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Old 13-04-2021, 15:47   #1
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Refrigeration cooling

I currently have two air to air Nova Cool units mounted under the Nav station seat. There are two vents at 90*, one is roughly 4x10 inches, the other is about 5x5. Both have screens.

I will be adding a 140mm Noctua (muffin, or computer type) fan, with its own new vent hole, wired with potentiometer to reduce the 2000 rpm speed (and 31db noise).

So the question for you engineers out there is should the fan blow hot air out of the vent, or into it?

Thanks!
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Old 13-04-2021, 16:12   #2
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Re: Refrigeration cooling

Where are the vents in relation to each other, including the new one? If the new fan is low in the compartment and one of the other vents is high (and not directly above) then blow in, this will enhance natural convection (cool air gets blown in low, warm air exits high). OTOH, if the fan is going up high, where the warm air naturally collects, then blow the warm air out, with the inlet down low and on the opposite side.
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Old 13-04-2021, 16:28   #3
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Re: Refrigeration cooling

I would direct the fresh air to blow directly across the control module.
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Old 13-04-2021, 16:34   #4
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Re: Refrigeration cooling

The top of both vents are about the same height. The larger vent goes lower. Inside, one compressor is lower than the other.

Both compressors have their own fans attached. This is to help remove the hot air.

I can make the new fan vent high or low.
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Old 14-04-2021, 06:30   #5
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Re: Refrigeration cooling

The general idea is to exhaust the warm air from high in the compartment creating a lower pressure in the rest of the area. Inlet air opening locations are low in compartment if possible. If either Nova kold is operated at max Rpm its control module will require extra cooling. Usually with many of these well designed condensing units placing its air intake tightly sealed opening allows area to be slightly pressurized while heat is exited through other openings. Remember adding a second fan to the Danfoss control module 1/2 amp max terminals is not recommended. I would recommend a temperature switch to activate second fan and module cooling fan if needed.
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Old 14-04-2021, 12:51   #6
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Re: Refrigeration cooling

Mount the fan as high as possible, with airflow leaving the enclosure at that point.
Draw that heat out the way it travels.
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Old 15-04-2021, 09:07   #7
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Re: Refrigeration cooling

What a fan does is funnel a massive volume of upstream air, into a very tight tunnel of fast moving downstream air.
With a single fan:
Suction systems are more effective in general compartment cooling.
Blowing systems are more effective in cooling a specific item (aim fan directly at ‘it’).
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