Mike Holmen

I've seen older gas turbines that look like a turbo charge except for that there are several stages of turbine blades. The compressor section was just like our turbo compressor side. I also read on the internet somewhere that some actually built a gas turbine off what looks like a HX-40 turbo charger. They just added a combustion chamber between the compressor and the turbine. They even had an afterburner. It ran off propane. It was pretty cool, some people just have too much time. Here is what I found on the internet, its not the same article but its close.
http://www.gasturbine.pwp.blueyonder.co.uk/page1.htm

600 Megawatts

Absolutely. Many, many home built gas turbine / jet engines have been built using a turbocharger. It is infact, perfect for such an exercise: It has a compressor and a turbine coupled to a common shaft, precisely what a gas turbine/jet engine has. I have a video of one running at 60,000 RPM with the entire turbine housing and exhaust yellow! !! not red, not cherry, not even orange... YELLOW !!!! Very fun stuff, just be careful with overspeed. One basic rule: Stand inliine with the shaft, never to the side


KP

smoke_pedal

I just want to clear up some confusion. Hot air means more volume, cold air going in, hot air coming out right? we have a big fan on the same shaft as a little fan, the big fan on the shaft can turn the little fan with less drive pressure than the little fan is putting out, because the big fan uses more volume to do the same amount of work. The principle behind a turbocharger producing more efficiency is well, we will deal with the turbine only right now, p1=turbine pressure in, p2=turbine pressure out, t1, t2, same, same. p1 35 psig, t1 1300 deg fthermodynamic potential of (humor me) 5000 joules/lb of air, now p2 0 psig, t2, 1000 deg f. 3500 joules/lb. If we compress this adiabatically, we only see the temperature come back to 1200 why? The turbocharger turbine used about 30% of the energy contained in the air to drive the wheel. It did not use heat energy to drive the wheel, We just see the energy reduction of the discharge gases as a decrease in temperature, but what is actually happening is a decrease in total energy contained in the gases. I lied. I confused all of us more, including myself. Well said Megawatt

600 Megawatts

You were heading in the correct direction, but I think you may have gotten lost on the way lol ..

I got a little crossed up reading your post, because I think you said air a few times where you probably meant exhaust.

As for compressing adiabatically back to where you were and only getting you back to 1,200, well that is in fact the second law of thermo in action right there!!!!! This is an irreversible process remember. The turbine is not isentropic, and the compressor is not adiabatic.

I dont have my gas tables handy right now, but I will work up a quick cycle using enthalpy and go through it. Of the top of my head, 1,300F exhaust has an enthalpy of about 430 BTU/Lbm and 1,000F exhaust should be down at about 375 BTU/Lbm, so right there you have a Delta h of 55 BTu/lb. Figure on about 2,500 Lb/Hr of exhaust flow and a turbine eff of .7 and you wind up with about 38 shaft horsepower delivered to the compressor section.

Now looking at the compressor section a pressure ratio of 2.4 (~35#'s boost) taking in ambient air at 80F with an enthalpy of about 130 Btu/Lb, and compressing 2,400 #/Hr with an comp eff of .8 uses about .......

You guessed it: 38 shaft horsepower!!!!

Which of course holds true the 1st law of thermo.


These are all ball-park numbers, as I dont have my gas tables with me here. ( I got my steam tables though !!! lol )


KP

Mike Holmen

I been wondering how efficient turbo are? I've heard that your only capable of collecting 40% of the power from the exhaust for a single turbo and you can collect around 50% for twins. This is theory but has anyone actually tested this out. I thought about doing the measurements but I always find something else better to do. The last thing you need to do is turn your truck into a lab experiment.

600 Megawatts

Mike, yes if you look at the total energy available in the exhaust, then it actually collects quite a bit less than even 40%, more like 20%. But if you look at the energy it does collect, and how it turns that energy into shaft work, then it is about 80% of that amount.

And yes, you are correct, in that "twins" (as long as they are compounds in series, not twins or duals in parallel) collect way more of the exhaust energy.

As for the calculations, there are a lot easier than you think. All you need is the pre turbo temps, the post turbo temps and your drive pressure.



KP

Mike Holmen

I have all ways thought about hooking up test equipment and do pretty much what a complete work over on the entire truck. Yes I could get it to work better than what it is, but I have to tell myself why??? The HP and engineering geek inside me wants to but if I did that I would have to re-engineer the entire truck. You can't have that, the perfrect truck!!!

goodtyms

Any updates on this project or photos/details of the merge collector?

what a ride

WHat ever happened to this? Did it run? Is it collecting dust in the corner of the garage? Please update.!!!

Ph4tty

If you'll notice the originator of the thread is banned, so you'll have to go to cummins forums or the like. He did build a set of twins using a ht3b.