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Old 03-15-2014, 07:19 PM   #21 (permalink)
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OilPan4 -

Water will also drive a turbine... you need sufficient flow and pressure. Never heard of a hydro dam?

Your experiment will not work not because it tests a principle you believe to be faulty, but because the test itself is faulty. The water will only contain as much kinetic energy as is supplied via a pump, of which only about 54% can be extracted, in connection with Betz's law. (Which is generally applied to wind, but is also recognized as a principle of fluid dynamics in general. Unless the water is turned into steam as it crosses the face of the turbine, being used to extract latent heat from the turbine itself as it passes, no 'extra energy is generated and thus, only the amount of energy put into the flow and pressure of the water, up to Betz limit, can be extracted. The result is a net loss.

As per the rest of your comment, your attitude is a waste of time and you're starting to come across as a stubborn child with the thinly veiled insulting tone of your commentary and your constant appeals to authority. This will be my last reply to you on this subject.

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Old 03-15-2014, 08:38 PM   #22 (permalink)
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Rusty, there isn't much temperature drop across the turbine stage, the mass flow is from heat/expansion in the combustion chamber, that is where the turbine gets its energy (like the mass flow below):

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Old 03-15-2014, 10:45 PM   #23 (permalink)
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I take that as no one is actually going to try this?
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Old 03-16-2014, 12:21 AM   #24 (permalink)
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Alright I lied a little bit... your friend heat wrapped his down pipe because keeping the heat in the pipe before the turbine increases the pressure difference across the turbine housing.

The problem with your thought that a turbine is inherently a heat engine isn't that it doesn't function with heat, its just that heat is not the root principle of its operation, which is what I'm trying to explain this whole time. A pressure differential of any kind, with any fluid medium, will drive the turbine. In the case of the exhaust driven turbocharger specifically, you can see that the turbocharger presents a restriction to flow, initiating a post-combustion pressure stage. The pipe between the engine and turbine is a heat sink, and we already known that pressure increases in a closed space as temperature is increased. Its a common fault, and I don't blame you for thinking this way at all.

Wrapping that pipe iaulates it against later heat loss, which keeps a maximum pressure differential between the input and output of the turbine allowing it to operate with greater efficiency. The maths refer to DeltaP here when calculating the output power of the turbine shaft, asking for the pressure differential as an input, and this can be derived with some certainty using a temperature input if one wishes to analyze a freeze frame of the potential output under a given set of circumstances. In order to fully analyze a turbocharger system, you would need the inputs of mass flow and engine exhaust flow, as well as downpipe volume and turbine sizing, pitch, etc.. a much more complicate set of maths that is such less commonly used where simplicity is a factor.

What the latter would tell you is, under at set of conditions in which a turbine might be found to operate, what efficiency and output it wud have. This is part of how flow maps re created for specific designs of turbochargers.

I think I covered everything now...
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Old 03-16-2014, 12:23 AM   #25 (permalink)
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Sorry fr typos... Tablet and shaky hands
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Old 03-16-2014, 08:20 AM   #26 (permalink)
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Those I know who run 30 psi of boost in their e85 conversions wrap the exhaust, snail, etc to reduce under hood heat. If it does help performance its soo little its unmeasurable.
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Old 03-16-2014, 11:53 AM   #27 (permalink)
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Diesels dont have extreme under hood temperatures like gas engines and diesels are not as sensitive to higher temperatures like gas engines.

I dont think this way, this is how engineers think, they showed me. I didnt make this up.
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Old 03-16-2014, 05:14 PM   #28 (permalink)
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Yeah, most of the heat in a diesel engine today is from the egr water cooler that uses the coolant. I know many diesel owners who had trucks that ran warm and went with an egr delete and instantly they started to run on the cool side.
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Old 03-17-2014, 11:13 AM   #29 (permalink)
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This is correct.

Quote:
Originally Posted by P-hack View Post
Rusty, there isn't much temperature drop across the turbine stage, the mass flow is from heat/expansion in the combustion chamber, that is where the turbine gets its energy (like the mass flow below):

Link
Preserving the energy to the turbo is the point of the exercise.
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Old 03-17-2014, 11:30 AM   #30 (permalink)
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Yes, but the turbine in a turbo isn't a peltier junction or a stirling engine. Preserving the exhaust heat is basic PV=NRT stuff, decrease T and P goes down. The IC is a gas generator, and waste heat is entropy's way of saying screw y'all (unless it is cold outside, then maybe you have a use for it).

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