[AR] Re: Fw: Hydrogen / oxygen news
- From: Lloyd Droppers <lloyd.droppers@xxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Thu, 31 Oct 2013 07:45:56 -0700
If your interested in the water electrolysis thrusers I ran across some
papers years ago from NASA Lewis on the Space Station Freedom thruster
design, and one of the baselines was gO2/gH2 propellants from water.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19870015989_1987015989.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19860023050_1986023050.pdf
I love the old NASA Lewis technically reports, they are so well put
together.
Lloyd
On Wed, Oct 30, 2013 at 4:46 PM, Henry Spencer <henry@xxxxxxxxxxxxxxx>wrote:
> On Wed, 30 Oct 2013, Christopher Buchanan Shay wrote:
> > For those who didn't see this, possible AR applications beyond
> fabrication?
> > http://www.safeflameproject.eu
>
> Pretty much nil. The key question to ask is, just how much electricity
> does it need? With no gas storage, production has to keep up with use...
> and electrolysis is terribly energy-intensive. (There is a reason why
> industrial/fuel hydrogen *isn't* routinely made by electrolysis.) There's
> a lot of power in even a modest flame, and that energy has to come from
> somewhere.
>
> For the sort of flame we're most interested in :-), the power is huge. A
> useful rule of thumb is that for many types of rocket engine, power input
> is roughly exhaust velocity (m/s) times thrust (N). (The jet power is
> half that, but there are enough inefficiencies to typically require
> something vaguely like a factor of two on the energy input...) A mere
> thousand pounds of thrust (call it 5kN) at 250s Isp (call it 2.5km/s) is
> circa a 12 *megawatt* flame. Megawatts of electricity involve serious
> hardware -- think bus bars, not mere cables. (At the upper extreme, big
> rocket engines typically are multi-gigawatt machines.) Not practical.
>
> The one borderline exception is spacecraft maneuvering propulsion, where
> there has long been interest in systems that slowly electrolyze water and
> store the resulting gases to be burned (much more rapidly) in a GOX/GH2
> thruster. This offers a dense non-hazardous main tank and fairly high
> Isp, at the cost of relatively heavy and complex hardware and a constraint
> that burns be small and widely spaced. (And also, tricky development --
> several past attempts at such systems ended in nasty explosions, in one
> case fatal to an experimenter. Although Tethers Unlimited recently
> successfully hot-fired such a system.)
>
> Henry Spencer
>
> henry@xxxxxxxxxxxxxxx
> (
> hspencer@xxxxxxxxxxxxx)
> (
> regexpguy@xxxxxxxxx)
>
>
>
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