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Insulation calculation to prevent condensation
2

Insulation calculation to prevent condensation

Insulation calculation to prevent condensation

(OP)
Hello people

I need to calculate the thickness of insulation required for a cylinder of inner radius 20cm. The temperature inside the cylinder is -165°C and
outside temperature being 25°C.

similarly how does it vary for a wall of thickness 50cm.

Do i need to provide any more information or is this sufficient.

the insulation coating is intended to prevent condensation.
can somebody provide the formulae for the calculation.

thanks in advance .............

RE: Insulation calculation to prevent condensation

What's the dewpoint of the air?

The air temp minus the dew point minus some margin is what the allowable convective temperature drop is. Use the convection equation to determine how much heat is allowed to flow inward. The allowable heat flow divided by surface temp minus the interior temp divided by thermal conductivity will get you to the required thickness.

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RE: Insulation calculation to prevent condensation

You can find this in ASHRAE volumes.

RE: Insulation calculation to prevent condensation

(OP)
Willard3 can you please provide a link

RE: Insulation calculation to prevent condensation

You have to own ASHRAE volumes or know somebody who does or be a member and subscribe to the publixcations.

Your best bet here may be to consult an Engineer who does HVAC.

RE: Insulation calculation to prevent condensation

2
ivoryhorseman: possible typo in your post? If the radius is 20 cm, then diameter = 40 cm, or 15.7 inches. But you said the wall thickness was 50 cm (= 19.6 inches ?) I'm lost. Anyway, just to get you "in the ballpark", you might try a few possibilities out at the attached site. Also, as others have said, you should study how to do the heat transfer calc by hand, so you really learn how the numbers work. Good luck!


RE: Insulation calculation to prevent condensation

And it sort of matters if the insulation is vapor permeable or not.

RE: Insulation calculation to prevent condensation

(OP)
Thank you.

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