Imagine a space station orbiting a star.
The station is not orbiting a planet.
The station has cylinder shape and is orienting its side to the sunlight.
The station is rotating just like any O'Neil Cylinder
It is filled with water. Assume salt water, just like Earth seas.
Near the central rod there are radiators. Likewise in the inner part of the structure there are radiators.
The wanted result is to have:
- general cooler temperature near the bottom (around 4°C the maximumm density of water)
- water in proximity of the outer structure is going to be warmed by sunlight
- outer structure is going to be cooled by the water
- warmer water (less dense) is going to go 'up ward'
- as the warmer water reaches the central rod area it gets in contact with radiators that absorb the heat and cool the water down
- the cooled water sinks again, closing the cycle
Design aim: Would convection cycles actually happen?
In other words what conditions should be adjusted to have convection?
What we want to achieve is an environment which will not develop extreme conditions (too cold / too hot).
Plus: Is the cycle in the drawing in the correct direction?
Note that my drawing is just to give a clarification of the question. To my understanding there are going to be many convection cycles of different sizes as the outer structure (and especially its radiators) is bound to have different temperatures in different places with H being the likely hottest and C the likely coolest.
- The star and orbiting distance can be planned to have the ideal amount for sunlight. But the station is not meant to change orbit. Just keep it stable.
- rotation speed should ensure some artificial gravity. But it is not necessary to reach 1g. Just in the 0.7 - 1 range (by the way fishes don't do so well in space).
Rotation speed and section radius can be adjusted to achieve the wanted result. Assume a minimum radius of 400 meters.
- outside structure can be engineered in order to have a variable amount of insulation / conduction. It would be possible to increase insulation on the shadow side and increase conduction on the sunlit side for instance. Still the sunlit side is going to be warmer until it rotates to shadows.
- heat at the central rod can be used for energy production though the station has other main power generators far more powerful
- the whole habitat should be able to sustain itself with minimal additional energy input (for instance to control the radiators and their flow).
- the structure was built with very advanced technology (imagine the feat of just bringing all the necessary materials in orbit, some of it from another star system far far away...) but is running on tech not so much more advanced than our own, e.g. nuclear fusion for main power. Consider current known physics for running operations. No magic alien tricks.
- keep the maximum size of the station within reasonable limit for narrative reasons. Let's say max length: 100km, max radius 2km. Min length: 2km, min radius 400 meters. But I don't think it matters and am not looking for the exact numbers.
Additional clarification: what you see in the drawing is just a section of the station where the water is. There are other compartments along the cylinder with the necessary equipment to run the station. For instance Fusion reactors.