Sunday 17 May 2015
I have recently been educated that “” neglecting heat transfer, combustion transients, and intake/exhaust restriction; all positive displacement engines having the same pressure bounds and same displacement will produce exactly the same power. The energy produced by a positive displacement is given by “”
This means that the combustion gases don’t care inside what kind of engine or geometry they are in, what is important is the initial and final pressure and temperatures that you are able to operate at.
The higher the initial combustion pressure value and temperature value and the lower the exhausted temperature and pressure values the more efficient your engine is. regardless of geometry or architecture of engine.
So the architecture or geometry of an engine doesn’t matter or affect the how much power or efficient the engine is at extracting workable energy from the fuel.
Based on that the rest of the blog is some how partially misleading.
Now some of the below info my be correct and other parts maybe wrong, so that is what you need to do as an engineer.
the advantage that this kind of engine offers is
1- full Atkinson cycle
2- lower power to wight ratio.
3-high volumetric efficiency (if done right).
The rest of this page and in fact all pages need to be scientifically reviewed by real
scientist and engineers.
Please make sure to ask an engineer about what i have written down and enjoy the links.
This blog still needs more work . still messy , need to remove stuff from this page.
Point one, the Torque arm, the mechanical conversion mechanism difference between RP-ICE and circular engines.
1- The First and most important and main difference of Circular Engines (C.E) or complete torque engine from any other engine, is that circular engines have the highest efficiency of mechanical conversion mechanism to convert pressure into torque , this is due to the COMPLETE and continues torque arm /Lever throughout the work and operations of the engine, from 1- induction to 2-ignition 3-combustion and 4-exhaust. Similar to JET engines.
The CIRCULAR engines FULL and COMPLETE and steady torque arm LENGTH means a much greater amount of Instantaneous TORQUE at TDC and throughout its operation.
how is that different from the classical “Reciprocating piston” engine , well basically it has a continuously changing or variable effective torque arm length , starting at TDC with ZERO effective torque arm length, as crank rotates around its self , this effective Length torque arm increases gradually until on the mark of 90 degrees from TDC , we get a momentarily full and complete effective length of torque arm , then it starts to decrees, until it gets back to zero effective length torque arm at BDC .
The first seven seconds of this film talks about the variable torque arm length, the rest I don’t care for as its part of explanation and comparison for an elliptical engine ( not discussed here) , i just keep it for intellectual respect of owner.
here is a great explanation of the effective length of torque arm.
The Wankel engine also has such a situation but I have not looked into it.
In order to compare both mechanisms lets just take a first look at the regular Reciprocating piston internal combustion engine.
Here is an over simplified representation a demo of the way piston engine works
Here is an over simplified mathematical equation of the Piston Connecting Rode mechanism for a reciprocating Internal Combustion engine
Force acting tangential to the crank radius is
Where F=Force, P=Gas Pressure, A=Piston Area , For Alfa and Beta at figs below .
F=(P.A. sin (α+β) Sin (β)
Figs explaining the effective length of arm torque in RP-ICE.
In plain words, most of the power ,thermal heat, pressure is wasted,Since the COS and SIN functions are a very small mathematical functions, they rang from zero to 1 and back to zero.
To further simplify 10000 x 1000000 x Cos (0.something) = is always very small amount, COS is a function that general leaves your final result of your input at the lower end.
Now lets take a look on how circular engines are different .
In the circular engine setup it converts the power of pressurized brunet gases directly into Radial torque, A Continuous Full torque – Continuous Complete torque – Continuous Circular torque – Continuous torque – Continuous Toroidal torque – Continuous Toroidal engine –Continuous Annular engine -Continuous Orbital torque orbital engine = would do this
T= P x A x R.
Where T=torque P=gas pressure A=Piston Area R= the radios of the rotor/connecting mechanism.
These engines are calculated to be 10 times more powerful , 3 time more efficient ,a reduction of fuel consumption of 75% , a huge increase of Maximum Revolutions Per minutes of 15000 RPM. (theoretical.)
Previous picture is from inventor Hekal Circular engine , click on picture if you want to go to original website. there are also wounder full explanations there. great real engineering work.
Radial engine have the arm complete at all times and the Piston is moving in a circular chamber.
so the pistons now go round and round inside a fully circular – toroidal – orbital annular combustion / expansion / compression / suction chamber.
And those pistons act directly on the arm of torque / disk.
So what does that mean ?
The key difference Between the RP-ICE and this Full Torque Circular engine design , is that the length of the torque arm or the actual torque or the Effective Length of Torque Arm (ELTA) in a normal RP-ICE is changing from ZERO length to Full length (equaling crank radius) and then back to ZERO length.
This Link to the site of one of those engines clearly illustrates the mathematical difference clear comparison link
While in these Circular radial engines the length of the torque arm or the effective torque is at Full length throughout the power stroke , in fact throughout the entire Revolution of the engine , not just for a moment. So it isn’t just for ONE moment during the entire Revolution of the crank that you have Full Lenght Torque Arm. but all the time. In the next pic , displayed is the Gas pressure and crank angle and Torque Generation . As you can see there is a delay between the Gas pressure Value and the Generation of the Actual torque. after a few degrees there is enough Effective Torque Arm Length to make use of the Gas pressure . Also please note that the Torque Value curvature goes beneath the Value Zero meaning you have Negative torque . this chart should be read in relation to the chart in Heakal engine. where there you can see the immediate generation of power torque and the huge gigantic generation of power in Hekal Engine while you can see the delayed Generation of power in any normal Engine Wankel or Piston, also the
2- Difference number Two is that there are no reciprocating pistons in these C.E engines.
Unlike the R.P.E that has to transmit the power through the con-rod-crank system to fly-wheel and back, and where the pistons are accelerated decelerated stopped then accelerated in the opposite direction suffering from huge amounts of stress and strain and momentum of pistons and friction and heat of friction, meaning huge forces opposing each other working against the engines parts structure,which forces engineers to build the crank shaft and engine head and pistons from materials that have to able to handle those kind and amount of forces , Please see chart from Wiki about the speed accelerations of a reciprocating piston ,
Here is link from Wikipedia showing the acceleration and deceleration and speeds that the piston has to do through to give us its power.
In Circular engines the “Piston” in these engines goes round and round in an orbital cavity (cylinder).
This means that the energy from the pressure is stored in the rotor directly just like a fly wheel, making the rotor its own fly wheel ,
Why ? because In C.E there are no reciprocating pistons and the actual circular path of its pistons means that the power is continually and incrementally pushing the pistons in the same direction, so less stress and strain on the parts, this mean smaller lighter parts.
So less parts less metal is needed = higher to weight ratio.
3- Difference number three is The practical real life application of the Atkinson cycle also called the Extreme Expansion cycle.
Circular Engines power strokes are much longer than their compression stroke and also much longer than power stork of the RP-ICE (see Hekal) , which allows for much more time for the hot gases to work or operate on the CROWN or head of the radial piston, hence a more complete conversion of heat into WORK, meaning more efficiency ,to the point that the exhaust is at 300 Kelvin i.e. room temperature. This is what is meant by more complete or A FULL EXPANSION RATIO using a very simple mechanism.
4- Difference number four is Less NEGATIVE TORQUE .
Explaining what is Negative torque in a four stroke spark ignited gasoline engine or a diesel engine :-
After induction of air into the cylindrical and the air valves has closed and piston has passed BDC and piston is now rising up towards TDC…
Pressurizing the air fuel mixture in a Gasoline engine and just air in diesel engine , in preparation for combustion , this pressurization of air requires lots of energy that is being taken from another pistons power stroke… and form the first amount of the negative torque , this energy is leach energy wasted ….
(Mixture pressurizing wasted energy-leach losses)
and since the real power in RP-ICE is to have peak gas pressure after approximately 15 degrees After ATDC, and since the Flame from propagation/spread from the spark plug ignition flame kernel takes time to spread through the combustion chamber, Ignition of both diesel fuel and Gasoline is started much earlier BEFORE pistons is at TDC. arises the need to start the ignition Kernel early enough to generate that peak gas pressure meets piston at approximately 15 degrees ATDC.(different for each engine)
So just before the piston reaches TDC in a gasoline engine the Spark plug engine ignites , creating the Kernel of the flame front while in diesel engine several consecutive diesel sprays are produced into the extremely hot pressurized air to create lots of Kernels of flames in the mixture …. in both cases the piston is still rising …. in both cases the increase in heat and pressure of air due to the combustion of part of the fuel creates higher pressures inside the combustion chamber that the piston actually has to push against, increasing the amount of it takes from another power stroke .
Thus the pressure build up inside the piston/combustion chamber starts AS the piston is moving UPWARDS , meaning further amounts of precious energy is being spent taken from another power stroke of engine just to keep pushing the piston going upwards AGAINST the Pressures of heat of combustion of the working fluids .
in other words the engine is working against itself.
so Negative torque consists of two parts
Part one : energy is spent compressing the air alone in diesel & GDI engines, and Air/ fuel mixture in fuel port injection and
Part two of the making of negative torque is piston is pushing against the pressure of the gases from the partially burned fuel
See here what is meant be negative torque
This is also a nice website showing the concept of negative torque in engine
The Miller cycle manipulates the valve timings to achieve separation of compression ratio from expansion ratio and changing the engine volume .
In none variable valve timing engines there is actually more air pressurized than required , so by throttling and manipulation of valve timing we reduce the negative torque.
Now in MY engine design there is an amount of energy spent to compress a much smaller amount of air , relative and absolute , but the MOST important part is the EVEN when the Air fuel mixture is ignited and the gases start to have higher pressure , because of the design there is NO negative torque pushing against another working piston.
i.e I have totally neutralized the concept of NEGATIVE TORQUE due to the advancing of ignition.
Can you imagine, on each cycle for this engine —- if we first reduce the amount of air we have to compress i.e. less energy spent to compress the air , and also we have ZERO negative torque ,meaning the build up of gas pressure does not work against the pistons , literary ,
for many reasons including the fixed volume combustion chamber, now put all of these together and imagine the possible results.
how efficient this engine would be ?
The idea is since the compression is independent from combustion chamber , the combustion chamber is fixed volume and it is independent from compression chamber ,and because of its nature the gases pressure WILL not ever be pushing back the piston or pushing the piston back , and lastly the power or stroke chamber which is independent from both previous ones .
I would personally dream of a 90% reduction in negative torque.
In my design , the pressure of burning/burnet gases ONLY pushes the piston in the right and only direction of Positive torque.
Great for diesel. think how .
Differences number Five from RP-ICE is that these C.E engines can use the split cycle principle WITHOUT the disadvantages of Split cycle, those disadvantages don’t exist in this type of engine .
First see here the principal of split cycle (Scuderi engine)
Now the Benefits of application the Split cycle principal in A Circulate/complete torque engine .
1- Full control of the air cycle , which means :-
The Separation or independence in the design and application/implementation of the working fluid chambers
A-Air compressing chamber is separated from the
B- Fixed volume Air/fuel combustion chamber and both are separated from
C-The hot gases (working fluids) expansion chamber .
Meaning I have one cavity for compressing the air , another fixed volume chamber for combustion and a third chamber is for power stork and gas expansion.
This results in:-
2- Cheap Variable Compression ratio. by throttling the air before compressing it I save energy , Air is then allowed under pressure into the Fixed volume combustion chamber, Only the amount I need exactly , then the burnt gases meet the piston at TDC with Peak gasses pressure to keep working on the piston in the long stork expansion chamber to do FULL EXPANSION .
That is how I get Cheap Variable Compression Ratio.
Peak Gas pressure one a full torque crank system .
These circular engines are supposed to reach at least 60% thermal efficiency (see Hekal) some say 90% .(I don’t think so)