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Post by newageofpower on Oct 7, 2017 14:23:40 GMT
Oh, okay. I thought someone might've modded it in already. If it's that good a fit, I'll see about doing it myself. I mean, CoADE currently doesn't model liquid vapor pressure, thus heavy metal coolants are likely to be strictly 'worse' to Molten Sodium; but I would like to see how a realistic reactor with extreme engineering would look like. Also, join us on the CoADE discord! |
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Post by apophys on Oct 7, 2017 16:14:43 GMT
Right now my harshest limit for a realistic reactor is thermocouple strength. It's really nasty to make a safety margin when what I really want to do is add a second stage of the thermocouple for a bigger temperature delta.
Niobium isn't a great fit. It's expensive, for one thing. Aluminum, silicon, or possibly zirconium would be better due to cost and density.
You can pressurize the working fluid somewhat to keep it liquid longer. 1 atm vapor pressure is at 2790 K for aluminum, 3537 K for silicon, 4678 K for zirconium.
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Post by newageofpower on Oct 7, 2017 16:33:57 GMT
Niobium has less than 0.1 atm pressure at 4400k, which requires far less structural reinforcement than a 1 atm pressure vessel - remember, it's best if your structural members don't melt at the heat of your reactor!
Zirconium is interesting for it's low density and low cost, but the jump from 10 kilopascal to 100 kpa is quite significant. Given one of the weaknesses of TaHfC is average mechanical strength, we may be forced to reduce operating temperature for a workable reactor.
Running a working fluid close to it's critical point is dubious; as their thermal properties change more and more the closer you get to criticality.
I really do want multistage thermocouples as well, single stage thermocouples have too much thermal stress.
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Post by apophys on Oct 7, 2017 19:45:45 GMT
newageofpowerI strongly suspect we won't be able to be mass-efficient and cost-efficient beyond the strength limits of amorphous carbon with our coolant, due to turbopump material. Considering that material weakens with temperature, ~3500 K is a reasonable point to expect to work the inner loop at, in which case even silicon is still fine. Your pressure in the loop is created more by the pump than by the vaporization of coolant. A few atmospheres is still easy to deal with by engineered reinforcement (structural fins, or simply thicker pipes). The critical temperature of aluminum is around 7963 K, so you're nowhere near for that being a problem.
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Post by newageofpower on Oct 7, 2017 19:56:36 GMT
apophysIndeed, I was overlooking pressure in the piping. I still think 4200K+ reactors can be made practical, even pre-Graphene, though, we are not purely reliant on amco; we can build ceramic pumping machinery.
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Post by evonix on Nov 20, 2017 1:46:48 GMT
I tryed out the 10MW reactor and found the outer turbopump needed the lithium replaced with polyethylene and it gives a bit less power by about a half MW but that can be fixed by increasing thermocouple length to 1.09mm. Do not mistake this for knowing what I'm doing, that was just a little bit of fiddling.
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Post by apophys on Dec 19, 2017 14:50:23 GMT
I tryed out the 10MW reactor and found the outer turbopump needed the lithium replaced with polyethylene and it gives a bit less power by about a half MW but that can be fixed by increasing thermocouple length to 1.09mm. Do not mistake this for knowing what I'm doing, that was just a little bit of fiddling. Replacing lithium with polyethylene does nothing other than increase the cost by 100 c. You must have changed something else too, but not mentioned it. Fiddling is good.  (Late response because I haven't been on the forum in a while; semester got pretty hectic.) |
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Post by David367th on Dec 19, 2017 14:53:57 GMT
I tryed out the 10MW reactor and found the outer turbopump needed the lithium replaced with polyethylene and it gives a bit less power by about a half MW but that can be fixed by increasing thermocouple length to 1.09mm. Do not mistake this for knowing what I'm doing, that was just a little bit of fiddling. Replacing lithium with polyethylene does nothing other than increase the cost by 100 c. You must have changed something else too, but not mentioned it. Fiddling is good. (Late response because I haven't been on the forum in a while; semester got pretty hectic.) He's back!!! \o/ |
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Post by jtyotjotjipaefvj on Dec 20, 2017 0:59:02 GMT
 rip I looked into it for 5 seconds and it looks like TaHfC got nerfed a bit in the temperature department, and the 8000% efficiency still hasn't been fixed. |
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Post by gedzilla on Dec 28, 2017 17:20:51 GMT
hey, do any of you guys have a good 20MW reactor in this new patch ?
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Prancer from mobile
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Post by Prancer from mobile on Dec 30, 2017 4:12:04 GMT
Just curious which propellant people recommend for NTRs? Why isn’t there a Decane NTR in this list?
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Post by bigbombr on Dec 30, 2017 8:29:09 GMT
Just curious which propellant people recommend for NTRs? Why isn’t there a Decane NTR in this list? Hydrogen deuteride gives the highest exhaust velocity, but it's low density means your propellant tanks will be massive. RP-1 has a much lower exhaust velocity, but is much denser (it behaves as dodecane). All hydrocarbons are in between these extremes, with longer chains being denser and shorter chains giving a higher exhaust velocity. I personally use methane for my NTR's. |
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Post by jtyotjotjipaefvj on Dec 30, 2017 10:05:40 GMT
Just curious which propellant people recommend for NTRs? Why isn’t there a Decane NTR in this list? Hydrogen deuteride gives the highest exhaust velocity, but it's low density means your propellant tanks will be massive. RP-1 has a much lower exhaust velocity, but is much denser (it behaves as dodecane). All hydrocarbons are in between these extremes, with longer chains being denser and shorter chains giving a higher exhaust velocity. I personally use methane for my NTR's. Their price for achieving a given dv level is something you should consider too. HD is by far the most expensive propellant, and the engines need to be larger as well. Methane is very cheap by comparison, and RP-1 a tiny bit cheaper than methane. Heavy water is so poor it is never the optimal choise, unless you need small size for some reason. My calculator doesn't have data for ethane or pentane, but they should be cheaper than any of apo's fuels while offering a bit higher acceleration levels. I'd also like to experiment with oxygen or CO2, they might be the best propellants if you need a low dv with high acceleration. H-Fl combustion engines tend to be the best choise if you need a fairly low dv, but they have less thrust with a similar engine size, meaning extreme acceleration levels are harder to achieve. |
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Post by apophys on Dec 31, 2017 1:35:48 GMT
hey, do any of you guys have a good 20MW reactor in this new patch ? The reactors listed should work in the current patch. For 20 MW, you'd want two 10 MW reactors. I'm not going to keep too many tiers for my standard reactors, because that would be too much effort to keep permanently updated. Case in point: I still haven't updated the broken resistojets, caused by the TaHfC nerf. Just curious which propellant people recommend for NTRs? Why isn’t there a Decane NTR in this list? RP-1 is nearly identical to decane. Methane is the usual recommended pick for NTRs, due to the exhaust velocity being the best after hydrogen & helium (which have very low density). Methane is also cheap. RP-1 is recommended when you want to armor your propellant tanks (instead of using drop tanks, for example), because RP-1 is fairly dense while not sacrificing too much exhaust velocity. RP-1 also gives the best thrust-to-weight ratio NTRs. Any of the hydrocarbons in between can be used when you want in-between properties, but the differences aren't really that significant (so I didn't bother adding NTRs for them). My calculator doesn't have data for ethane or pentane, but they should be cheaper than any of apo's fuels while offering a bit higher acceleration levels. I'd also like to experiment with oxygen or CO2, they might be the best propellants if you need a low dv with high acceleration. H-Fl combustion engines tend to be the best choise if you need a fairly low dv, but they have less thrust with a similar engine size, meaning extreme acceleration levels are harder to achieve. Methane is the cheapest hydrocarbon. If you need high acceleration at higher thrust than H-F is good for, you'll probably do best with RP-1. In fact, I have received reports from at least two people using my RP-1 NTRs that their ship killed its crew instantly upon accelerating forward.  Oxygen and CO2 are more or less just useful for realistically cheap propellants in MPD-only craft. The average mass of constituent atoms is too high for any reasonable NTR use. (I will probably add oxygen MPDs sometime.) |
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Post by Rocket Witch on Dec 31, 2017 3:47:49 GMT
Prancer More obscure stuff: - Pure deuterium falls between HD and methane on the cost/density/velocity scale. - Hydrogen peroxide is the densest practical NTR propellant, though it's a bit of a pain to tune an engine for dissociation, and a lot of a pain when your ship explodes because it's also a detonatable monopropellant.
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