[invest_in_politics]

It appears that a fundamental flaw in thermodynamic heat engine analysis has been discovered. For details see

http://www.greencarcongress.com/2005/06 ... gines.html

or the original paper at

http://www.dvrhome.com/articles/Heat_Engine_Tinker.pdf

This discovery seems to allow a marked (~30%) improvement in fundamental internal combustion engine (ICE) efficiency no matter what fuel is used or other techniques of combustion enhancement that may be employed. The technology for its implementation does not require significant engine modification, may possibly take the form of a "bolt-on" aftermarket product for existing engines, and can presumably be realized in a short period of time.

Since it is the fundamental efficiency of the engine that is enhanced, the same output power simply requires less fuel, so fuel consumption will be reduced without an associated loss in engine performance. In fact, if an existing engine is so modified and the fuel injection system not restricted, it will provide approximately 30% greater maximum power than it could before its modification.

How will this discovery affect oil prices, vehicle manufacturer R&D efforts, hybrid sales, and political futures?

IIP

[Jack]

Great first post!

Welcome to Peak Oil!

[Devil]

It has long been known that increasing the CR will increase the efficiency. The problem with increasing it with petrol engines is having the right fuel. My memory data is probably out of date by 20 years, but I understand most engines work nowadays with a CR of 10 -12, for use with fuels with an OR of 90 - 100 (ballpark figures). By having a CR up to 15, I believe some engines will work with special fuels but with a very peaky power curve. What kind of fuel would be required for a CR of 19-20?

On the practical side, with such CRs, I suggest that current piston ring technology would need to be improved to avoid leakage and that the higher temperatures would need special exhaust valve and seatings materials.

If the fuel and materials problems could be solved, it is probably feasible, ébut I'm less sure of the economics (engine lifetime, peaky power/torque curves requiring more expensive 6 - 8 speed gearboxes etc).

[Antimatter]

It seems the issue here is that the energy needed to perform the compression of the fuel/air mix (or air in a diesel) on the compression stroke must (of course) come from the energy provided by a previous power stroke through the momentum of the flywheel. This was traditionally assumed to be a 100% efficient process, ie the energy to compress is re-gained in full when the piston moves down again and the gas decompresses. The author claims that this is not the case, as most of the energy provided during the power stroke is lost as heat. He proposes this problem can be overcome by a spring and cam system or other method to balance out the pressure exerted by the gas as the piston moves in the cylinder, ie make the work needed to move the piston up or down the cyclinder zero (w/o those pesky friction losses etc of course).

$this->bbcode_second_pass_quote('', 'I')n the traditional model, the work provided by the decompression of the working substance is seen as being applied directly to its compression. In so doing, the net energy change in the system is zero and I W is eliminated as a contributor. However, consider this more closely.
There is no argument that compression of the working substance constitutes work done. There is also no argument that the decompression corresponding to this compression constitutes a component of work output. So, the traditional view assumes that the compression work, in contrast to any other work performed by the engine, is done with 100% efficiency by employing only the corresponding decompression. This possibility seems remote. The key to the derivation of the theory offered here is the realization that the inefficiency of the engine itself in providing the work necessary to compress the gas requires the application of more heat energy than is returned as work when the gas decompresses. In essence, then, the conservative force arising from the compression of the working substance is made manifestly non-conservative when coupled with the operation of the inefficient engine.

[invest_in_politics]

The author does not identify increased compression ratio as the key to the increased efficiency. In fact, the paper specifically shows that his theory nearly exactly reproduces the experimentally obtained efficiency of internal combustion engines over the entire range of compression ratios (from 6:1 to 19.5:1). This is a theoretical achievement that is simply unprecedented. No other theory has been able to match the experimental data. The usual explanation offered for the failure of a theory to predict experimental outcome (the root purpose of a theory!) is that heat is being unintentionally lost somewhere in the process.

In its success, this new theory identifies the reason for the discrepancy between existing theory and experimental results as the inefficient engine itself having to perform the work required to compress the gas in the cylinder. By employing some other conservative force to perform this compression, the inefficient engine is relieved of the burden and the efficiency is increased. This increase is over all compression ratios. According to the paper, a 26% increase at 6:1 compression ratio and a 42% increase at 19.5:1. At the normal 9.5:1 compression ratio of most automobile engines, the improvement should be about 30%. This takes a 30 mpg vehicle to 40 mpg without loss of engine performance and without the need for weight-addition and the increased complexity of hybridization.

IIP

[invest_in_politics]

The author correctly points out that the rotational motion of the flywheel is due entirely to the work done on it by the engine. Therefore, any kinetic energy of the flywheel is achieved at the efficiency of the engine. So, employing the flywheel to compress the gas is, by construction, done at the efficiency of the engine.

IIP

[Caoimhan]

Yeah, I understood it that way, too.

Increasing the CR is all well and good... it's part of the reason why diesel engines are more efficient than spark-ignition engines.

Basically, look at it this way:

Assume you have a 4 cylinder engine and the engine is off.

Each of the 4 cylinders, no matter where in the cycle they are located, will have an exactly equal pressure on either side of it. On the chamber side, the pressure is the compressed air in the chamber. On the other side, it's mechanical pressure from a spring or some other means. Such and engine should be easily turned by a simple hand-crank. (It seems another side effect of this engine would be greatly reduced energy needed on the starter motor. In fact, since compression is maintained in the engine, a diesel engine of this type would be a fantastically simple and elegant design).

Correct me if I'm wrong.

[invest_in_politics]

That's the way I understand it. You get up in the morning and start your 1-ton diesel pickup with a length of fishing line around the pull starter.

Interestingly, the technology seems applicable to any engine cycle -- Otto, Diesel, Miller, etc. The derivation is completely general, so it probably also applies to turbines.

IIP

[Antimatter]

That was my understanding too. Though i don't see how the hell you would apply it to a turbine.

Any engineers with experience in this field who can comment?

[invest_in_politics]

Turbines employ a Joule-Brayton cycle (http://www.taftan.com/thermodynamics/BRAYTON.HTM) that incorporates an isentropic compression phase. Since there is compression going on, the theory would seem to hold. However, I'm with you in being unable to envision how one could apply a counterforce to such a system. Perhaps the best result in the turbine case is simply a more accurate method of predicting efficiency.

IIP

[Caoimhan]

I think turbines already have this built in to a certain extent. Since the de-compression side of the turbine feeds energy back into the compression side in equal measure (in a frictionless ideal turbine). This could be the main reason why turbines are inherently much more efficient than an Otto cycle (although Tinker may have discovered the reason why, and found a way to negate the difference to a large degree).

[invest_in_politics]

I would have to partially disagree. The entire premise of this new theory is that the use of the inherently inefficient engine in doing unnecessary work (that of compression) reduces the engine's efficiency. This would be true in the case of turbines as well as reciprocating engines. If this source of inefficiency is not already taken into account by turbine efficiency theory, then this new result may provide a better theoretical estimate. However, I suspect that you are right that it cannot be alleviated.

IIP

[Caoimhan]

You may be right about that.

If that's the case, then I can't see a way to balance the compression in a turbine, either, given that a turbine is rotary in nature, how could you provide an equal magnitude vector of force with in the opposite direction, without relying on the engine power?

I'm completely at a loss. The fact that a piston engine reciprocates is an advantage with this concept.

The trickiest thing is... with a regular spring, the more you compress the spring, the more force the spring exerts. You'd want to reverse that. At Bottom Dead Center of the stroke you'd want very little counter pressure, and at Top Dead Center of the stroke, you'd want maximum counter pressure.

[invest_in_politics]

The discussion on the greencarcongress web site indicates that the intention is to use a cam to modify the spring deflection distance so that the work done by the spring is equal to that done in compressing the gas. This would allow matching the two exactly. The author also indicates that magnetic forces can match the pressure forces without the use of a cam. Magnetic pistons?

I would like to be a fly on the wall of this physicists lab to see who is licensing the technology in the background. Now THAT might be a good investment!

IIP

[Caoimhan]

I thought of the same thing. Magnets in the pistons and magnets around the cylinder head, so that at TDC, the attraction is greatest, which is when pressure is greatest, too.

This would also allow for a nice 4 stroke cycle, because during the exhaust and fuel injection strokes, when the valves are open, you're only looking for a change in gas volume in the cylinder, not a significant change in pressure, if I understand correctly.

By cycling on and off an electromagnet to correspond with the power stroke (on), and during the exhaust/injection stroke (off), perfect balance can be achieved.

[invest_in_politics]

The problem with using electromagnets is that they are far from efficient. Use of permanent magnets would be better, but four-stroke engines would be a problem. At least with springs and cams it would be trivial to just mechanically lock the counterforce mechanism in place every other stroke with a pawl or something while exhaust/intake was occuring.

IIP

[SolarDave]

$this->bbcode_second_pass_quote('invest_in_politics', 'T')he author correctly points out that the rotational motion of the flywheel is due entirely to the work done on it by the engine. Therefore, any kinetic energy of the flywheel is achieved at the efficiency of the engine. So, employing the flywheel to compress the gas is, by construction, done at the efficiency of the engine.

IIP

[SolarDave]

My previous post was a little terse.

The invention is not claiming to increase the efficiency of compressing the air-fuel mixture (indeed, the piston goes up against the gasses, and that efficiency is what is is - the forces cannot be "balanced" or the piston would not move...).

The invention instead appears to claim to capture energy from the downward motion of the piston (for later re-use in the compression stroke) more efficiently than the current combination of piston/connecting rod/crankshaft.

Well, if that's the case, why not hook the contraption to the transmission instead of the crankshaft. For that matter, why have a crankshaft at all. Have the contraption take over and do the job of moving the piston more efficiently, and the car too.

It just does not add up.

Flywheels are almost perfect energy storage devices. Really - try to find an example that is more efficient. Springs are not.

The claim appears to be that this contraption can capture energy from the downward stroke of the piston more efficiently than the connecting rods and crankshaft, store it more efficiently than the flywheel, and then deliver the stored energy back to the piston as the upward motion needed to compress the next charge.

The difference between inefficient and efficient power capture and re-use for charge compression just can't be 30% of the engine's overall power.

Thought problem (don't actually do this!): Get to a freeway in your manual transmission car. Put the transmission in high gear, and get up to the speed limit. Turn the engine off but keep it in gear. Floor it. ALL the energy required to compress the air entering the engine is now coming from the momentum of the vehicle. NONE of it is coming from the downstroke of the pistons, propelled by explosions. If this claim were true, the "braking" effect of the engine running in this manner would be AT LEAST equal to the claimed improvements of the contraption - like 30% of the engine's horsepower. Well, you will find that the deceleration is nothing like the feeling of accelerating at 1/3 throttle. Nowhere near 1/3 of the engine's power is being used to compress that air, and even with the contraption, the air still has to be compressed.

Another thought problem: this precise energy loss cannot be equivalent in a Wankel, but the Wankel known to be LESS efficient than traditional piston engines.

"More research is needed"

[invest_in_politics]

I don't believe the author claims anything about capturing the power stroke work more efficienctly. It appears to me to be simply an accounting difference. In the traditional analysis, the only heat that is attributed to one cycle of operation is the heat that is added in that cycle. In this new analysis, the author finds that the heat energy introduced in previous cycles necessary to do the compression in the current cycle must also be included in computing the efficiency. By doing so, he produces a theoretical result that obviously matches the empirical data, which indicates that his theory is sound.

By identifying the heat energy required to perform the compression as the source of the discrepancy between the currently accepted theory (fuel-air cycle model) and the empirical data, he finds that eliminating that compression work will reduce his efficiency equation to that of the fuel-air model. This means that eliminating the compression work will make the fuel air model predictions correct giving a 30% increase in ICE efficiency.

What doesn't "add up" is the fuel-air model with respect to experimental data. The fuel-air model assumes, as you do, that the "perfect energy storage" of the flywheel equates to a "perfect energy conversion" of heat to rotational kinetic energy. In so doing, it fails miserably in predicting the outcome of experiment. The new model relies on the "perfect energy storage" of the flywheel in transferring that energy from one cycle to another. However, it also takes into account the inefficiency of converting heat energy into the rotational energy of the flywheel in the process and, in so doing, achieves unprecedented success in duplicating the empirical data.

IIP

[SolarDave]

$this->bbcode_second_pass_quote('invest_in_politics', 'T')his means that eliminating the compression work will make the fuel air model predictions correct giving a 30% increase in ICE efficiency.