free electricity possible?

Discussion in 'General Science & Technology' started by elct, May 24, 2012.

Thread Status:
Not open for further replies.
  1. spacecadet earth bound Registered Senior Member

    Messages:
    20
    aqueous id
    your reply to das energy Peter
    your last paragraph "... completely harmless..." is true if it is contained. i.e. not in the earths atmosphere. would leaky systems be a threat like the old refrigerants CFC ??
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. Hertz Hz Registered Senior Member

    Messages:
    60
    Why not write a computer program that generates electricity?
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. DaS Energy Registered Senior Member

    Messages:
    223
    Hello spaceadet,

    Yes you are not the first one to find me confusing.

    You be correct that it be like the Sterling engine in that it heats a gas then uses its expansion force for work effort. Sterling engine draws in ambient temperature gas into a cylinder where it is heat expanded by solar focus before going to piston stroke then exhausted to atmopshere at end of the work stoke.

    DaS open technology is more like a condensing engine such as the Steam piston or turbine. However in place of liquid H2O as the liquid medium it has liquid CO2.

    It may be used with either a gas turbine or hydro turbine. In gas drive configeration its fitted with a gas turbine and the process works like a Steam turbine. Liquid H2O is pumped into a boiler where it is heated into a high pressure gas which drives a gas turbine before the gas is cooled back down to liquid and repumped back into the boiler.

    The other way involves the more efficient Hydro turbine. The the process begins the same as in the Steam turbine. However liquid CO2 is pumped into the boiler where it is heated into a high pressure gas. However after the gas leaves the boiler it is cooled down to liquid, (but that liquid remains under high pressure because of the hot gas build up behind it), then the liquid CO2 drives a hydro turbine before the CO2 liquid is pumped back into the boiler.

    Kilowatt power of either gas or hydro turbine remains calculated the same. That is one litre of liquid or gas at a pressure of 9 bar (9 times attmosheric pressure) must pass through the turbine every second in order to produce 720 watts of power. Any increase in the pressure of the gas or liquid fed to the turbine shall increase the wattage output. So will any increase in the volume per second of gas or liquid passing through the turbine.

    Why we chose CO2 to work with is because that at a temperature of minus 10% Celsius it has enough minimum force to spin the turbine. At the boiling point of water it has 40 times the force of Steam at a temperature of 550* Celsius.

    Peter
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. DaS Energy Registered Senior Member

    Messages:
    223
    Hello burban4

    The answer is yes to your question. Household supply of 14kW requires a heat source of 20* Celsius and a one litre turbine cycling at 60 RPM. The refrigerant return to boiler temperature of 2* Celsius.

    14kW is Francis hydro turbine/generator. The output of a gas turbine/generator is not known, sorry.

    To create the compressor cut a thread into extended turbine shaft then case. A hose conectiong front and rear of turbine shaft allows water pick up to make mobile seal. Causing pulse in compression but doing no harm.

    Cheers Peter
     
  8. FTLinmedium Registered Senior Member

    Messages:
    106
    Maybe post singularity, if that ever comes to pass. In the here and now we are tied to economy, so somebody is ultimately paying for it even if the end user doesn't have to (if it is 'too cheap to meter').
     
  9. DaS Energy Registered Senior Member

    Messages:
    223
  10. Gravage Registered Senior Member

    Messages:
    1,241
    Even if there is free electricity they would find a way to charge it one way or another.
     
  11. billvon Valued Senior Member

    Messages:
    12,810
    You are going to need some truly massive radiators (and gas/fluid flow) to get 14kW out of an 18C temperature differential. We'd be talking thousands of gallons a minute water flow if water is used, for example. OTEC has done similar sorts of systems but their machinery is pretty massive.
     
  12. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    That´s true.

    Also the efficiency of conversion of heat energy to shaft power, will be less than (Th -Tc)/Th or in this case 1 - 275/(273+20) = 1- 0.94 = ~5.5% or in practice certainly less than 5% so to get 14Kw out he must dump 19 times more thermal energy into the cold source (refrigerator, I think he is calling that) There is no way he can elevate that quantity of 2 degree C heat back up to 20C and close the cycle with the 14Kw power developed. He will need more power from the electric company. I.e. you don´t need to be able to follow his confused text to know it is nonsense. There is no free energy.

    If he is not planning a closed cycle, but using solar energy in an open cycle, he could get double (or more) the power from simple same size collector of solar cells. Even the cheapest ones give 12% conversion efficiency today. They would cost far less than just the large OTEC-like heat exchangers he would need. To move 20 times 14Kw thru the input heat exchanger with only a few degrees drop across it does require the enormous OTEC-like heat exchangers.
     
  13. DaS Energy Registered Senior Member

    Messages:
    223
    Hello billvon,

    Sorry for not drawing in an expansion chamber. (alternate Radiator cooling does work.) A volume of one litre is required to generate 14kW at a heat differential of 18* Celsius. The system physics are that of an absorption fridge (see How Stuff Works web). The difference here being refrigerant gas leaving the boiler is blocked by a turbine not a restrictor plate. The expansion chamber at turbine dump is kept under vacuum by the compressor intake. So far refrigeration engineers have not supplied a graph of vacuum needed or internal volume of expansion chamber to reduce the gas temperature by 18* Celsius in one second.

    The sizing of radiators at OTEC would reflect the voume per second cycled. Do you know what that volume is ?

    Cheers Peter
     
  14. DaS Energy Registered Senior Member

    Messages:
    223
    Hello Billy T,

    The system is closed cycle. Turbines of today dependant on type have a shaft efficiency of 60% to 90%. Commercial power generation Toshiba Steam turbine requires a heat differential of 400* Celsius (550* Celsius to 100* Celsius per second). A heat differential of 18* Celsius per second seems somewhat puny to that. Absorption fridges work by dumping heat to atmosphere. They are quite able to reduce temperature from 20* Celsius to 2* Celsius. I have not yet discovered any Solar cell of size/volume one litre that can output 14kW.

    Air is free so is the heat contained in it. Solar is reknown for its free energy, ie electricity. The expression free energy is common usage and does not take in material and construction costs.

    Cheers Peter
     
  15. DaS Energy Registered Senior Member

    Messages:
    223
    Hello billvon,

    Thank you for the lead on OTEC, Wikipedia has them using refrigerants such as ammonia or R-134a neither of which has the thermic activity of the natural refrigerant Carbon Dioxide-Co2, R744.

    Cheers Peter
     
  16. billvon Valued Senior Member

    Messages:
    12,810
    Like I said, to maintain such a heat flow at an 18 degree difference you are going to need huge radiators. Thousands of square feet in air; thousands of gallons a minute if you are using water. That's how OTEC works, by exploiting a small heat differential with lots and lots of mass.

    Scaling a recent reference design to your power level, you'd need 113kg/s, or 13200 pounds a minute, or 1650 gallons per minute to produce 14kW. That is a big pipe! A 12" pipe would do it with a moderate (10 foot or so) head.

    A solar panel 36 feet on each side would output 14kW. The radiator for your system would be much, much larger.

    Butane is another popular working fluid. All have their advantages and disadvantages.
     
  17. DaS Energy Registered Senior Member

    Messages:
    223
    Hello billvon,

    I agree with you IF WATER not CO2 was the driver agent. However the device would not work at all under 100* Celsius if water was used let alone it be powering the family home at 20* Celsius.

    The technology is cited on the Francis turbine, it requires one litre per second, which in fact is less than 15 gallons per minute movement. Pipe sizing is very small needing only to carry one litre per second. Much smaller than 12". Vertical fall of water 10 feet produces only one third of a bar pressure. A vertical water fall of 32.5 feet is required to produce one bar pressure.

    18 bar pressure if produced by water fall would require a dam wall of 180 meters in height.

    Cooling is not by radiator but using expansion chamber vacuum created by the intake of the compressor. This type of cooling occurs in the electric fridge. The exact size and vacuum needed is not known by me.

    That little radiator attached to your ICE is reducing 800* Celsius to 100* Celsius per second at 60 RPM. However no ICE has an idle speed of 60 RPM so in fact more than one litre per second is being cooled.

    Thank you for the Solar pannel square footage. An area of 1,296 square feet or 398 square meters or 99 meters each side.

    Butane is another refrigerant gas however its pressure to temperature is quite low. This is why its used in plastic cigarette lighters.

    The best gas for turbine drive purpose is the one giving maximum bar pressure for least heat and is easily compressible to a liquid.

    Cheers Peter
     
  18. billvon Valued Senior Member

    Messages:
    12,810
    Uh, right. I agree that an 18C temperature differential can drive a heat engine - but thermodynamics will require huge radiators. Has nothing to do with the type of working fluid; the heat still has to enter and exit the device.

    No, you misunderstand. That is the head required to move the cooling water through the pipe. The cooling water is merely the heat source; your working fluid is different than the heat source (or the cold sink.)

    You could go to a larger pipe (16"?) and then you'd need less head to move that much water.

    That is not a cooling method that you can use during operation. If you are claiming that you can cool it by pulling a vacuum, and then maintain that vacuum through the energy generated by the device, you have described a perpetual motion machine - and they never work.

    That is completely incorrect. ICE coolant is not at 800C. And cooling 800C to 100C with 2C ambient air is several orders of magnitude easier than cooling 22C to 4C with 2C ambient air.
     
  19. DaS Energy Registered Senior Member

    Messages:
    223
    Hello billvon,

    "That is not a cooling method that you can use during operation. If you are claiming that you can cool it by pulling a vacuum, and then maintain that vacuum through the energy generated by the device, you have described a perpetual motion machine - and they never work."

    If such was to be correct then the Icecream in your fridge would have long time melted. A web search How Things Work-electric fridge may be of assistance.

    " ICE coolant is not at 800C." I agree the coolant is not at 800*C. 800*C is the engine temperature residue of burning Petrol. Burning Diesel increases that temperature to 1,200*C. These are the reasons why the ICE parts melt to become a seized engine if your dont keep the radiator full of coolant.

    Cheers Peter
     
  20. billvon Valued Senior Member

    Messages:
    12,810
    That works quite well. It works because you ADD energy in the form of a mechanical compressor. This both creates the high pressure on the high side and the low pressure on the low side. If you are saying that your device needs power input as well, then that's fine, if a bit confusing; thus thread was about generating electricity, not using it.

    Engine parts do not "melt." (Steel does not melt until about 1400C.) Unlubricated IC engines seize due to friction destroying the bearing surfaces, and uncooled IC engines seize because parts get VERY hot and either deform (crack) from the heat or expand until they lock against other (cooler) parts.
     
  21. DaS Energy Registered Senior Member

    Messages:
    223
    Hello billvon,

    Have you ever wondered how a steam train gets the water into the boiler. That requires a force which oddly enough comes from the same boiler supplying steam to the pistons on the driver wheels.

    IC engines of today are liight weight alloy. The only thing that differentiates the piston from the engine block at loss of coolant is the conrod sticking out of what once was the piston.

    Cheers Peter
     
  22. billvon Valued Senior Member

    Messages:
    12,810
    Nope. They use pumps, which require power. (Nuclear reactors are immensely more complex, but the same basic principle holds.)
     
  23. DaS Energy Registered Senior Member

    Messages:
    223
    Hello billvon,


    "Nope. They use pumps" I'll pay that

    Please Register or Log in to view the hidden image!



    Ok, two more questions,. Have you ever wondered where Steam trains get the power/energy to drive the water pump filling the engine boiler.

    Have you considered a compressor is in fact a pump, though usualy pumping gas, which can easily be changed to punping water if a hose is put into the air intake of the compressor.

    Cheers Peter
     
Thread Status:
Not open for further replies.

Share This Page