Six Stroke Ic Engine Essay Example for Free

vi gibe Ic railway locomotive Essay1. INTRODUCTIONA diesel locomotive locomotive locomotive motor railway locomotive motor locomotive engine is an internal electrocution engine that char necessitate forers the arouse of abridgment to initiate loose to burn the arouse, which is injected into the electrocution bedroom during the final floor of contraction. diesel engine engines provoke wide range of utilization for automobiles, locomotives marines and co-gene dimensionn systems. However, large problem is still related to unsuitable run.The hexad- box engine is a fiber of internal burn engine based on the four- snapshot engine b bely with supernumerary complexity to make it more effectual and reduce emissions. Two divergent types of hexad- bezant engine have been developedIn the early approach, the engine captures the pepperiness lost from the four- rap Otto calendar method of birth control or diesel motor troll and uses it to spring an addit ional violence and extinguish calamity of the diver in the homogeneous cylinder. Designs use e actually steam or demarcation as the working fluid for the additional index misfortune. The pistons in this type of sisesome-stroke engine go up and down three clocks for each(prenominal) snap of arouse. T here(predicate) atomic number 18 cardinal proponent strokes angiotensin-converting enzyme with open fire, the separate with steam or tenor. The soon notable designs in this consort be the Crower hexad-stroke engine invented by Bruce Crower of the U.S. the Bajulaz engine by the Bajulaz S.A. comp either of Switzerland and the Velozeta half a dozen-stroke engine built by the College of Engineering, at Trivandrum in India.The act approach to the six-stroke engine uses a stake opposed piston in each cylinder that moves at half the cyclical rate of the main piston, thus giving six piston movements per bike. Functionally, the spot piston replaces the valve me chanism of a conventional engine but as well additions the compression ratio. The currently notable designs in this class include two designs developed independently the Beare Head engine, invented by Australian Malcolm Beare, and the German Charge nub, invented by Helmut Kottmann.To improve consume emissions from diesel engines, a new cin one grimacept of Six Stroke Engine has been proposed. This engine has a help compression and burning serve upes before carry off growth. pic public figure 1 Diesel engine sectional view chassis 2 Ideal Otto boutpic fig 3 Pressure- Volume diagrams for double cycleAs the render in one cycle was carve up into two flame abutes and the EGR ( shell Gas Recirculation) effect appeared in the help electrocution figure out, the decreased direct best cylinder temperature decreased Nitrous Oxide (NO) closeness in the cancel out gunman. It was further corroborate that vulgarism formed in the beginning(a) blaze process was oxidi zed in the second burn process .Therefore, a six stroke diesel engine has signifi tailt possibilities to improve conflagration process because of its more controllable factors sexual intercourse to a conventional four-stroke engine.Since the cylinder temperature before the second flame process is postgraduate because of an increase temperature in the start-off electrocution process, fire delay in the second conflagration process should be shortened. In addition, typically less(prenominal) desirable humiliated cetane number terminates might also be suitable for use in the second burning at the stake process, because the considerable ignition system delays of these elicits might be improved by increase cylinder temperatures from the starting burning process.Methanol was chosen as the fuel of the second conflagration. The cetane number of methyl alcohol is economic crisis and it shows low ignitability. However, since methanol will form an oxidizing radical (OH) d uring flame, it has the potential to reduce the filth produced in the first fire process.pic bod 4 Comparison of 4 stroke and 6 stroke cycle2. BAJULAZ SIX STROKE ENGINEThe majority of the actual internal fire engines, ope judge on different cycles have one common feature, electrocution chancering in the cylinder after each compression, resulting in bollix up expansion that acts directly on the piston (work) and limited to 180 degrees of crankshaft fee.According to its mechanical design, the six-stroke engine with outside and internal combustion and double flow is similar to the actual internal reciprocating combustion engine. However, it differentiates itself entirely, due to its thermodynamical cycle and a modified cylinder head with two subsidiary domiciliates burning, does not occur within the cylinder within the cylinder but in the supplementary combustion chamber, does not act immediately on the piston, and its duration is independent from the 180 degrees of cranks haft rotation that occurs during the expansion of the combustion gases (work).The combustion chamber is sumly en closed in(p) within the air- heating chamber. By heat switch through the vehement combustion chamber walls, air squash in the heating chamber increases and generate power for an a supplementary work stroke. Several advantages result from this, one genuinely cardinal being the increase in thermal efficiency. IN the contemporary internal combustion engine, the necessary cooling of the combustion chamber walls generates important hot losses. 2.1 AnalysisSix-stroke engine is mainly due to the radical hybridization of two- and four-stroke technology. The six-stroke engine is supplemented with two chambers, which allow parallel function and results a full eight-event cycle two four-event-each cycles, an external combustion cycle and an internal combustion cycle. In the internal combustion in that location is direct come to among air and the working fluid, whereas t here is no direct contact betwixt air and the working fluid in the external combustion process. Those events that affect the motion of the crankshaft are called dynamic events and those, which do not effect are called static events.picFig 5 Prototype of Six stroke engine internal view1. dream valve, 2.Heating chamber valve,3.Combustion chamber valve,4. Exhaust valve,5. cylinder, 6.Combustion chamber,7. Air heating chamber, 8.Wall of combustion chamber,9.fire injector and 10.Heater plug.2.1.1 Analysis of eventspicFig 6 Event 1 splendid air use in the cylinder (dynamic event)1. Intake valve.2. Heating chamber valve3. Combustion chamber valve.4. Exhaust valve5. Cylinder6. Combustion chamber.7. Air heating chamber.8. Wall of combustion chamber.9. Fuel injector.10. Heater plug.picFig 7 Event 2 Pure air compression in the heating chamber.Event 3 retention virginal air pressure in closed chamber where a maximum heat ex exchange occurs with the combustion chambers walls, without direc t action on the crankshaft (static event).picFig 8 Event 4 elaborateness of the Super heat air in the cylinder work (dynamic Event).picFig 9 Event 5 Re-compressions of pure heated air in the combustion chamber (dynamic event).Events 6 fuel barb and combustion in closed combustion chamber, without direct action on the crankshaft (static event).picFig 10 Events 7 Combustion gases expanding in the cylinder, work (dynamic event).picFig 11 Events 8 Combustion gases gravel (dynamic event).picFig 12 Six-stroke engine cycle diagram2.1.2 External combustion cycle ( divided up in 4 events)No direct contact between the air and the heating source.e1. (Event 1) Pure air intake in the cylinder (dynamic event). e2. (Event 2) Compression of pure air in the heating chamber (dynamic event). e3. (Event 3) Keeping pure air pressure in closed chamber where a maximum heat exchange occurs with the combustion chambers walls, without direct action on the crankshaft (static event).e4. (Event 4) Expansion of the super heated air in the cylinder, work (dynamic event).2.1.3 subjective combustion cycle (divided in 4 events)Direct contact between the air and the heating source.I1. (Event 5) Re-compression of pure heated air in the combustion chamber (dynamic event) I2. (Event 6) Fuel crack and combustion in closed combustion chamber, without direct action on the crankshaft (static event). I3. (Event 7) Combustion gases expanding in the cylinder, work (dynamicevent). I4. (Event 8) Combustion gases exhaust (dynamic event).2.2 Constructional detailsThe sketches shows the cylinder head fitted out(p) with both chambers and four valves of which two are conventional (intake and exhaust). The two others are do of industrial heat-resisting material. During the combustion and the air heating processes, the valves could open low the pressure within the chambers. To avoid this, a piston is installed on both valve shafts which compensate this pressure. Being a six-stroke cycle, the camshaft sp eed in one third of the crankshaft speed.The combustion chambers walls are glowing when the engine is running. Their small thickness allows heat exchange with the air-heating chamber, which is surrounding the combustion chamber. The air-heating chamber is isolated from the cylinder head to reduce thermal loss.Through heat transfer from the combustion chamber to the heating chamber, the work is distributed everywhere two strokes, which results in less pressure on the piston and greater smoothness of operation. In addition, since the combustion chamber is isolated from the cylinder by its valves, the pathetic separate, curiously the piston, are not subject to any excessive stress from the very high temperatures and pressures. They are also protected from explosive combustion or auto-ignition, which are observed on ignition of the air-fuel commixture in conventional gas or diesel engines.The combustion and air-heating chambers have different compression ratio. The compression ratio is high for the heating chamber, which operates on an external cycle and is supplied solely with pure air. On the other hand, the compression ratio is low for the combustion chamber because of effectively increase saturation, which operates on internal combustion cycle.The combustion of all injected fuel is insured, first, by the supply of preheated pure air in the combustion chamber, then, by the glowing walls of the chamber, which acts as multiple spark plugs. In order to facilitate coldstarts, the combustion chamber is fitted with a heater plug (glow plug). In contrast to a diesel engine, which requires a heavy construction, this multi-fuel engine, which can also use diesel fuel, may be built in a much spark fashion than that of a gas engine, e finically in the eggshell of all moving parts.Injection and combustion take place in the closed combustion chamber, therefore at a constant volume, over 360 degrees of crankshaft tap. This feature gives plenty of sequence for the fue l to burn ideally, and releases every potential calorie (first contribution to contaminant reduction). The stab may be split up, with twofold fuel using the SNDF system (Single Nozzle, Dual Fuel). The glowing walls of the combustion chamber will calcite the residues, which are deposited there during fuel combustion (second contribution to contaminant reduction).As well as regulating the intake and exhaust strokes, the valves of the heating and the combustion chambers allow importantly additional adjustments for improving efficiency and reducing noise.2.3 Factors Contributing To the Increased Thermal Efficiency, Reduced Fuel Consumption, and Pollutant rise 1. The heat that is evacuated during the cooling of a conventional engines cylinder head is recovered in six-stroke engine by air-heating chamber surrounding the combustion chamber. 2. After intake, air is compressed in the heating chamber and heated through 720 degrees of crankshaft angle, 360 degrees of which in closed chamb er (external combustion). 3. The transfer of heat from thin walls of the combustion chamber to the air heating chambers put downs the temperature, pressure of gases on expansion and exhaust (internal combustion). 4. Better combustion and expansion of gases that take place over 540 degrees of crankshaft rotation, 360 of which is in closed combustion chamber, and 180 for expansion. 5. Elimination of the exhaust gases crossing with dulcet air on intake. In the six stroke-engines, intake takes place on the first stroke and exhaust on the fourth stroke. 6. Large reduction in cooling power.The water pump and fan outputs are trim. Possibility to suppress the water cooler. 7. Less inertia dueto the lightness of the moving parts. 8. Better filling of the cylinders on the intake due to the spurn temperature of the cylinder walls and the piston head. 9. The glowing combustion chamber allows the finest burning of any fuel and calcinate the residues. 10. Distribution of the work two expansio ns (power strokes) over six strokes, or a third more than the in a four-stroke engine. Since the six-stroke engine has a third less intake and exhaust than a four stroke engine, the depression on the piston during intake and the back pressure during exhaust are reduced by a third. The gain in efficiency balances out the losses due to the passage of air through the combustion chamber and heating chamber valves, during compression of fresh and superheated air. Recovered in the six-stroke engine By the air-heating chamber surrounding the combustion. Friction losses, theoretically higher in the six-stroke engine, are balanced by a better distribution of pressure on the moving parts due to the work being spread over two strokes and the elimination of the direct combustion. 3. DUAL give notice SIX STROKE ENGINE3.1 WorkingThe cycle of this engine consists of six strokes1. Intake stroke2. start-off compression stroke3. First combustion stroke4. Second compression stroke5. Second combustio n stroke6. Exhaust strokepicFig 13 Concept of a Six-stroke diesel engine3.1.1 Intake or Suction strokeTo start with the piston is at or very near to the T.D.C., the doorway 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 isjust being started. As the piston moves from circus tent 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 going away 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.3.1.2 First Compression strokeBoth 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 compres sion are 35-40 kgf/cm2 and 600-700 0C3.1.3 First combustion strokeThis stroke includes combustion of first fuel (most probably diesel) and expansion of return 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 scene process, the fuel in finely atomized form is injected in combustion chamber. When fuel vapors raises to self ignition temperature, the combustion of accumulated oil commences and there is sudden rise in pressure at or so 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 or so constant pressure.Due to expansion of gases piston moves downwards. The reciprocating motion of piston is converted into rotary motion of crankshaft by connectingrod and crank. During expansion the pressure slide down is due to increase in volume of gases and absorption of heat by cylinder walls.3.1.4 Second compression strokeBoth 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.3.1.5 Second combustion strokeThis 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 stoppage or ignition lag as the fuel being tested under same operating conditions on same engine). The combustion of the charge commences when the piston approaches to TDC.The second fuel injected into recompressed fire gas can be burnt in the second combustion process. In other words combustion process of the second fuel takes 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.3.1.6 Exhaust strokeThe 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 obscure at high speed. Much of the noise associated with automobile engine is due to high exhaust velocity. The counterbalance of burnt gases is cleared of the swept volume when the piston moves from TDC to BDC. During this stroke pressure inside the cylinder is meagrely above the atmospheric value. Some of the burnt gases are howeverleft in the clearance space. The exhaust valve closes shortly after TDC.The inlet valve opens slight ly before the end of exhaust stroke and cylinder is organize 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.3.2 act analysis3.2.1 Modification over four stroke diesel engineThis 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. 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 fl ow 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.The nozzle is located near the nubble of a piston cavity, and has four injection holes. For the six-stroke diesel engine, one extra nozzle was added on the cylinder head. This extra nozzle was of the same design as that of the four-stroke engine. picFig 14 Volume Angle diagram for six stroke engineDiesel 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 fourstroke 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 eng ine, crank angle of the first combustion TDC is 180 degrees. The second combustion TDC is 540 degrees.Specifications of the test engines are shown in circuit card 1. The conventional four-stroke diesel engine that was chosen as the basis for these experiments was a single cylinder, air cooled engine with 82 mm bore and 78 mm stroke. The six-stroke engine has the same engine specifications except for the valve timings. However, the volumetric efficiency of the six-stroke engine showed no significant difference from that of the four-stroke engine.Characteristics of the six-stroke diesel engine were equalized with the conventional four-stroke diesel engine. In this paper, the engine speed (Ne) was fixed at 2,000 rpm. Cylinder and line pressure indicators were equipped on the cylinder head. NO concentration was measured by a chemiluminescences NO meter, and soot emission was measured by a Bosch smoke meter.The physical and combustion properties of diesel fuel and methanol are shown in Table. 2. Since combustion heats of diesel fuel and methanol are different, injection flow rates of the first and the second combustion processes are defined by the meat of combustion heat. Here, the supplied combustion heat for the first combustion process is denoted by QI. The second combustion stroke is denoted by QII. The ratio of QII to Qt (Qt = QI+QII) supplied combustion heat per cycle) is defined as the heat assignation ratio H H = QII = QII QI +QII QtTable 1. Specifications of the test engine iv stoke Six strokeDiesel Engine Diesel Engine Engine type DI, Single cylinder, Air cooled, OHV Bore x Stroke mm 82 x 78Displacement cc 412Top Clearance mm 0.9 Cavity Volume cc 16 Compression ratio 21 Intake Valve Open100 BTDC70 BTDCIntake valve Close1400 BTDC1450 BTDCExhaust Valve Open1350 ATDC1400 ATDCExhaust Valve Close120 ATDC30 ATDCValve Overlap 220 100Rated power 5.9 kW /3000rpmBase Engine -Table 2. Physical and combustion properties of diesel fuel and methanol Diesel Fuel Me thanol Combustion heat MJ/kg 42.7 19.9 Cetane number 40-55 3.0 Density kg/m2 840 793 Theoretical air-fuel ratio 14.6 6.5 3.3 surgery of six stroke diesel engine3.3.1 Comparison with four stroke diesel engineA 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 building block epoch constant, the combustion heat supplied to one six-stroke cycle should be 3 or 2 times larger than that of the four-stroke engine.There are many ways to canvas performance between the four-stroke and six-stroke engines. For this paper, the authors have chosen to comparethermal efficiency or SFC 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 proportion, fuels supplied per unit time wer e 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. precise conditions for similarity 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 H = 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, 0.75 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 (15BTDC) or 174 degrees (6BTDC), and the second injection timing was changed from 520 degrees (2000 BTDC) to 540 degrees (TDC).picFig 15 Valve timing diagram four stroke engineTable 3. Detailed conditions of comparison between the four stroke and six stroke diesel engines and performance of engine Four Stroke Six Stroke Engine ParametersDiesel Engine Diesel Engine Engine vivify Ne rpm 2007 2016 Supplied combustion heat per cycle Qt KJ/cycle 0.50 0.68 Supplied combustion heat per unit time Ht KJ/s 8.36 7.62 Intake air flow per cycle Ma mg/cycle 358.7 371.4 Injection quantity per cycle Mf mg/cycle 11.8 16 excess air ratio 2.40 1.83 Intake air flow per unit time Ma g/cycle 6.00 4.16 Injection quantity per unit time Mf g/sec 0.197 0.179 Brake tortuousness Tb N-m 15.52 15.28 Brake power Lb KW 3.26 3.24 BSFC. b g / KW-h 217.9 520.3 IMEP Pi Kgf / cm2 5.94 4.37 Indicated torque Ti N-m 19.10 18.71 Indicatedpower Li KW 4.01 3.75 ISFC bi g / KW-h 177.2 163.3 Indicated torque of the six-stroke engine is almost same level with that of the four-stroke engine under various injection timings. NO concentration in exhaust gas of the six-stroke engine was lower than that of the four-stroke engine. NO emissions from both engines were reduced by the suss out of injection timing. The effect of stop in the second injection timing of the six-stroke engine was similar to that of the check off in the four-stroke engine.For the six-stroke engine, from the comparison between Xi I = 165 degrees (15BTDC) and Xi I = 174 degrees (6BTDC), it seemed that the NO reduction effect appeared with the timing hold up in the first combustion process.soot emission in the exhaust gas of the four-stroke engine was low level and it was not affected by the timing retard of injection. However, the level of soot emissi on from the six-stroke engine was strongly affected by the timing of the second injection. When the injection timing was advanced from 528 degrees (12 BTDC), it was confirmed that the soot emission was lower than that of the four-stroke engine.From numerical analysis, it was considered that the soot formed in the first combustion process was oxidized in the second combustion process. On the contrary, when the injection timing was retarded from 528 degrees (12 BTDC), soot emission increased with the timing retard. Then, it was considered that the increased part of the soot was formed in the second combustion process because an purchasable period for combustion was shortened with the retard of injection timing.Experimental conditions were Xi = Xi I = clxx degrees (100 BTDC) and XiII=530 degrees (100 BTDC). The heat allocation ratio of six stroke enginewas H=0.5.The cylinder temperature and heat release rate were calculated from the cylinder pressure. The ensample of heat release r ate in the first combustion stroke of the six-stroke engine was similar to that of the heat release rate of the four-stroke engine. It was the typical combustion pattern that contained a pre-mixed combustion and diffusion combustion. On the other hand, since an increase of cylinder temperature in the second combustion process was caused by the compression of the burned-over gas formed in the first combustion stroke, a pre-mixed combustion in the second combustion process was suppressed by a short ignition delay. The maximum cylinder temperature in the first combustion process was lower than that in the four-stroke engine. It was caused by little amount of fuel which was injected in the first combustion process. Considering these results, it was proved that NO concentration in the exhaust gas was reduced by the decrease of the maximum cylinder temperature in the first combustion process and EGR effect in the second combustion process.The performance of these two engines could be co mpared by Table. 3. Since BSFC of the six-stroke engine obtained by the brake power suffered, SFC is compared with ISFC for the Xi = 163 degree (170 BTDC), ISFC of the four-stroke engine was 177.2 g/KW-h.On the other hand, for the Xi I = 165 degrees (15 BTDC) and Xi II = 523 degrees (170 BTDC), I.S the six-stroke engine was 163.3 g/KW-h. i.e. ISFC of the six-stroke engine was slightly lower than that of the four-stroke engine.It was considered that this advantage in ISFC was caused by a small cut-off ratio of constant pressure combustion. Because, in the six-stroke engine proposed here, the fuel divided into two combustion processes resulted in a short combustion period of each combustion process. Furthermore, in the reduction of NO emission, the six-stroke engine was topnotch to the four-stroke engine.3.3.2 Effect of heat allocation ratioInjection conditions were Xi I = 170 degrees (1000 BTDC) and Xi II = 530 degrees (100 BTDC). Both fuels in the first and second combustion proces ses were diesel fuel. Total fuel at the combustion heat basis was Qt = 0.68 KJ/cycle. It meant a high fill up in this engine because the total excess air ratio was 1.83 as previously shown in Table 3.The maximum value of the indicated torque appeared around H = 0.5 NO concentration in exhaust gas was reduced by an increase of heat allocation ratio. In other words, NO emission decreased with an increase of the fuel of the second combustion process.In the case of H = 0.5, there is a relatively long ignition delay in the first combustion process and pre-mixed combustion was the main combustion phenomena in it. NO of high concentration was formed in this pre-mixed combustion process. On the other hand, in the case of H = 1, diffusion combustion was the main combustion phenomena and NO emission was low. smut fungus emission in exhaust gas increased with an increase of heat allocation ratio. Since the injection flow rate in the second combustion process increased with an increase of the heat allocation ratio, the injection period increased with an increase of the heat allocation ratio. It caused the second combustion process to be long, and unburnt fuel that was the origin of soot remained after the second combustion process.The heat release rates on H = 0.15 and H = 0.85. For H =0.15, since injection flow rate in the first combustion process was high and injection period in it was long, the combustion period in the first combustion process became long as compared with case of H = 0.85. On the other hand, for H = 0.85, the combustion period in the second combustion process became long as compared with case of H=0.15. It was also observed that the long combustion periods in both the first and second combustion were caused by the long diffusion combustion. Further, diffusion combustion was the main combustionphenomena of the second combustion process.When the heat allocation ratio was 0.85, the ratio of heat release rates between the first and second combustion shoul d be 15 85, however the actual ratio obtained from the figure was 46 54. This inconsistency was caused from the drift of the base lines of the heat release diagrams. For H = 0.15, the actual ratio of heat release rates was 73 27 with the similar reason.The cylinder temperature for the H = 0.15 condition was higher than that of the H = 0.85 condition. This could be explained as follows. In the first combustion stroke, since the injection flow rate of H = 0.15 was higher than that of H = 0.85, the combustion temperature for the H = 0.15 condition was higher than that of H = 0.85. In the second compression stroke, since the high temperature burned gas was re-compressed, the temperature of H = 0.15 was also higher than that of H = 0.85.As a result, the temperature at the beginning of the second combustion stroke was high in H = 0.15 condition as compared with H = 0.85 condition. At the posterior stage of the second combustion, however, the opposite relationship between these two temper atures were observed, because the injection flow rate of the second combustion process was low in H = 0.15 condition.The maximum temperatures in the first and second combustion process decreased with an increase of the heat allocation ratio. Then, it could be reason out that the reduction of NO concentration with the heat allocation ratio, was caused by the decrease of the cylinder temperature.3.4 Performance of the dual fuel six stroke diesel engine3.4.1 Comparison with diesel fuel six stroke engineOperating conditions of comparison between the diesel fuel and the dual fuel six-stroke engines are shown in Table. 4. Experimental conditions were Xi I= 170 degrees (100 BTDC), Xi II = 530 degrees (10o BTDC) and H = 0.5.In dual fuel six-stroke engine, diesel fuel and methanol were supplied into first and second combustion process, independently. Combustion heats supplied per one cycle of the diesel fuel and dual fuel six-stroke engines were same. The combustion heat supplied per one cy cle was selected as Qt = 0.43 KJ/cycle under the centerfield load condition. Performance of the dual fuel six-stroke engine was compared with the diesel fuel six-stroke engine under various injection timings in the second combustion process. Indicated torques of both engines was revealed constant around 15 N-m. As a result, it could be concluded that states of combustion of the diesel fuel and the dual fuel six-stroke engines had similar contributions on the engine performance. NO emissions from the dual fuel six-stroke engine were lower than those of the diesel fuel six-stroke engine. This effect appeared prominently at the advanced injection timing of the second combustion. Further, NO concentrations of both engines were reduced by the injection timing retard in the second combustion. picFig 16 Torque- Angle diagram for six stroke engineSoot emission in the exhaust gas of the diesel fuel six stroke engines increased with a retard of the injection timing in the second combustion. For the dual fuel six-stroke engine, the exhaust level of soot was very low under various injection timings of the second combustion process. Soot was formed clearly by the combustion of diesel fuel in the first combustion process and it was oxidized in the second combustion process. Considering these results, it was possible to estimate that soot was almost oxidized by methanol combustion in the second combustion process. This estimation is supported by a dual fuel diesel engine operated with diesel fuel methanol.The combustion heat supplied per one cycle was selected as Qt = 0.68 KJ/cycle under the high load condition. Indicated torques of both engines was also revealed constant around 20 N-m. NO concentration had the same list as the cases of the middle load. Soot emission level of the diesel fuel six-stroke engine was high in this high load condition. For the dual fuel six-stroke engine, however, soot was very low under various injection timings of the second combustion process .The performance of these engines was compared in Table. 4. For the second combustion process, since combustion heats of diesel fuel and methanol were different, injection quantities of both engines were different. BSFC and ISFC of the dual fuel six-stroke engine was sensibly higher than that of the diesel fuel engine. To compare the performance of these engines, injection quantity of both engines was defined by an amount of combustion heat, and SFC should be calculated from it. As a result, indicated specific heat inlet of the diesel fuel six-stroke engine was 5.59 MJ/KW-h, and that of the dual fuel six-stroke engine was 5.43 MJ/KW-h. For the high load conditions shown in Table. 5, the similar advantage of the dual fuel six-stroke engine was observed.Table 4. Detailed conditions of comparison between the diesel fuel and dual fuel diesel engines and performance of engines under H = 0.5 and middle load Diesel Fuel Six Stroke Diesel Dual Fuel Six Stroke Engine Diesel Engine Engin e Speed Ne rpm 2016 2003 Supplied combustion heat per cycle Qt KJ/cycle 0.43 Injection quantity per cycle 5.0 (First Combustion Stroke) (Diesel Fuel) Mf1 mg/cycle Injection quantity per cycle 5.0 10.7 (Second Combustion Stroke) (Diesel Fuel) (Methanol) Mf2 mg/cycle Excess air ratio 2.98 3.15 Brake torque Tb N-m 3.14 3.14 Brake power Lb KW 0.66 0.66 B.S.F.C. b g / KW-h 610.9 952.9 I.M.E.P. Pi Kgf / cm2 3.43 3.53 Indicated torque Ti N-m 16.70 15.12 Indicated power Li KW 3.1 2.77 I.S.F.C. bi g / KW-h 130.1 198.4 Indicated specific heat consumption bi MJ /KW-h 5.59 5.43 In order to confirm the advantage of dual fuel six-stroke engine, the performance of these engines was compared with four-stroke engine as shown in Table. 6. NO concentrations of the diesel fuel and the dual fuel six-stroke engines were improved with 85 90% as compared with that of the four-stroke engine. Soot emission of the diesel fuel six-stroke engine was much higher than that of the four-stroke engine. However, for the dual fuel six-stroke engine, soot level was very low.Furthermore, the indicated specific heat consumption of the diesel fuel and dual fuel six-stroke engine were lower than that of the four-stroke engine. Especially, for the dual fuel six-stroke engine, the indicated specific heat consumption was improved with 15% as compared with that of the four stroke engine. From these results, it could be confirmed that the dual fuel six-stroke engine was choice to the diesel fuel six-stroke engine, and also it was superior to the four-stroke engine.Table 6. Percentage improvements of exhaust emission and specific heatconsumption Four Stroke Diesel Six Stroke Diesel EngineDual Fuel Six Stroke Engine Engine NO ppm 113 90.5 ( % improvement) 768 (85.3%) (88.2%) Soot % 28.8 0 (%improvement) 6.8 (- 323.5%) (100%) Indicated specific heat consumption bi MJ/KW-h 7.51 6.61 6.37 (% improvement) (12.0%) (15.2%) Table 5. Detailed conditions of compar ison between the diesel fuel and dual fuel diesel engine and performance of engines under H =0.5 and high load Six Stroke Diesel Engine Dual Fuel Six Stroke Engine Engine Speed Ne rpm 2016 2006 Supplied combustion heat per cycle Qt kJ/cycle 0.68 Injection quantity per cycle 8.0 (First Combustion Stroke) (Diesel Fuel) Mf1 mg/cycle Injection quantity per cycle 8.0 17.2 (Second Combustion Stroke) (Diesel Fuel) (Methanol) Mf2 mg/cycle Excess air ratio 1.86 1.93 Brake torque Tb N-m 6.18 6.08 Brake power Lb kW 1.52 1.5 B.S.F.C. b g / kW.h 504.0 777.7 I.M.E.P. Pi kgf / cm2 4.56 4.75 Indicated torque Ti N-m 21.68 20.38 Indicated power Li kW 3.45 2.98 I.S.F.C. bi g / kW.h 155.5 236.2 Indicated specific heat consumption bi MJ /kW.h 6.61 6.37 3.4.2 Effect of injection timingPerformance of the dual fuel six-stroke engine under various injection timings in the second combustion process was investigated on middle and high load. Experimental conditions were Xi I = 170 degrees (100 BTDC) and H = 0.5.Performance of the dual fuel six-stroke engine under both load conditions had the similar tendency with the timing retard. NO concentrations in the high load condition were higher than those of the middle load condition. However, soot emission levels of both load conditions were extremely low under various injection timings of the second combustion.3.4.3 Effect of heat allocation ratioPerformance of the dual fuel six-stroke engine under various heat allocation ratios was investigated on middle and high load. Injection conditions were Xi I = 170 degrees (100 BTDC) and Xi II = 530 degrees (100 BTDC). Since the combustion heat of methanol was low, experimental range of heat allocation ratio was limited by the smooth operation of the engine. solo the range from H = 0.25 to 0.75 (on Qt = 0.43 KJ/cycle), and from H = 0 to 0.5 (on Qt = 0.68 KJ/cycle) could be tested..Indicated torque increased with an increase of the heat allocation ratio. NO concentra tion in exhaust gas was reduced with an increase of the heat allocation ratio. Soot was very low, irrespective of the methanol flow rate. Even if the load condition was high, it was concluded that soot was much eliminated by a small amount of methanol in the second combustion process (8% of total fuel).4. ADVANTAGES OF SIX STROKE OVER FOUR STROKE ENGINESThe 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 leechlike but is a net contributor to and an integral part of the power generation within exhaust stroke. The compression ration 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 seizure of valves within the combustion chamber allows considerable design freedom.4 .1 Main advantages of the duel fuel six-stroke engine4.1.1 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 throttle 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 thermalefficiency compensating for the issue due to the two additional strokes.4.1.2 Two expansions (work) in six strokesSince 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.4.1.2 Dramatic reduction in pollutionChemical, noise a nd thermal pollution are reduced, on the one hand, in proportion to the reduction in specific consumption, and on the other, through the engines own characteristics which will help to considerably lower HC, CO and NOx emissions. Furthermore, its 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.4.1.3 MultifuelMultifuel 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. Its 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.5. CONCLUSIONSThe performance of the dual fuel six-stroke engine was investigated. In this dual fuel engine, diesel fuel was supplied int o the first combustion process and methanol was supplied into the second combustion process wherethe burned gas in the first combustion process was re-compressed. The results are summarized as follows.1. Indicated specific fuel consumption (ISFC.) 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 th e 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.5. As the fuel in one cycle was divided into two combustion processes and the EGR effect appeared in the second combustion process, the decreased maximum cylinder temperature reduced NO concentration in the exhaust gas It was further confirmed that soot formed in the first combustion process was oxidized in the second combustion process .Therefore, a six stroke DI diesel engine has significant possibilities to improve combustion process because of its more controllable factors relative to a conventional four-stroke engine. Considering these results, it was confirmed that the dual fuel six-stroke engine was superior to the four-stroke engine.6. REFERENCES1. Tsun aki Hayasaki, Yuichirou Okamoto, Kenji Amagai and Masataka Arai A Six-stroke DI Diesel Engine under Dual Fuel Operation SAE Paper No1999-01-15002. S.Goto and K.Kontani, A Dual Fuel Injector for Diesel Engines, SAE paper, No. 851584, 1985 3. Internal Combustion Engines A book by Mathur Sharma. 4. Internal Combustion Engines Tata McGraw-hill publications,Author V Ganesan7. NOMENCLATURENe Engine speedX Crank angleXi Injection timing of the four-stroke diesel engineH Heat allocation ratioQ Supplied combustion heatQt Supplied combustion heat per cycleP Cylinder pressureV Cylinder volumeVs Stroke volumePi Indicated mean effective pressure (LM.E.P)Ti Indicated torqueLi Indicated powerTb Brake torqueLb Brake powerHt Supplied combustion heat per unit timeMa Intake air flow per cycleMa Intake air flow per unit timeMf Injection quantity per cycleMi Injection quantity per unit time Excess air ratiob Brake specific fuel consumption (B.S.F.C.)bl Indicated specific fuel cons umption (I.S.F.C.)bi Indicated specific heat consumptionSUBSCRIPTSI first combustion strokeII second combustion stroke4 four-stroke diesel engine6 six-stroke diesel engine