Subs in Spaccccccccccce Query

[kerick]

The "excess heat port" is a great idea ... if you have atmosphere to spare.

An "excess heat port" works by passing a medium (usually liquid or air) over a radiating surface & then pumping that medium away from the volume being cooled. This doesn't work in space because it can't, there's no medium to heat & eject, unless you're pumping out your water or air.

Yeah but it looks cool if you light it up with red LEDs. (See what I did there?)

[jcf]

^^^^^^

[Old Wombat]

[sigh] Yes. 

[zenrat]

If you are in deep space light years from the nearest star then surely it is better to conserve energy rather than radiate it out into space?

Okay in principle. Now, a) how are you going to store it? and b) How are you going to utilise it?

FIIK mate.  How do they prevent nuclear subs radiating any heat?  They must have to have a heat signature identical to the surrounding water or they will be detectable, and they also have the same issue of excess heat inside.

[Weaver]

If you are in deep space light years from the nearest star then surely it is better to conserve energy rather than radiate it out into space?

Okay in principle. Now, a) how are you going to store it? and b) How are you going to utilise it?

FIIK mate.  How do they prevent nuclear subs radiating any heat?  They must have to have a heat signature identical to the surrounding water or they will be detectable, and they also have the same issue of excess heat inside.

They don't need to prevent nuclear subs from radiating heat, because they radiate/conduct it straight into the dense conducting medium surrounding them, i.e. water. That rapidly dissipates it (water has a huge heat capacity). A moving sub leaves the slighty warmed water behind it, and for a stationary sub, the warmed water rises away from it by convection, dispersing in the process. The water around and behind a sub is slightly warmer than it was before the vessel passed through it, but it's within the natural variation of the water anyway, so it's not much use as a tell-tale. It's a bit like trying to track an aircraft by it's effect on the breeze at ground level as it flies past at 10,000 ft.

In space, none of this works. The only thing you can do to get rid of heat is radiate it away, which is inefficient and lights you up like a searchlight in a coal cellar. The only way to keep the heat safely is to transfer it internally into some kind of medium (like a gas or liquid), or a heat-sink (like the hull or fuel tanks), and try to make it do some work while avoiding the problems it causes, and avoiding that work converting it straight back into heat again.

Also, you may be spending the majority of your time in deep space, far from stars, but you must have started out near a star and presumably you're going to end near one. This means you also have ot deal with the fact that a spacecraft in orbit around a planet like the Earth can experience outside temperatures ranging from +hundreds of degrees in direct sunlight to -hundreds of degrees in shade.

[zenrat]

Some kind of melting/refreezing cycle where the melting (of some exotic substance like Whiffium Hydride) removes energy from where the people are and the refreezing releases it into where the plants grow (which also convert CO2 into O2).  Maybe the refreezing process also releases energy in the form of light?

How does Iain M Banks address this issue?  Oh that's right, by ignoring it...

[PR19_Kit]

........ Whiffium Hydride)................

[scooter]

Some kind of melting/refreezing cycle where the melting (of some exotic substance like Whiffium Hydride) removes energy from where the people are and the refreezing releases it into where the plants grow (which also convert CO2 into O2).  Maybe the refreezing process also releases energy in the form of light?

How does Iain M Banks address this issue?  Oh that's right, by ignoring it...

H. Paul Honsinger, in his Man of War trilogy (which I highly recommend by the way), uses a liquid medium, heatsinks, and directional radiators.  All excess waste heat is whisked away to either the heat sinks (if they're operating in stealth mode), or the radiators (if they're not).  But the heatsinks are finite, especially when in combat or extended stealth mode.

[frank2056]

How does Iain M Banks address this issue?  Oh that's right, by ignoring it...

The Minds just send it to the Grid. Just like they do with all the wastes generated aboard a ship. Especially about a GSV with a billion critters flushing toilets and the like.

[Weaver]

How does Iain M Banks address this issue?  Oh that's right, by ignoring it...

In all fairness, that's how many other sci-fi writers and nearly all sci-fi TV/film scriptwriters deal with it too.

Arthur C. Clarke didn't ignore it, specifying that the Discovery in 2001 had large triangular radiators on it's spine. However he was overruled by Kubrick who insisted that the audience would think they were wings...

It was supposed to look something like this. The rear radiators are triangular so that they stay within the 'shadow' of the radiation shield protecting the rest of the ship from it's nuclear propulsion system:



Model by Warren Zoell here: https://thegreatcanadianmodelbuilderswebpage.blogspot.com/2011/09/discovery-dragonfly.html

[zenrat]

I wasn't singling out Banks for criticism.  He, as IMO the greatest of all sci fi authors, was serving as an example.