free electricity possible?

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

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  1. billvon Valued Senior Member

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    Nope. They get the energy from the output of the engine. Since the water is a liquid, which is much denser than gas, it is easy to pump. Early locomotives just sprayed the resulting steam into the air, which meant they did not have to condense it - but they then ran out of water and had to stop after 50 miles or so to take on more water. Later locomotives recycled the water by using huge condensers to condense the steam back to water. (Google a picture of one; they took up a massive amount of space.)

    A compressor is a kind of pump, although a pump is not a compressor. Most pumps do not phase change the fluid they are working with, nor are they designed to significantly compress any gases they pump.
     
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  3. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    Correct as usual, but let me make that more quantative, assuming the steam exits from same chamber the water is pumped into the difference between work the steam can do and the energy required for the pump for constant H2O mass in the chamber is a factor equal to the steam / water volume ratio which is huge.

    To keep the chamber pressure constant, you must also add 540 calories per gram of water injected (or more if water is not at 100C). For example if water is at 40C you must add 600 calories per gram of water added. Earlier steam trains supplied this energy by burning coal and converted part of the coal´s chemical energy into over coming friction against their motion. Obviously they were not a closed system.

    Again, no amount of smoke and mirrors via confused text will over come fact that there is no free energy from any closed system designed to produce energy* for external use, no mater how complex the design details are. Too bad DaS Energy is ignorant of this basic thermodynamic fact. He calls his system closed in post 72, but also speaks of taking in free heat energy from the environment so has several confusions.

    * Any real attempt to do that will be a net consumer of energy perhaps useful for heating your house with energy from the power company but no moving parts resistance wires are much less costly.
     
    Last edited by a moderator: Jul 31, 2012
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  5. DaS Energy Registered Senior Member

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    Hello billvon,
    I think we have now answered your concerns.

    "They use pumps, which require power" - "They get the energy from the output of the engine" Though more correct to say, they use steam/gas from the boiler to drive the pump.

    The boiler having enougth steam/gas pressure not only to drive the wheels of the engine but to operate the return pump filling the boiler.

    "A compressor is a kind of pump" "they designed to significantly compress any gases they pump" Fully agree which is why you find a compressor in the design. Just like in an electricric fridge the intake draws in recycle gas and compresses it to a liquid, however instead of driving that liquid through a tiny little hole in the restrictor plate, it drives the liquid back into the boiler.

    Possitive action pumps (those with a piston) are in fact compressors, centrifical pumps are not. The word pump is usualy taken to mean pressurising water and compressor is taken to mean pressurising a gas.

    Cheers Peter
     
    Last edited: Jul 31, 2012
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  7. billvon Valued Senior Member

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    Originally, yes. (The output of the engine, of course, _is_ the power from the expanding steam.)

    Agreed. That's because the condenser has re-condensed the fluid by dumping heat to the heat sink side of the system; thus the amount of work the pump has to do is minimal. If that pump were trying to re-condense the steam by compressing it it would take more power than the engine could generate.
     
  8. DaS Energy Registered Senior Member

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    Hello billvon,

    "If that pump were trying to re-condense the steam by compressing it it would take more power than the engine could generate."

    No. The boiler or engine as you call it, has to build up enougth CO2 force/pressure to both compress the CO2 gas into liquid then push it into the boiler. The more force/pressure in the boiler the more force/pressure needed to reinsert the liquid. Example a boiler of 10,000 requires a pump capable of the same or greater force/pressure. A boiler of 100 bar requires a pump capable of the same or greater force/pressure. Despite the boiler of 10,000 bar having 9,900 more bar force/pressure than the 100 bar force/pressure boiler it doesnt blow up because it was built to take that pressure. In the case of steam/gas boilers they are built to withstand forces/pressures greater than that needed to operate all the machinary its driving. Think of it this way, a boiler producers 10,000 bar force/pressure, the force/pressure needed to drive the turbine then condense the gas and pump the liquid back into the boiler is 10,000 bar.

    Cheers Peter
     
    Last edited: Jul 31, 2012
  9. billvon Valued Senior Member

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    Yes. And that will ALWAYS be more energy than you can extract from its expansion.

    Correct! And compressing the fluid back to the original pressure/state will always take more energy than you can recover from its expansion. (Unless, as mentioned before, you have an external temperature differential to help you out.)
     
  10. DaS Energy Registered Senior Member

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    Hello biillvon,

    I can see where your coming from and can understand your reasoning.

    The boiler return pump requires X force/pressure to return liquid to the boiler. That force/pressure is greater than the force/pressure needed to compress the gas into liquid. if you like the compression of the gas can be said as thrown in as a freeby.

    Cheers Peter
     
  11. DaS Energy Registered Senior Member

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    Hello Billy T

    You raise an intersting point. So many people have been fooled for so long by steam engineers pretending the the pump attached to the boiler was actualy pumping water in while the boiler was lit. Damn they are good.

    The steam engine has been with us for over two centuaries and the steam turbine/generator for over a half centuary. Both have only the force/pressure coming out of the boiler to drive the machinary and boiler return pump.

    Any closed system such a recycling gas turbine. Draws in external heat. People pay good money to go to Universities and be taught that any system where insides dont get out is called a closed system.

    So many appear to ignorant of your knowledge.

    Cheers Peter
     
  12. Aqueous Id flat Earth skeptic Valued Senior Member

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    DaS Energy,

    I suggest you try to learn the most basic of modeling and calculation. Start with the ideal gas law and calculate how much mass of working fluid is required to develop 14 kW over a temperature difference of 18 °C.

    That's how much mass in kilograms you must move per second. You will need this to look at the power draw of your compressor/pump.

    Knowing the mass, take the fluid density to get volume. That gives you your flow rate in cubic meters per second. It gives you insight into basics like the diameter of pipe.

    From that you can multiply the compression factor to get your expansion volume. It think for CO[sub]2[/sub] you have to multiply by about 780. You can figure that out. This will lead to the volume of your condenser.

    Knowing the volume of material that needs to be changed 18 °C per second, you can look into copper, just to prove a point, and estimate the surface area required of such a heat exchanger.

    Until you can do this you will never understand what Billy T and billvon have been saying.

    One other thing: earlier you mentioned pulling a vacuum on the low side of the turbine. Presumably that's a relative term, since you're already above 72 atm. But calculate the pressure difference and account for the cost of repressuring (presumably a pump). Figure out what size of pump is needed to acquire that pressure improvement over that much volume. Per second. The last step will be to estimate the size of turbine required.

    When all of this is finished, you can go back and account for losses in efficiency, and loss in general, and rescale your design accordingly.

    I think you'll be surprised by the results.
     
  13. DaS Energy Registered Senior Member

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    Copy of prior not meant to post in reply
     
    Last edited: Aug 1, 2012
  14. DaS Energy Registered Senior Member

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    Hello Aqueous Id,

    I am reliant on California University for mass calculation.

    The power draw of the screw compressor/pump and piping is provided in the same manner used by steam trains and steam turbines. Sizing is done to volume needs per second, as so with steam trains and steam turbines.

    There be no condensor, but a vacuum expansion chamber to strip away heat. So engaged by both absorption and compressor fridge.

    Copper pipe unfortunately is out of the question given the high force/pressure 30*C is 60 bar (852+ PSI ) At 100* Celsius the working force/pressure is 7,000 bar so mid grade line pipe need be engaged in construction.

    Please note if boiler temperature is above 32*C a different boiler configuration is used as CO2 above 32*C begins to form Dry-Ice within the boiler. The compressor is done away with and straight pump is engaged.

    To date I have not gone to surface areas for heating or volume size of the expansion chamber cooler it varies with the heat absorption needed to the pressure setting. Being Open Technology I leave that to others and their particular power needs.

    As in a electric fridge there is large force/pressure prior to the restrictor plate (replaced by a turbine) at the entrance to the expansion chamber which inside has much less pressure as its drawn to vacuum.

    Compression of gas to liquid. As in all fluid pumps if a gas is allowed to enter it shall be compressed by the internal fluid without need of extra energy input.

    Should ambient heat absorption be employed in place of fuelled heating which being the intention Eficiency is not of great importance to myself unlike if fuel heat was being provided.

    Turbine and pump sizing. Again I am reliant on California University Each litre of fluid per second at 9 bar pressure the generator output is 720watts. 10 litres of fluid per second at 18 bar pressure provides 14kW at 60 RPM. CO2 having a heat differential of 18*C (2*C to 20*C ) provides the necessary 18 bar force/pressure.

    Pump sizing needs be matched with the volume per second of fluid exiting the boiler. In the posted example that pump would need to return 10 litres of fluid per second.

    Turbine sizing for posted example is 10 litres.

    Efficiency is dependant on type of turbine employed these range between 60% and 90%.

    Efficiency losses to the screw pump/compressor is not known.

    Given the data and feed back provided by Universities and Industries and Engineers engaged in refrigeration and steam/gas turbine operation I am quite happy with the results.

    Cheers Peter
     
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