Quote from Lynx on January 9th, 2013, 06:57 AM

10000 bar of pressure?
Sounds dangerous to me.

I still don't understand exactly how it works, but thanks anyway.

Isn't there any online community building these things?

Thanks.

Hello Lynx,

I do agree that outside of mining 10,000 bar pressure is not much heard off. However it be included to give a comparison to Steams starting point +100*C.  
CO2's 20 bar pressure at +20*C is more domesicated. Micro hydro generation receives water at the same pressure as if coming from a vertical drop of 200 meters.

The concept is Einstein fridge, where Ammonia is boiled out of water making it a high pressure Refrigerant gas.  (R744 is a much more power Refrigerant gas than Ammonia, it also needs far less heat)

The difference lays in the fridge uses the cold gas to make the beer cold, DaS puts the cold gas back in the boiler where it expands and pushes out the water.

There be many ways of doing the same thing, some not as complicated in simplicity, yet all following the principal of blowing water out of a straw, took us ten years to get there, dont expect it flash into anybodies mind.

Conglomeration NASA R744, California University Hydro turbine. Pumping cold gas into the pipe then heating the gas so its blows the water through the turbine was easy, next came how to stop the gas reaching the turbine, answer water pipeline air bleed valve, cooling the gas not a problem it freezes everything around it.

Dont know of any community build but right in there if there was one.

Been built before then converted to high pressure failure of turbine seals, so rebuilt in Aluimium to find it wont take direct heat.

Micro Pelton  with Fisher and Pykle washing machine motor. Off shelf screw together or cut and weld, may also be glued.

Thanks.

   

Quote from Lynx on January 9th, 2013, 06:57 AM

10000 bar of pressure?
Sounds dangerous to me.

I still don't understand exactly how it works, but thanks anyway.

Isn't there any online community building these things?

Thanks.

Hello Lynx,

I do agree that outside of mining 10,000 bar pressure is not much heard off. However it be included to give a comparison to Steams starting point +100*C.  
CO2's 20 bar pressure at +20*C is more domesicated. Micro hydro generation receives water at the same pressure as if coming from a vertical drop of 200 meters.

The concept is Einstein fridge, where Ammonia is boiled out of water making it a high pressure Refrigerant gas.  (R744 is a much more power Refrigerant gas than Ammonia, it also needs far less heat)

The difference lays in the fridge uses the cold gas to make the beer cold, DaS puts the cold gas back in the boiler where it expands and pushes out the water.

There be many ways of doing the same thing, some not as complicated in simplicity, yet all following the principal of blowing water out of a straw, took us ten years to get there, dont expect it flash into anybodies mind.

Conglomeration NASA R744, California University Hydro turbine. Pumping cold gas into the pipe then heating the gas so its blows the water through the turbine was easy, next came how to stop the gas reaching the turbine, answer water pipeline air bleed valve, cooling the gas not a problem it freezes everything around it.

Dont know of any community build but right in there if there was one.

Been built before then converted to high pressure failure of turbine seals, so rebuilt in Aluminium to find it wont take direct heat.

Micro Pelton  with Fisher and Pykle washing machine motor. Off shelf screw together or cut and weld, may also be glued.

Thanks.

   

May help in understanding,

Peter :-)

http://i1225.photobucket.com/albums/ee397/DaSEnergy/workings_zps74b94142.png

Hello Lynx,
A small correction. Turbines as well as the Stirling engine turn heat into electricity.
Only some refrigerators have a compressor others have a boiler.
The pupose of a refrigerant is not to carry heat but to get cold by pressure loss. This is done in both  boiler and compressor fridges. Both type build up high pressure behind a restrictor plate/valve, that is a solid plate with tiny hole in it.

However it must be noted the purpose of a heat pump is not to make things cold but transfer heat from one place to another making it idealy usless in power generation, when the ground heat where it is is all that is needed to exite CO2 to turbine drive pressures.Hello Lynx,
A small correction. Turbines as well as the Stirling engine turn heat into electricity.
Only some refrigerators have a compressor others have a boiler.
The pupose of a refrigerant is not to carry heat but to get cold by pressure loss. This is done in both  boiler and compressor fridges. Both type build up high pressure behind a restrictor plate/valve, that is a solid plate with tiny hole in it.

However it must be noted the purpose of a heat pump is not to make things cold but transfer heat from one place to another making it idealy usless in power generation, when the ground heat where it is is all that is needed to exite CO2 to turbine drive pressure.
Dont yet know why but Photobucket has starting listing diagrams withdrawn hope this one stays.
Peter

http://i1225.photobucket.com/albums/ee397/DaSEnergy/fridge_zpsa202eed8.png

Hello all,

This thread not just me are on the right track.

I am the worlds worst writer but eventualy get there.

To begin at the start, both absorption and compressor fridge have a common which is pressurising the refrigerant (in the case CO2) onto a restrictor plate/valve. The hot refirigerant having passed the restriction is cold.

To the turbine generator this is great as the return refrigerant to the boiler is cold.

As with Steam there is some energy/force at low temperature but that energy/force increases as it gets hotter.

Commercial turbine generators work to the factor of one litre per second at nine bar pressure/force produces 720 watts.

By using the force that gathers at the restrictor plate/valve, replaced by a turbine which acheives exactly the same thing which is depressurising/loss of force, the energy is converted not wasted.

CO2 has a particular curve commencing at 30*C on through to 100*C. It goes from 64 bar to 10,000 bar. Which is converted to electricity would safely deliver 720KW.

The best way to heat a gas is to pass it through water which in this case needs be maintained at 100*C.

Having 30*C refrigerant enter the water and leave the water at 100*C, the heating must occur within the one second. This means the water must heat by 70*C in the one second to shift from refrigerant cooling to 30*C.

Watllow Industry and sciences gives us that the electrical energy needed to heat by 1 degree Celsius one litre of water in one minute requires 0.076KW.  Multiple by 60 to get heating in one second is 4.56KW.  To acheive 70*C this becomes 319.2KW. One litre of 9,000 bar force per second generates 720KW.

The tables dont reveal any overunity at the lower heat settings howver on past the 30*C mark it shows it face.

I dont have the money to build a 720KW turbine generator to prove it one way or the other. However either the science has it wrong or overunity is staring us in the face.

Reguards PeterHello all,

This thread not just me are on the right track.

I am the worlds worst writer but eventualy get there.

To begin at the start, both absorption and compressor fridge have a common which is pressurising the refrigerant (in the case CO2) onto a restrictor plate/valve. The hot refirigerant having passed the restriction is cold.

To the turbine generator this is great as the return refrigerant to the boiler is cold.

As with Steam there is some energy/force at low temperature but that energy/force increases as it gets hotter.

Commercial turbine generators work to the factor of one litre per second at nine bar pressure/force produces 720 watts.

By using the force that gathers at the restrictor plate/valve, replaced by a turbine which acheives exactly the same thing which is depressurising/loss of force, the energy is converted not wasted.

CO2 has a particular curve commencing at 30*C on through to 100*C. It goes from 64 bar to 10,000 bar. Which is converted to electricity would safely deliver 720KW.

The best way to heat a gas is to pass it through water which in this case needs be maintained at 100*C.

Having 30*C refrigerant enter the water and leave the water at 100*C, the heating must occur within the one second. This means the water must heat by 70*C in the one second to shift from refrigerant cooling to 30*C.

Watllow Industry and sciences gives us that the electrical energy needed to heat by 1 degree Celsius one litre of water in one minute requires 0.076KW.  Multiple by 60 to get heating in one second is 4.56KW.  To acheive 70*C this becomes 319.2KW. One litre of 9,000 bar force per second generates 720KW.

The tables dont reveal any overunity at the lower heat settings howver on past the 30*C mark it shows its face.

I dont have the money to build a 720KW turbine generator to prove it one way or the other. However either the science has it wrong or overunity is staring us in the face.

Reguards Peter

Quote from Lynx on December 1st, 2012, 04:11 PM

Well the purpose of the Sterling engine is that it can turn heat energy into
mechanical (electric) energy, but it's efficiency grade is rather poor at this, the
overall grade here is only about in the range of 15-20% in converting heat into
electricity.

The Pelton wheel and the Francis turbine turns kinetic energy into mechanical (or
if you will electric) energy, it's not the same as turning heat into electricity.

But thanks anyway!

I am releasing a Stirling engine Excel file that I created some 10 years ago (back when I was smarter :) It uses equations based on the Schmidt theory to calculate the theoretical shaft output power in Watts.

For a given set of inputs (various engine dimensions and volumes), mean pressure (for a pressurized engine/system), an estimated engine speed, and the two temperatures, it will plot the P-V curve and provide the net shaft output power for each of the three basic engine configurations, alpha, beta, and gamma.

To the best of my knowledge the calculations are correct, but never publicly released for scrutiny.  Feedback, comment and corrections welcome.

Hopefully, this will take some of the guesswork out of some of the ideas that are floating around.

Enjoy,

kcd

SchmidtTheoryRevA.xls

Thanks for the spreadsheet KC, but I must admit that it's way over my head what you got there.
How can I tell the efficiency grade, in percentage, of the different configurations?
Thanks

Quote from Lynx on August 27th, 2013, 11:13 AM

Thanks for the spreadsheet KC, but I must admit that it's way over my head what you got there.
How can I tell the efficiency grade, in percentage, of the different configurations?
Thanks

Hmm, good question :)  Overall efficiency will be a total bear to evaluate, depends on the heat transfer efficiencies and conduction losses from the hot end to the cold end.  Of course if you want relative efficiencies as applicable to the three engine types, I suppose you can set the three worksheets up with the same inputs and look at the outputs.  With the default inputs supplied in the file, the alpha and beta types look like better performers.  But work with the numbers, I suspect the configuration with the least dead space may be the best performer.

The most interesting number to change and observe the changes in output is the mean (average) pressure. The funky circle on the P-V diagram looks the same, but shifts upward (centered at the mean pressure) as the mean pressure is increased.  Note that the output power increases as well.  That is why most high efficiency engines operate at high pressures.

There was an example in one of the Stirling engine books I have of a fellow that built a small pressurable engine, with air as the working fluid.  He applied heat, and a load to the shaft and observed the speed.  He then slowly increased the pressure.  I don't recall what pressures were used, not much, possibly 3 to 4 atm tops.  Initially, the engine sped up, producing more power, but he soon reached a point where the speed leveled off, and then decreased with more added pressure.  The author of the book provided no explanation.  

But I believe that I can explain.  The increased pressure moves the 'circle' on the P-V curve upward, and more work is produced.  But the pressure increase also increases the density of the working fluid, which in turn provides a greater burden at both the hot and cold heat exchangers.  The circle may move up on the chart, but the actual hot and cold temperature difference of the working fluid is decreasing, thus squeezing the circle smaller in the other dimension.

Heat exchanger design is critical to getting a Stirling engine running efficiently.  The pressurized systems using Helium or Hydrogen do so in order to get the best performance possible for a given engine/heat exchanger design. Note that the Schmidt calculations are based on 'ideal' heat transfer, which is a bit of a stretch, but they are still very helpful to evaluate various 'what if' power generation ideas.

kcd

Ok, you're clearly up to date regarding the properties of Sterling engines, good for us to have you on our side
Thanks for the explanation but I'm afraid my wheel is spinning and the hamster's dead in this case........would a rule of thumb say that the overall efficiency for a Sterling engine is in the neckar of woods of about 20-30% -ish.....?

Quote from Lynx on August 27th, 2013, 01:02 PM

Ok, you're clearly up to date regarding the properties of Sterling engines, good for us to have you on our side
Thanks for the explanation but I'm afraid my wheel is spinning and the hamster's dead in this case........would a rule of thumb say that the overall efficiency for a Sterling engine is in the neckar of woods of about 20-30% -ish.....?

If I recall correctly, the Stirling engine cycle is the only thermodynamic cycle that can theoretically approach the Carnot cycle efficiency. The Carnot efficiency being the best that you can ever hope to achieve: efficiency = 1 - (Tc / Th), where the temperatures (hot and cold) are in degrees absolute (such as Kelvin, or Rankin)  So to answer your question, it is a function of the two temperature extremes.

The whole point of posting the Excel file was for the folks that are thinking of generating power with low grade heat to do the calculations for them selves.  Once that is done, one will see that the power is just not there.  Yes, there are novel little engines that will run sitting on top of a hot cup of coffee - but these are otherwise not of much practical value, even if scaled up.

Sorry...

EDIT: Corrected typo on efficiency equation: was: 1 - (Tc - Th), SHOULD BE: 1 - (Tc / Th)

Ok, thanks KC, appreciate it

Hello Lynx,

"The Pelton wheel and the Francis turbine turns kinetic energy into mechanical (or
 if you will electric) energy, it's not the same as turning heat into electricity"

In Sterling engine heat applied to air supplies the driving force.

In DaS heat applied to gas provides the driving force.

It is the gas heating that supplies the force not the water passaging through the turbine.

 Hello Lynx,

"The Pelton wheel and the Francis turbine turns kinetic energy into mechanical (or
 if you will electric) energy, it's not the same as turning heat into electricity"

In Sterling engine heat applied to air supplies the driving force.

In DaS heat applied to gas provides the driving force.

It is the gas heating that supplies the force not the water passaging through the turbine.

 

A little rant then:
On the bottom of a lake the temperature is about 36 - 39 F.
Using say solar energy to heat the "hot" part of a Stirling engine and pumping cold water from the bottom of the lake
for the "cold" part could then be one way of cranking up the difference in temperature, hence upping it's efficiency grade.
The downside would of course be when the sun isn't shining and/or when the lake is 'particularly' hot, drilling a hole in the ground would also be another way of getting cold water, but anyway.
The engine would of course be used to generate electric energy, if you're out to get hot water then solar energy alone would be the right way to go here.
As it "only" would give you energy in intervals then storing energy would be the way to go here, so charging batteries is, to my knowledge anyway, the best way of storing electric energy there is, feel free to correct me here.
To save some on pumping up the water, temp sensors could be used to guide lowering or raising the pump's hose/pipe to find cold enough water.

/rant

A little rant then: Like your style :-)A little rant then: Like your style :-)

Quote from Lynx on August 28th, 2013, 01:28 AM

A little rant then:
On the bottom of a lake the temperature is about 36 - 39 F.
Using say solar energy to heat the "hot" part of a Stirling engine and pumping cold water from the bottom of the lake
for the "cold" part could then be one way of cranking up the difference in temperature, hence upping it's efficiency grade.
The downside would of course be when the sun isn't shining and/or when the lake is 'particularly' hot, drilling a hole in the ground would also be another way of getting cold water, but anyway.
The engine would of course be used to generate electric energy, if you're out to get hot water then solar energy alone would be the right way to go here.
As it "only" would give you energy in intervals then storing energy would be the way to go here, so charging batteries is, to my knowledge anyway, the best way of storing electric energy there is, feel free to correct me here.
To save some on pumping up the water, temp sensors could be used to guide lowering or raising the pump's hose/pipe to find cold enough water.

/rant

Instead of solar use geothermal energy, just a thought.:D

BINGO!
Instead of solar use geothermal energy, just a thought.:D[/quote]John Howard mapped Australia Urban Geothermal 2006.
Stirling engines run a treat on CO2 gas.
Trick is to bubble exhaust gas through cold water before putting the gas back to expansion. BINGO!
Instead of solar use geothermal energy, just a thought.:D[/quote]John Howard mapped Australia Urban Geothermal 2006.
Stirling engines run a treat on CO2 gas.
Trick is to bubble exhaust gas through cold water before putting the gas back to expansion.

Quote from Jeff Nading on August 28th, 2013, 06:57 PM

Quote from Lynx on August 28th, 2013, 01:28 AM

A little rant then........

Instead of solar use geothermal energy, just a thought.:D

Cheers Jeff
Sure, geothermal energy is of course also out there, for free if you will
Such a setup with a pump for both the hot and cold water providing energy to a Stirling engine could prove to be a total winner, provided that the generated active electric effect from the alternator driven by the Stirling engine exceeds the waterpumps total effect, the rest would then be the sweetest free electric energy you could come to think of
Much like what they could do in Iceland, only they have far shorter distances to their geothermal energies as opposed to having to drill a hole X miles down for the rest of us.....
http://open-source-energy.org/?tid=769&pid=10105#pid10105
I'm still curious to why no one has found out a more efficient way of turning heat into mechanical/electric energy, it seems as though the Stirling engine is still the best option there are for achieving this.

Quote from Lynx on August 28th, 2013, 08:54 PM

Quote from Jeff Nading on August 28th, 2013, 06:57 PM

Quote from Lynx on August 28th, 2013, 01:28 AM

A little rant then........

Instead of solar use geothermal energy, just a thought.:D

Cheers Jeff
Sure, geothermal energy is of course also out there, for free if you will
Such a setup with a pump for both the hot and cold water providing energy to a Stirling engine could prove to be a total winner, provided that the generated active electric effect from the alternator driven by the Stirling engine exceeds the waterpumps total effect, the rest would then be the sweetest free electric energy you could come to think of
Much like what they could do in Iceland, only they have far shorter distances to their geothermal energies as opposed to having to drill a hole X miles down for the rest of us.....
http://open-source-energy.org/?tid=769&pid=10105#pid10105
I'm still curious to why no one has found out a more efficient way of turning heat into mechanical/electric energy, it seems as though the Stirling engine is still the best option there are for achieving this.

Of course adding solar energy here when the sun is shining would boost performance, perhaps enough to charge enough many batteries which in turn provides energy for the pumps when the sun is down, just to prevent the pumps from shutting down during the night.
There is still the "small" matter of finding the successor to the Stirling engine, the machine that turns heat, or should I say difference in heat, into mechanical energy far more efficiently compared to what any Stirling engine can do.
Once that one is found then we're one giant step forward to all the free energy we possibly could need.

Permanent Green Power produces electricity from any heat source above -40*C. Micro or commercial with its hydro turbine powered by liquid piston, or alternate fully turbine. Giant footprints leading to the giant. However the competition to keep things as they are comes from far more than many would think. Permanent Green Power produces electricity from any heat source above -40*C. Micro or commercial with its hydro turbine powered by liquid piston, or alternate fully turbine. Giant footprints leading to the giant. However the competition to keep things as they are comes from far more than many would think.

Quote from Lynx on August 29th, 2013, 06:55 AM

Quote from Lynx on August 28th, 2013, 08:54 PM

Quote from Jeff Nading on August 28th, 2013, 06:57 PM

Quote from Lynx on August 28th, 2013, 01:28 AM

A little rant then........

Instead of solar use geothermal energy, just a thought.:D

Cheers Jeff
Sure, geothermal energy is of course also out there, for free if you will
Such a setup with a pump for both the hot and cold water providing energy to a Stirling engine could prove to be a total winner, provided that the generated active electric effect from the alternator driven by the Stirling engine exceeds the waterpumps total effect, the rest would then be the sweetest free electric energy you could come to think of
Much like what they could do in Iceland, only they have far shorter distances to their geothermal energies as opposed to having to drill a hole X miles down for the rest of us.....
http://open-source-energy.org/?tid=769&pid=10105#pid10105
I'm still curious to why no one has found out a more efficient way of turning heat into mechanical/electric energy, it seems as though the Stirling engine is still the best option there are for achieving this.

Of course adding solar energy here when the sun is shining would boost performance, perhaps enough to charge enough many batteries which in turn provides energy for the pumps when the sun is down, just to prevent the pumps from shutting down during the night.
There is still the "small" matter of finding the successor to the Stirling engine, the machine that turns heat, or should I say difference in heat, into mechanical energy far more efficiently compared to what any Stirling engine can do.
Once that one is found then we're one giant step forward to all the free energy we possibly could need.

Yes you could use both, geothermal and solar. I still think a potential difference between a cold and hot source will create electrical current .:D

http://i1225.photobucket.com/albums/ee397/DaSEnergy/PermanentGreenPower_zps5fed1210.png

Quote from Jeff Nading on August 29th, 2013, 03:50 PM

I still think a potential difference between a cold and hot source will create electrical current .:D

Thanks Jeff.
:D :cool: :P

http://en.wikipedia.org/wiki/Thermocouple
"A thermocouple consists of two dissimilar conductors in contact, which produce a voltage when heated. The voltage produced is dependent on the difference of temperature of the junction to other parts of the circuit. Thermocouples are a widely used type of temperature sensor for measurement and control[1] and can also be used to convert a temperature gradient into electricity."

Quote from Ravenous Emu on August 29th, 2013, 06:52 PM

Quote from Jeff Nading on August 29th, 2013, 03:50 PM

I still think a potential difference between a cold and hot source will create electrical current .:D

Thanks Jeff.
:D :cool: :P

http://en.wikipedia.org/wiki/Thermocouple
"A thermocouple consists of two dissimilar conductors in contact, which produce a voltage when heated. The voltage produced is dependent on the difference of temperature of the junction to other parts of the circuit. Thermocouples are a widely used type of temperature sensor for measurement and control[1] and can also be used to convert a temperature gradient into electricity."

Yes, some where on this forum I posted how thermocouples [30mv] work and also how thermopiles [750mv] put out more voltage because they are more than a few thermocouples connected in series. This is how old submarines used to charge there batteries. :cool:  

Once upon a time I was thinking of building a large 55 gallon drum Stirling engine.  The concept is a scaled up version of a twin soda can design.  The pistons use a liquid (water or oil) seal.

I have generated and attached a sketch.

This design does have advantages and disadvantages:

Advantages:

Liquid sealed pistons.

Can be scaled up (more??)

Can use multiple transfer tubes to connect barrels.

Liquid heat transfer from outer barrel to tubes in center of barrel.

Interconnecting (cross tubes connected between barrels) can be thermally isolated from both the hot and cold barrel (connected with rubber tubing) to reduce conduction losses.

Cross tubes can be enclosed and insulated and will function as a regenerator.

The hot barrel could be heated by solar power, and concentrated using an array of mirrors.

The hot barrel could be insulated with a window for reflected solar input.

The cold barrel could have cooling fins on the outside.

Disadvantages:

Slosh - cannot run too fast, or extract too much torque.

A pressure bleed will be needed to reduce the operating air volume as the entire operating temperature increases - need to keep the mean liquid level inside and outside of the piston the same.

Dead space.  There is dead space at the top of each piston, and in the tubing bundle.  The tubing bundle should be large enough for adequate flow back and forth, as well as act as hot and cold heat exchangers, and regenerator.  

Liquid in the tubes could be a big problem, possibly provide a means for a manual drain.

If anyone builds one of these monsters, I would like to see it!

Use the Excel sheet to estimate output power...

kcd