Question How to cool a robot that will be outside?

Aug 13, 2019
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I am building a robot that will live primarily outside and will need to be cooled. I think humidity will be an issue so I think a vent and a fan will not work but I may be wrong.

If humidity will be an issue i wanted to see if anyone would have any suggestions on how I can cool a robot that has air tight casing around it?

Thanks so much!!!
 

kanewolf

Titan
Moderator
I am building a robot that will live primarily outside and will need to be cooled. I think humidity will be an issue so I think a vent and a fan will not work but I may be wrong.

If humidity will be an issue i wanted to see if anyone would have any suggestions on how I can cool a robot that has air tight casing around it?

Thanks so much!!!
You could use a closed loop liquid cooler. The radiator is exposed but the rest of the system is enclosed.

You may still want to put the radiator on the bottom or other protected area to minimize solar gain.
 

rubix_1011

Contributing Writer
Moderator
Can you give more info on this project?

Is there only a certain part of the robot that needs to be cooled, similar to a computer CPU? Or is this more of a general 'the whole thing needs to be cooled' kind of scenario?

Humidity only has an impact in terms of temperature perception with living organisms; it limits how well water can evaporate based on saturation of the ambient air, which is how most organisms regulate body temperature. A piece of metal or concrete (for example) does not understand a difference of temperature based on this concept because it does not perspire in attempt to exchange heat with the ambient surroundings.

You would not be able to use any form of air or ambient liquid cooling to cool something that is airtight...by definition, access to ambient airflow is required to dissipate thermal energy from the absorbed location (computer CPU, for example) into a larger surface area that is then dissipated using convection by air movement (fan). Even liquid cooling still relies on air transfer.
 
Aug 13, 2019
2
0
10
0
Can you give more info on this project?

Is there only a certain part of the robot that needs to be cooled, similar to a computer CPU? Or is this more of a general 'the whole thing needs to be cooled' kind of scenario?

Humidity only has an impact in terms of temperature perception with living organisms; it limits how well water can evaporate based on saturation of the ambient air, which is how most organisms regulate body temperature. A piece of metal or concrete (for example) does not understand a difference of temperature based on this concept because it does not perspire in attempt to exchange heat with the ambient surroundings.

You would not be able to use any form of air or ambient liquid cooling to cool something that is airtight...by definition, access to ambient airflow is required to dissipate thermal energy from the absorbed location (computer CPU, for example) into a larger surface area that is then dissipated using convection by air movement (fan). Even liquid cooling still relies on air transfer.
Thanks for the reply
The entire robot would need to be cooled

I think a liquid coolant would work I just would have to make an air tight seal for the radiator but I dont know how to protect it from rain.

Thanks for the help
 

Azzyasi

Distinguished
Jan 24, 2011
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what exactly you try to protect from rain? what do you want to cool?
How cool?, cooler than ambient? or just enough to still function and not melt components?

As for movin heat around i suggest getting some heatpipes from aliexpress or something and some chunks of aluminium or copper. Drill a hole to fit the heatpipe, drill a radiator (finned solid or finstack) to fit the radiator in an exposed area.
Cooling can be passive (some testing must be done)

As for waterproofing, depends what to waterproof.. pcb of electronics? motors? actuators? senzors?
Anyway, for bought items check the IP rating. You need a motor to run underwater.. no problem get IP 68
Same for senzors or senzor housings, or pcb housings.

About resistance to environment here is an example: car ECUs have the lamest lowpower CPU because it needs to keep the heat down, and while a rasberryPi will outclass the car ECU, it's massive heat generation is a problem, so they put a poket calculator cpu in ECU if that floats the boat. (bear in mind the workload is fixed, not wildly variable like in PC where you want the latest game istalled and performance drops.. here a fixed set of instructions are done with the same software as designed for its entire life)
Also the entire pcb is coated with a resin (with components as well, not just the pcb) to make it very resistant to water, also the entire thing is placed inside into a hermetically sealed aluminium box that acts as a passive radiator.

You can put that arduion or whatever in a box like this https://www.alibaba.com/product-detail/112-pin-waterproof-auto-car-Aluminum_60471598388.html

and if heats build up faster than what you need get drilling into it and make a tree of heatpipes and surounding heatsyncs like theese https://www.aliexpress.com/item/32757122124.html?spm=a2g0o.productlist.0.0.3d05d04dVUIj6Y&algo_pvid=00e6c0ca-e96c-4da5-8d0d-1fc2c3810f1e&algo_expid=00e6c0ca-e96c-4da5-8d0d-1fc2c3810f1e-0&btsid=e27cb76d-9f04-47b4-86ac-55b833e74bf8&ws_ab_test=searchweb0_0,searchweb201602_1,searchweb201603_53

keep the rads in the shade so it will not heat up from the sun.
 

rubix_1011

Contributing Writer
Moderator
Thanks for the reply
The entire robot would need to be cooled

I think a liquid coolant would work I just would have to make an air tight seal for the radiator but I dont know how to protect it from rain.

Thanks for the help
So you want to cool your robot with liquid cooling, and the entire robot has to be cooled, but it has to be shielded from rain? How can the entire thing liquid cooled but not able to get wet? Is it an outdoor robot by design, or is it home made or designed for inside use and being used outside, instead? How is this robot normally meant to be cooled?

I'm looking more for specifics on 'what part of the robot needs the cooling'? What is generating the heat? What are the thermal limits of these components? What temperatures are they currently running at?

Does the robot move or is it stationary? Can you provide any more detail, like photos or description about what it does, how it should be cooled, how many components on it should be cooled, etc? Depending on these details there could be some options, but it is difficult to get specific without knowing more detail.
 

kanewolf

Titan
Moderator
You "water tight" pass through for cooling might be simplest if they are permanent fittings of some kind. Then you can epoxy or silicone the penetrations. You are going to have problems with electrical penetrations also.

I did some work on outdoor devices. The best way to design is to make the case an umbrella. All penetrations come from the underside of the umbrella.
 
What is the expected power draw? How many watts are you dissipating?

What materials will be used in the robot "skin"? The easiest solution is to simply thermally bond the computing bits to an exterior metal surface and use it to passively dissipate the heat. The wattage and ambient operating temp dictates how much surface area is needed. If ambient temps and/or surface area make cooling insufficient, there are weather resistant fans that you could externally mount (think the radiator fan on your car)
 
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