If steam engine cycles were implemented would the average Joe refill water every day?

[maxc]

Some assumes that steam engines need too be refilled with water. LOL

[wumpus]

[QUOTE=oil pan 4;413251][QUOTE=Christ;413214]Turbochargers are /pressure/ engines, not heat engines. If the water evaporates while crossing the face of the turbine, the steam expansion rate creates a higher pressure differential across its face, thus increasing the power by which it can be driven. The heat is completely circumstantial to this

If this worked why isnt it in use on large turbodiesel power generators, ship engines or gas turbine power plants?

I know some engineers I can pitch this idea to. I already know their first reaction will be to laugh at me.

Not to mention the idea of having liquid water droplets in contact with the turbine is a bad idea. Causing drag, erosion things things you dont want.

Some notes:
Gas turbine power plants and ship turbine engines already get this effect without adding water. The use compound turbines to wring all the heat out of the turbine. This is an old trick that dates back to steam turbines.
Large turbodiesel engines *can* do this. I think Audi (or maybe BMW) does this in research cars. It was originally done in military bombers:
Turbo-compound engine - Wikipedia, the free encyclopedia
Wright R-3350 Duplex-Cyclone - Wikipedia, the free encyclopedia
After dealing with the complexity of these engines, the engineers switched to turboprops and (and jets) and never looked back. I don't think piston-turbine-compound engines have any advantages over normal turbines (I'll explain the reason it at least justifies the research for the Germans a bit later).

As far as adding water to a heat engine: a simple experiment will help here (EPA willing). Do an A-B-A experiment changing from E0 to E10/E15/E85. Since there is almost certainly a degree of water in the alcohol mix, you will be adding water to your car's engine. If you notice a gain over the actual engergy containted in the gas, it was likely the water (unless your car can detect the E85 and crank up the CR), like the reverse. I know from at least one other time this was suggested, at least one forumite had a strong agrument that adding water *reduced* the pressure. It certainly removes a lot of heat (good old phase change) and the pressure of the resulting water vapor + air was indeed lower (our trusty forumite had checked the expansion coeffecients).

The real reason you would add steam (especially for automotive turbo-compounding apps) is that gas turbines operate in the 10k-100k rpm region and steam engines operate in the 100-10k regions. I wouldn't be surprised if the Germans didn't need any gearing (but I think running the steam at half the engine speed might be ideal). Steam makes it possible to directly couple the two engines without the huge gearboxes needed for turbines, and likewise is missing the exotic material requirements for ultra-high rpms. I'm still not convinced you couldn't mount a turbine (really, half a turbocharger) to a hybrid/range extender and drive a generator with it.

[edit: just noticed a thread with this link in it. Apparently adding water *does* work, just that you will be adding gallons/mile]
http://ecomodder.com/forum/180860-post10.html
detailed explanation about heating steam (never mentions the effects of pressure due to steam expansion. You really need to include that).
http://ecomodder.com/forum/showthrea...y-21437-3.html

[oil pan 4]

If these turbochargers are not heat engines then why are rear mounted turbos typically 5% to 10% less efficient and more laggy?

[Christ]

I can't believe you're still on this... honestly.

Rear mounted turbos are more laggy and lose efficiency because latent heat in the exhaust dissipates as it travels through the pipe, reducing the overall pressure across the face of the turbine.

I know that's exactly what answer you were looking for, and you're going to pick one word out of that answer to try to prove your point, but trust me, it doesn't. The fundamental working principle behind turbine engines is pressure. How you get that pressure makes zero difference, as long as it's there.

[RustyLugNut]

Originally Posted by Christ

I can't believe you're still on this... honestly.

Rear mounted turbos are more laggy and lose efficiency because latent heat in the exhaust dissipates as it travels through the pipe, reducing the overall pressure across the face of the turbine.

I know that's exactly what answer you were looking for, and you're going to pick one word out of that answer to try to prove your point, but trust me, it doesn't. The fundamental working principle behind turbine engines is pressure. How you get that pressure makes zero difference, as long as it's there.

The crux is the work derived from the mass flow through the turbine. Pressure and temperature provide the impetus to move your working fluid through the turbine which then extracts work from the fluid mass. Higher temperature and pressure in a gas turbine inlet result in potentially greater mass flow into the turbine. A drop in exit pressure and temperature is a direct result of the loss in energy of the working fluid which was transferred to the turbine. The fluid ( or gas as it may ) is assumed constant. Note that lighter (less dense gas or fluid ) will produce less power at a given pressure and temperature. Hydrogen gas will produce less power than steam. Some lab work has been done in the past using vaporized mercury to take advantage of the high specific mass density.

[oil pan 4]

So which is it? Mass flow or pressure drop?

If its not a heat engine then why isnt some one injecting water into the exhaust stream and seeing major gains in turbine performance, proving aerospace and mechanical engineers all wrong.
If a turbocharger is not a heat engine then why did an aerospace engineer I know go to great lengths to insulate the piping on his diesel for the specific reason of getting as much heat as possible to the turbine inlet?

Maybe you are right and engineers are all just stupid. It could easily be proven with the water injected steam turbine thingy. Seems easy enough to prove, take a diesel put water injection on the exhaust, flip the switch on off on off results in test complete. I would do it but I know it would be a waste of time, first of all it wont work and then when it fails you will claim it failed because my bias.
A true believer needs to see it fail first hand, back to back, over and over.

[RustyLugNut]

Originally Posted by oil pan 4

So which is it? Mass flow or pressure drop?

If its not a heat engine then why isnt some one injecting water into the exhaust stream and seeing major gains in turbine performance, proving aerospace and mechanical engineers all wrong.
If a turbocharger is not a heat engine then why did an aerospace engineer I know go to great lengths to insulate the piping on his diesel for the specific reason of getting as much heat as possible to the turbine inlet?

Maybe you are right and engineers are all just stupid. It could easily be proven with the water injected steam turbine thingy. Seems easy enough to prove, take a diesel put water injection on the exhaust, flip the switch on off on off results in test complete. I would do it but I know it would be a waste of time, first of all it wont work and then when it fails you will claim it failed because my bias.
A true believer needs to see it fail first hand, back to back, over and over.

Of course temperature and pressure directly affect the flow through the turbine. They are also linked together. Increasing temperature usually results in increased pressure and the ability to move the mass of the gas more rapidly providing more potential for work per unit time ( power ).

This why it makes sense to have a free flowing exhaust to reduce pressure robbing bends. And insulating the exhaust preserves as much of the heat ( temperature ) to do work on the turbine. Again, the temperature of a gas is a measure of how much each molecule is vibrating and moving and impacting a barrier resulting in pressure.

And sometimes injecting water into the exhaust stream can yield greater mass flow and power out of a turbo but under very specific caveats.

[jeff88]

Originally Posted by RustyLugNut

Again, the temperature of a gas is a measure of how much each molecule is vibrating and moving and impacting a barrier resulting in pressure.

I think you just put this to bed, right here (again).

A turbo is a pressure based engine. Heat is, in essence, a form of pressure, in that the molecules react more creating a larger pressure on the surroundings (e.g. turbine). Calling it a heat engine is only a part of the puzzle, it's not the wrong answer, it's just that it's only a part of the right one.

[Cobb]

http://www.youtube.com/watch?v=b7t2VjZ1DvY

Originally Posted by maxc

Some assumes that steam engines need too be refilled with water. LOL

[RustyLugNut]

Originally Posted by jeff88

I think you just put this to bed, right here (again).

A turbo is a pressure based engine. Heat is, in essence, a form of pressure, in that the molecules react more creating a larger pressure on the surroundings (e.g. turbine). Calling it a heat engine is only a part of the puzzle, it's not the wrong answer, it's just that it's only a part of the right one.

The same way you can have a static torque reading and produce no power until that torque results in movement over a period of time, so is the need to produce motion from the turbine. However, if the mass moving through the turbo charger turbine is too small the power produced by the turbo will also be small even though you may have a high pressure/temperature reading at the inlet reiterating the need for free flowing exhaust systems.

In the case of a turbo charger, pressure and temperature are a good measure of the mass flow through the turbo charger since one can assume the exhaust gas is constant for this calculation.