Jump to content

Kerosine in Nuclear Thermal Engines and ISRU

FreeThinker

By FreeThinker
in Science & Spaceflight

 Share

Recommended Posts

FreeThinker

FreeThinker

Posted
Posted (edited)

I'm looking for ways to use Kerosine in Nuclear Thermal Engines and in IRSU. I want to answer scientifically accurate so I can use the result in KSPI-E

I came up with several ways.

-NTR Cracking: the Kerosine would beput directly into an NTR at 3200K, where the molecules would break up into smaller molecules and Carbon. Not sure if this would work. but I could not find any literature about is. I need to know if this is at all possible, and what performance to expect.

-Preburning Kerosine with an Oxygen into CarbonMonoxide, CarbonDioxide and Water, which then get Heated to 3200K by the NTR Heat Exchanges. Would this work would it generate extra propulsion for the NTR (compaired to unheated CO, CO2, H2O mixture)

-Dehydrogenation (PDh) This process which is similar to Wat Gas Swift process, uses steam to convert the Kerosine and Oxygen onto CarbonMonoxide, CarbonDioxide and Hyrogen. The Question I need answered is, How much energy would it cost to Convert 1 Ton of resources (Kerosine + Water + Oxygen)

- Burning Kerosine with Oxygen, generating Heat with can be converted by a Thermal Electric Generator into Electricity which subsequent can be used by for electric magnetic propulsion of the Exhaust Gases. Now a Question I need answered is "How Much Heat does 1 Ton of Kerosine Produce when burned"?

Edited by FreeThinker
Link to comment
Share on other sites
Guest

Guest

Posted
Posted (edited)
-NTR Cracking: the Kerosine would beput directly into an NTR at 3200K, where the molecules would break up into smaller molecules and Carbon. Not sure if this would work. but I could not find any literature about is. I need to know if this is at all possible, and what performance to expect.
It probably is possible, and you'd likely get isps worse than, say, liquid ammonia. Not to mention that breaking down a hydrocarbon would likely foul the engine quite quickly, rendering it useless and possibly a hazard to the rest of the ship.
-Preburning Kerosine with an Oxygen into CarbonMonoxide, CarbonDioxide and Water, which then get Heated to 3200K by the NTR Heat Exchanges. Would this work would it generate extra propulsion for the NTR (compaired to unheated CO, CO2, H2O mixture)
Using water as reaction mass for an NTR has actually been studied (I think...), though I don't know where to find the data. The problem with pre-burning your kerosene is that you might as well just use it in a conventional engine because if it fouls those you don't have to worry about any potential nuclear side-effects.
-Dehydrogenation (PDh) This process which is similar to Wat Gas Swift process, uses steam to convert the Kerosine and Oxygen onto CarbonMonoxide, CarbonDioxide and Hyrogen. The Question I need answered is, How much energy would it cost to Convert 1 Ton of resources (Kerosine + Water + Oxygen)
No idea here.
- Burning Kerosine with Oxygen, generating Heat with can be converted by a Thermal Electric Generator into Electricity which subsequent can be used by for electric magnetic propulsion of the Exhaust Gases. Now a Question I need answered is "How Much Heat does 1 Ton of Kerosine Produce when burned"?
This might help. Edited by regex
Link to comment
Share on other sites
cryogen

cryogen

Posted
Posted

Here's some Isp's in the context of Mars ISRU for NTR. Wrote this comment in another thread:

I found out that Zubrin looked at NTR propellants other than hydrogen. His idea (1991) was to land an NTR on the surface of Mars, and use the NTR as an ascent rocket using Martian fuel (CO2). (NASA's modern concept is to bring a refrigerated zero-boil-off LH2 tank to Mars, and leave that in Mars orbit for the return trip. The surface ascent would be CH4/LOX, the CH4 from Martian ISRU).

Some of the theoretical Isp's Zubrin cites are (at 2800 K): 283 s for CO2, 370 s for H2O, and 606 s for CH4. (So in particular, CH4 can be much better than chemical LH2/LOX at 450 s, but still worse than hydrogen NTR at ~900 s).

Nuclear Rocket Using Indigenous Martian Fuel (Zubrin, 1991)

Mars Design Reference Architecture 5.0 (NASA, 2009)

Xi8s1Jk.png

Link to comment
Share on other sites
sgt_flyer

sgt_flyer

Posted
Posted (edited)

NTR, as a thermal engines, gets it efficiency from simply accelerating stuff thanks to thermal expansion :) and lighter atoms / molecules accelerate faster than heavier atoms / molecules. Since ISP scales directly from rocket exhaust velocity, you want light atoms :)

Though for sure, something might be at hand with N2 / CO to be so inneficient. (Bad thermal expansion compared to others ? - maybe their atomic bonds have more difficulties splitting at those temperatures)

Edited by sgt_flyer
Link to comment
Share on other sites
K^2

K^2

Posted
Posted
Though for sure, something might be at hand with N2 / CO to be so inneficient. (Bad thermal expansion compared to others ? - maybe their atomic bonds have more difficulties splitting at those temperatures)

CO2 and H2O thermalize very quickly between DoF. I suspect, CO and N2 don't thermalize well within the engine's bell, which leads to a lot of the heat lost in rotational and vibrational DoF. This is consistent with higher losses at higher temperatures, since vibrational modes are likely to be partially frozen out on the low end of temperature spectrum.

I'll crunch actual numbers a bit later to try and see what sort of ISP I'd expect with full and no thermalization.

Link to comment
Share on other sites
K^2

K^2

Posted
Posted
Kerosene produces heat? ...I don't think that's how it works...

I'm assuming he means combined with O2.

And I absolutely CANNOT reproduce numbers above. Here are my, "Givin' 'er all she's got, Cap'n," numbers.

	CO2	H20	CH4	CO	N2	Ar
1400K	157.322	259.194	325.018	173.915	173.903	95.3362
2800K	222.487	366.555	459.644	245.953	245.936	134.826
3000K	230.296	379.421	475.777	254.586	254.568	139.558
3200K	237.849	391.864	491.38	262.935	262.916	144.135
3500K	248.749	409.821	513.898	274.984	274.964	150.74

I can understand why some of these are a bit higher than the table. This is most optimistic. But I cannot see how ISP can possibly go above these, and some of the table entries are higher.

Link to comment
Share on other sites
Xannari Ferrows

Xannari Ferrows

Posted
Posted
I'm assuming he means combined with O2.

And I absolutely CANNOT reproduce numbers above. Here are my, "Givin' 'er all she's got, Cap'n," numbers.

    CO2    H20    CH4    CO    N2    Ar
1400K    157.322    259.194    325.018    173.915    173.903    95.3362
2800K    222.487    366.555    459.644    245.953    245.936    134.826
3000K    230.296    379.421    475.777    254.586    254.568    139.558
3200K    237.849    391.864    491.38    262.935    262.916    144.135
3500K    248.749    409.821    513.898    274.984    274.964    150.74

I can understand why some of these are a bit higher than the table. This is most optimistic. But I cannot see how ISP can possibly go above these, and some of the table entries are higher.

Mind if I take some of those numbers myself and do a few checks of my own? Any more thorough checks and I'll be here I'll day... Oh well, I have the time.

Link to comment
Share on other sites
K^2

K^2

Posted
Posted

Knock yourself out. Amount of thermal energy in 1 mole of gas is dRT/2, where d is maximum number of available degrees of freedom, and I've assumed all of it becomes kinetic energy for the above. Can't find where more energy could possibly be coming from.

Link to comment
Share on other sites
FreeThinker

FreeThinker

Posted
  • Author
Posted (edited)
It probably is possible, and you'd likely get isps worse than, say, liquid ammonia. Not to mention that breaking down a hydrocarbon would likely foul the engine quite quickly, rendering it useless and possibly a hazard to the rest of the ship.

Yes, I have already taken those consideration into account. It produces about 33% more Soot then Methane. The soot creates a layer on the heat exachanges cause it to be less efficient (less thrust) and causing engine overheating forcing lower throttle or the engine blows up. I gave it a base Isp multiplier of 21.888% Hydrogen (based on molecular mass of propane) and decomposition energy of 2/3 of Methane (due to lower Hydrogen percentage) resulting in 69.4% thrust improvement an effective Isp of 32% Hydrogen. It will therefore perform worse then all alther performance proellant but better then Water (which has about the same Isp but worst lower thrust).

Edited by FreeThinker
Link to comment
Share on other sites
FreeThinker

FreeThinker

Posted
  • Author
Posted
Wouldn't it be better for ISRU to use hydrogen? It's much more common...

The Problem is not everyone want to use Hydrogen and LiquidFuel is clearly not Hydrogen, so I'm trying to make it work as good as is realistically possible

Link to comment
Share on other sites
K^2

K^2

Posted
Posted

If you want to have best possible ISP with an NTR while still using liquid fuel that's more or less consistent with KSP, your best bet is Hydrazine. It will decompose into Nitrogen and Hydrogen in the chamber, producing quite decent ISP. In fact, you might get close to numbers used in KSP.

Link to comment
Share on other sites
FreeThinker

FreeThinker

Posted
  • Author
Posted (edited)
Where would you find kerosene to do ISRU in the first place?

If you're not doing ISRU, why use Kerosene....

I don't really see why one would bother with this?

Well, the Kerosine (LiquidFuel) would be produced by all the black magice devices that create LiquidFuel are taken with them from KSP launch site

Edited by FreeThinker
Link to comment
Share on other sites
Jovus

Jovus

Posted
Posted
I'm assuming he means combined with O2.

And I absolutely CANNOT reproduce numbers above. Here are my, "Givin' 'er all she's got, Cap'n," numbers.

    CO2    H20    CH4    CO    N2    Ar
1400K    157.322    259.194    325.018    173.915    173.903    95.3362
2800K    222.487    366.555    459.644    245.953    245.936    134.826
3000K    230.296    379.421    475.777    254.586    254.568    139.558
3200K    237.849    391.864    491.38    262.935    262.916    144.135
3500K    248.749    409.821    513.898    274.984    274.964    150.74

I can understand why some of these are a bit higher than the table. This is most optimistic. But I cannot see how ISP can possibly go above these, and some of the table entries are higher.

Zubrin says he's assuming infinite expansion/no nozzle losses, if that helps. (I know jack all about how to actually get theoretical Isp, sorry.) Interestingly, though, the numbers he cites in the text while pointing us to Figure 5 - the table in the paper - are lower (though in cases still higher than your calculations). For example, he says the Isp of CO2 at 2800K is 265s, where the table entry is clearly 283s.

Link to comment
Share on other sites
K^2

K^2

Posted
Posted (edited)
Zubrin says he's assuming infinite expansion/no nozzle losses, if that helps.

Sort of. It clarifies things, but I've basically assumed as much with numbers above. Infinite expansion allows total conversion of thermal energy into mechanical, which is where these numbers come from.

I would suspect that decomposition is a factor, but that won't explain Argon. That simply has the 3 degrees of freedom and that's that. It can't possilby have exhaust velocity above sqrt(3RT/M), and that gets me specific impulse of 95s at 1400K and no higher. There is absolutely no place for another 15s to come from.

Edit: Just making sure. Argon, first ionization energy: 1520.6 kJ/mol. 1400K won't even make a dent in that. So additional thrust from plasma is impossible here as well.

Edited by K^2
Link to comment
Share on other sites
FreeThinker

FreeThinker

Posted
  • Author
Posted
The Problem is not everyone want to use Hydrogen and LiquidFuel is clearly not Hydrogen, so I'm trying to make it work as good as is realistically possible

Yes I know, check out the Propellants table of supported KSPI propellants.

- - - Updated - - -

Edit: Just making sure. Argon, first ionization energy: 1520.6 kJ/mol. 1400K won't even make a dent in that. So additional thrust from plasma is impossible here as well.

Regarding Ionisation op propelants. I understand they have a big effect on the efficiency of electromagnetic Thrusters. Could you please very the efficiency of all propellants


ELECTRIC_PROPELLANT
{
    name = QVP
    guiName = Quantum Vacuum
    ispMultiplier = 2
    efficiency = 0.78
    type = 8
    effectName = electric_qvp
    PROPELLANT
    {
        name = VacuumPlasma
            ratio = 1
        DrawGauge = True
    }
}

ELECTRIC_PROPELLANT
{
    name = LqdHydrogen
    guiName = LqdHydrogen
    ispMultiplier = 1
    efficiency = 0.72
    type = 11
    effectName = electric_hydrogen
    PROPELLANT
    {
        name = LqdHydrogen
            ratio = 1
        DrawGauge = True
    }

}
ELECTRIC_PROPELLANT
{
    name = LiquidHydrogen
    guiName = LiquidHydrogen
    ispMultiplier = 1
    efficiency = 0.72
    type = 11
    effectName = electric_hydrogen
    PROPELLANT
    {
        name = LiquidHydrogen
            ratio = 1
        DrawGauge = True
    }

}
ELECTRIC_PROPELLANT
{
    name = LqdHelium
    guiName = LqdHelium
    ispMultiplier = 0.7
    efficiency = 0.72
    type = 11
    effectName = electric_argon
    PROPELLANT
    {
        name = LqdHelium
            ratio = 1
        DrawGauge = True
    }

}

ELECTRIC_PROPELLANT
{
    name = Lithium
    guiName = Lithium
    ispMultiplier = 0.577
    efficiency = 0.86
    type = 11
    effectName = electric_red
    PROPELLANT
    {
        name = Lithium
            ratio = 1
        DrawGauge = True
    }

}

ELECTRIC_PROPELLANT
{
    name = NeonGas
    guiName = NeonGas
    ispMultiplier = 0.447
    efficiency = 0.7
    type = 11
    effectName = electric_argon
    PROPELLANT
    {
        name = NeonGas
            ratio = 1
        DrawGauge = True
    }

}

ELECTRIC_PROPELLANT
{
    name = LqdMethane
    guiName = LqdMethane
    ispMultiplier = 0.354
    efficiency = 0.5
    type = 9
    effectName = electric_hydrogen
    PROPELLANT
    {
        name = LqdMethane
            ratio = 1
        DrawGauge = True
    }    
}

ELECTRIC_PROPELLANT
{
    name = LqdAmmonia
    guiName = LqdAmmonia
    ispMultiplier = 0.34
    thrustMultiplier = 1.832
    efficiency = 0.54
    type = 11
    effectName = electric_ammonia
    PROPELLANT
    {
        name = LqdAmmonia
            ratio = 1
        DrawGauge = True
    }

}

ELECTRIC_PROPELLANT
{
    name = LqdCO
    guiName = LqdCO
    ispMultiplier = 0.3273
    efficiency = 0.54
    type = 9
    effectName = electric_ammonia
    PROPELLANT
    {
        name = LqdCO
            ratio = 1
        DrawGauge = True
    }

}
ELECTRIC_PROPELLANT
{
    name = LqdNitrogen
    guiName = LqdNitrogen
    ispMultiplier = 0.2756
    efficiency = 0.78
    type = 11
    effectName = electric_ammonia
    PROPELLANT
    {
        name = LqdNitrogen
            ratio = 1
        DrawGauge = True
    }

}
ELECTRIC_PROPELLANT
{
    name = Hydrazine
    guiName = Hydrazine
    ispMultiplier = 0.25
    thrustMultiplier = 2.5
    efficiency = 0.54
    type = 11
    effectName = electric_argon
    PROPELLANT
    {
        name = Hydrazine
            ratio = 1
        DrawGauge = True
    }
}
ELECTRIC_PROPELLANT
{
    name = KryptonGas
    guiName = KryptonGas
    ispMultiplier = 0.236
    efficiency = 0.6
    type = 11
    effectName = electric_argon
    PROPELLANT
    {
        name = KryptonGas
            ratio = 1
        DrawGauge = True
    }

}

ELECTRIC_PROPELLANT
{
    name = Argon
    guiName = Argon
    ispMultiplier = 0.22222
    efficiency = 0.76
    type = 11
    effectName = electric_argon
    PROPELLANT
    {
        name = ArgonGas
            ratio = 1
        DrawGauge = True
    }

}

ELECTRIC_PROPELLANT
{
    name = LqdCO2
    guiName = LqdCO2
    ispMultiplier = 0.21987368
    efficiency = 0.82
    type = 9
    effectName = electric_ammonia
    PROPELLANT
    {
        name = LqdCO2
            ratio = 1
        DrawGauge = True
    }
}

ELECTRIC_PROPELLANT
{
    name = LiquidFuel
    guiName = LiquidFuel
    ispMultiplier = 0.21888
    efficiency = 0.5
    type = 9
    effectName = electric_hydrogen
    PROPELLANT
    {
        name = LiquidFuel
            ratio = 1
        DrawGauge = True
    }    
}

ELECTRIC_PROPELLANT
{
    name = Xenon
    guiName = Xenon
    ispMultiplier = 0.1234
    efficiency = 0.69
    type = 11
    effectName = electric_xenon
    PROPELLANT
    {
        name = XenonGas
            ratio = 1
        DrawGauge = True
    }

}

How to calculate the required energy required to ionize a propellant, and how to calculate the effect on efficiency?

Link to comment
Share on other sites
Bill Phil

Bill Phil

Posted
Posted
The Problem is not everyone want to use Hydrogen and LiquidFuel is clearly not Hydrogen, so I'm trying to make it work as good as is realistically possible

Well, Kerosene doesn't just show up in places. It would have to be synthesized. But in other plans, Methane is synthesized! you might say. Yes, but Methane has a single Carbon.

Kerosene on Earth is made from Oil...

Maybe it's Kerosene with a strange Oxodizer?

You can't base propellants off of Isp alone. ISP is very dependent on engine design as well. With RP-1 having engines ranging from about 290s to 340s.

Link to comment
Share on other sites
Guest

Guest

Posted
Posted (edited)
Kerosene on Earth is made from Oil...
You can also make it (or the chemical equivalent that is used for RP-1 calculations, I'm Not A Chemist But I Play One In The Real Fuels Thread, C12H26) via the Fischer-Tropsch process, but that typically uses coal. Either way, you need carbon monoxide and hydrogen. Edited by regex
Link to comment
Share on other sites
Bill Phil

Bill Phil

Posted
Posted
You can also make it (or the chemical equivalent that is used for RP-1 calculations, I'm Not A Chemist But I Play One In The Real Fuels Thread, C12H26) via the Fischer-Tropsch process, but that typically uses coal. Either way, you need carbon monoxide and hydrogen.

Well... as far as I know most kerosene is produced by refining oil.

Rocket grade kerosene comes from a specific type of oil, and it's not exactly very common..

Link to comment
Share on other sites
This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
 Share
Go to topic listing
×
×
  • Create New...