Thermal control and radiators

Key results

• Radiator placement depends on orientation.
• Sun-pointing stations put radiators on the back of the arrays or out the back in shadow Paul451, 2015-08-30; Paul451, 2022-10-27.
• Edge-on tori can hide fixed radiators inside the ring's shadow Paul451, 2022-10-27. mikelepage prefers edge-on for large stations for this reason mikelepage, 2022-11-26.
• Radiating axially from inside the wheel 1, 2018-07-06.
• Constant sunlight means a constant radiator load whitelancer64, 2022-10-07.
• Solar radiators that swap between sun and shade lamontagne, 2019-03-12.
• On the BIS Avalon the hub carries the radiators (low MoI) and the radiators hang out the ends lamontagne, 2023-09-29; lamontagne, 2023-09-28.
• Equatorial radiators instead of sun-pointing, to avoid precession propellant lamontagne, 2026-09-19.
• Liquid droplet radiators suit rotating stations. Spray counter-spinward to a collector on the next spoke Paul451, 2022-10-28; Paul451, 2019-03-31.
• Heat pumps vs bigger radiators.
• With abundant power, heat pumps shrink radiators DanClemmensen, 2023-10-02.
• lamontagne's spreadsheet: heat pumps win in many cases with heavy radiators, but as radiators shrink the turbomachinery dominates, so minimize radiator unit mass lamontagne, 2023-10-03.
• Twark_Main (Carnot): better to run a heat engine at a warmer T_cold than to add a heat pump Twark_Main, 2023-10-03.
• A Stirling scavenger is a reverse heat pump. It subtracts some heat but the radiator grows; realistic low-ΔT Stirling power density is far worse than 3 kg/kW, so it adds more mass than it saves Twark_Main, 2023-11-13.
• Heat loads from lighting and crops.
• Crops need ~1000 W/m² of light; parks 200–300 W/m². LEDs are ~60–70% efficient; solar cells absorb more than they output and run hot lamontagne, 2026-09-15.
• Equal illumination means equal heat, whatever the source Paul451, 2023-10-18.
• Glass lets IR out at night lamontagne, 2023-02-19.
• "Barbecue roll." Slow rotation (~1/6 rpm) shows thermal variation is not an issue. Point the smallest cross-section at the sun Paul451, 2018-07-05.
• "Water walls." Flexible water mats pumped through structural pillars for thermal control, doubling as storm shelter mikelepage, 2019-04-08.
• Spokes as solar-updraft ducts for air heat transport (BIS) lamontagne, 2023-09-28.
• Kubrick removed Discovery's radiators for aesthetics lamontagne, 2023-10-02.
• Heat-sensitive seals. Payload-door seals and latches are heat-sensitive (Shuttle "zipper" latches) Twark_Main, 2023-04-12.

Open questions

• Radiator mass and area for 1000-person stations with farms: does thermal rejection, rather than power, limit agriculture in orbit?
• Can liquid droplet radiators be made reliable in the rotating frame?

Related pages

• Power · Agriculture · Lighting · Sun-pointing

Sources

Forum posts

• Paul451, 2015-08-30 (reply #574): Radiators on back of arrays. Post.
• Paul451, 2018-07-05 (reply #878): Barbecue roll. Post.
• 1, 2018-07-06 (reply #890, 2 likes): Radiators inside wheel radiating axially. Post.
• lamontagne, 2019-03-12 (reply #1347, 2 likes): Solar/radiator swap. Post. Attachments: Dumbell station.jpg, Dumbell stationb.jpg.
• Paul451, 2019-03-31 (reply #1454): Droplet radiators suited. Post.
• mikelepage, 2019-04-08 (reply #1505, 1 like): Water walls. Post. Attachments: Pods_closed.png, Pods_ajar.png, Pods_open.png, Pods_turning.png.
• whitelancer64, 2022-10-07 (reply #1895): Constant sunlight = constant radiator load. Post.
• Paul451, 2022-10-27 (reply #2237): Radiators out the back. Post.
• Paul451, 2022-10-27 (reply #2240, 1 like): Radiators inside ring shadowed. Post. Attachments: Spin station not pointing at sun.jpg.
• Paul451, 2022-10-28 (reply #2250, 2 likes): Liquid droplet radiators. Post. Attachments: Liquid droplet radiator concept.png, Liquid Droplet Radiator spiral example.jpg.
• mikelepage, 2022-11-26 (reply #2447, 1 like): Edge-on better for large stations. Post.
• lamontagne, 2023-02-19 (reply #3354, 3 likes): Glass lets IR out. Post. Attachments: ring1a.jpg, ring1b.jpg, ring1c.jpg.
• Twark_Main, 2023-04-12 (reply #3599): Heat-sensitive door seals. Post.
• lamontagne, 2023-09-28 (reply #4036): Radiators hang out ends. Post.
• lamontagne, 2023-09-28 (reply #4042): Spokes as updraft heat transport. Post.
• lamontagne, 2023-09-29 (reply #4060): Avalon hub radiators. Post.
• DanClemmensen, 2023-10-02 (reply #4110): Heat pumps shrink radiators. Post.
• lamontagne, 2023-10-02 (reply #4112): Kubrick removed radiators. Post.
• Twark_Main, 2023-10-03 (reply #4117): Carnot argument. Post.
• lamontagne, 2023-10-03 (reply #4118): Rad vs heat pump spreadsheet. Post. Attachments: Rad vs heat pump.xlsx.
• Paul451, 2023-10-18 (reply #4215, 1 like): Equal illumination = equal heat. Post.
• Twark_Main, 2023-11-13 (reply #4347, 1 like): Stirling adds mass (1 like). Post. Attachments: Rad vs stirling.xlsx.
• lamontagne, 2026-09-15 (reply #5107, 3 likes): Crop light & thermal loads. Post. Attachments: Image51_002.jpg.
• lamontagne, 2026-09-19 (reply #5158, 2 likes): Equatorial radiators better. Post.