Hydrogen is found in abundant quantities in various forms and can be considered to be analmost inexhaustible fuel.• It can be adapted as a fuel to engines without major design changes.
  • 28. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringHydrogen as Fuel in IC Engine• The problems generally experienced in a hydrogen-fueled engine are thebackfiring, pre-ignition, knocking and rapid rate of pressure rise during thecombustion process because of the higher flame speed.• Backfiring is mainly due to less ignition energy for a hydrogen-air mixtureLocalized hot points in the chamber and the temperature of the residual gasare sometimes sufficient to cause backfiring.• Hydrogen-fuelled engines can be run at a much leaner equivalence ratio than agasoline-fuelled engine, although lean operations of hydrogen-fuelled enginegenerally reduce NO emissions and show improved thermal efficiency.• Problems associated with too lean mixtures increase the ignition delay andcause severe cyclic variations.• The hydrogen peroxide is present in the exhaust products of a hydrogen-fuelled engine operating with very lean mixtures.
  • 29. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringHydrogen as Fuel in IC Engine• Compared with hydrocarbon fuels, hydrogen has certain advantages due to its highchemical reactivity: (a) a higher flame propagation speed, (b) wider ignition limits, and (c)lower ignition energy.• The high flame propagation speed of hydrogen certainly benefits the thermodynamicefficiency of the engine as the combustion process is closer to the optimum theoreticalcombustion at constant volume.• The wider ignition limits provide the possibility to run with extremely lean mixtures. A lowerignition energy is favourable for ignition of lean mixtures in SI engines, but has thedisadvantage of resulting in abnormal combustion (knock and surface ignition), especiallynear stoichiometry.• Because backfire must be avoided at all costs, it is necessary to avoid knock and surfaceignition. This can be done by leaning the mixture.• Since this reduces the available power, its use should be limited. Knocking and the rate ofpressure rise can also be controlled by increasing the flame travel distance.• This can be done by locating the spark plug near the periphery, away from the centre of thecylinder head.
  • 30. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringHydrogen as Fuel in IC Engine• On-board storage of hydrogen remains a major technical challenge. As a gas, hydrogenhas a very low energy density.• This leads to a large tank size even with high pressure storage and short vehicle range.• Storing hydrogen in liquid form is also problematic as it liquifies at --235 C Storage ofhydrogen may be achieved by solid state hydride storage materials, liquidhydrides, microglass sphere storage, storage in carbon, storage in zeolites, and similarsuch storage.
  • 31. ME2041 Advanced Internal Combustion EnginesUnit II Department of Mechanical Engineering, St. Joseph’s College of EngineeringHydrogen as Fuel in IC EngineThe properties of hydrogen, natural gas (methane) and gasoline

×