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SEMINAR ON SIX STROKE ENGINE

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SEMINAR ON SIX STROKE ENGINE Powered By Docstoc
					                          A
                       Seminar
                         On


              “Six Stroke Engine”


                          By
                   Vinod B. Desai


               Under The Guidance Of
                 Prof. Sandip A. Kale


Submitted In Partial Fulfillment of the Requirement For
              Engineering (Mechanical)


                University of Pune




 Department Of Mechanical Engineering
    Dhole Patil College of Engineering,
                   Pune-412207
                     2012-2013



            DPCOE, Mechanical Engineering
                        1
                           Dhole Patil Education Society’s

    Dhole Patil College of Engineering, Pune




                        CERTIFICATE
        This is to certify that Mr. Vinod Desai has successfully completed the
Seminar work entitled “Six Stroke Engine,” under my supervision, in the
partial fulfillment of Bachelor in Mechanical Engineering of University of
Pune.


Date :
Place :




    Prof. Sandip kale                                           Prof. B.J.Patil
        Guide Name                                                 H.O.D




                                                     Prof. ……………….
                                                             Principal,
            Seal



                         DPCOE, Mechanical Engineering
                                     2
                              ACKNOLODGEMENT

       Gratitude is the hardest of emotion to express an often does not find adequate
words to convey all that one feels.
       It has been my good fortune to come across so many good hearted persons during
my seminar activity. Although it is as good as impossible to include the names of each of
them here, I gratefully thank them for their invaluable help and guidance in adding a fund
of technical as well as general knowledge.
       Here I take the opportunity to express my deep gratitude to my seminar guide
Prof. Sandip A. Kale who helped me a lot for the preparation of this seminar and
encouraged me to put in my best of myself. I am also thankful to our Head of Department
Prof. B. J. Patil for his words of encouragement.
       Without guidance of all these people, the submission of this seminar would not
have been possible.


                                                                     Mr. Vinod B. Desai




                            DPCOE, Mechanical Engineering
                                        3
                                          INDEX


 Sr.No                                Name of Topic           Page Number




         List of Figures                                             5
         List of Tables                                              5
         Abstract                                                    6


1.       Introduction                                                1
2.       Working
         2.1 Intake /Suction Stroke
         2.2 First Compression Stroke
         2.3 First combustion stroke
         2.4 Second compression stroke
         2.5 Second combustion stroke
         2.6 Exhaust stroke
2.       Modification over Four Stroke Engine                        12
3.       Performance Analysis                                        14
         3.2 Performance of Six Stroke Diesel Engine
         3.2.1 Comparison with Four Stroke Diesel Engine
4.   Advantages                                                      16
     4.1 Main Advantages
5.       Graphs                                                      18
6.       Conclusions                                                 20
7.       References                                                  21




                              DPCOE, Mechanical Engineering
                                          4
List of Figures:

Fig 1. Concept of Six Stroke Diesel Engine

Fig. 2. Proposed six-stroke diesel engine and a conventional four-stroke diesel engine


Fig3.Details of nozzle position of 4-stroke & Details of extra nozzle position for 6-Stroke




List of Tables:

Table 1. SPECIFICATIONS OF THE TEST ENGINE:

Table 2. DETAILED CONDITIONS OF COMPSRISION BETWEEN THE FOUR STROKE AND SIX
STROKE DIESEL ENGINES AND PERFORMANCE OF ENGINE




                            DPCOE, Mechanical Engineering
                                        5
                                        ABSTRACT


       Six Stroke engine, the name itself indicates a cycle of six strokes out of which two
are useful power strokes. According to its mechanical design, the six-stroke engine with
external and internal combustion and double flow is similar to the actual internal
reciprocating combustion engine. However, it differentiates itself entirely, due to its
thermodynamic cycle and a modified cylinder head with two supplementary chambers:
combustion and an air heating chamber, both independent from the cylinder. In this the
cylinder and the combustion chamber are separated which gives more freedom for design
analysis. Several advantages result from this, one very important being the increase in
thermal efficiency.


       It consists of two cycles of operations namely external combustion cycle and
internal combustion cycle, each cycle having four events. In addition to the two valves in
the four stroke engine two more valves are incorporated which are operated by a piston
arrangement.


       The Six Stroke is thermodynamically more efficient because the change in
volume of the power stroke is greater than the intake stroke and the compression stroke.
The main advantages of six stroke engine includes reduction in fuel consumption by
40%, two power strokes in the six stroke cycle, dramatic reduction in pollution,
adaptability to multi fuel operation.


       Six stroke engine’s adoption by the automobile industry would have a tremendous
impact on the environment and world economy.




                             DPCOE, Mechanical Engineering
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   1. INTRODUCTION:


       The majority of the actual internal combustion engines, operating on different
cycles have one common feature, combustion occurring in the cylinder after each
compression, resulting in gas expansion that acts directly on the piston (work) and limited
to 180 degrees of crankshaft angle.


       According to its mechanical design, the six-stroke engine with external and
internal combustion and double flow is similar to the actual internal reciprocating
combustion engine. However, it differentiates itself entirely, due to its thermodynamic
cycle and a modified cylinder head with two supplementary chambers: Combustion, does
not occur within the cylinder within the cylinder but in the supplementary combustion
chamber, does not act immediately on the piston, and it’s duration is independent from
the 180 degrees of crankshaft rotation that occurs during the expansion of the combustion
gases (work).


       The combustion chamber is totally enclosed within the air-heating chamber. By
heat exchange through the glowing combustion chamber walls, air pressure in the heating
chamber increases and generate power for an a supplementary work stroke. Several
advantages result from this, one very important being the increase in thermal efficiency.
In the contemporary internal combustion engine, the necessary cooling of the combustion
chamber walls generates important calorific losses.




                            DPCOE, Mechanical Engineering
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2. WORKING OF SIX STROKE DIESEL ENGINE




The cycle of this engine consists of six strokes:
       1. Intake stroke
       2. First compression stroke
       3. First combustion stroke
       4. second compression stroke
       5. Second combustion stroke
       6. Exhaust stroke




                             DPCOE, Mechanical Engineering
                                         8
2.1 Intake /Suction Stroke:
       To start with the piston is at or very near to the T.D.C., the inlet valve is open and
the exhaust valve is closed. A rotation is given to the crank by the energy from a flywheel
or by a starter motor when the engine is just being started. As the piston moves from top
to bottom dead centre the rarefaction is formed inside the cylinder i.e. the pressure in the
cylinder is reduced to a value below atmospheric pressure. The pressure difference causes
the fresh air to rush in and fill the space vacated by the piston. The admission of air
continues until the inlet valve closes at B.D.C.


2.2 First Compression Stroke:
       Both the valves are closed and the piston moves from bottom to top dead centre.
The air is compressed up to compression ratio that depends upon type of engine. For
diesel engines the compression ratio is 12-18 and pressure and temperature towards the
end of compression are 35-40 kgf/cm2 and 600-700 0C




                             DPCOE, Mechanical Engineering
                                         9
2.3 First Combustion Stroke:
       This stroke includes combustion of first fuel (most probably diesel) and expansion
of product of combustion. The combustion of the charge commences when the piston
approaches T.D.C.
       Here the fuel in the form of fine spray is injected in the combustion space. The
atomization of the fuel is accomplished by air supplied. The air entering the cylinder with
fuel is so regulated that the pressure theoretically remains constant during burning
process.
       In airless injection process, the fuel in finely atomized form is injected in
combustion chamber. When fuel vapors raised to self ignition temperature, the
combustion of accumulated oil commences and there is sudden rise in pressure at
approximately constant volume. The combustion of fresh fuel injected into the cylinder
continues and this ignition is due to high temperature developed in engine cylinder.
However this latter combustion occurs at approximately constant pressure.
       Due to expansion of gases piston moves downwards. The reciprocating motion of
piston is converted into rotary motion of crankshaft by connecting rod and crank. During
expansion the pressure drop is due to increase in volume of gases and absorption of heat
by cylinder walls.


2.4 Second Compression Stroke:
       Both the valves are closed and the piston moves from bottom to top dead centre.
The combustion products from the first compression stroke are recompressed and utilized
in the second combustion process before the exhaust stroke. In typical diesel engine
combustion the combustion products still contains some oxygen.


2.5 Second Combustion Stroke:
       This stroke includes combustion of second fuel having low cetane (Cetane
number of fuel is defined as percent volume of cetane (c16h34) in a mixture of cetane
and alpha-methyl-naphthalene that produces the same delay period or ignition lag as the




                            DPCOE, Mechanical Engineering
                                        10
fuel being tested under same operating conditions on same engine). The combustion of
the charge commences when the piston approaches to T.D.C.
       The second fuel injected into recompressed burnt gas can be burnt in the second
combustion process. In other words combustion process of the second fuel took place in
an internal full EGR (Exhaust Gas Recirculation) of the first combustion.
       This second combustion process was the special feature of the proposed Six
Stroke DI Diesel Engine.


2.6 Exhaust Stroke:
       The exhaust valve begins to open when the power stroke is about to complete. A
pressure of 4-5 kgf/cm2 at this instant forces about 60% of burnt gases into the exhaust
manifold at high speed. Much of the noise associated with automobile engine is due to
high exhaust velocity. The remainder of burnt gases is cleared of the swept volume when
the piston moves from T.D.C. to B.D.C. During this stroke pressure inside the cylinder is
slightly above the atmospheric value. Some of the burnt gases are however left in the
clearance space. The exhaust valve closes shortly after T.D.C.
       The inlet valve opens slightly before the end of exhaust stroke and cylinder is
ready to receive the fresh air for new cycle.
       Since from the beginning of the intake stroke the piston has made six strokes
through the cylinder (Three up And Three down). In the same period crank shaft has
made three revolutions. Thus for six stroke cycle engine there are two power strokes for
every three revolutions of crank shaft.




3. MODIFICATION OVER FOUR STROKE DIESEL ENGINE:
       Schematic constructions of a proposed six-stroke diesel engine and a conventional
four-stroke diesel engine are shown in Fig. 2. This six-stroke diesel engine was made
from a conventional four-stroke diesel engine with some modification. A sub-shaft was
added to the engine, in order to drive a camshaft and injection pumps.



                             DPCOE, Mechanical Engineering
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Fig. 2. Proposed six-stroke diesel engine and a conventional four-stroke diesel engine


       The rotation speed of the sub-shaft was reduced to 1/3 of the rotation of an output
shaft. To obtain similar valve timings between a four-stroke and a six-stroke diesel
engine, the cam profile of the six-stroke diesel engine was modified. In order to separate
the fuels, to control each of the injection timings and to control each injection flow rate in
the first and the second combustion processes, the six-stroke diesel engine was equipped
with two injection pumps and two injection nozzles. The injection pumps were of the
same type as is used in the four-stroke diesel engine.




                             DPCOE, Mechanical Engineering
                                         12
Fig3.Details of nozzle position of 4-stroke & Details of extra nozzle position for 6-Stroke

       Details of nozzle position of the four-stroke diesel engine are shown in Fig. 3. The
nozzle is located near the center of a piston cavity, and has four injection holes. For the
six-stroke diesel engine, one extra nozzle was added on the cylinder head as shown in
Fig. 3. This extra nozzle was of the same design as that of the four-stroke engine.
       Diesel fuel for the first combustion process was injected through this extra nozzle,
and methanol for the second combustion process was injected through the center nozzle.
Here, we denoted the injection timing of the four stroke diesel engine as Xi. The injection
timings of the first and second combustion strokes for the six-stroke diesel engine are
shown as Xi I and Xi II, respectively. Crank angle X was measured from the intake BDC. In
the six-stroke engine, crank angle of the first combustion TDC is 180 degrees. The
second combustion TDC is 540 degrees.


                            DPCOE, Mechanical Engineering
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3. PERFORMANCE ANALYSIS OF SIX STROKE DIESEL ENGINE
3.1 Comparison with Four Stroke Diesel Engine:
         A four-stroke engine has one intake stroke for every two engine rotations. For the
six-stroke engine, however, the intake stroke took place once for every three engine
rotations. In order to keep the combustion heat per unit time constant, the combustion
heat supplied to one six-stroke cycle should be 3/2 times larger than that of the four-
stroke engine.
         There are many ways to compare performance between the four-stroke and six-
stroke engines. For this paper, the authors have chosen to compare thermal efficiency or
S.F.C. at same output power. If the thermal efficiency was the same in both engines, the
same output power would be produced by the fuels of equivalent heats of combustion.
Therefore, in order to make valid comparison, fuels supplied per unit time were
controlled at the same value for both engines and engine speeds were kept constant. In
this section, fuel supplied for the engines was only a diesel fuel. Performance of the six-
stroke engine was compared with that of the four-stroke engine under various injection
timings.
         Exhaust NO, soot emissions, and indicated torque of the four-stroke and the six-
stroke engines are shown in Fig. 5. Detailed conditions for comparison of the four-stroke
and six-stroke engines are listed in Table. 3. The heat allocation ratio of the six-stroke
engine was set at αH = 0.5. Injection flow rate of fuel was Qt4 = 0.50 kJ/cycle for the four-
stroke engine and Qt6 = 0.68 kJ/cycle for the six stroke engine. For six stroke engine, it
meant that the amount of 0.34kj was supplied at each combustion process. At the
viewpoint of combustion heat, 075 kj/cycle of heat should be supplied for the six stroke
engine to make the equivalence heat condition. However diesel fuel of 0.68 kj/cycle was
supplied here because of difficulties associated with methanol injection.
         Injection timing of the four-stroke engine was changed from 160 degrees
(200BTDC) to 180 degrees (TDC). For six -stroke engine, the injection timing of the first
combustion process was fixed to 165 degrees (15°BTDC) or 174 degrees (6°BTDC), and
the second injection timing was changed from 520 degrees (200BTDC) to 540 degrees
(TDC).


                             DPCOE, Mechanical Engineering
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Table 1. SPECIFICATIONS OF THE TEST ENGINE:


                                 Four stoke                          Six stroke
                                Diesel Engine                      Diesel Engine
Engine type                            DI, Single cylinder, Air cooled, OHV
Bore x Stroke [mm]                                     82 x 78
Displacement [cc]                                       412
Top Clearance [mm]                                     0.9
Cavity Volume [cc]                                      16
Compression ratio                                       21
Intake Valve Open                100 BTDC                                 70 BTDC
Intake valve Close               1400 BTDC                                1450 BTDC
Exhaust Valve Open               1350 ATDC                                1400 ATDC
Exhaust Valve Close              120 ATDC                                 30 ATDC
Valve Overlap                       220                                    100
Rated power                      5.9 kW /3000rpm
                                 Base Engine                       ----------------




Table 2. DETAILED CONDITIONS OF COMPSRISION BETWEEN THE FOUR STROKE AND SIX
STROKE DIESEL ENGINES AND PERFORMANCE OF ENGINE
                                                    Four Stroke                Six Stroke
                                                   Diesel Engine            Diesel Engine

         Engine Speed Ne [rpm]                         2007                       2016

   Supplied combustion heat per cycle
                                                        0.50                          0.68
                Qt [kJ/cycle]
 Supplied combustion heat per unit time
                    Ht [kJ/s]                           8.36                          7.62

         Intake air flow per cycle


                                DPCOE, Mechanical Engineering
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              Ma [mg/cycle]                          358.7                  371.4
       Injection quantity per cycle
              Mf [mg/cycle]                          11.8                    16


            Excess air ratio λ                       2.40                   1.83

       Intake air flow per unit time
                                                     6.00                   4.16
              Ma’ [g/cycle]
     Injection quantity per unit time
               Mf’ [g/sec]                           0.197                  0.179
         Brake torque Tb [N-m]                       15.52                  5.88
          Brake power Lb [kW]                        3.26                   1.24
         B.S.F.C.   b [ g / kW.h]                    217.9                  520.3
         I.M.E.P. Pi [kgf / cm2]                     5.94                   4.37
        Indicated torque Ti [N-m]                    19.10                  18.71
        Indicated power Li [kW]                      4.01                   3.95
         I.S.F.C. bi [g / kW.h ]                     177.2                  163.3




4. ADVANTAGES OF SIX STROKE OVER FOUR STROKE ENGINES:
   The six stroke is thermodynamically more efficient because the change in volume of
the power stroke is greater than the intake stroke, the compression stroke and the Six
stroke engine is fundamentally superior to the four stroke because the head is no longer
parasitic but is a net contributor to – and an integral part of – the power generation within
exhaust stroke. The compression ratios can be increased because of the absent of hot
spots and the rate of change in volume during the critical combustion period is less than
in a Four stroke. The absence of valves within the combustion chamber allows
considerable design freedom.




                              DPCOE, Mechanical Engineering
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4.1 Main advantages of the six-stroke engine:
4.1.1 Reduction in fuel consumption by at least 40%:
        An operating efficiency of approximately 50%, hence the large reduction in
specific consumption. The Operating efficiency of current petrol engine is of the order of
30%. The specific power of the six-stroke engine will not be less than that of a four-
stroke petrol engine, the increase in thermal efficiency compensating for the issue due to
the two additional strokes.


4.1.2 Two expansions (work) in six strokes:
                   Since the work cycles occur on two strokes (3600 out of 10800) or 8%
more than in a four-stroke engine (1800 out of 720 ), the torque is much more even. This
lead to very smooth operation at low speed without any              significant effects on
consumption and the emission of pollutants, the combustion not being affected by the
engine speed. These advantages are very important in improving the performance of car
in town traffic.


4.1.3 Dramatic reduction in pollution:
        Chemical, noise and thermal pollution are reduced, on the one hand, in proportion
to the reduction in specific consumption, and on the other, through the engine’s own
characteristics which will help to considerably lower HC, CO and NOx emissions.
Furthermore, it’s ability to run with fuels of vegetable origin and weakly pollutant gases
under optimum conditions, gives it qualities which will allow it to match up to the
strictest standards.


4.1.4 Multifuel:
        Multifuel par excellence, it can use the most varied fuels, of any origin (fossil or
vegetable), from diesel to L.P.G. or animal grease. The difference in inflammability or
antiknock rating does not present any problem in combustion. It’s light, standard petrol
engine construction, and the low compression ration of the combustion chamber; do not
exclude the use of diesel fuel. Methanol-petrol mixture is also recommended.


                              DPCOE, Mechanical Engineering
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5. GRAPHS:
5.1 Volume-angle diagram for six stroke engine:




5.2 Volume-angle diagram for four stroke engine:




                         DPCOE, Mechanical Engineering
                                     18
5.3 Torque Angle diagram for Four Stroke Engine:




5.4 Torque Angle diagram for Six Stroke Engine:




                         DPCOE, Mechanical Engineering
                                     19
6. CONCLUSION:
       There is, at this day, no wonder solution for the replacement of the internal
combustion engine. Only improvements of the current technology can help it progress
within reasonable time and financial limits. The six-stroke engine fits perfectly into this
view. It’s adoption by the automobile industry would have a tremendous impact on the
environment and world economy, assuming up to 40% reduction in fuel consumption and
60% to 90% in polluting emissions, depending on the type of the fuel being used.
        The performance of the dual fuel six-stroke engine was investigated. In this dual
fuel engine, diesel fuel was supplied into the first combustion process and methanol was
supplied into the second combustion process where the burned gas in the first combustion
process was re-compressed. The results are summarized as follows.

 1. Indicated specific fuel consumption (I.S.F.C.) of the six-stroke engine proposed here
   is slightly lower than that of the four-stroke engine (about 9% improvement). NO and
   soot emissions from the six-stroke engine was improved as compared with four-stroke
   engine under advanced injection timings in the second combustion stroke.
 2. For the dual fuel six-stroke engine, the timing retard and an increase of heat allocation
   ratio in the second combustion stroke resulted in a decrease of the maximum
   temperatures in the combustion processes. It caused the reduction of NO emission.
 3. For the dual fuel six-stroke engine, soot was practically eliminated by a small amount
   of methanol in the second combustion process.
 4. From the comparison of the performance between the dual fuel six-stroke and the
   four-stroke engine, it was concluded that indicated specific heat consumption of the
   dual fuel six-stroke engine was improved with 15% as compared with the four-stroke
   engine.
   NO concentration of the dual fuel six-stroke engine was improved with 90%.
   Furthermore, soot emission was very low in the dual fuel six-stroke engine




                            DPCOE, Mechanical Engineering
                                        20
7. REFERANCES:
[1] Vellguth G. Performance of vegetable oils and their monoesters as fuels for
   diesel engines. SAE 1983;831358.


[2] Demirbas A. Biodiesel production from vegetable oils via catalytic and noncatalytic
   Supercritical methanol transesterification methods. International
   Journal of Progress in Energy and Combustion Science 2005;31:466–87.


[3] Jajoo BN, Keoti RS. Evaluation of vegetable oils as supplementary fuels for
   diesel engines. Proceedings of the XV National Conference on I.C. Engines and
   Combustion, Anna University, Chennai-25; 1997.


[4] Altin R, Cetinkaya S, Yucesu HS. The potential of using vegetable oil fuels as
   fuel for diesel engines. International Journal of Energy Conversion and
   Management 2000;42:529–38. 248.


[5] Nwafor OMI. Effect of advanced injection timing on the performance of
   rapeseed oil in diesel engines. International Journal of Renewable Energy
   2000;21:433–44.


[6] Nwafor OMI. The effect of elevated fuel inlet temperature on performance of
  diesel engine running on neat vegetable oil at constant speed conditions.
  Renewable Energy 2003;28:171–81.


[7] Kaupp A, Goss JR. Small scale gas producer engine systems. Wiesbaden: Friedr
  Vieweg and Sohn Braunschweg; 1984.


[8] Vyarawalla F, Parikh PP, Dak HC, Jain BC. Utilization of biomass for motive
   power generation: gasifier engine system. Biomass 1984;3:227–42.



                            DPCOE, Mechanical Engineering
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[9] Parikh PP, Bhave AG, Kapse DV. Shashikantha. Study of thermal and emission
   performance of small gasifier dual fuel engine systems. International Journal
   of Biomass 1989;19:75–97.


[10] Tsunaki Hayasaki, Yuichirou Okamoto, Kenji Amagai and Masataka Arai
    “A Six-stroke DI Diesel Engine under Dual Fuel Operation “ SAE Paper No

    1999-01-1500

[11] S.Goto and K.Kontani, "A Dual Fuel Injector for Diesel Engines", SAE paper, No.
  851584, 1985
[12]“Internal Combustion Engines “ A book by Mathur & Sharma.




                           DPCOE, Mechanical Engineering
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