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  • Users: wbogen
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  1. wbogen

    Heat transfer between warm air and cold water

    The sides will be 3/4 covered with PV solar panels (and 1/4 with fixed mirros bringing in sunlight to illuminate the interior). The PV panels (if using current PV technology) will convert sunlight at about 12% efficiency to electricity (3.4 GW) for use in the city. The rest of the energy...
  2. wbogen

    Heat transfer between warm air and cold water

    So if a raindrop forms 1000m 'up' (halfway between axis and floor), it will have a tangential velocity of 70 m/sec (r=1000m, w=0.07 radians/sec rotation, velocity=wr). Since it is now much denser than the air around it, it will plow in a somewhat straight line toward the floor. As it gets...
  3. wbogen

    Heat transfer between warm air and cold water

    To LostHippie: Yes, I thought that fog and water might accumulate near the axis at the endcaps. I suppose it would be best _not_ to have heatpipes too close to that area or that water may freeze into tons of ice that, if perturbed somehow, may 'calve' and come crashing down, slowly but...
  4. wbogen

    Heat transfer between warm air and cold water

    To Xera: Oops, miscalculated: Hyperion 'Lake' would actually cover the US about 1800 meters deep.
  5. wbogen

    Heat transfer between warm air and cold water

    To LostHippie (man, I should have thought of a cool handle): Yes, assuming 14.7 psi at the floor, I get 13.1 psi at the axis or a drop of 1.6 psi. So I get an adiabatic cooling effect of 32 degrees C non-condensing. So if the RH at the floor (or 'ground') is more than 32%, and some of that air...
  6. wbogen

    Heat transfer between warm air and cold water

    ivymike, I'd be happy to get the 'dry' solution but I'm not sure how to find that in a textbook, especially since some weird version of variable gravity convection will be necessary to bring more warm air against the cold wall. At the endcaps, a little distance from the axis, the 'gravity'...
  7. wbogen

    Heat transfer between warm air and cold water

    The plane that the city/cylinder rotates in is the same as its orbital plane so the ends face darkness constantly and the sides of the cylinder (underside of the 'floor') receive sunlight, some used as power by PV panels, about 1/4th of it conveyed inside to illuminate the interior. So the...
  8. wbogen

    Heat transfer between warm air and cold water

    "A large _spinning_ space city". Turns once every 90 seconds, producing 1 gee of acceleration on the inside floor of the cylinder and zero gee at the axis. Google 'O'Neill Colonies'. Mine is a simpler design than those. So convection will vary with distance from the axis of the cylinder. All...
  9. wbogen

    Heat transfer between warm air and cold water

    Thanks but I've done the calcs already on the distribution of air pressure and forces inside the cylinder, etc. What I'm trying to do now is balance the heat flow into and out of the city/cylinder. I would prefer to use simple conduction through the metallic endcaps and then radiation to 3K...
  10. wbogen

    Heat transfer between warm air and cold water

    A large spinning space city, a cylinder 2000 meters in radius, 5000 meters long, with sunlight directed to the floor of the interior constantly, but the ends of the cylinder facing not the Sun but black space (3 degrees K). Assuming a steady-state, with the endcaps radiating as much heat out as...
  11. wbogen

    Heat transfer between warm air and cold water

    Nope, not homework. Just playing with a design idea for a space settlement, to possibly use in a SF story, need to verify the heat balance will work. I'd rather not take excessive literary license with physical reality.
  12. wbogen

    Heat transfer between warm air and cold water

    For your consideration: A very large (100s of meters) vertical metal (stainless steel) wall maintained at, say, 35F. Warm (72F) moist air flowing over the wall (natural convection, not forced). Condensation flowing down the wall (at 35F?). How to find the heat transfer rate between the warm air...

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