ABSTRACT
The modern day world is a fast paced world and automobiles play a major role in keeping this world up to its pace. The heart of any automobile is the Engine. Since automobiles have come to life, researchers have been trying to develop newer and better versions of the Engine so that the world is exposed to more efficient, more cleaner and at the same time relatively cheaper sources of power. The most established forms of the Engine in the present day are the Two-Stroke and the Four-Stroke Engines. The Four-Stroke engines were developed first and are still the most widely used engines in the world. The Two-Stroke engines provide a compacter and cheaper design and have found their utility in motorcycles and small-engine devices. Through the ongoing a research, a newer version of the Engine, a Six-Stroke Engine has come to life. The primary objective of this paper is to analyse the various different models of the Six-Stroke Engines that have been developed. In the following paper, different models of the Six-Stroke Engine have been discussed, analysed, compared, and the most suitable and plausible model has been found out. In addition to this, the Six-Stroke engines have also been compared to Four-Stroke and Two-Stroke Engines. Eventually, the advantages of this newer version of the engine over the older engines have been found out and presented in a logical manner.
INTRODUCTION AND LITERATURE SURVEY
WORKING OF SIX STROKE ENGINE
The basic reason that a Six-Stroke Engine is being considered as a good alternative to Two-Stroke and Four-Stroke Engines is that irrespective of which model of the SixStroke engine is being considered, there are two power strokes delivered in six strokes of the piston. A standard Four-Stroke Engine delivers only a single power stroke in four strokes or two rotations of the crankshaft, while a standard Two-Stroke Engine delivers a power stroke in two strokes of the piston and one rotation of the crankshaft. The Six-Stroke Engine also differentiates itself in terms of its fuel consumption. In most models of this most recent form of the Engine, the first stroke comes from the standard Fuel-Air mixture itself while the second stroke comes from utilizing normal air/steam without any additional heating requirements. Even intuitively, this procedure gives an entire additional power stroke with about the same quantity of fuel as a Four-Stroke Engine. The thermal efficiency of a four stroke internal combustion engine is found to be approximately equal to 33%. This points out the fact that almost 67% heat of fuel is absorbed up by the components in the cylinder or lost to the surroundings. Therefore, if the energy released during this combustion is utilized efficiently and used to heat up water or air for another power stroke, significantly larger amounts of energy can be released with same amount of charge.This paper is based upon how to use this simple, intuitive idea and design an engine which can run according to the above mentioned procedure. The survey from various sources of literature shows that there are two major types of designs of Six-Stroke Engines have been brought to life since 1890s. These are: a) Single Piston Design b) Opposed Piston Design Both these designs are aimed at making the traditional Four-Stroke Engine more efficient and with reduced emissions. However, they come at the cost of increased complexity. In the first approach, the engine captures the heat lost from the four-stroke Otto cycle or Diesel Diesel cycle and uses it to power an additional power and exhaust stroke of the piston in the same cylinder. Designs use either steam or air as the working fluid for the additional power stroke. The pistons in this type of six-stroke engine go up and down
three times for each injection of fuel. There are two power strokes: one with fuel, the other with steam or air. The second approach to the six-stroke engine uses a second opposed piston in each cylinder that moves at half the cyclical rate of the main piston, thus giving six piston movements per cycle. Functionally, the second piston replaces the valve mechanism of a conventional engine but also increases the compression ratio. The four key models based on the first method of design are: a) b) c) d)
Griffin Six Stroke Engine Bajulaz Six Stroke Engine Crower Six Stroke Engine Velozeta Six Stroke Engine
The two key models based on the second method of design are: a) Beare Head Six-Stroke Engine b) M(4+2) Six Stroke Engine
Figure 1: Illustration of an Opposed Piston Design
Figure 2: Illustration of a Single Piston Design
Therefore, Six-Stroke Engines have been a popular field of research for a lot of researchers. In this paper also, as we analyse the various models available in the present day, we come across a number of things that are different in Six-Stroke Engines as compare to the conventional Four-Stroke Engines. Significant and notable changes have been observed in the following characteristics of engines: a) b) c) d) e)
Power Output Efficiency and torque delivered Peak pressures and temperatures reached Fuel Consumption Weight and complexity of the engines
METHODOLOGY
Our approach to this project is based on reading various research papers and journals and understanding the ongoing research in the field of six stroke engines and its various modifications. The primary objective of the project is to understand the difference in the working of a Four-Stroke Engine and a Six-Stroke Engine. After reading through and and analyzing the working of Six-Stroke Engines we try and list the advantages of Six-Stroke Engines over Four-Stroke Engines. In the following section, we briefly describe the steps undertaken in the complete study and analysis of our project. a) Theoretical approach The first step in the project preparation was to understand the theory behind the working of Six-Stroke Engines. Through various sources of information, it was brought to our knowledge that as of now, six major models of Six Stroke Engines have been develop all across the world. Four of these models are based on the „Single Piston Design‟ and two of the major models are „Opposed Piston Design‟. Bo th these designs involve different methods of functioning of the Six Stroke Engine. A detailed study was done about the various processes involved in the working of all these different models. The major theoretical study involved studying about the two additional stroke in the Six Stroke Engines. The most important processes of the six stroke engine were Water Injection and Recompression. Water Injection involves the efficient utilization of the heat energy released in a standard four stroke engine to generate an additional power stroke. We studied the role of water injection in 6 stroke engines from the following research paper – A highly efficient six-stroke internal combustion engine cycle with water injection for in-cylinder exhaust heat recovery James C. Conklin, James P. Szybist*
After extensive research on the additional strokes we shifted gears to the study of various modifications to the camshafts and crankshafts of the previously developed conventional Four-Stroke Engines. This involved the development of the specific ratio
which generates maximum power. The major research paper required for the study in the above mentioned topic was: Camshaft and Crankshaft to camshaft ratio modifications – International Research Journal of Humanities, Engineering & Pharmaceutical Sciences b) Analytical Approach
After gaining sufficient knowledge about how a Six Stroke Engine works, and what different steps and processes should be adopted in its working, we analysed what are the factors affecting the thermal efficiency and fuel consumption of a standard engine. A detailed and major part of the discussion is devoted to mentioning the points affecting the efficiency and fuel consumption. After this, we moved on to discussions about how a Six Stroke Engine is different and better from a standard Four Stroke Engine. This involved listing down the proper advantages and disadvantages of the studied models.
Towards the end, after extensive research, we present the detailed benefits and limitations that the most viable models of Six Stroke Engines process, and thereby conclude our project.
Results and discussion
TYPES OF SIX STROKE ENGINE A) Single piston designs
These designs use a single piston per cylinder, like a conventional two- or four-stroke engine. A secondary, non-detonating fluid is injected into the chamber, and the leftover heat from combustion causes it to expand for a second power stroke followed by a second exhaust stroke. (A.1) Griffin six-stroke engine
Heated exhaust-jacketed external vaporiser, into which fuel was sprayed, was the main principle of working of griffin six stroke engines. The temperature was held around 550°F, sufficient to vaporise the oil but not to break it down chemically. This fractional distillation supported the use of heavy oil fuels, the unusable tars and asphalts separating out in the vapouriser. (A.2) Bajulaz six-stroke engine
The Bajulaz six-stroke engine is similar to a regular combustion engine in design. There are, however, modifications to the cylinder head, with two supplementary fixed capacity chambers: a combustion chamber and an air preheating chamber above each cylinder. The combustion chamber receives a charge of heated air from the cylinder; the injection of fuel begins an isochoric (constant-volume) burn which increases the thermal efficiency compared to a burn in the cylinder. Advantages:
1. 2. 3. 4.
Reduction in fuel consumption by at least 40% Two Power strokes in one cycle. Dramatic reduction in pollution (up to 65%) due to more complete combustion. Adaptable for different fuel types.
Disadvantages:
1. Engine size increases due to many number of cylinders & additional components. 2. Brake power & indicated power per cycle per cylinder is comparatively lesser 3. Higher manufacturing cost (A.3) Velozeta six-stroke engine
In a Velozeta engine, fresh air is injected into the cylinder during the exhaust stroke, which expands by heat and therefore forces the piston down for an additional stroke. The valve overlaps have been removed and the two additional strokes using air injection provide for better gas scavenging. Advantages of Velozeta Six Stroke Engine Reduction in fuel consumption Dramatic reduction in pollution normally up to 65% Better scavenging and more extraction of work per cycle Lower engine temperature - so , easy to maintain the optimum engine temperature level for better performance Less friction – so , less wear and tear The six-stroke engine does not require any basic modification to the existing engines
(A.4) NIYKADO Six Stroke Engine
This is the only engine that is categorized as a fully working prototype. The first prototype was developed in 2004, which used only two valves. The second prototype, developed in 2007, was an improved design using four valves. (A.5) Crower six-stroke engine
In a six-stroke engine prototyped in the United States by Bruce Crower, water is injected into the cylinder after the exhaust stroke and is instantly turned to steam, which expands and forces the piston down for an additional power stroke. Thus, waste heat that requires an air or water cooling system to discharge in most engines is captured and put to use driving the piston
B) Opposed piston designs
These designs use two pistons per cylinder operating at different rates, with detonation occurring between the pistons. (B.1) Beare Head
The term "Six Stroke" was coined by the inventor of the Beare Head, Malcolm Beare. The technology combines a four stroke engine bottom end with an opposed piston in the cylinder head working at half the cyclical rate of the bottom piston. Functionally, the second piston replaces the valve mechanism of a conventional engine.
(B.2) M4+2 The M4+2 engines have much in common with the Beare Head engines, combining two opposed pistons in the same cylinder. One piston works at half the cyclical rate of the other, but while the main function of the second piston in a Beare Head engine is to replace the valve mechanism of a conventional four stroke engine, the M4+2 takes the principle one step further. WORKING OF SIX STROKE ENGINES 1st stroke (suction stroke) The inlet valve is kept open. Due to cranking, Piston moves downward which results in the formation of a pressure difference due to which pure air enters the cylinder. 2nd stroke (compression stroke) The inlet valve closes and the heating chamber valve opens. The piston moves upward due to cranking forcing air into heating chamber. The air at this stage is converted to high pressure. 3rd stroke (1st power stroke) The combustion chamber valve opens and gases of combustion enter the cylinder. 4th stroke (exhaust stroke) The exhaust valve opens. The piston moves upwards and the exhaust gases are removed via this valve. 5th stroke (2nd power stroke) The chamber valve opens and the pure air now at high pressure and high temperature enters the cylinder which does work on the piston and hence it moves downward resulting in the 2nd power stroke.
6th stroke (2nd exhaust stroke) Finally the combustion chamber valve opens. The piston moves upwards forcing the pure air into the combustion
To summarize in graphical form in Figure 1, there were representative valve lifts and their resultant combustion chamber pressure values are plotted versus crank angle where the proposed exhaust recompression and water injection are explicitly shown.
. Figure 1: Example of exhaust valve events and cylinder pressure for the six-stroke cycle ADDITIONAL TWO STROKES OF SIX-STROKE ENGINES a) Re-compression An additional assumption that the recompression process is isentropic from
State 1 to State 2 yields the additional state property required by the State Postulate of Thermodynamics for a simple compressible system to determine completely the thermodynamic properties at State 2. The work required by the recompression process is thus known for a given crank angle closing.
Figure 2: Pressure trace schematic for exhaust recompression and steam injection showing thermodynamic states The identity of mass conservation was employed to equate the mass at State 3 to the mass at State 2 and the mass of the injected water. Now that the two properties of internal energy and specific volume are known at state point 3, the thermodynamic state is uniquely determined. Thus the temperature and pressure at the start of the additional power stroke are known. b) Additional Power Stroke Expansion Because there is no mass flow across the combustion chamber control volume During the expansion process and assuming that the recompression process is adiabatic. An additional assumption that the expansion process is isentropic from State 3 to State 4 yields the additional state property required by the State Postulate to determine completely the thermodynamic properties at State 4. The work output from the expansion process can be calculated. EFFECT OF THE ADDITIONAL TWO STROKES
The net work is the expansion work less the recompression work. The net mean effective pressure (MEP) of the early exhaust valve closure and water injection (the fourth and fifth strokes) is then determined by dividing the expansion work of the fifth stroke less the compression work of the fourth stroke by the displacement volume. Although having the units of pressure, the MEP is a measure of the performance of any engine irrespective of size or volumetric displacement. Condensation during an expansion is generally undesirable because of potential equipment damage due to droplet erosion and also because of the resultant decrease in specific volume. An increase in specific volume results in desirable expansion work. WATER INJECTION IN SIX-STROKE ENGINES
There are fluctuations in the engine-out exhaust temperature from 400 to 600 C. The exhaust temperature ranges of naturally aspirated gasoline engine is higher, typically from 450 to 800 C. The total fuel energy consumed during the course of the driving cycle is approximately 58.5 MJ, or about 1.7 L of unleaded gasoline fuel. The percentage of fuel energy converted to useful work for this driving cycle (i.e. the vehicle thermal efficiency) is 10.4%. A much larger portion of fuel energy, 27.7%, exits the vehicle in the form of thermal energy in the exhaust, while the remaining 61.9% of the energy balance consists of energy losses to friction, coolant, and others. Improving the efficiency of internal combustion engines is an ongoing area of active research. Numerous designs have been proposed based on the traditional Otto or Diesel cycles, and all of these include four sequential thermodynamic processes or „strokes‟ of the piston. These are the following strokes: 1) air –fuel intake 2) air –fuel compression 3) post-combustion expansion 4) exhaust gas discharge Fig. 2 illustrates a graph of the typical four-stroke sequence for an Otto cycle Fig. 3 illustrates the corresponding P-V diagram.
The modified cycle proposed here adds two additional strokes that increase the work extracted per unit input of fuel energy. These additional strokes involve trapping and recompression of some of the exhaust from the fourth piston stroke, followed by a water injection and expansion of the resulting steam/exhaust mixture. The residual exhaust gas is trapped in the cylinder by closing the exhaust valve earlier than usual, i.e., well before the top dead center (TDC). Energy from the trapped, recompressed exhaust gases is transferred to the liquid water, causing it to vaporize and increase the pressure. This added pressure then produces more work from another expansion process. The steam –exhaust gas mixture is expelled to ambient pressure near the point of maximum expansion. The modified sequence of strokes is illustrated in Fig. 4, and the corresponding pressure –volume trace is shown in Fig. 5.
IMPORTANT PARAMETERS FOR WATER INJECTION PROCESS
There is one parameter that is important to the feasibility of this concept, and that is the temperature of the pressurized water injected. It is observed that the engine coolant heats the injection water to a temperature of approximately 100 C with a heat exchanger in the coolant circuit. The injection water is moderately pressurized to prevent the water from boiling in the heat exchanger, and pumped to the higher pressure necessary for in-cylinder injection. The sensitivity of the MEP (Mean Effective Pressure) steam to this temperature is noticeable. Calculations with the thermodynamic model for injection water temperatures of 25 C showed an MEP steam performance decrease of 40% as compared to a water injection temperature of 100 C and an MEP steam performance increase of 40% if the injection water were heated to 175 C. Because it should be relatively easy to heat the injection water to 100 C with a liquid to liquid heat exchanger transferring heat from the engine coolant, the 100 C case is presented here. Although heating the water beyond 100 C is feasible with either exhaust gas or an external combustion heater, this would require a gas-to-liquid heat exchanger and would require additional engineering considerations beyond the very simple liquid-to-liquid heat exchanger. Thus only the 100 C water injection temperature is considered for now.
It is also important to note that this is an idealized thermodynamic model and several assumptions were made that may not hold true in a real engine system:
1. It is assumed that water injection, vaporization, and perfect homogeneity are instantaneous. In a real engine system, the vaporization and mixing processes will take a finite time, which could result in a lower power output. 2. Assumptions were made to prevent the in-cylinder temperature from being lower than the dew point and the in-cylinder temperature from being less than 1 bar. These constraints may not be realistic in a real engine when higher temperatures may be needed to prevent condensation throughout the exhaust, and to maintain proper function of exhaust after treatment equipment. 3. The thermodynamic modeling does not account for heat transfer between the combustion chamber walls and the cylinder contents. Some heat transfer will occur during the course of the engine cycle, but the thermodynamic modeling shows that there is a sufficient amount of heat in the exhaust gas for the steam cycle without extracting any heat from the walls directly. FACTORS AFFECTING THERMAL EFFICIENCY AND FUEL CONSUMPTION
1) The heat that is evacuated during the cooling of a conventional engine‟s cylinder head is recovered in the six-stroke engine by the 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 chamber (external combustion). 3) The transfer of heat from the very thin walls of the combustion chamber to the air heating chambers lowers the temperature and pressure of the 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) The glowing combustion chamber allows the optimal burning of any fuel and calcinate the residues. 6) Distribution of the work: two expansions (power strokes) over six strokes, or a third more than the in a four-stroke engine. 7) Better filling of the cylinder on the intake due to the lower temperature of the cylinder walls and the piston head.
8) Elimination of the exhaust gases crossing with fresh air on intake. In the six strokeengines, intake takes place on the first stroke and exhaust on the fourth stroke. 9) Large reduction in cooling power. The water pump and fan outputs are reduced. Possibility to suppress the water cooler. 10) Less inertia due to the lightness of the moving parts. 11) Lower oil temperature. With combustion taking place in a closed chamber, the high temperatures less stress the oil and the risk of dilution is reduced, even in cold starts. 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 12) Pressure during exhaust is 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. ENGINE MODIFICATIONS 1. Crankshaft to camshaft ratio modification In a four-stroke engine, the gear at crankshaft must rotate 720 degree while the camshaft rotates 360 degree to complete one cycle. However, in a six-stroke engine, the gear at the crankshaft must rotate 1080 degree while the camshaft rotates 360 degree to complete one cycle. Hence their corresponding gear ratio is 3:1 whereas in four stroke engine the gear ratio is 2:1. In sixstroke engine gear at the crankshaft has 18 teeth and gear at camshaft has 54 teeth. The type of gear used is helical because it is suitable for high speed, high power application and quite at high speed rotation.
2. Camshaft Design
In the six stroke engine the 360 degree of the cam has been divided into 60 degree among the six strokes. The exhaust cam has two lobes to open the exhaust valve at fourth stroke (first exhaust stroke) and the sixth stroke to push out the steam.
Now talking about the cam follower, the bottom shape of regular follower has the flat pattern, which is suitable with the normal camshaft for four stroke engine. When reducing the duration of valve opening from 900 degree to only 600 degree the shape of the follower must be changed from flat to roller or spherical shape. And after all these modifications the engine was checked and it resulted as a smooth six-stroke engine which was running smoothly with six-stroke cycles. 3) Cam follower modification The bottom shape of regular follower has the flat pattern, which is suitable with the normal camshaft for four stroke engine. When reducing the duration of valve opening from 9000 to only 6000 the shape of the follower must be changed from flat to roller or spherical shape. ADVANTAGES OF SIX-STROKE ENGINES OVER FOUR-STROKE ENGINES
1. In 6 stroke engine there can be a reduction in fuel consumption by approximately 40%. This is because there is an operational efficiency of about 50%. Due to two additional strokes there is an increase in the thermal efficiency of the engine which compensates for the lesser specific power of the 6 stroke engine against the 4 stroke engine. 2. Since the work cycles occur on two strokes (360 ⁰ out of 1080 ⁰ ) or 8% more than in a 4 stroke engine (180 ⁰ out of 720 ⁰ ), the torque is much more even in a 6 stroke engine. 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.
3. Due to reduction in fuel and specific consumption there is a considerable reduction in noise, chemical and thermal pollution. Also the design of the engine itself helps to lower the HC, CO and NOX emissions. It also has the ability to run in oils of vegetable origins and weakly pollutant gases which will help to reduce pollution. 4. The 6 stroke engine can be use fuels of different types and origins ranging from fossil or vegetable, diesel, LPG or animal grease. The difference in the inflammability or the antiknock qualities of the fuel does not present a large problem in combustion. Also the light and standard petrol engine construction of the six stroke engine does allow us to use diesel as a fuel. 5. A petrol-methanol mixture can be used as a dual fuel in the 6 stroke engine. The methanol present in the second combustion cycle helps to practically eliminate soot and nitrous oxide. 6. The basis for the 6 stroke engine remains same as that of the 4 stroke engine and all the technological experiences and production methods for the 4 stroke engine remain unaltered for the 6 stroke one. Also the cost of modification to the cylinder head (combustion chamber and heating chamber) is balanced by the simplification of several elements particularly by the lightening of the moving parts, the reduction of the cooling system, the simplification of direct injection with no spark plug, etc. 7. There is better scavenging in the 6 stroke engine. 8. There is a lower overall engine temperature in a 6 stroke engine as compared to 4 stroke engine. Therefore it is easier to maintain the optimum level of temperature for better engine performance. 9. There is a lesser level of friction among the various parts of the 6 stroke engine as compared to the 4 stroke engine. Therefore there is less wear and tear and a longer life. DISADVANTAGES OF SIX-STROKE ENGINES
1. The break power and indicated power per cycle per cylinder of a 6 stroke engine is comparatively lesser than that of a 4 stroke engine. 2. The 6 stroke engine is a bulky engine and requires a lot of space. This increase in engine size is due to the increase in the number of cylinders and due to additional parts required for its working. 3. The cost of manufacturing of 6 stroke engine is high as compared to the 4 stroke engine due to its intricate design and many more parts and chambers.
4. The camshaft and cam follower design for a 6 stroke engine is more complex than a 4 stroke engine. References
1. Oak Ridge National lab, Knoxville, USA http://info.ornl.gov/sites/publications/Files/Pub15584.pdf 2. Technologies to recover exhaust heat from internal combustion engines http://www.sciencedirect.com/science/article/pii/S1364032112003474 3. Velozeta Six Stroke Model, Sree Narayana Gurukulam of Engineering http://dspace.sngce.ac.in/bitstream/handle/123456789/1807/55Eldhose%20Paul-Six%20Stroke%20Engine-2.pdf?sequence=1 4. A Six-Stroke, High-Efficiency Quasiturbine Concept Engine With Distinct, Thermally-Insulated Compression and Expansion Components By George Marchetti and Gilles Saint-Hilaire http://www.energycentral.com/reference/whitepapers/102265/ 5. 2010 2nd International Conference on Mechanical and Electronics Engineering (ICMEE 2010) http://1000projects.org/mechanical-seminar-on-six-stroke-engine.html 6. International Journal of Engineering Research & Technology (IJERT) http://www.ijert.org/view.php?id=5620&title=six-stroke-engine 7. Computer controlled multi-stroke cycle power generating assembly and method of operation By Satnarine Singh http://www.google.com/patents/US7021272 8. Multi-stroke cylinder operation in an internal combustion engine By Donald J. Lewis, John D. Russell, Nate Trask,Thomas W. Megli http://www.google.com/patents/US7401606 9. Patent of Six Stroke Internal Combustion Engine By Gerhard B. Schmitz http://www.google.com/patents/US4917054
10. Patent of Engine with a six-stroke cycle, variable compression ratio, and constant stroke By Gregory J. Larsen http://www.google.com/patents/US4736715 11. 15 th Int. AMME Conference, 29-31 May, 2012 http://umpir.ump.edu.my/2688/1/maisara_six_stroke_engine_arrangement.pdf 12. International Journal for Engineering Applications and Technology Bruce crower‟s six-stroke engine By Kishor Gite, Pawan Bobade, Kumar Dibyanshu 13. Thermodynamic Analysis, Testing and Evaluation of a 6 Stroke Engine Undergraduate Awards of Ireland and Northern Ireland 14. Working of Six Stroke Engine By Shashank Sharma International Research Journal of Humanities, Engineering & Pharmaceutical Sciences 15. Experimental study of six-stroke engine for heat recovery By Faculty of Mechanical Engineering University Malaysia Pahang 16. Camshaft design for a six-stroke engine By Faculty of Mechanical Engineering University Malaysia Pahang 17. Method for the transformation of thermal energy into mechanical energy by means of a combustion engine as well as this new engine Patented by Roger Bajulaz 18. Internal combustion engine Patented by Roger Bajulaz 19. A highly efficient six-stroke internal combustion engine cycle with water injection for in-cylinder exhaust heat recovery By James C. Conklin, James P. Szybist
SUMMARY
Exhaust gas compression, water injection at top centre, and expansion were a modification to recover energy from two waste streams that adds two strokes to the ideal four-stroke internal combustion engine. The additional two strokes require substantial modifications to the exhaust valve operation as well as a manner to inject water directly into the combustion chamber. The hardware necessary to accommodate these modifications to an internal combustion engine is currently available, although significant research is needed to develop the concept. These concepts have a great way to utilize the waste heat which normally gets wasted. These concepts has the potential of a substantial increase in fuel efficiency over existing conventional internal combustion engines while potentially not decreasing the power density significantly BENEFITS: 1) 40% more efficiency(less fuel consumption) regular engine 30% 2) Reduction of exhaust emissions due to less fuel being consumed. Up to 50 % less emission. 3) No need of extra cooling system- Free of a radiator and its associated air ducting, fan, plumbing, coolant. 4) No need of catalytic converter( “cling on hydrocarbons”) 5) Compression ratio 13-to-1 can be achieved. 6) Longer service intervals possible due to lower operating temperatures LIMITATIONS: 1) Wrong time water injection during the six-stroke cycle can result damage to the engine due to the “instant” expansion force created. 2) Will have to carry as many as gallons of water as fuel. That cause engine more bulky than normal 4 stroke engine. 3) Keeping water from freezing will be another challenged. 4) Water causes scale and sludge formed in the water tank required water must purify. 5) Increase in engine weight and complexity
