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Post by amimai on Nov 23, 2016 1:50:16 GMT
Since the reactor can't run above 3200K hot side, the thermocouple's best efficiency is at 500K dT, and the mathematical optimum radiator temperature suggests ~2400K, I would expect going above 2700K will only increase radiator area for a given electrical power output. Do you observe differently? I observe different, the problem with that calculation is that it assumes no radiator loss will occur in combat... As I said, 2400 is great for a civilian boat. No need to carry a spare set of radiators in case one pair is shot to pieces, and you can ignore armour, that's fine too. Now on a military boat? Well I don't know about your boats but most of my ships cross section is radiators, they are also the firsts thing to fall off. You will loose sets of radiators left and right in battle, you need to carry spares, lots of spares, if that ship needs to get in close I want at least 4 redundant sets in case they get blown off. It does not matter if the reactor itself is 10x as heavy, as long as you save the difference in radiators. Since (combat) radiators are easily 50x the mass of the reactor, a tiny gain in radiator efficiency equals massive savings in total mass. here is the original bit of science I did on it: OK I made a range of reactors for 2500-2800k, they are by no means the "most efficient" but they are close enough to be serviceable i.imgur.com/JG17Og2.png?2i.imgur.com/my9LgyI.png?1i.imgur.com/iviQqz7.png?1i.imgur.com/o1Nvd6W.png?1I did the math on them for combined radiator+reactor mass/kW, looks like once you pass 2600K you really start taking hits to mass efficiency because reactors start getting less efficient and simply bigger due to pump size. Although this will be heavily offset of you are using armoured radiators, if you are using x3 or x4 mass in armoured radiators going up to even 2800 could be doable. When I tried it 2600 came out marginally ahead but if you use even more redundancy 2800 or higher temperatures may become viable using no redundant radiators, 2cm armour temp : kg/MW 2800K : 461 2700K : 321 2600K : 268 2500K : 256 using quad redundant 2cm armour radiators, 8cm armour 2800K : 4048 2700K : 4294 2600K : 3703 2500K : 3761 |
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Post by Easy on Nov 23, 2016 2:23:51 GMT
I observe different, the problem with that calculation is that it assumes no radiator loss will occur in combat... As I said, 2400 is great for a civilian boat. No need to carry a spare set of radiators in case one pair is shot to pieces, and you can ignore armour, that's fine too. Now on a military boat? Well I don't know about your boats but most of my ships cross section is radiators, they are also the firsts thing to fall off. You will loose sets of radiators left and right in battle, you need to carry spares, lots of spares, if that ship needs to get in close I want at least 4 redundant sets in case they get blown off. Do people not put radiators on the far side of the ship? I run very little redundancy on capships. More point defense seems to be lighter and less expensive than more radiators. |
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Post by n2maniac on Nov 23, 2016 3:08:30 GMT
Are you claiming that, for a given electrical power, you can decrease radiator area going from 2700K to 2800K? My math on your designs (plus a few quick ones at 2900K and 2400K) indicates the 2600K design would minimize radiator area.
Radiator Temp (K)
Relative radiator area per thermal output
Reactor efficiency (electrical per thermal)
Comparative radiator area (area per electrical)
Relative radiator area (area per electrical)
2900 75% ~4% 1878% 185%
2800 86% 7.09% 1219% 120%
2700 100% 9.83% 1017% 100%
2600 116% 13.10% 888% 87%
2500 136% 14.60% 932% 92%
2400 160% ~15% 1068% 105%
If you multiply this area for redundancy you still want to minimize radiator area as long as that remains a pain point. This implies 2600K is near optimal, maybe 2550K.
Am I still missing something?
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Post by amimai on Nov 23, 2016 13:05:07 GMT
hmm good point, I did a bit more tweaking and experimenting and that about matches what I got out in designs even after i optimised reactors to eek out every last ounce of power/heat
didn't really factor in the amount waste heat increases with thermocouple temperature over 2600K
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Post by newageofpower on Nov 26, 2016 0:41:44 GMT
i did some experimentation on this a while back using a spread of reactors 2500-2800 outlet temperatures, here is a quick and dirty summary of it: (I use diamond radiators because of structural strength and cheapness to armour efficiently) <2400: civilian boat territory, only way this thing will work is with radiators that have 100nm armour and are big enough to be used as solar sails 2500 : efficient for civilian ship with armoured radiators(2cm) with 1 redundancy - this thing might win vs a pure laser boat if its lucky 2600 : best for medium combat ships with 2-4 set of redundant radiators with medium armour(<8cm) - can survive a light peppering of kinetic ammo 2700 : an in between reactor use as and when 2800+ : best for mele brawlers with 5+ sets of redundant and heavy armour on radiators (>8cm) - bring on the rain for I fear no railgun! I should probably test if its possible to make a 3000k outlet radiators but when I tried efficiency drops were harsh My U235 Reactors melt down above 2400K output temperature. Even my U233 reactors can't go above 2500K radiator temp. |
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Post by apophys on Nov 26, 2016 2:36:09 GMT
Your inner coolant loop must be anemic then. It is certainly possible to make reactors with output temperatures above 2500K (although mass and cost of the reactor begin to balloon greatly, so I disagree that it's worth doing).
Whether you use U-235 dioxide or U-233 dioxide has no inherent bearing on meltdown temperature. You just need to use more U-233 dioxide to get the same heat generation in the core (worth it, because of cost).
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Post by n2maniac on Nov 26, 2016 9:26:52 GMT
My U235 Reactors melt down above 2400K output temperature. Even my U233 reactors can't go above 2500K radiator temp. I have had to dump around 10% or more of the output electricity into the inner loop with sodium coolant. Example: |
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Post by newageofpower on Nov 26, 2016 19:47:31 GMT
Your inner coolant loop must be anemic then. It is certainly possible to make reactors with output temperatures above 2500K (although mass and cost of the reactor begin to balloon greatly, so I disagree that it's worth doing). Whether you use U-235 dioxide or U-233 dioxide has no inherent bearing on meltdown temperature. You just need to use more U-233 dioxide to get the same heat generation in the core (worth it, because of cost). Huh. I took a look and realized this is exactly what I've been doing with my better designs. These are my scratch-built designs; I felt exceptionally proud of the N-type... then I took a look at a 100MW reactor floating around on Steam forums which had a far superior mass/power ratio ;_; Currently trying to optimize a ~11.2 GW/2500K output temperature reactor for minimal radius while retaining 13m or less radius and 14% or better efficiency. |
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Post by n2maniac on Nov 26, 2016 20:10:14 GMT
Currently trying to optimize a ~11.2 GW/2500K output temperature reactor for minimal radius while retaining 13m or less radius and 14% or better efficiency. Best of luck on that. Output power scales with the thermocouple area, which is the cylinder wall. Might be better to reduce its radius and just pack more reactors into the vessel in question, which sounds like it will be more radiator than vessel. FYI: there is a bit of a tradeoff between pump power and mass, and in that regime you might be better off making the pump slightly larger. Only 5-10% electrical power output increase available, though, so optimize intelligently. |
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Post by newageofpower on Nov 26, 2016 20:24:18 GMT
Currently trying to optimize a ~11.2 GW/2500K output temperature reactor for minimal radius while retaining 13m or less radius and 14% or better efficiency. Best of luck on that. Output power scales with the thermocouple area, which is the cylinder wall. Might be better to reduce its radius and just pack more reactors into the vessel in question, which sounds like it will be more radiator than vessel. FYI: there is a bit of a tradeoff between pump power and mass, and in that regime you might be better off making the pump slightly larger. Only 5-10% electrical power output increase available, though, so optimize intelligently. Using the ludicrously overtuned 100MW design means I have to add an unholy amount of crew, something I don't want ;( |
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Post by n2maniac on Nov 26, 2016 20:47:29 GMT
Best of luck on that. Output power scales with the thermocouple area, which is the cylinder wall. Might be better to reduce its radius and just pack more reactors into the vessel in question, which sounds like it will be more radiator than vessel. FYI: there is a bit of a tradeoff between pump power and mass, and in that regime you might be better off making the pump slightly larger. Only 5-10% electrical power output increase available, though, so optimize intelligently. Using the ludicrously overtuned 100MW design means I have to add an unholy amount of crew, something I don't want ;( I would probably suggest 1-5GW range, but that is up to you. Crew members are heavy. |
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Post by apophys on Nov 26, 2016 23:31:02 GMT
These are my scratch-built designs; I felt exceptionally proud of the N-type... then I took a look at a 100MW reactor floating around on Steam forums which had a far superior mass/power ratio ;_; Currently trying to optimize a ~11.2 GW/2500K output temperature reactor for minimal radius while retaining 13m or less radius and 14% or better efficiency. Those are excellent reactors. I've been fiddling with 2400K temperatures recently, and that is roughly the same mass/power ratio I'm getting (like with my 25GW reactor I posted a few days ago). Where is this 100MW reactor you speak of? I want to see it. Because I suspect its outlet temperature is quite a bit lower than 2400K. My 10GW @2500k weighs 152t and costs 5.29Mc (it's in the reactor thread and standards thread). The radius happens to be exactly 13m.  |
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Post by newageofpower on Nov 28, 2016 4:34:18 GMT
Using the ludicrously overtuned 100MW design means I have to add an unholy amount of crew, something I don't want ;( I would probably suggest 1-5GW range, but that is up to you. Crew members are heavy. If you can find an amazing 5 GW reactor (would have to be under like, 6M radius/13m diameter though, to squeeze 3 into a 26m box) that would be awesome. EDIT: Nevermind. I worked it out. |
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