heating and cooling a starship?

[Birdog]

A starship in a vacuum is a closed system that is generating heat, you must remove that heat or the whole thing melts. The skin of a space craft is a very poor radiator. It's surface area is not large enough to transfer the heat into vacuum. Look as ISS it has massive radiators compared to it's size. You would not believe the surface area of a modern industrial radiator for just a 250 horsepower engine. Refrigeration plants need somewhere to transfer heat to or they don't work. Refrigeration plants are also a very crappy way to cool a power-plant due to the massive amount of power required to run them. That's why I design radiators the same way my company has been doing it for 80 years. Because it works.

 

[Trekker4747]

There's nothing in thermodynamics that precludes the capture and/or storage of heat in another vessel for use by another part of the ship's systems; it only becomes impossible in a closed system where you're trying to run the heat pump entirely off the waste heat being reclaimed, which requires greater than 100% efficiency. In this case, the heat pumps are being powered by the ship's fusion reactors, and enough of that thermal energy can be converted into other forms of energy that it no longer becomes necessary to radiate all of it.

But the fusion reactors themselves generate huge amounts of waste heat, so that would be a major part of the heat you're trying to convert. So it's basically the same situation. And even if you do recapture much of the heat energy, you're then going to use it for other processes that will themselves generate waste heat. You can add a few extra steps along the way, but ultimately you're still churning out waste heat and it all has to be radiated into space. A starship simply couldn't function without some kind of radiator surfaces. And the fact that most fictional starships don't have them is a mistake, plain and simple.

In trek ships just because we don't see heatsinks on the outside of the ship doesn't mean they're not there. Given all of the technology of Trek ships employ for all we know the entire hull of the ship is a heatsink on a microscopic scale.

 

[Crazy Eddie]

A starship in a vacuum is a closed system that is generating heat, you must remove that heat or the whole thing melts.

If you're generating enough heat from entropy alone to melt your entire space craft (which is thermodynamically impossible because of equilibrium conditions) then you're generating enough heat to run a heat exchanger steam generator to the tune of a few dozen megawatts of energy.

All you really need is a source of energy that doesn't depend on the reclaimed energy from the thermal loop to run the heat pumps and cooling apparatus. If the idea of simply controlling the heat distribution in the ship doesn't help you, consider that such a cooling system could also be driven by ordinary solar power, which--by definition--means the ship is no longer a closed system.

The skin of a space craft is a very poor radiator. It's surface area is not large enough to transfer the heat into vacuum.

That rather depends on the space craft and what it's made of. Some space craft are not even equipped with radiators and actually use some of their energy for HEATING.

Refrigeration plants need somewhere to transfer heat to or they don't work.

Did I.Q.s drop sharply while I was away? Did I not just finish explaining that the simplest explanation is to transfer all of that heat to a boiler system to generate steam for electrical turbines and/or hot water sources and internal heat for use by the crew?

That's simple energy reclamation. You only need to dump that heat overboard if you can't find a way to reuse it.

Refrigeration plants are also a very crappy way to cool a power-plant due to the massive amount of power required to run them.

As if power requirements would be an obstacle for a starship fueled by antimatter.

 

[Captain Robert April]

Yeah, I don't think a ship capable of destroying the habitable surface of a typical Class M planet would have a problem meeting the energy requirements of a good cooling system.

There's a point where you have to set the real science to one side and embrace Star Trek science (close relative to comic book science on many points) and just accept as fact that the Enterprise has a system of some sort capable of dissipating the heat generated by the various reactors, just as those teeny tiny engines in Tony Stark's boots are capable of launching him through the air, and Peter Parker can cling to walls because he was bitten by a radioactive spider.

If you must, credit the fine engineers at Yoyodyne-McGuffin Aerospace for devising a damn fine starship.

 

[Mytran]

You mean...it's science fiction?

 

[Good]

If you're generating enough heat from entropy alone to melt your entire space craft (which is thermodynamically impossible because of equilibrium conditions) then you're generating enough heat to run a heat exchanger steam generator to the tune of a few dozen megawatts of energy.

Yeah, but that's the problem with your theory. I have no doubt that starships get every last possible amount of use out of waste heat, but what do you do with those few dozen megawatts of energy? You run stuff with it. Stuff like Troi's curling iron, Washing machines for Wesley's sweater, Spock's plug in Vulcan fiery idol thingy. Each of these take that power and do something with it. That something always produces waste heat. Even refrigerators cheat by removing heat from one area and putting it into another (your kitchen) Entropy says you will always have more of that heat than you need, so you have to get rid of some of it.

Heat sinks, no matter how efficient, are just a way of putting off the problem. You have to radiate off the heat!

Now I have no problem with assuming, Like Capt. April, that trek science has come up with a way to easily do this. I assume that it's somehow tied to subspace. Radiate all that pesky heat off into another spacetime. Subspace! Good for what ails you!

 

[sojourner]

A starship in a vacuum is a closed system that is generating heat, you must remove that heat or the whole thing melts.

If you're generating enough heat from entropy alone to melt your entire space craft (which is thermodynamically impossible because of equilibrium conditions) then you're generating enough heat to run a heat exchanger steam generator to the tune of a few dozen megawatts of energy.

All you really need is a source of energy that doesn't depend on the reclaimed energy from the thermal loop to run the heat pumps and cooling apparatus. If the idea of simply controlling the heat distribution in the ship doesn't help you, consider that such a cooling system could also be driven by ordinary solar power, which--by definition--means the ship is no longer a closed system.

The skin of a space craft is a very poor radiator. It's surface area is not large enough to transfer the heat into vacuum.

That rather depends on the space craft and what it's made of. Some space craft are not even equipped with radiators and actually use some of their energy for HEATING.

Refrigeration plants need somewhere to transfer heat to or they don't work.

Did I.Q.s drop sharply while I was away? Did I not just finish explaining that the simplest explanation is to transfer all of that heat to a boiler system to generate steam for electrical turbines and/or hot water sources and internal heat for use by the crew?

That's simple energy reclamation. You only need to dump that heat overboard if you can't find a way to reuse it.

Refrigeration plants are also a very crappy way to cool a power-plant due to the massive amount of power required to run them.

As if power requirements would be an obstacle for a starship fueled by antimatter.

The big flaw in your argument is assuming you can use the surplus heat faster than you generate it.

Ever hear the joke about the two investors that get stuck on a desert island with only a dollar between them?

When they were found they were rich from investing in each other over 20 years.


Closed loops, depending on the situation, do one of 2 things. They either wither and die, or run amok and explode.

 

[Captain Robert April]

^ Quantum mechanics in a nutshell.

 

[sojourner]

^you sure? Sounds more like chaos theory.

 

[Crazy Eddie]

If you're generating enough heat from entropy alone to melt your entire space craft (which is thermodynamically impossible because of equilibrium conditions) then you're generating enough heat to run a heat exchanger steam generator to the tune of a few dozen megawatts of energy.

Yeah, but that's the problem with your theory. I have no doubt that starships get every last possible amount of use out of waste heat, but what do you do with those few dozen megawatts of energy? You run stuff with it. Stuff like Troi's curling iron, Washing machines for Wesley's sweater, Spock's plug in Vulcan fiery idol thingy. Each of these take that power and do something with it. That something always produces waste heat. Even refrigerators cheat by removing heat from one area and putting it into another (your kitchen) Entropy says you will always have more of that heat than you need, so you have to get rid of some of it.

But again, this only applies to a closed system where the only thing you can use is the heat already in the system. "Entropy" is, by definition, useless heat that you do not have enough energy to reclaim (because moving that heat around requires a certain amount of energy too). Starships have fuel supplies which they get from somewhere else. This means they are OPEN systems, and entropy is no longer a problem.

Back to the water tower analogy: you don't need to dump the water into the sewer, you just need your pumps to send the leaking water back into the tower at least as fast as it leaks out again. Sometimes you might want more water in the building, sometimes less, but you can control the amount of leaking water in your apartment just by adjusting the pump speed and making sure they have enough energy to function.

Heat sinks, no matter how efficient, are just a way of putting off the problem. You have to radiate off the heat!

Only in a totally closed system. Sooner or later, though, you would run out of even useable heat and you would have to open the system anyway to get more energy. If the system is already open, this is not a problem.

Closed loops, depending on the situation, do one of 2 things. They either wither and die, or run amok and explode.

Which, again, is why it's a good thing starships are not closed loops. The bigger flaw in your objection is that 1) starships have to make use of a fuel supply they apparently collect from the ramscoops or other means and 2) no matter how slow heat radiation from the skin is, NO starship hull is a perfect insulator and it will radiate some excess heat whether you want it to or not.

 

[Captain Robert April]

^you sure? Sounds more like chaos theory.

Same thing, from my perspective.

 

[sojourner]

If you're generating enough heat from entropy alone to melt your entire space craft (which is thermodynamically impossible because of equilibrium conditions) then you're generating enough heat to run a heat exchanger steam generator to the tune of a few dozen megawatts of energy.

Yeah, but that's the problem with your theory. I have no doubt that starships get every last possible amount of use out of waste heat, but what do you do with those few dozen megawatts of energy? You run stuff with it. Stuff like Troi's curling iron, Washing machines for Wesley's sweater, Spock's plug in Vulcan fiery idol thingy. Each of these take that power and do something with it. That something always produces waste heat. Even refrigerators cheat by removing heat from one area and putting it into another (your kitchen) Entropy says you will always have more of that heat than you need, so you have to get rid of some of it.

But again, this only applies to a closed system where the only thing you can use is the heat already in the system. "Entropy" is, by definition, useless heat that you do not have enough energy to reclaim (because moving that heat around requires a certain amount of energy too). Starships have fuel supplies which they get from somewhere else. This means they are OPEN systems, and entropy is no longer a problem.

Back to the water tower analogy: you don't need to dump the water into the sewer, you just need your pumps to send the leaking water back into the tower at least as fast as it leaks out again. Sometimes you might want more water in the building, sometimes less, but you can control the amount of leaking water in your apartment just by adjusting the pump speed and making sure they have enough energy to function.

Heat sinks, no matter how efficient, are just a way of putting off the problem. You have to radiate off the heat!

Only in a totally closed system. Sooner or later, though, you would run out of even useable heat and you would have to open the system anyway to get more energy. If the system is already open, this is not a problem.

Closed loops, depending on the situation, do one of 2 things. They either wither and die, or run amok and explode.

Which, again, is why it's a good thing starships are not closed loops. The bigger flaw in your objection is that 1) starships have to make use of a fuel supply they apparently collect from the ramscoops or other means and 2) no matter how slow heat radiation from the skin is, NO starship hull is a perfect insulator and it will radiate some excess heat whether you want it to or not.

It doesn't radiate enough. Ref: space shuttle and ISS radiators. If it doesn't work for NASA I doubt it will work for you.

Energy generation from heat only works if you have a temperature difference somewhere in the system. With a ship in a vacuum you very quickly end up with the entire ship being heat soaked. A refrigeration system on board is going to introduce more heat to the ship than cold it generates. If you want to generate energy from waste heat you need big honking radiators to create a heat imbalance.

Trying to think of a good example... A pot of hot water in a vacuum? (our ship) yes, it will cool slowly by radiating the heat away, but essentially everything in the vessel is the same temp. How do you get rid of the waste heat if you have say a chemical heating pack(our onboard equipment/people) in the water? The temperature would start to rise without radiators to help dissipate the heat.

 

[Mytran]

Couldn't the heat be channelled into the engines? We know that "you can't mix matter and antimatter cold", so the energy to do that has to come from somewhere.

 

[Captain Robert April]

Maybe the warp field itself could serve to suck away the heat from the ship (sort of the aforementioned "dump the heat in subspace" solution)?

 

[Anticitizen]

A very good article on this topic:

http://www.projectrho.com/rocket/rocket3au.html

 

[Good]

A very good article on this topic:

http://www.projectrho.com/rocket/rocket3au.html

Gotta love Atomic Rocket! That pretty much says what I was trying to say, but in a more sciency way.

 

[Crazy Eddie]

It doesn't radiate enough. Ref: space shuttle and ISS radiators. If it doesn't work for NASA I doubt it will work for you.

Neither the space shuttle nor the ISS have a multi-gigawatt fusion reactor on board capable of powering an advanced cooling system. Actually, both have power budgets in the tens of kilowatts, which makes such a system totally impractical.

Energy generation from heat only works if you have a temperature difference somewhere in the system.

Exactly. And in any working power system, the difference can be maintained simply by keeping the high side considerably warmer than the cool side. All that is required is a way of actively re-concentrating waste heat back into the heat sinks instead of letting it bleed out into the ship's environment unchecked. For that you need a power source that doesn't depend on the thermal loop for energy, i.e. the ship's fusion reactors and/or warp core.

A refrigeration system on board is going to introduce more heat to the ship than cold it generates.

Only if you're stupid enough to put the system's radiators inside the ship's environments. Leaving them in an isolated heat sink solves that problem entirely.

If you want to generate energy from waste heat you need big honking radiators to create a heat imbalance.

Or a power source capable of running the heat pumps independent of the thermal loop.

Trying to think of a good example... A pot of hot water in a vacuum? (our ship) yes, it will cool slowly by radiating the heat away, but essentially everything in the vessel is the same temp.

Bad example, since the ENTIRE pot of water has the same temperature and possesses no mechanism for concentrating some of that heat from one part of it to another.

How do you get rid of the waste heat if you have say a chemical heating pack(our onboard equipment/people) in the water? The temperature would start to rise without radiators to help dissipate the heat.

Simple: you concentrate all of that heat to one corner of the pot and keep it there until you need it. Concentrating all of that heat requires a source of energy from outside the system which a starship--unlike a pot of water--has.

 

[sojourner]

Everything you have just stated describes a closed loop feeding back on itself.

Neither the space shuttle nor the ISS have a multi-gigawatt fusion reactor on board capable of powering an advanced cooling system. Actually, both have power budgets in the tens of kilowatts, which makes such a system totally impractical.

A bigger generate just means more heat. which means you need a bigger generator which means more heat ad infinitum...

Exactly. And in any working power system, the difference can be maintained simply by keeping the high side considerably warmer than the cool side. All that is required is a way of actively re-concentrating waste heat back into the heat sinks instead of letting it bleed out into the ship's environment unchecked. For that you need a power source that doesn't depend on the thermal loop for energy, i.e. the ship's fusion reactors and/or warp core.

again, your power soruce is going to be adding to the heat you have to disipate.

Only if you're stupid enough to put the system's radiators inside the ship's environments. Leaving them in an isolated heat sink solves that problem entirely.

OK, I am beginning to see the disconnect here. What is your definition of a heat sink?

Or a power source capable of running the heat pumps independent of the thermal loop.

again, the bigger power source is going to generate even more heat.

Bad example, since the ENTIRE pot of water has the same temperature and possesses no mechanism for concentrating some of that heat from one part of it to another.

yea, not a great example, but I was hoping you would understand that the entire pot is like the entire ship. You may be able to make variations in temperature in parts, but over all your temperature will increase do to the vacuum isolation.

Simple: you concentrate all of that heat to one corner of the pot and keep it there until you need it.

Here in lies the problem. You will collect more than you need. eventually something is going to melt.

Concentrating all of that heat requires a source of energy from outside the system which a starship--unlike a pot of water--has.

how are the ship's power generators "outside" the system of the ship? They are attached, they generate heat, they conduct that heat to the rest of the ship.

 

[Anticitizen]

I imagine our favorite fictional ships convert heat into reverse-anti-left-handed tharyon particles or something that get handwaved away into space.

 

[JarodRussell]

^Replication is not turning energy into matter. It's rearranging the particles within a stored matter supply.

Besides, you can't game the laws of thermodynamics like that. Every process loses energy in the form of waste heat. You can capture and repurpose some of the heat, but not all of it. And any machinery you use to try to reprocess heat is going to produce its own waste heat. You can't beat entropy in the long run. No matter how magically advanced your tech is, you're still gonna have waste heat.

And I thought the amount of heat their engines and machines produce is never exceeding the temperature of plot.