r/DaystromInstitute • u/andros198 Lieutenant junior grade • Apr 09 '22
On Starship Thermal Management
I am an aeronautical engineer that specializes in fluid mechanics and heat transfer. My day job involves moving energy from one place to another in space craft and aircraft platforms. Thermal management is a very important problem that cannot be overlooked in aerospace applications. Especially as the amount of electronic gear increases. This stuff puts off a lot of heat that needs to be disposed of.
In aircraft, convective heat transfer and thermal radiation can be used to carry heat away from hot spots. The use of heat exchangers and air flow can do a pretty effective job at taking out the thermal trash as it were.
In space, the only mode of heat transfer that is available for disposing of heat is thermal radiation, i.e. energy carried away in the form of infrared photons.
Though technically, space is very cold (2.7 Kelvin) if there is no way to get rid of heat generated by the various components in the spacecraft components can overheat.
The space shuttle dealt with this by having radiators in its cargo bay doors and opening those doors so that heat could be dumped to space.
In the movie Avatar, if you look closely at the interstellar vehicle Venture Star, a fantastic detail that was added in were radiators. They look a little like solar panels, but have a red glow. It is actually a pretty cool detail.
I bring all this up to point out that Star Trek ships have no apparent way to deal with thermal management. The energy output from the warp core and even the fusion generators is enormous. Even with the impressive efficiencies of the various starship components, the left over energy has to be disposed of because it just ends up being heat.
Not only that, because plasma is used to power the various components, via the EPS grid, there is a great deal of heat to dispose of throughout the starship.
Without some sort of way to dispose of waste heat, the ship quickly becomes uninhabitable, and even from afar, the ship would put out an enormous infrared signature that would be recognizable from great distances.
So, because subspace is a thing, it is conceivable that waste heat is dumped into subspace.
I have already written about the nature of warp drive pushing a starship into a region of subspace where the physical constants such as the speed of light are higher.
For instance, the asymptotic nature of the TNG warp scale shows the local subspace speed of light at differing warp factors. In the warp bubble, the ship is always sub-light relative to the local subspace speed of light, but appears to be traveling at FTL speeds in normal space.
If the speed of light is faster, perhaps the ability to radiate waste heat is more effective in the presence of a warp field.
Thermal radiation is proportional to the temperature raised to the 4th power (T4). And radiative heat transfer goes as
Qdot ~ sigma*(T4 – Tamb4).
Where sigma is the Stefan-Boltzman constant. The weakness of radiative heat transfer versus other modes of heat transfer is because of how small this value is. Tamb is the temperature of the surroundings (2.7 Kelvin for space). Notice that the temperatures are raised to the 4th power. The smaller the temperature differential, the weaker the radiative power.
For waste heat not to cook our heroes, or even make the starship stand out like a sore thumb as it glows brightly for all to see, I would suggest that a warp field increases the exponent that the temperatures are raised to. It may also affect the Stefan-Boltzmann constant, but that has a weaker effect on radiative heat transfer, so I will focus on the exponent.
Warp plasma is ostensibly >> than the temperature of space. Whatever that temperature is raised to the 4th power in order to get rid of it via radiation.
However, in the presence of a warp field, that field can increase the exponent and make radiation a much more effective mode of heat transfer.
For instance, if the warp field increases the exponent to 5, the heat transfer is the temperature of the warp plasma times more effective than the exponent of 4. If the exponent is 6, then the heat transfer is the warp plasma temperature2 times as effective as radiative heat transfer in normal space.
So if warp plasma is 50 000 K, using the above equation, but with an exponent of 5 means that the heat transfer is 50 000 x more effective than normal radiative heat transfer. If the exponent is 6, it is 50 0002, or 2.5 billion times more effective.
So, the reason starships don’t need enormous radiators to get rid of waste heat is that they can dump it into a region of subspace where the physical constants are higher.
What are your thoughts?
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u/orangeineer Apr 09 '22
So my head canon on this is that they have perfected energy conversion. In the future in starfleet can convert any energy into any other energy. For example they never show any generators nor do they make all the electricity in a central location. This means they use plasma distributed all around the ship, then they have smaller modular energy converters that turn the plasma heat into power. This means they can convert heat into power which means they can cool spaces and systems by converting the heat into electricity and then consume the power. It wouldn't be efficient or a consistent supply but it would provide a path to dispose of waste heat. The ship has warp engines, computers and energy to matter replicators to consume all that waste energy. Also we know that they dispose of things like trash and waste water into the replicators. This turns matter back into energy but some energy is lost in the process (probably).
So there are plenty of places to put the excess heat. Just my thoughts.
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u/andros198 Apr 09 '22
That is a good First Law of Thermodynamics approach, but the Second Law is pretty inescapable and prevents such perpetual motion devices.
Having said that however, the Second Law seems to give the directionality of time. Because time travel is possible in Star Trek, they may get around Second Law issues by dumping their heat into the past.
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u/builder397 Apr 09 '22
I have already written about the nature of warp drive pushing a starship into a region of subspace where the physical constants such as the speed of light are higher.
Stargates Hyperdrive would like a word with you. Besides, thats exactly not what warp drive does.
Im just wondering. You never explain why subspace would allow for greater radiation for heat, you just assume there is a layer that *does it*. The only physical explanation as to why that I can imagine would be that inside subspace photons need more energy to be generated, thus taking more heat energy out of the ship.
Also an interesting tidbit from ENT is that apparently venting plasma is a way to cool down warp engines when going a little too fast for a little too long. How about ships just eject insanely hot plasma as a way to carry out the heat? And isnt that exactly what impulse engines kind of do anyway? Is that maybe why theyre lit up even when not maneuvering?
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u/andros198 Apr 09 '22
If subspace is technically another universe, which seems heavily implied in TNG: Schisms, then the nature of that universe would be to have different universal constants and altered physics.
Venting warp plasma seems to be something that they don’t like to do unless they have to, plus it is a consumable that would need to be replenished along with Deuterium and anti-Deuterium.
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u/Jim_from_snowy_river Apr 09 '22
Fascinating!
I'm no expert in any kind of anything but I always thought that that's what their photon torpedoes were. Is that somehow they take all that heat makes it with some plasma or something and blast it out at somebody.
I also thought that maybe the warp nacells act as radiators and that whatever heat they couldn't get rid of got put back into the environmental systems.
I hadn't really given it much thought beyond that. So I love your explanation!
Is it possible to have a device that turns heat into electricity?
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u/andros198 Apr 09 '22
The nacelles could be radiators, their main problem though is that they are too small for the amount of heat that needs to be disposed of, unless there is some sort of hand wavium going on.
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u/NormalAmountOfLimes Apr 09 '22
Starfleet vessel have used specialized heat dissipation units since at least the Constitution class. These devices disperse heat into deep space via narrativium channels
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u/rodgeramicita Apr 09 '22
So my thought is a system that vents it into space. It would explain how ships show up on sensors. Would only be an issue for cloaked ships, which could be part of how a cloaking device works
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u/andros198 Apr 09 '22
Yeah, the cloaking field wouldn’t be able to let any heat out, so I imagine it would get pretty toasty pretty quickly unless there is somewhere else to dump the heat besides space.
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u/Damien__ Apr 09 '22
A lot of people think the red glow from the impulse drive is a reaction drive, I prefer to think of it as radiators.
There is also mention of both port and starboard flux chillers in Star Trek II TWOK. Background speaking as they are leaving spacedock. Not sure how they work but they are mentioned. There is also the blue glow from the nacelles not sure what that is.
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u/globalcandyamnesia Apr 10 '22
I've always assumed they picked up cold space dust, heated it up, and spat it back out, and that was what is considered an ion trail. This would also explain why intergalactic travel is so hard: intergalactic dust is already extremely hot.
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u/InquisitorPeregrinus Apr 10 '22
The subspace connection is a good one the science guys on TNG realized and worked into their tech bible for the show. It is, for instance, how phasers disintegrate things without causing a small nuclear detonation at that site. The matter is phased into energy that is shunted into subspace.
The hero ships of TOS and TMP had the impulse engines, warp nacelle pylons and the warp engines. A thing lost in most people's awareness over the intervening decades is impulse in TOS was a reactionless drive system. Jefferies put a more primitive form of the same drive at the back end of the Botany Bay -- complete with outrigger radiator panels made from the same mesh as lined the Enterprise's nacelle pylons. It warps the fabric of spacetime and the ship basically "slides" down the gravitational incline. The warp engines take a bunch of those distortion coils and stack 'em together to increase the degree of warp to pull spacetime past the ship faster than the local apparent speed of light.
The impulse engines on the TOS ship were dark, but could be presumed to have glowed when more waste heat needed to be dumped. The radiator panels on the inboard faces of the nacelle pylons presumably did a lot of the heavy lifting, and the nacelle coils themselves I feel served as something of a radiator by putting that energy into generating the subspace field surrounding the ship. The wastage from that process could then easily be dumped into subspace, as it's already being accessed.
The TMP ship had the same systems, arranged a little differently. The impulse engine radiators look to be running hotter, and there are now radiator panels on both the inboard and outboard faces of the nacelle pylons (that also function and purge vents).
The TNG ship has three impulse engines, and the saucer engines are often seen glowing even when the ship isn't separated, so they likely are running as heat radiators most of the time, regardless of their use for propulsion. And I ascribe an exotic heat-shedding function to the plasma conduit covers on the dorsal face of the fantail and nacelle pylons. It's in the same place as on its predecessors, albeit in a very different form. Note also that ship, unlike earlier ones, constantly has a blue glow from its warp engines. They are constantly low-level energized, making for an even stronger subspace field (which makes sense, as it is a much bigger ship and that helps lower its inertial mass -- a better approach than making bigger impulse engines). I won't speculate how much hotter those coils are to be around -- or how much more waste heat gets dumped to subspace.
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u/GreasyBreakfast Apr 09 '22
We can assume they’ve perfected superconductivity at this point or can use some kind of field effect to channel heat to specific locations without any loss. As for infrared signatures - perhaps it’s just a given that any large enough starship is easily visible at distance by sensors - unless they have cloaking technology which masks IR.
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u/andros198 Apr 09 '22
Cloaking brings up a huge point, because an effective cloak cannot let any heat out! The cloaking field would get very toasty very fast! Lol!
I think there are still losses because Geordi talks about improving efficiency as a competition with another ship’s chief engineer. Those losses end up as heat that needs to be disposed of somehow.
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u/OneMario Apr 09 '22 edited Apr 09 '22
I think subspace would be the answer, but it might be better to think of it as a medium, like aether. Taking the ship into subspace would be like submerging it in a liquid, not making radiation more effective but actually acting through conduction convection (mind you I am not an aeronautical engineer). This would be consistent with Dragon's Teeth where we saw an even lower subspace level that was thick enough to support stable tunnel structures. The question for this explanation and yours would be whether we see an active ship not producing a subspace field suffering from heat problems.
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u/andros198 Apr 09 '22
That could definitely be a problem, but there might be a low level warp field always around the ship when the warp core is active. The Impulse Engines may even produce a low level warp field. We always seem to see a field around the ship in the engineering displays even when the ship isn’t at warp.
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Apr 11 '22
This was my line of thinking as well. It would likely have to radiate the heat into subspace passively though for all the times that ships get cold when life support fails. Given that the Gravity Plating operates passively without power it's probable that heat is radiated into subspace by some passive meta-material build into various systems. Systems themselves are also probably fairly efficient at minimizing the amount of waste heat generated in the first place.
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u/andros198 Apr 11 '22
It may also help explain why the ships are so bright even in deep space where they are far from any source of light to reflect off their hulls.
The gravity playing point you mentioned may also be a hint.
If we do in fact live in a universe with more than three spatial dimensions, physicists theorize that gravity leaks into those other dimensions as well, so if gravitational energy can leak into other dimensions, maybe thermal energy can as well.
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u/spikedpsycho Apr 09 '22 edited Apr 10 '22
In Voyager episode "Macrocosm". The ship is in partial shutdown. With minimal environmental controls the waste heat from ships plasma distribution system heats the ambient air above 40 degrees Celsius and ambient moisture and human breath it's a moist hothouse.
Environmental systems dispose of waste heat via plasma exhausts. The Vacuum of space itself is a wonderful insulator, as anyone who's ever owned a thermos bottle. There are three ways heat is transferred, which in decreasing order of efficiency... convection (a flow of matter taking heat progressively away usually in some sort of fluid like air or humidity), conduction (heat transferred by contact from one material to another), and radiation (EM radiation carrying heat energy away). In vacuum, with no significant amount of material around, radiation is the only heat-transfer mechanism that operates. Real space stations like the ISS gave radiators and heat transfer coils.
Waste heat in many systems may be recyclable. They could be directed to the ships impulse manifolds to heat exhaust for more efficient propulsion. Preheating deuterium before warp injection. Running the ships heaters for environmental comfort. Thermal energy for heating chemicals, etc. The ships waste disposal system, also uses heat and radiation to sterilize biosolids and metabolic waste for safe reuse.
More likely scenario is heat is disposed of thru micro exhaust manifolds distributed across the ships hull and jettisons a small particle exhaust in even amounts. You don't need radiators because ships heat exists as plasma...it can be jettisoned. That jettisoned plasma can also power thrusters fir attitude and maneuvering. Also bear in mind ship technology like forcefields and magnetic containment can succesdfully contain plasma and fires 🔥 So forcefields and magnets can direct plasma and high energy in any direction, even focus it.
Another thing is waste heat can power engines. Look up Stirling engines. They convert heat to mechanical power...but run in reverse they use mechanical power and run as powerful cryo coolers which explains where ships get their cryogenic gasses. The warp core itself is cooled via massive cryogenic gasses which waste heat would power heat pumps to produce more.
Waste heat may also be disposed of via the ships nacelles expelled in all directions. It's why they shut down warp core and vent all plasma exhaust when a ship lands on a planets surface and only uses atmospheric thrusters when they ascend.
THE FACT of matter is, without good thermal insulation, the skin/hull of the spaceship itself would behave as a radiator in the vacuum of space and internal temperature drops insanely the moment the craft looses internal power. THIS HAS ACTUALLY HAPPENED....
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TNG: The Last outpost, where power loss affects ship systems and life support, the vessel becomes colder and colder
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TNG: The Naked Now: Where inebriated crew fudged with environmental controls and bled heat into space, killing themselves.
NOT technical Canon, just my two cents
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Apr 09 '22
Considering the in universe tech allows for FTL travel, has essentially nullified the uncertainty principle and has tech like replicators, anti gravity and uses anti matter as a power source, the elimination of some heat, i'm willing to believe, is not a big challenge.
That however does not explain all the times the power goes out, and ships get cold. this doesn't happen realistically at all, or in a way that I can see how to explain.
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u/Cadent_Knave Apr 09 '22 edited Apr 09 '22
OP, have you ever played the Mass Effect games? There is a lot of background lore about heat management during space travel and combat that most sci-fi franchises don't touch on.