HPP

Speaking of alternate fuels and improved economy and such, anyone have and schematics or hardcore tech data on the Doble Steamers?
http://www.popularmechanics.com/auto...o/1302916.html

Pretty amazing bit of kit. Sounds like it might be very efficient. Not much use for performance, but for a daily driver, sounds like a good idea.

BigMikeGXP

Yes the valves stop moving. If they didn't it would not drive smooth at all. I read somewhere that it keeps the exhaust gas in also. Forget where that was though. A majority of the heat from expansion would be absored by the engine fairly quickly. Same cooling plus 4 less cylinders firing = more cooling. The transition is also during very low load conditions. I was going to try typing it out but i just copied from GM's website:

And yes the oil company does rule the world, we are already moving towards hydrogen and that ethanol mix crap as the next fuel and thats the way its gonna be. Sorry money grubbing bastards... However LOTS of people would lose jobs if the oil companys suddenly were no longer needed. We would all get through it eventually though.

LS_RX-7

It traps the exhaust to attempt to reduce the probability of artificially induced valve float on the downstroke. If the gas were evacuated as normal before cylinder deactivation, the piston would begin its descent toward BDC, but without the intake valve opening IVO event occurring.

This sealed chamber would effectively depressurize to a degree equal to the static compression ratio, facilitating a strong pressure difference across the intake valve. Being as the intake valve is larger in diameter than the exhaust valve, a given pressure difference across it translates to more force (due to the greater face area) that effectively reduces the seat pressure of the valvespring.

This can lead to some interesting effects.

Another very important reason for not evacuating the gas is for emissions and durability. If strong vacuum is drawn in the sealed cylinder repeatedly, the piston rings run into some serious sealing issues, and crankcase oil and vapors can be sucked upward past the rings into the cylinder and chamber. Without combustion and exhaustion to continuously clean them away, they build up very quickly and cause poor combustion, decreased effective octane in the cylinder during their presence, and poor emissions. Being as this system was designed both for fuel economy increases and emissions control, this is entirely counterproductive to it's purpose.

This 'Crower Cycle' engine is very hit and miss. I am extremely surprised that someone as intelligent as Mr. Crower didn't / doesn't see the obvious true design he is inadvertently avoiding, that offers both dramatically increased efficiency, power, and negates all of the complexity issues of odd valve control.

DAVESS02

iTrader: (30)

Looks pretty awesome to me. I hope it works out to be a worth while idea!!!

MadBill

Another major factor in the mechanization of disabling the cylinders is the 'air spring' effect. The sealed, ambient pressure cylinder absorbs less power than one operating with any kind of flow in or out. Theoretically, it would be better if it could be sealed with a vacuum, but that's impractical, as LS points out..

spy2520

iTrader: (3)

i also heard the DOD doesnt work against the engine as much as people think because because when the pistons in the deactivated cylinders moves down from top dead center the gas inside helps push it down, if anything i think it would cancel out any loss since it is probably equal to the amount of resistance the air inside put on the piston as it moves up.

BJM

iTrader: (1)

Its not obvious what the final power output would be. The Crower cycle completes 2 full cycles over 12 strokes versus the same engine conventionally completing 3 full cycles over 12 strokes.

The gas engine therefore has 3 normal expansion strokes making power and 9 "drag" strokes taking away power (Intake, compression, exhaust). Let's give a power stroke 10 points and a drag stroke -1 point (my educated guess). This gives the gas engine a total of 30-9=21 energy output points for an input of 3 fuel units (the 3 combusted fuel charges).

The Crower version has 2 normal expansion strokes then 2 apparently 40% expansions and 8 drag strokes. This score is 20 +2*4 -8=20 energy output points for an input of 2 fuel units (the 2 intake strokes).

The power output falls a little for a huge increase in efficiency.

If the drag strokes were -1.5 each then the scores are

Gas engine: 30-13.5=16.5 for 3 fuel units
Crower: 20+2*4 -12 =16 for 2 fuel units

Similar result but the power outputs are very close.

I hope this engine sees the light of day.

LS_RX-7

Mr. BJM, not to sound rude, but your reasoning is flawed in this analysis. While water steam reactions do in fact hold a major key to increasing efficiency and thus output per fuel consumed (BSFC), it is a step in the wrong direction to employ this principle as Mr. Crower has presented it.

I have my own theories why it was presented as such without regard for better design, but that's off topic.

I did not imply that the power output of his design was obvious, but rather that the theory behind his specific design is obvious, and that his design is overcomplicated, underefficient, and outright counterproductive in many areas. If he were to employ the base theory in the simplest, most proper manner, the design would be simpler, even more efficient, wouldn't sacrifice power in favor of fuel efficiency, etc.

But then you don't have anything to publish.

I'm not trying to take away from anyone's designs. But I am far from impressed with his specific engine configuration, either.

Standing on the shoulders of giants allows one to reach high places without having to rise to the top on one's own two feet. Take that for what you will.

BigMikeGXP

Yes his first engine was somewhat thrown together, but im sure he was so excited he just wanted to see if it would work. He did mention designing another engine. It really is very simple (in my opinion of course). Due to the 6 strokes use a cam running 1/3 speed instead of 1/2 with the appropiate lift and duration (would be alot shorter duration since it is running at less speed that normal). Use direct injection water, and hell go ahead and do direct injection gas also, which is being implemented already by many automakers beyond just diesel applications. Of course ignition timing would have to be altered also, not much of a problem there though. Im sure many things would have to be worked out such as longevity, corrosion, etc due to the massive amount of steam. And controlling the amount of steam injected would control the amount of heat absorbed so there really wouldn't be massive changes in temperature. An iron block would probably work better that aluminum as it would not dissapate the heat from combustion so quick, since you would want to keep the heat till the steam power stroke. Anything new has to have kinks worked out though.

One main problem I see is the water mixing with oil, the engine needs to run hot enough to boil water out of the oil. If the engine never warms up then the oil would be contaminated very quickly. But I guess that could be easily solved with a crankcase heater. A/C compressers in some commercial applications such as communications switchrooms already use a crankcase heater to keep the oil hot since cold air is always passing over the compressor while it is not running.

1 intake stroke - intake valve open
2 compression stroke - inject gas + ignition
3 power stroke - combustion stroke
4 compression stroke - inject water
5 power stroke - steam expansion stroke
6 exhaust stroke - exhuast valve open

Within 12 strokes - 6 stroke motor
2 intake strokes
4 compression strokes
4 power strokes
2 exhuast strokes

Within 12 strokes - 4 stroke motor
3 intake strokes
3 compression strokes
3 power strokes
3 exhuast strokes

You would be adding another compression stroke and another power stroke. Power output of the engine would depend of the output of the steam stroke. If there was any loss of power in my opinion it would be minimal. Steam engines are very powerful, though I don't know if I have ever seen a steam engine run 4, 5, or even 6 thousand rpms. I would imagine torque output may drop more as rpm increases. However 2 power strokes from 1 intake stroke. That is brilliant in my mind. This guy has a hell of an idea.

However even if the motor itself became a simple design automakers would want to steer away from it because the don't want to tell the consumer it must be filled up with water and gas or else it won't run. I know most of us would be glad to, but automakers have to make these things idiot proof these days.

Edit: I think I reached my quota for using the word "stroke" for a few months

BJM

iTrader: (1)

You didn't sound rude, but perhaps I misunderstood the engine's operation. I thought water was imply added to the engine to flash into steam using up existing waste heat. The additional strokes are not a combustion process. Am I wrong? If I am right my clearly simplistic analysis seems notionally correct.

What specifically do you not like about the Crower version?

LS_RX-7

My original post is too long, so I'm cutting it into two posts.

Your understanding is not flawed; in fact that is exactly how water-steam injection raises output. From now on I will use the term 'raised output' or 'increased output' instead of specifying power, torque, or fuel efficiency. The reason why is that they are all related, if not outright the same, at least mathematically. 'Output' will refer to all of them simltaneously, since their interrelationship can be changed at whim based on engineering design.

Output is increased by redirecting energy flow within the engine, as previously described by someone else. In 'normal' operation, there are multiple pathways for energy transport (heat), and only one of them leads to output: mechanical conversion. In addition to this, several of the other energy pathways are in direct opposition to mechanical conversion, which facilitates the need to specify both a gross mechanical conversion (representing total energy successfully converted), and net mechanical conversion (representing the total energy available for measurable output after accounting for opposed pathways).

Some of these opposed pathways are of course pumping loss (expressed as PMEP) and motoring friction (represented as FMEP, which includes other sources of parasitic drain other than friction, such as accessories, pressure differentials in coolant and oil fluids, etc).

I'm not going to beat around the bush anymore. Flat out, unsugarcoated and with no love (sorry, Mr. Crower. I do admire you immensely): The Crower Cycle is an attempt to publish via twisting an age old theory into a new shape of operation; one which happens to be far more complex and far less efficient (and I suspect less reliable) than the original preceeding design, as presented by Sir Harry Ricardo (a man who I would, among others, consider to be a 'standard reference' for a scale of genius.)

There are some extremely simple thermodynamic principles that illustrate and demystify the 'strokes' in the Crower Cycle, and illustrate why they are unnecessary and inefficient. Much of the previous analyses have unfortunately been polluted by common misconceptions and irrelevant/incomplete theorems. For example, a common reference is the 'power required to compress the charge' arguement.

Power calculations are useful with respect to time. In engineering it is far simpler to use a time constant than an actual measure of the time required for that constant to elapse. For internal combustion engines, this time constant is the revolution of the crankshaft. This turns all power calculations into energy, force, and torque calculations, expressed simply as 'per revolution'.

The energy required to compress a charge is nothing more than outright irrelevant in 90% of calculations. If you consider what is going on during compression on it's most fundamental physical level, this becomes clear: Any time the piston (a prime mover) changes position inside a closed system (sealed chamber) we have a conversion of energy in that system to facilitate the movement. I am not trying to confuse anyone, but I realize this may be too cryptic to understand what I mean.

If you seal a cylinder, and neglect accountability of thermal rejection to the cylinder walls, etc., and you move the piston from BDC to TDC and compress the charge, what changes? The volume changes, the pressure changes, and the only thing that's truly important: the energy of the gas changes. By how much? Well the pressure and volume change because the energy/heat changes, so we don't care about them here, they are dependent variables that can be solved later.

The energy added to the charge came from the prime mover. The energy consumed from the rotating assembly in this operation is equal to the amount of heat added to the charge. In effect, it is simply the difference in total energy of the charge between TDC and BDC (plus friction in the real world). This should be clear now. So, with the current popular design geometry in engines, it is very easy to see that this 'compression' process is mirrored as the piston descends from TDC toward BDC.

Energy is added to the rotating assembly as the piston descends toward BDC. The energy added (other pathways neglected) is equal to the difference in total internal energy of the charge between TDC and BDC (assuming a statically sealed chamber). The end result is that if we took friction and heat rejection out of the equation, assumed perfect sealing and a sealed chamber all the way from TDC to BDC and back again, the energy required to perform a 360deg rotation would theoretically be ZERO.

Energy required for compression is a true value. The point is that it is less valuable to account for it as a pathway for energy transfer. It is far more valuable to account for this pathway on the power stroke, since more careful analysis is required of it anyway. (Much more careful).

This brings us all the way back to the Crower Cycle. Considering the two modes of proposed operation: exhausting none of the gas on the 4th stroke, and partially exhausting the 4th stroke, gives us two different systems to evaluate; both with less than stellar results. (I am recounting most of this from an email I sent to a friend back home, as he didn't understand why I was not impressed either. It's interesting to re-type this arguement and notice how I do it differently.)

In the first system, the one where no gas is exhausted, I seriously want to laugh. I really hope this was a misinterpretation of the actual Crower Cycle, and that Mr. Crower did not first attempt to operate it this way. By not evacuating any of the post-combustion gas, we effectively mirror the power stroke as another compression stroke. What does this equate to?

It equates to, again neglecting thermal rejection, sealing, and friction for a second, it means re-absorbing 100% of the energy added to the crank during the power stroke. By recompression of the charge, you are in effect negating the power stroke in its entirety, and travelling back in time-constant to the point of TDC, but post combustion. Why even have a power stroke?

Not to mention that reality is not so kind as to let us negate the phenomena we don't like. The friction, sealing losses, and thermal rejection to the coolant and oil still exist, so the end result in this situation is that at TDC for the second time, the gas has LESS energy than it did the first time, which means less energy to 'extract more of' with the steam. This, is outright pointless.

Now the actual Crower Cycle, as I understand it, employs partial exhaustion, in which 'some' of the exhaust gases are evacuated, and some are trapped to extract more energy from them. While this may sound like the answer to the previous problem, I assure you, it is not; and is almost equally laughable. In many ways, it is even poorer engineering, it is just less juvenile. (I apologize for the harsh critique Mr. Crower, and understand if this aggravates you. I just can't believe this design is so falsely represented.)

By partially exhausting, we relieve the requirement to recompress the whole charge which negates the full power stroke. So you want some energy from that power stroke? Exhaust some gas. Seems like a logical answer right? Wrong. All this does is introuce two negative attributes to the system: Reducing the effective expansion ratio of the power stroke, and opening the closed system for the wrong reason. What does this mean?

The effective expansion ratio (which outright determines and puts the physical ceiling on the amount of energy converted to mechanical, the gross mechanical conversion specified earlier) was zero in the previous design, fully negating the power stroke. In this design, the partial exhausting allows some realization of an expansion ratio, but less than the whole. This is because when the exhaust valve IS closed, and the recompression begins, the power stroke that occured between TDC and the piston's placement at time of EVC is still negated. This reduces the effective stroke, and thus effective expansion ratio of the system.

But wait! We can get that energy back from further energy extraction with steam. And maybe some more on top of that! Right............? Well, possibly, but it won't be easy, because of the other attribute introduced; you shot yourself in the foot: By unsealing the chamber for the purpose of letting energy OUT of the system via a pathway we do not intend to measure (heat exhaustion) to have reduced the total energy of the system BEFORE you convert more of it to mechanical energy.

In simpler terms, you can only use water steam injection to raise efficiency anmd extract energy from gas that is PRESENT. The more you exhaust, the less gas present. We now have a dilemma. We need to partially exhaust the gas so as to not negate the power stroke, but we need to retain as much gas as possible for the best additional conversion. How would we do this?

By not using this funky Crower Cycle. In my not-so-humble opinion, this was a publishing adventure with little regard for 'best out of the box' engineering. But that is just an opinion.

On the simplest level, how does this principle work? The SIMPLEST. What one thing makes this possible? It is how we get the working fluid, specifially the steam, into the system. It's NOT steam when it is introduced. Why is this important? Because then we don't have to compress it. But we still get the benefit on the power stroke mirror side. All that is required is an extraction of energy to vaporize the water. This toll is actually VERY high in terms of thermal absorption. This would seem like a bad quality.

LS_RX-7

But it doesn't matter, because we get that energy back in the power stroke. The water-steam is but a temporary home for that thermal energy. Let's look at what is REALLY happening here, in an ideal system:

We induct the proper amount of fluid (air) into the system with the lowest loss (pmep), and seal the system, which now has static total energy. This energy resides chiefly in two forms: mechanical (flywheel energy) and chemical energy in the bonds of the fuel. We exact a toll of mechanical energy to compress the charge, turning it into thermal energy. Alternatively we could represent this as 'potential' energy, that is, energy of position. The system is still closed. All the energy at the time of closure is still present.

At this point we burn the fuel, converting chemical enmergy into thermal energy/WAY MORE potential energy. In a normal engine, the power stroke converts the potential/thermal energy into mechanical energy back to the flywheel. Much more is passed back into the flywheel than was given out. Then we open the exhaust valve, opening the system, and expell the working fluid.

Where are our losses? What is a loss? A loss is an energy pathway that fails to convert system energy to mechanical energy for output. Where are those pathways and how do they operate? There are many, but the one's we are concerned with here are thermal rejection to the coolant/oil, and thermal rejection outside the system (exhaustion).

By injecting water near TDC *after* combustion, at the beginning of the power stroke, we temporarily convert the thermal potential energy into pressure potential energy. Now the pressure doesn't actually rise too much on the actual piston. The amount of conversion is dependent upon the quantity of water injected. So what is really going on here?

By injecting water that is not of equal temp to the surrounding fluid, we facilitate a thermal energy transfer from the fluid to the water, until the temperature has equalized. The more water introduced, the more transferred heat, and the lower the end final equalized temperature. As heat goes down so does pressure in a static system. This system is static, but the heat has not gone down, only the temperature. The heat has been redistributed throughout the medium. In short, the introduction of more matter, the water, is what is important. Temperature doesn't create force on the piston, heat does, which facilitates pressure. Though our temperature drops immensely, the heat in the system stays the same. Our heat just relocates to a new home (the water/steam).

So if we have the same amount of heat with the water as withoiut it, why is there a difference in output with it than without it, if heat facilitates the output, and it hasnt changed? In two words: Thermal Rejection.

Temperature facilitates thermal energy transfer. By reducing the temperature, we are reducing the quantity of heat rejected to the coolant. That's step one in increasing output. Remember that in order for conversion to mechanical energy, that heat must be part of the system. Heat lost to the coolant is no longer part of that system.

You are in effect redirecting an energy pathway by introducing this water. The heat pathway normally leading to the radiator, now puts more to the flywheel. The other effect is thermal rejection to the exhaust. There is a grey area in determining which pathway ends where and where the other takes over once you introduce the water. It's easiest to simply combine the two pathways (coolant and exhaust) for heat loss, and not worry about what actually goes where.

The end result however is that since the charge has a lower temperature at the time of exhaustion, less heat can thus be 'lost' to that pathway. It's a simple relationship until you try to quantify the heat compared to another pathway. So we won't.

The best way to use this water steam injection is to inject near TDC after combustion when the temperature is high. No need to hold in the exhaust, near perfect time cycles, minimization of thermal rejection by minimizing hot time, and minimization of friction by not adding strokes to a complete cycle. You reduce inefficiencies on every front.

But this isn't publishable. Because someone else already did it with great success. Sir Harry Ricardo invented direct water injection decades ago. It just never caught on and was difficult at the time due to archaic engineering that produced slow flamespeeds, low operational speeds, and quenching problems.

With modern internal combustion engineering, none of these issues exist anymore. I need to go to work now, but when I get back, I will illustrate what is required to perform water-steam injection with maximum efficiency. There are 3 key things that must be maintained in order for peak realization of this theory to prevail.

Hope I have helped clear up some issues.

DeltaT

iTrader: (5)

Wouldn't there be a further demand on the power produced by having to pump water at a high enough pressure to enter the cylinder? I haven't read every post in this thread but have not seen that mentioned.

Jim

BigMikeGXP

Yes a system similar to what a direct injection diesel engine would have to be used. I don't know much about the diesel engines, but I think they inject at several thousand psi. Correct me if im wrong?

LS_RX-7

The current DID (direct injection diesel) standard is 22ksi (22,000psi at the injector).

Yes, a similar system is necessary, and in fact is even how Mr. Crower's prototype functions. Yes, it requires energy to drive the pump, but it is far far outweighed by the gains in efficiency and output.

Just about all diesel fuel systems employ a common rail system in which system pressure is just a few thousand psi, usually less than 5,000, and an in-rail pressure pump driven by the camshaft raises the pressure at the injector via positive displacement.

HPP

Couldn't those losses be reduced by using electric pumps to build that pressure? (or are electric pumps not up to the task yet?)

LS_RX-7

Electric pumps would work fine. But they won't provide much of an efficiency advantage, if one at all. The only way that electric accessories really provide any gains is because they provide a convenient way to power down when not needed. Under full load, most electric versions of mechanical items actually require more energy to operate than their pure mechanical counterparts. This of course assumes equal design, with the only variation being the input energy source.

The main advantage of any electric accessory, including this proposed one, is that of intelligent control. You could for instance, program the voltage regulator controller to cut the alternator out of the loop under WOT, which would cut the alternator-induced crankshaft drag to 10% or less than that of normal.

Due to the presence of a battery, all electric accessories could still operate as normal for short durations. The battery would be charged by the alternator, which would be reactivated after leaving WOT condition. Protocols and conditional arguements such as these are simple to employ with electronics, but can be very difficult and many times heavy to employ mechanically.

HPP

I was referring to a horsepower/torque/mpg loss, rather than total "energy".

Electric fans and waterpumps, for example. While you could turn off the fans when not needed, you can't really turn off the water pump (plus many electric fans anymore are sealed in such a way it looks like they would choke off any significant airflow if they were shut down and be dangerous any time other than warm up).

I guess I'm missing something. (sorry for the n00bish questions )

LS_RX-7

As the locals here in Iraq say, "Same, same." The only difference between hp/fuel efficiency/etc and 'energy' is that energy is measured per revolution, which makes it easier to understand and calculate; whereas hp is measured over time. In effect, they are the same, only in a different frame of reference.

Electric fans don't really shut off, just like you mentioned. But they do throttle down of sorts, and they are of more efficient design than a clutch fan anyway, which helps whether or not they are electrically powered. Electric water pumps are more efficient because they are not constricted to the same design parameter as a belt pump.

See, with a coolant pump that sees a direct proportional speed to the crankshaft (that is, it's geared), has to output a near parabolic-shaped curve of flow vs. speed in order to efficiently provide enough flow at idle speeds. This forces a major constraint on impeller profile design that is far less than optimum.

Electric pumps are not constrained by this need. Their control is not tied to crank rpm, and as such, they are free to be designed for peak efficiency at maximum flow, to achieve maximum hp gain, and are simply operated at whatever speed is necessary to maintain the required flow. Conventional OEM pumps on the other hand, are designed to provide higher efficiency at low and midrange speeds, where the engine spends most of its time.

No problem at all. I don't really consider these n00b questions, either, really. And if they were, still no problem. No one is lucky enough to be born knowing everything they ever wanted to know about. We all learn as we go along.

HPP

Ah, so then adding more current draw to the alternator in turn puts more load on the engine? I think that was the stumbling point. By "energy" was including electricity, which seemed to be something of a free resource as the alternator was already spinning anyway to power the radio, lights, charge the battery, fans, etc.

I guess it's that I always read in the mags about how electric water pumps and such helped improve power output because it was eliminating a draw on the crank. But what you said about efficiency of flow vs speed makes sense.