Sealed CO2 Turbine Drive

Hello Yellowjacket.

Any thermal engine having a Carnot efficiency of 18% is a wonder it even goes.

Carnot. The loss of heat.
Force. Bar measurement of pressure.
Economy. Quantity of fuel usage.
All three apply to thermal engine.

Carnot. Submersed source of heating absorbs all heat to point of liquid boil.
Single cylinder one litre Diesel heat shed is 1200* Celsius.
Liquid may be held at 100* Celsius by twelve one litre takes of 100* Celsius.
Perimeter of heat sink leaks heat. Insulation limiting.

Force. CO2 gas at temperature of 100* Celsius has pressure of 7,000 bar.
CO2 gas at temperature of 32* Celsius has pressure of 64 bar.

Economy. Best Diesel 300 PSI compression heat expanded five times,1500 PSI or 100 bar pressure. Each combustion of one litre Diesel engine provides 100* Celsius heat to twelve separate litres of CO2. Each one litre of CO2 at 100* Celsius has pressure of 7,000 bar, or the forces of 700 Diesel engines. Heat from one Diesel engine combustion stroke provides to the same forces as 8400 Diesel engines.

Minimising sizing to complete the hot cold loop draws on refrigeration physics and the odd behaviour of CO2.

Containerised CO2 at 100* Celsius creates an internal Dry-Ice field.
Hidden inside the ice field is a cooling radiator, top and bottom accessing the outside.
Radiator top connected to outside expansion chamber. Radiator bottom connected to turbine suction hub.

Working. Cylinder having hot gas at top provides a downward force onto the liquid gas at bottom of cylinder. Liquid gas at force rotates the turbine runner till the liquid gas flash off to gas upon reaching the turbine exit expansion chamber entry point. Expansion cooled gas is then suction drawn through the Dry-Ice radiator, cooling the gas to liquid. Constant incoming of liquid gas ensures the cylinder never fully empties of liquid, thereby ensuring hydro turbine constant liquid pressure.


http://i1225.photobucket.com/albums/ee397/DaSEnergy/Untitled.png

Peter

 

Peter,

You are missing one key point. You can create huge forces, but work is defined as force times a distance. I have no doubt that you will create huge forces, but with a working fluid temperature difference of only 70 degrees you can't do much work. You have to look at how much heat you transfer into and out of your machine, and then calculate the potential work, When you do that you will find there isn't much useful work that can be done with this concept.

Thermodynamics isn't just a suggestion, it's the law...

 

Yellowjacket: I admire the patience and the pedagogic approach you have shown here in this thread; not allowed to give you any points though.....

DaS Energy: It's time for you to find (and read, and then reread) a basic textbook on thermodynamics before you carry on with this thread. It is obvious that Yellowjacket is wasting his wisdom as long as you don't understand the basic facts of the discipline.

Then you come back and we will have a discussion at length over the qualities of the various working fluids possible for a thermal energy process; there is certainly a lot to be said on that topic!

 

Hello baeckmo,

Thermodynamics - Royal Navy, NASA and Textbook.

Thermodynamics of heating and cooling may provide 100% recycle of driver substance.

Theromdymanics is the energy (pressure/force) acheivable when a substance is heated from a solid or liquid to a gas then returned to original state.

A good place to start is temperature phase graph of the chosen driver substance.

Water at 0*C -Ice. Water at 100*C tipping point of gas Steam -1 bar pressure/force.

CO2 at -40*C -Ice - 0 bar pressure/force.
CO2 -39*C to -10*C Gas 40 bar.
CO2 -10*C to + 32*C liquid 64 bar pressure/force.
CO2 32*C liquid to +100*C gas 7,000 bar pressure/force.

Turbine rotation is caused by high pressure (hot) gas entering at high pressure/force inlet. Low pressure (cool) gas needs exit the turbine. Turbine drive force force is that pressure differential existant between high pressure/force inlet and low pressure/force outlet. That force having caused the turbine runner to travel some distance.

Pressure/force between the points of high pressure/force inlet and low pressure/force outlet can be taken away by turbine shaft transference of force or by cooling of the driver substance.

Cheers Peter

 

All this big buck tech , just to steal some power from the exhaust.

Does anyone remember what was called a PRT , power recovery turbine , as used on aircraft engines , from the 1950s?

A 3350 radial engine had 3 PRT that each made 150 HP , delivered to the crank by quill shafts.

Not much maint , not much cost , and I would assume in 60 years the turbines are a bit better?

KISS , always a goal!

FF

 

If you have a reciprocating engine the pressure (and a lot of noise) that is emitted when the exhaust valve opens can be recovered with a turbine in the exhaust. While you can get about a 20% improvement in efficiency at wide open throttle conditions, as you close the throttle you get a lot less energy out of the exhaust turbines. Turbines like this were already pretty efficient. While you could get a few percent more energy than you did back then, it really isn't much more. Over the last 50 years compressor technology improved greatly, but turbines were already near 90% efficient, and haven't improved that much.

Bottom line is that it only makes sense if you are running at very high throttle openings all the time.

The other thing is that as you shrink a turbine to make it small, you have to increase the speed to get good efficiency and useful work. If you look at turbocharges you are seeing rotational speeds of up to 90,000 or 100,000 rpm. In the old engines they geared the turbines to the crankshaft, and that's probably the best way to do it. If you use a generator on the turbine you have to make sure you don't drop the load, or the turbine will overspeed very quickly and burst.

 

Hello Fast Fred,

"All this big buck tech , just to steal some power from the exhaust"

There be no exhaust heat invoved!, though exhaust or indeed all of combustion engine heat may be exploited. Either means of heating requires a combustion engine radiator be fitted for gas cooling.

The real gain is in power performance. Example, at best Diesel combustion (heat
1200*C) produces 100 usable bar of force. CO2 heated from 32*C to 100*C produces 7,000 bar usable force.

Am most interested to learn more of the "power recovery turbine"

Cheers Peter

 

Hello Yellowjacket,

Turbochargers use the force coming off the piston when at exhaust. The heat of combustion is not recycled. Turbines increase their power by increase of force at inlet or increase of force at outlet. Power increase also done by volume per second, which may be acheived by making the turbine bigger or having it rotate faster.

Fully agree that if a generator load is lost the turbine will overspin, however safety valves preclude this from happening, They work much like the old fashioned spinning govenor, though instead of throttle regulation it opens and closes a pressure relief valve.

Cheers Peter

 

Peter,

You are on shaky ground telling Yellowjacket how turbos work my friend.

I suspect he knows a great deal more about it than you judging by your post I'm sorry to say.

However, he is always the gentleman and will likely handle you with kid gloves.

Perhaps it is simply a matter of terminology, but some clarity will come of it I am sure.

Turbos are incredible devices which are as close to magic as it gets with internal combustion engines in my opinion.

I fabricated a self limiting system years ago on an old Datsun 510 with staggering results.

They are little less than brilliant when designed/coupled effectively with an internal combustion engine.

 

Peter, your really need to take a few courses in thermodynamics...

Turbochargers are just like any other turbine. They expand a gas that is at a higher pressure to a lower pressure and extract work from the gas flow, but the amount of energy that can be extracted during that expansion is a direct function of the turbine inlet temperature. To put it another way, if you have a gas at high temperature, for each unit of mass flow, you can get more work out of the higher temperature gas than a lower temperature gas.

The best way to do that is to compare the enthalpy before and after your expansion process. If you do that you will see that the higher the temperature going in, the more work you can do in the expansion process. Even if the pressures coming into and going out of the turbine are the same, the higher temperature inlet turbine produces more work for the same mass flow.

So yes the heat coming into the turbocharger, or any exhaust turbine makes a difference in the amount of power that is recovered.

If you look at any reciprocating engine, unless it has an expansion ratio that is different than the compression ratio, there will always be a volume of gas that hasn't been fully expanded when the exhaust opens. This expansion is what causes exhaust noise and there is a pressure component to that mass of gas, as well as a temperature component. Expanding that gas across some device, and taking work from it will reduce the pressure and temperature of the gas. So any machine that you put in there to take work from the exhaust is reducing the temperature and is "recycling" (bad use of words here, but I'm trying to be consistent with your terminology) the heat energy in the exhaust flow.

 

Hello Yellowjacket,

Thermal turbine engage expanding gas to provide drive force.

So known as thermodynamics. Kilowatt/Horsepower of both piston and turbine is calculated volume of force per second. Force being measured in bar. 82% efficient 720 watt turbine requires a force of 9 bar at volume of 1 litre per second.

The internal combustion engine uses expanding gas to push down on a piston.
The returning piston then up pushes the spent gas out of the cylinder via a turbocharger.

Gas being forced against the turbocharger vane exerts an "egual opposite force" against the piston, it matters not if all forces have been spent during the piston down travell, some type of force is needed to keep the piston travelling up despite the back pressure existant between turbocharger vane and piston top, this is acheived by piston attachment to crankshaft.

In both piston and turbine once the force has been taken by the shaft the residue heat is of no value except for heating.

Carnot got it wrong, Heat=Energy, when in fact Force=Energy. Heat exists without force and force may exist without heat.

When guaging the turbine inlet force, its force that needs be looked at not heat. Heat may inhabit a force, heat alone has no force. Force comes from the substance the heat is emerged in. Example water at 550*C exhibits 175 bar of force, CO2 at 100*C exhibits 7,000 bar of force, Air compressed to 20 bar then heated (Diesel combustion) to 1200*C exhibits a force of 100 bar.

Cheers Peter

 

Peter,

I'm sorry but I don't know where to start....

The only reason I'm bothering to put together an answer is that others might see this and think that you are on to something.

You are totally missing the concept. These systems are called heat engines for the simple reason that they extract energy by means of moving HEAT. Whether that energy transfer comes from expanding a gas or causing a phase change, it doesn't matter. They are all heat engines. What do you think causes those phase changes, it is the addition or removal of heat that creates the changes that allow you to extract the energy.

Carnot has never been proven wrong. Period. You can use the Carnot cycle analysis to predict exactly how much energy you can possibly recover from a heat engine thermodynamic cycle, and it has nothing to do with pressure, it's ALL a matter of temperatures. Remember too, that you simply can't do any better than that. If you believe you can you are simply uninformed and do not understand or are doing something wrong in performing your calculations.

You need to go entirely through you cycle and calculate all of the energy transferred into and out of your cycle, and, oh by the way, make sure you don't violate the first or second law of thermodyamics when you do that, and when you do, you will eventually see and understand why it won't work the way you think it will.

I'm sorry, but I simply can't help you if you refuse to understand the concept of thermdynamics.

 

Heat and gas volume count , when extracting power

On the old recips at cruise the RPM was way down , but leaning for better fuel burn would raise the EGT , so there should be more energy in the exhaust.

Lean burn was done by the flight engineer , but with todays electronic diesels , I assume a 5c computer chip would do.