Enclosure Panel Material and Heat Transfer

[Scott Chapel]

We built our first production skid and are working to reduce the heat load in the electronics compartment. Referring to the attached CAD drawing, the bottom right of the skid is the compartment. Currently the external walls/panels are 20-gauge steel sheet powder coated yellow. There is 1-inch of R-6 foam board insulation on the inside of all six external walls. The two outside facing panels are exposed to both ambient heat as well as direct sunlight when the skid is unloaded on site. What I have been unable to figure out is, if we were to replace the 20-gauge sheet steel with aluminum sheet, would this reduce the heat transfer into the compartment or is the powder coating and color the deciding factors in the heat transfer.

Appreciate any help!

Scott

 

[MintJulep]

It will make no practical difference.

Is the cabinet actively cooled?

 

[Scott Chapel]

4400BTU of compressor HVAC.

So the material, color, and texture of the external panels won't make any difference?

 

[Scott Chapel]

Attached is a picture showing the two sides of the compartment with the most exposure to the sun and the gravel pad.

 

[IRstuff]

What I have been unable to figure out is, if we were to replace the 20-gauge sheet steel with aluminum sheet, would this reduce the heat transfer into the compartment or is the powder coating and color the deciding factors in the heat transfer.

Aluminum has a better thermal conductivity than steel, which is why heat sinks are almost always made from aluminum; you will actually make it ever so slightly worse.

You've said nothing about ambient temperatures, other heat sources, etc. How much heat is inside your box, etc.?

Barring any other information, vacuum insulation panels might get you reduction in heat transfer, assuming that's the actual issue.

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[Scott Chapel]

Ambient in a West Texas August on a well pad is 110F. We are able to maintain 76F in the compartment with two 2200BTU HVAC units, but they are running all the time. We run all the internal equipment on shore power at 15A 120VAC.

 

[IRstuff]

OK, I don't get your design concept. Your ACs have a cooling capacity of 1290 W, but your electronics dumps 15*120 = 1800W?

What am I missing with this picture? Why are you worrying about the insulation when your AC can't even keep up with the electronics?

TTFN (ta ta for now)
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[Scott Chapel]

In addition to the PLC, computer, modem, and 120VAC-24VDC power supply putting out heat, there is a heated head pump, a heated filter, and a heated valve. This train is connected with 1/4" stainless tubing with Swagelok fittings. All three devices maintain 375F and are insulated. The tubing connections are wrapped in felt insulation to maintain the same temperature. With all of the insulation, the heat does not immediately radiate into the compartment and some of it is expelled through an exhaust line. Once the PLC stops heating the equipment, it takes about 1.5 hours for the HVAC to cool the compartment down to ambient, depending on the ambient temperature at the time. Obviously this is because the heated devices are radiating through the insulation over that period of time. We are upgrading one of the two 2200BTU HVAC units to a 5000BTU unit to give us 7200BTU.