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Post by newageofpower on Dec 18, 2016 19:59:11 GMT
Okay this just occurred to me, but what the hell is cooling our radiators? Is there even any fluid inside them? Or are they quite actually pure thermal solid state radiators? The cutaway diagram of your radiators seem to indicate pipework on the inside of the radiator; working fluid (probably sodium/aluminum for high temperature reactor fanatics like us) is likely. EDIT: Annnd ninja'd
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Post by lawson on Dec 19, 2016 16:47:19 GMT
Because steam turbine required tons of water and....we can't carry all of the water? Uh... "Steam" turbines work with any liquid that can be boiled. In the case of our >3000K reactors, I'd guess that a 'nice' Aluminum liquid/vapor cycle would work well. More conventionally, Super-critical C02 is currently being considered as a better working fluid that H20 for coal and natural gas power plants. I suspect that steam turbines and gas turbine engines aren't included in the game because they're considerably more complex to design realistically than a giant, inefficient, effective thermocouple.
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Post by bigbombr on Dec 19, 2016 17:34:15 GMT
Because steam turbine required tons of water and....we can't carry all of the water? Uh... "Steam" turbines work with any liquid that can be boiled. In the case of our >3000K reactors, I'd guess that a 'nice' Aluminum liquid/vapor cycle would work well. More conventionally, Super-critical C02 is currently being considered as a better working fluid that H20 for coal and natural gas power plants. I suspect that steam turbines and gas turbine engines aren't included in the game because they're considerably more complex to design realistically than a giant, inefficient, effective thermocouple. They also require more maintenance, break down more often and generate considerable torque.
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Post by goduranus on Dec 19, 2016 18:07:30 GMT
I we had turbines, could they offer better power to weight ratio?
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Post by shurugal on Dec 19, 2016 18:26:43 GMT
Uh... "Steam" turbines work with any liquid that can be boiled. In the case of our >3000K reactors, I'd guess that a 'nice' Aluminum liquid/vapor cycle would work well. More conventionally, Super-critical C02 is currently being considered as a better working fluid that H20 for coal and natural gas power plants. I suspect that steam turbines and gas turbine engines aren't included in the game because they're considerably more complex to design realistically than a giant, inefficient, effective thermocouple. They also require more maintenance, break down more often and generate considerable torque. All of which are simply engineering problems. We already have turbines today that will run for months on end without needing repairs (hello, Navy), it is hardly a stretch to imagine that if we can grow monocrystal diamonds into impellers for turbopumps (see what i did there?), that we could also make turbine wheels the same way. Torque is a laughably easy problem to solve: two contra-rotating turbines of equal power. Slightly more complex (and compact) solution: one turbine with two counter-rotating wheels. I we had turbines, could they offer better power to weight ratio? by a huge margin, yes. Take the 25GW reactor we are already familiar with, who's thermocouple weighs most of a kiloton. A turbine handling the same power would only be a few hundred tons; lighter if we made it out of something exotic like pure diamond. Sure, we'd need another hundred tons of water (or a similar high-expansion high-heat-capacity medium), but so what? We'd still end up with a turbine that weighs half as much and, likely as not, makes more power from the same heat energy (since our gigantic thermocouples are so horrifyingly inefficient). if we take the heat energy remaining after passing through the turbine, the steam can be cooled on a much smaller and lighter thermocouple (less extreme temperature means less thermal expansion stress to force us to get huge), further adding to the efficiency gains.
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Post by newageofpower on Dec 19, 2016 18:36:00 GMT
Years, in the case of nuclear submarines. But I digress. Everything Shurugal said. Please implement turboelectric machinery; I suspect it will be more mass-efficient than thermocouples at powers greater than 100-200 MW.
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Post by argonbalt on Dec 19, 2016 19:26:58 GMT
This may have already been mentioned, but there is a good chance their shielding would be far lighter as well. Consider that most ground based nuclear reactors outputting into and beyond the GW range must have hundreds of tons of concrete(quite reasonably so) as a means towards preventing even the slightest of leaks. For our ships though as long as the radiation sphere is adequately shadowed towards our crew sections most if not all of that shielding is not needed.
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Post by goduranus on Dec 19, 2016 20:45:08 GMT
More like thousands of tons for a 25GW generator right? Since real world turbines that are hundred of tons only generate less than 1 Gigawatt. Also, lower end thermoelectric reactors in game are more mass-efficient, with the 2GW generator and its radiators only weighting in at about 60 tons, so 30 ton per GW.
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Post by shurugal on Dec 19, 2016 21:25:31 GMT
More like thousands of tons for a 25GW generator right? Since real world turbines that are hundred of tons only generate less than 1 Gigawatt. Also, lower end thermoelectric reactors in game are more mass-efficient, with the 2GW generator and its radiators only weighting in at about 60 tons, so 30 ton per GW. see "exotic materials"
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Post by newageofpower on Dec 19, 2016 21:55:34 GMT
Today's turboelectric machinery on Earth is usually stationary, and therefore not at all optimized for mass/volume. Also, lower end thermoelectric reactors in game are more mass-efficient, with the 2GW generator and its radiators only weighting in at about 60 tons, so 30 ton per GW. Are you a deliberate troll? The old 25 GW Apophys had a PWR of less than 15t/GW. The newest 30-35 GW reactors run almost 10t/GW.
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Post by Crazy Tom on Dec 19, 2016 22:40:32 GMT
Before people go crazy over turbo-electrics, I'm going to have to dampen their enthusiasm.
The issue with high temperature nuclear turbo-electrics comes down to material science and neutron embrittlement. Ironically, modern coal fired power-plants can be more thermodynamically efficient than nuclear plants because they can use a type of steel with higher melting temperature than what is possible in a nuclear plant - which must use a type of steel that has a lower melting temp but is less susceptible to neutron embrittlement over its lifetime. Even the Gen 4 Very High Temperature reactors only go up to ~1273K.
Now, this is for stationary power plants with extreme factors of safety and very long operational lifetimes, so there could be quite a bit of wiggle room there. Just don't get too hyped up.
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Post by shurugal on Dec 19, 2016 23:33:49 GMT
what is the susceptibility of diamond to neutron embrittlement, though?
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Post by Crazy Tom on Dec 19, 2016 23:55:19 GMT
what is the susceptibility of diamond to neutron embrittlement, though? You would have to ask someone with a better understanding of material science, I'm afraid. I can't do much more than speculate.
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Post by newageofpower on Dec 20, 2016 2:34:27 GMT
Before people go crazy over turbo-electrics, I'm going to have to dampen their enthusiasm. The issue with high temperature nuclear turbo-electrics comes down to material science and neutron embrittlement. Ironically, modern coal fired power-plants can be more thermodynamically efficient than nuclear plants because they can use a type of steel with higher melting temperature than what is possible in a nuclear plant - which must use a type of steel that has a lower melting temp but is less susceptible to neutron embrittlement over its lifetime. Even the Gen 4 Very High Temperature reactors only go up to ~1273K. Now, this is for stationary power plants with extreme factors of safety and very long operational lifetimes, so there could be quite a bit of wiggle room there. Just don't get too hyped up. To be honest, reactors make up maybe 10% of an warship's cost. Replacing reactors wholesale is expensive, but if it offers enough performance... Plus, I assumed CoADE reactors were remanufactured at the end of their service life anyhow. These designs (and even the stock designs) look like an absolute pain to perform maintenance and repairs on. Another solution is running the reactor at annealing temperatures; this reduces structural strength but reverses neutron swelling and Wigner energy buildup. Additionally, some reactor components may have very high annealing temperatures, requiring you to redesign entire sections of the reactor to use materials that do not melt (and preferably anneal) at normal temperatures. While expensive on Earth, in space we have Noble Metals that cost less than tool steel alloys...
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Post by n2maniac on Dec 20, 2016 7:02:45 GMT
I don't understand why we don't have steam turbines. Our ships are already huge and massive, why can't we have a 10-ton steam turbine that will be half the size and twice the efficiency of a 100-ton thermocouple? A Carnot engine with a hot side of 3000K and cold side of 2500K has an efficiency of 16.7%. Reactors we run ingame at those conditions come in at about 14.6%. They are so close to Carnot engines as is that another engine's efficiency gain wouldn't really matter (aside from maybe increasing the delta T). IIRC, turbines tend to get ~ 8 kW/kg power density on the high end IRL, whereas ingame total reactors (minus radiators) get about 40 kW/kg. Would still be interesting to try to make a turbine that beats them given we could probably stretch delta T to be much wider and ignore creep limitations of materials, but I would rather have a few other things first (eg. coilguns not exceeding 100% efficiency).
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