exceeding RH100%

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shinya
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exceeding RH100%

Post by shinya » Mon Feb 04, 2008 8:24 pm -1100

In a result of my calculation, the RH exceeded 100%.
It was 100%~105%.

Is this calculation correct?
What does the part of over 100% mean?

Please give me some information.
shinya ogata

Thomas
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Re: exceeding RH100%

Post by Thomas » Tue Feb 05, 2008 2:16 am -1100

Hi shinya,

a relative humidity exceeding 100% means that the water content of the material exceeds free saturation.

Free saturation is the water content up to which a material can absorb liquid water to which it is exposed (rain, for example). Since during the absorption of liquid water air pockets will be trapped in the pores, free saturation is less than maximum saturation where the complete pore volume is filled.

Water contents between free and maximum saturation can be reached if condensation occurs (because condensation starts at the tiny ends of the pores and pushes all air out of the pores). While for humidities below 100% there is a unique mathematical relationship (the "moisture storage function") between relative humidity and moisture content, no unique relationship exists above 100%.

However, WUFI needs such a relationship in order to mathematically solve the moisture transport equations. Therefore WUFI artificially assigns relative humidities above 100% to the moisture contents between free saturation and maximum saturation. In all places where this occurs in your calculation you should also see a water content above free saturation.

These relative humidities above 100% have no real physical meaning and should be treated as being 100% (this is what you would measure in an experiment). WUFI only uses them for mathematical consistency in its equations. Maybe we should limit all relative humidities in the output of the program to 100% in order not to confuse the user...

Regards,
Thomas

Alberto Morales
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Re: exceeding RH100%

Post by Alberto Morales » Thu Jun 02, 2022 12:43 am -1100

hi Thomas,

is this still valid (see message above)?

Thanks

Thomas
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Re: exceeding RH100%

Post by Thomas » Thu Jun 02, 2022 1:32 am -1100

Hi Alberto,

the internal handling of moisture contents exceeding free saturation is still the same. In the one-dimensional WUFI-Pro the relative humidities in the output data are automatically limited to 100 %. I'm not really sure right now about WUFI-2D. I think it's limited there now as well, but I'm not 101 % ( :D ) sure. Should you see humidities exceeding 100 % in the output, please treat them as 100 %.

Kind regards,
Thomas

Alberto Morales
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Re: exceeding RH100%

Post by Alberto Morales » Thu Jun 02, 2022 1:54 am -1100

Thanks

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