[IamIan]

Originally Posted by t vago

Using the law of partial pressures, we add the new steam at 14.7 psia to the existing exhaust gas at 82 psia. We come up with 96.7 psia total for the system final pressure, which is roughly 2/3 of the original exhaust gas pressure.

Thanks ... that result makes more sense to me... than the original post with just 14.7

- - - - -
one other minor thing.
- - - - -

Originally Posted by t vago

The 1700:1 so-called expansion factor that drmiller100 keeps bandying about is misleading in this, because it is for standard atmospheric conditions

For that tiny amount of liquid, we just saw a 975:1 expansion factor, which is not 1700:1

correct ... but doesn't that just mean we need to compensate for that with the ideal gas law ... to prevent the steam from expanding with a fixed volume container , the lack of expansion is compensated for with greater than standard atmospheric partial pressure from the steam.

So wouldn't the steams partial pressure when confined to 39.04cc be around ~26 psi.

Which brings the system up to ~108 psi.... which is still about ~28% less than initial pressure at the 100C.

It works in a steam engine because there is more energy available from the cylinder walls due to the heat of what ever is being burned ... than the energy just from the hot air.

Originally Posted by t vago

Like I said, this idea of spraying water into exhaust gas is merely a novel way to cool off said gas.

I didn't have a problem with the concept / point itself ... I just didn't see how you were getting such low 14.7 psi figure ... thanks for the corrections.

Three side notes:

#1> In a different engine designed to take advantage of it ... the timing of the piston being exhausted could be set equal to the power stroke of an opposed piston ... lower pressure on the second part from cooler temperature exhaust gasses creates a larger pressure difference to move the power stroke piston with.

#2> If the water is inside a confined heat exchanger pipe ... the water will expand in the pipe which could drive a turbine or other piston... thus extracting some useful energy / work from the otherwise exhaust gas.

#3> The biggest thing from my perspective often missed in a lot of the water injection type of discussions is the weight penalty of the additional device and the additional water ... even if a system does manage to increase real time efficiency from one mechanism or another ... it won't be a net benefit unless the pro is bigger than all the cons added together.

Originally Posted by t vago

That's because I wasn't clear, and I apologize for the resulting confusion.

Thanks for the clarification and correction.

Originally Posted by t vago

This just goes to show how complicated an ideal example is. Real-world modelling is even more complicated. There are steam tables that must be consulted. There are gas tables that must be consulted. The example here has been ridiculously simplified in order to make it as understandable as possible.

agreed.
yeah computer models.