[Alastor187]

Originally Posted by Polygon

Guys, before this gets started it really does belong in the Forced Induction forum. Besides, there are a lot of people in there that will have some good insight as well.

Thanks, I was not sure where to put it.

Originally Posted by Zgringo

I know for a fact the 2 identical compressors, one driven with a DC electric motor an the other by exhaust turbin the discharge air on the DC driven compressor was cooler than the exhaust driven turbine leading us to believe that the exhaust turbine transfered heat to the compressor.
The compressors were driven to 10# psi and the only difference being scorce of drive.

Do you have access to or remember the differences in the compressor discharge air temperatures? If so do you know what the EGTs were for the exhaust gas driven setup?

Originally Posted by Zgringo

Another test was with compressed dry air and another with air with 20% water mist. In both tests 150lbs of compressed air was used and the one with moist air had much more power.

How well does this type of procedure replicate real world turbocharger performance? In this type of procedure the pressure ratio is high and I am guessing that the volumetric flow rate is low, with respect to real applications. Or were both of the parameters realistic in your testing? Also, this leads me to wonder if you know what kind of pressures exist in the exhaust manifold of engine mounted turbocharger.

I would image that the water mist greatly increases the mass flow rate with respect to dry air, while only moderately increasing the volumetric flow rate. How likely is that water will exist in the liquid phase inside the exhaust manifold? As the density of water vapor is about three orders of magnitude lower than that of liquid water, how does this effect your results?

Originally Posted by Zgringo

The exhaist in a 4 cycle engine has particals in it and these particals striking the turbine help increase the power of the turbine. This is the reason a turbo'd engine running a fat (rich) mixture develops more power. Under load is when a turbo is at it best. More particals in the exhaust.

Basically you are saying that the change in momentum of these particles imparts energy to the turbine blades. The use of the word “particle” indicates to me that you are taking about relatively massive objects with respect to the exhaust gases. Correct?

Is this not what the exhaust gases are doing, imparting energy to the turbine blades as they pass through? While increasing the temperature of the gases makes them more energetic?

I thought that you also stated in another thread that a rich mixture helps to ensure that unburnt fuel is introduced into the exhaust manifold where it combusts due to the high temperature. This creates higher pressures and temperatures inside the manifold.

Originally Posted by Zgringo

Because most people see a turbo run harder with higher heat they think heat is what is making the power when in fact the heat is expanding air very quick and raising the pressure causing the particals to strike the turbin blades at a hi-velocity which in turn drives the turbine.

I am not trying to push the topic of high temperature exhaust gases out of total ignorance or stubbornness. I am just trying to understand everything and I am relying on what I have learned in thermodynamics. Unfortunately, my thermodynamics is orientated towards power plant design and not automotive applications.

Looking at a steam powered turbine with some fixed inlet and outlet pressures, more shaft work can be obtained if the steams temperature is increased. It seems reasonable to me that the same should be true of turbochargers.

However, you are indicating that a portion of that heat is passed to the compressor discharge air and negatively effects your net power gains. Also, you are indicating that hi-velocity particles in the exhaust gases are contributing a significant amount of the energy used by the turbocharger. Finally, you are stating that the particles obtain their high velocity via the high pressures. All these factors would make the problem much more complicated than a simple steam powered gas turbine.