New Aluminum-Ice Rocket Propellant Tested

eldavojohn writes "With the problem of moving conventional rocket fuel to the Moon and Mars on their minds, researchers from Purdue and Penn State successfully tested and demonstrated the use of aluminum-ice (ALICE) as fuel. In a paper from last August they outlined how it would work (PDF), and now they know it does. Space.com also has more information on the paper and how nano-scale aluminum functions as a fuel."

Comments

Old news, but not to /.

[confused one]

MIT Technology Review is a little late here. This was covered by numerous sources back in October. Surprisingly, I can't find it in the /. archives; so, it may not be a dupe.

Thermite + Water Vapor = BOOM

[Azarael]

For a neat visual presentation of the physics they're relying on, Mythbusters did an experiment on the explosive power of thermite powder and water vapor http://www.youtube.com/watch?v=BnHR4cMXiyM.

Re:ALICE?

[Ethanol-fueled]

You may be too young to remember, but it was acceptable and even funny to beat your wife in the '50's.

Get off my lawn or one of these days...POW! Right in the kisser!

Its seeing things like this ..

[OzPeter]

that highlight the safety instructions I've had at Aluminium plants. You never, ever, ever drop anything like used aluminium cans into the feed that is headed for melt shop as any bit of liquid still in the can will cause a rather powerful explosion

Re:Its seeing things like this ..

[mangu]

You never, ever, ever drop anything like used aluminium cans into the feed that is headed for melt shop as any bit of liquid still in the can will cause a rather powerful explosion

It's also a known rule that you use sand, never water, to extinguish a fire where molten aluminum is present.

However, the biggest danger from dropping aluminum cans in the melt is from the steam expansion, not from burning aluminum. Having *any* humidity at all where molten metal runs, any metal, not just aluminum, will produce large quantities of steam, which will expand explosively throwing molten metal all around.

I know this from personal experience, when I was about twelve years old I was burned while melting lead to make fishing weights. I dropped the mold in water to cool it and the next time I poured metal in it I got a spray of molten lead right in my face. Lucky me, none of it hit my eyes.

Re:In other words

[TheRaven64]

Really? Because hydrogen is the most common element in the universe, and oxygen is also pretty close to the top of the list (third most abundant element overall). Comets contain a lot of water ice. Aluminium is on of the three most common elements in the Earth's crust, but it's not nearly as common as hydrogen and oxygen in the universe at large.

Isp and Exhaust Velocity

[Baldrson]

Assuming a 2 to 3 Al to H2O molar ratio, it looks like the exhaust velocity is about 900 m/s so the Isp is about 90s.

If that's right, that sucks compared to normal mixtures.

Of course, if you're lifting off the moon or asteroids, it may be ok.  Mars?  Probably not.

Computing case 1
Fixed enthalpy-pressure equilibrium - adiabatic flame temperature

Propellant composition
Code  Name                                mol    Mass (g)  Composition
34    ALUMINUM (PURE CRYSTALINE)          2.0000 53.9631   1AL
976   WATER                               3.0000 54.0458   2H  1O
Density :  1.458 g/cm^3
3 different elements
AL H  O
Total mass:  108.008918 g
Enthalpy  : -7944.26 kJ/kg

24 possible gazeous species
8 possible condensed species

                       CHAMBER
Pressure (atm)   :     340.230
Temperature (K)  :    3166.569
H (kJ/kg)        :   -7944.256
U (kJ/kg)        :   -8685.762
G (kJ/kg)        :  -33443.801
S (kJ/(kg)(K)    :       8.053
M (g/mol)        :      35.507
(dLnV/dLnP)t     :    -1.00584
(dLnV/dLnT)p     :     1.13099
Cp (kJ/(kg)(K))  :     3.30500
Cv (kJ/(kg)(K))  :     3.00720
Cp/Cv            :     1.09903
Gamma            :     1.09264
Vson (m/s)       :   900.11114

Molar fractions

AL                   6.0290e-004
ALH                  9.2486e-004
ALH2                 2.8353e-005
ALH3                 2.1470e-005
ALO                  2.4478e-005
ALOH                 5.6133e-003
AL(OH)2              3.4527e-005
AL(OH)3              3.1024e-006
AL2                  1.4157e-006
AL2O                 1.3669e-003
AL2O2                1.1545e-005
H                    1.0276e-002
HALO                 2.7342e-006
HALO2                3.5370e-007
H2                   7.2954e-001
H2O                  7.8723e-003
O                    3.5048e-007
OH                   4.1466e-005
Condensed species
AL2O3(L)             2.4364e-001