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Air conditioners that can work in any orientation

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radar_macgyver:
I have an application housed in an enclosure that's mounted to a moving platform such that the enclosure can be at any angle with respect to vertical. Most air conditioner compressors that I've come across cannot be operated in any orientation other than vertical, so that rules out their use here. My understanding is that the lubrication systems in the compressors depend on being mounted vertically to drain down into a sump. On previous iterations of the design, I've used commercial thermoelectric cooler modules to regulate the enclosure temp, though these are very inefficient and expensive. I'm curious if there are any non-TEC cooler modules available for this purpose that can tolerate being rotated away from vertical.

coppice:

--- Quote from: radar_macgyver on February 24, 2024, 12:34:17 am ---I have an application housed in an enclosure that's mounted to a moving platform such that the enclosure can be at any angle with respect to vertical. Most air conditioner compressors that I've come across cannot be operated in any orientation other than vertical, so that rules out their use here. My understanding is that the lubrication systems in the compressors depend on being mounted vertically to drain down into a sump. On previous iterations of the design, I've used commercial thermoelectric cooler modules to regulate the enclosure temp, though these are very inefficient and expensive. I'm curious if there are any non-TEC cooler modules available for this purpose that can tolerate being rotated away from vertical.

--- End quote ---
You don't just have to put most heat pumps the right way up. You have to leave them that way for some time before switching them on, or you can stall them. I think even the chillers made for refrigerated trucks still have to be used the right way up. I believe they have special designs to tolerate the sloshing around of oil as the truck moves, but it wouldn't be OK to completely reorient the thing while in operation. I wonder what is available for airborne use?

ejeffrey:
I don't know of any air conditioner that can do that, you might be able to modify one?  Like a dry sump oil system on a racing engine that pumps oil into a secondary reservoir that then feeds the main oil pump?  Can you guarantee a certain amount of time in normal orientation?  Or is it required to be able to turn upside down and run indefinitely? 

I'm guessing you have to keep your product all together inside the enclosure, otherwise I would look at mounting the compressor somewhere else and using flexible refrigerant lines or a chilled water loop with flexible lines, or even rotary couplings to allow infinite rotation.


NiHaoMike:
I would say putting a regular heat pump in a large gimbal would be the easiest solution, but still not that easy.

radar_macgyver:

--- Quote from: coppice on February 24, 2024, 12:40:54 am ---You don't just have to put most heat pumps the right way up. You have to leave them that way for some time before switching them on, or you can stall them.

--- End quote ---
Most industrial enclosure coolers come with a warning that they must be left upright for a minimum of a few hours after installation, prior to switching them on.


--- Quote from: coppice on February 24, 2024, 12:40:54 am ---I wonder what is available for airborne use?

--- End quote ---
That's what I was wondering too, this is the only other instance I can think of where one would need an off-vertical AC. Civilian aircraft don't spend much time in steep banks and dives, I suppose.

The end application is for a radar receiver that's mounted on a scanning antenna. As the antenna scans around, it can be moved off-vertical. It is returned back to zero degree elevation periodically, but I don't want to risk a compressor failure and loss of cooling. I'm aware of at least one design that uses a water chiller and a glycol loop passed through a rotary union. The folks who operate those systems complain about the leaks, so that's something I would like to avoid.

The total heat load in this enclosure isn't much - just about 150-200W. TEC coolers are available in this capacity, though they are bulky and super inefficient through most of the useful delta-T range.

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