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Post by apophys on Nov 24, 2016 0:23:19 GMT
So, we just replace our sodium with aluminum. Or something like titanium or gold, which wouldn't boil in the first place.
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Post by lawson on Nov 24, 2016 8:01:36 GMT
So, we just replace our sodium with aluminum. Or something like titanium or gold, which wouldn't boil in the first place. I think molten Copper would work better. Melts below 2500K and it's boiling point at "standard pressure" is over 3200K. Low operating pressure is a GOOD thing for a light reactor that will get shot at... A few of the Floride salts may be good low pressure coolants as well. Or for a truly crazy design, liquid Uranium metal would work as a low pressure coolant at these temperatures. Though if you're using Uranium coolant, you might as well just build a liquid core reactor and circulate the liquid metal fuel between a critical zone, and a sub-critical thermocouple. If the thermocouple is built compact enough, it would go critical as well. A critical thermocouple leads to a compact and interesting design with Uranium fuel foils/liquid sandwiched between cylindrical thermocouple stacks and the whole mess repeated and nested together many times for efficient and compact heat transfer with the "cold side" coolant. Who wants pie?
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erik
New Member
Posts: 34
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Post by erik on Nov 24, 2016 8:15:35 GMT
I think molten Copper would work better. Melts below 2500K and it's boiling point at "standard pressure" is over 3200K. Low operating pressure is a GOOD thing for a light reactor that will get shot at... A few of the Floride salts may be good low pressure coolants as well. Or for a truly crazy design, liquid Uranium metal would work as a low pressure coolant at these temperatures. Though if you're using Uranium coolant, you might as well just build a liquid core reactor and circulate the liquid metal fuel between a critical zone, and a sub-critical thermocouple. If the thermocouple is built compact enough, it would go critical as well. A critical thermocouple leads to a compact and interesting design with Uranium fuel foils/liquid sandwiched between cylindrical thermocouple stacks and the whole mess repeated and nested together many times for efficient and compact heat transfer with the "cold side" coolant. Who wants pie? Who'd volunteer to ride anything powered by that? Also, you'd think that being able to safely shut down and power up systems cooled by liquid uranium must include interesting engineering solutions.
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Post by apophys on Nov 24, 2016 9:14:26 GMT
The main reason I look to aluminum first, among metals with high thermal conductivity and boiling point, is its low density. Coolant is already the heaviest component in a reactor. Having a good specific heat (for a metal) makes its low density not a problem for cooling capacity.
The pressure to keep aluminum liquid at ~2900K shouldn't be too high when it boils at 2743K and its critical temperature is way up at 6300K. Ingame reactors with output at 2400K have their sodium coolant at 2680K, so for those no pressure would even be needed.
Something else to possibly consider is liquid silicon.
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Post by coaxjack on Nov 24, 2016 19:48:27 GMT
Now that I think about it, how do you even idle or shut down a liquid core reactor? Wouldn't it just re solidify requiring a huge energy input to fire it up again?
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Post by concretedonkey on Nov 24, 2016 19:59:45 GMT
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Post by lawson on Nov 24, 2016 22:51:44 GMT
The main reason I look to aluminum first, among metals with high thermal conductivity and boiling point, is its low density. Coolant is already the heaviest component in a reactor. Having a good specific heat (for a metal) makes its low density not a problem for cooling capacity. The pressure to keep aluminum liquid at ~2900K shouldn't be too high when it boils at 2743K and its critical temperature is way up at 6300K. Ingame reactors with output at 2400K have their sodium coolant at 2680K, so for those no pressure would even be needed. Something else to possibly consider is liquid silicon. I think the excessive coolant weight is due to the simple thermocouple geometry CoaDE uses in it's reactors. The thermocouple acts like there is a single cylindrical stack and potentially thousands of cubic meters of coolant volume inside the single stack. A more compact design would nest many thermocouple stacks with only enough space between them to efficiently flow coolant. This would also work better with low thermal conductivity coolants due to shorter heat transfer paths. Good point with aluminum, probably need less than 10 atmospheres to keep it liquid. Regarding liquid core reactors and shutdown, mostly you wouldn't fully shut down the reactor just throttle it back to zero electrical output. Full shut down would still be possible, just only done in dry-dock or emergencies. It helps that even when sub-critical, the core is still generating significant heat due to fission products decaying.
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Post by n2maniac on Dec 3, 2016 8:42:03 GMT
Diamond being used near its melting point and not turning back into graphite.
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