Dessicant Sizing
Dessicant Sizing
(OP)
Folks-
Given a sealed electronics enclosure, if one knows the outside air temperature, pressure, and humidity profiles, is there a way to analytically predict how much moisture will condensate within? The seal is a conventional linear O-ring in an O-ring gland of traditional design. Also given are the inside surface area and volume. I dug out my old thermo textbook but it contained no problems remotely close to this one! Everywhere else I've looked, including a Google search turned up nothing. TIA for your help!
Given a sealed electronics enclosure, if one knows the outside air temperature, pressure, and humidity profiles, is there a way to analytically predict how much moisture will condensate within? The seal is a conventional linear O-ring in an O-ring gland of traditional design. Also given are the inside surface area and volume. I dug out my old thermo textbook but it contained no problems remotely close to this one! Everywhere else I've looked, including a Google search turned up nothing. TIA for your help!
Tunalover





RE: Dessicant Sizing
> What temperature range do you want to have non-condensation?
> This establishes the dewpoint, which dictates the amount of water allowable at room temp
> Which determines the RH at RT
> Which determines the steady-state desiccant demand
> What is your max temp and how much leakage, both outflow and inflow
> Which determines the amount of potential moisture introduced into the structure
> Which determines the amount of moisture to be removed at any given time
TTFN
RE: Dessicant Sizing
I'm trying to determine the amount of dessicant to use in the enclosure and how long it will last until requiring recharge. I know the time history of outside RH, temperature, and altitude. I just need to know how much condensate will form inside the enclosure. Do you know of any papers on the subject where someone actually comes up with NUMBERS?
Tunalover
RE: Dessicant Sizing
Condensation occurs when heated air, containing a higher moisture level, is cooled beyond the dewpoint temperature of the air-water vapor mixture. Now, that may seem like stating the obvious, but the rest is up to you.
Out of IRStuff's list, I would count airflow into and out of the enclosure, and heat transfer through the enclosure's surface as most important - and totally dictated by your specific situation, your estimates, and your measurements.
RE: Dessicant Sizing
If you can safely assume that there is no air exchange with the outside then the problem is relatively straight-forward.
If there is air exchange things get more complicated.