Em 22/10/2013 20:31, RussellMc escreveu:
> Brief.
>
> "All models are wrong. Some models are useful." ~~~=3D George Box.
> Voltage is pumping pressure =3D head of water equivalent.
> Current is current flow.
> If the pressure is supported by an infinitely strong pump then using larg=
er
> and larger pipes gives more flow limited only by the pressure drop in the
> pipes.
> Analogy breaks down if you start looking at wall resistance, boundary
> layers, turbulence etc - just consider a pipe has "resistance to flow".
> Energy is water mass you can pump to a given head or flow from a given
> head. Power is rate of pumping a given mass.
> V =3D pressure =3D head.
> I =3D current =3D current =3D mass per time.
> R =3D resistance =3D resistance.
> Power =3D V x I =3D Head x (mass per time)
> Energy =3D V x I x t =3D Head x mass per time x time =3D head x mass (=3D=
 mgh)
>
> There is a very solid finite upper limit on chemical efficiency based on
> the bond energies.
> Actual can approach theoretical for thermal release.
> Useable in engines is lower.
> Most hydrocarbons have around 10 kWh/kg bond energy
> LPG about 14 kWh/kg.
> Hydrogen gives about 40 kWh/kg.
> High explosives are in the same approximate range as hydrocarbons - they
> are just "better" at breaking all their bonds at once than is eg petrol.
> Fortunately.
> A cup of petrol and a stick of dynamite are of about same energy content.
> Petrol (as usually used) needs to be vaporised and mixed with air to
> liberate its energy. Do this "in the open" and you have a FAE - fuel air
> explosive. Flour does it too! (grain milling plants sometimes manage to
> explosively decompose due solely to grain dust and air igniting).
>
> Hydrogen is low density (as gas or liquid and not much better as a solid)
> so getting a Hydrogen store to have energy densities that are useful
> requires pressures beyond reasonableness, or liquid Hydrogen (which is
> still rather un-dense).
> (Hydrogen at many MPa pressure diffuses through steel.
> The steel "embrittles".
> Hydrogen at MPa pressure in embrittled steel containers is not usually go=
od
> for your health.
>
> Armstrong et al went to the Moon on liquid Hydrogen fuel. LH is not a
> friendly substance for a pocket battery.
>
> In an unfinished SciFi story I wrote long ago I posited personal power
> packs that used matter / antimatter  annihilation as the energy source.
> That gives you densities as useful as you want if you can make the
> antimatter containment pocket weight and deal with the reaction products.
> The likely ranges of "if" seems quite limited.
> Energy available approaches E =3D m.c^2 (which formula you may have met :=
-) ).
> For mere milligrams of antimatter you get useful power for a lifetime.
> On grams you can fly as required.
> 1 gram gives you about 20 kilotonne of fuel or explosives equivalent.
>
> I can dig the notes out sometime maybe.
>
> Below are a few notes from a 10 year old file. There will be MUCH more on
> web about this.
>
>
>   Russell McMahon
>
>
> __________________________________________________
>
>
> Below: eg 1m3 =3D 10^-3
>
>
> ANTIMATTER                     "AMAT"
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
> ** ENERGY CONTENT OF AMAT:
>
> 1 gram of amat is energy equivalent to 20,000 tonnes of chemical fuel
>         ie ratio of energies is (2e4 x 1e3) Kg / (1m3) Kg =3D 2e10
>         ie Antimatter is about 2E10 (20 billion) times more
>         "energetic" than chemical fuel.
>
> 1.8E14 joules/gram      (?=3D 6e20 antiprotons)
>         ie 6e20/2e14 ap's/joule =3D 3e6 antiprotons/joule
>         or minimum energy release per particle is about 0.3 microjoule
>
> ** COST OF AMAT:
>
> $10 billion / gram is amat breakeven cost with chemical fuels
>
>
> Proton/Antiproton --> pions and gamma rays. (?3 types of pions made)
>         ?2 pions are charged and therefore trappable and 1 is uncharged
> 20 Ktonne Hiroshima bomb >< 1gram amat
> (20 megatonne / kilogram?)
> 10m6 gram amat suitable for bullet source
> 10m9 gram per bullet for neutral particle beam ?
>
> A universal space plane would have a mass ratio of 3 (?e) to use the
> minimum amount of amat for a given mission. As the mission gets more
> energetic the % of "fuel" which is amat grows.


Dr. Robert L. Forward wrote that antimatter is a fuel with 200%
efficiency, because it must react with an equal mass of normal matter
that you can gather as you go (even in the interstellar space).

Even better, you can use a tiny amount of antimatter to heat a really
huge amount of plain matter and eject it at unbelievable speeds.

Isaac

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