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Re: [EnergyPlus_Support] moisture simulation with MTF or EMPD



Hans:

The dimensionless coefficients (a, b, c, and d) are used to establish a 
relationship between mositure content and relative humidity. The 
relationship equation is given in Eq. (35) on page 30 in the EnergyPlus 
Engineering Reference. As long as you have measured sorption data, you may 
get the coefficients through curve fit.

The section of Effective Mositure Penetration Depth (EMPD) Model in the 
EnergyPlus Engineering Reference provided references.

It is hard for me to say whether the MTF model works or not without knowing 
detailed inputs. You can try it first.

Please let me know if you have more concerns.

Thanks.

Lixing Gu
----- Original Message ----- 
From: "Hans Hatt" <hatt@xxxxxxxxx>
To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Thursday, July 13, 2006 11:27 AM
Subject: AW: [EnergyPlus_Support] moisture simulation with MTF or EMPD


Dear Lixing Gu

thanks for your response. How can I find the right dimensionless
coefficients a, b, c and d for light clay in the EMPD model? The isothermal
moisture capacity is about 2.2 m3/kg. Is there some literature about the
EMPD model?

If the EMPD model doesn't work because of its limitations to small
penetration depth, do you think the MTF model could work better.

Thanks a lot for your help.

Hans

  -----Ursprüngliche Nachricht-----
  Von: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]Im Auftrag von Lixing Gu
  Gesendet: Thursday, July 13, 2006 3:13 PM
  An: EnergyPlus_Support@xxxxxxxxxxxxxxx
  Betreff: Re: [EnergyPlus_Support] moisture simulation with MTF or EMPD


  Hans:

  The EMPD model assumes a sum of moisture adsorption and desorption at an
  interior surface during a short period is near zero. Although increasing
the
  penetration depth may not be a reasonable approach (possible beyond the
  model capability), I would suggest to try it and see whether you get
  reasonable results or not. If you have measured data, you may know the
model
  limitation.

  Please let me know if you need more information on the model.

  Thanks.

  Lixing Gu

  ----- Original Message -----
  From: "Hans Hatt" <hatt@xxxxxxxxx>
  To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
  Sent: Wednesday, July 12, 2006 2:14 AM
  Subject: AW: [EnergyPlus_Support] moisture simulation with MTF or EMPD

  > Thanks a lot for your reply.
  >
  > Do you think we can use the MTF model, if the relative moisture in the
  > materials will remain between 30% and 70%. For the MTF model we have
  > already
  > an idea about the needed coefficients.
  >
  > The penetration depth in the EMPD model is just about 10 to 15 mm. For
the
  > anual storage of moisture I think we need more than 100 mm of storage
  > material. The Engineering Reference says, that the EMPD equation just
  > holds
  > for a short period of time. We would like to study the moisture storage
  > over
  > a whole year. Can we use in this case the EMPD model?
  >
  > Best wishes
  >
  > Hans, Lenum AG
  >
  >
  >
  > -----Ursprungliche Nachricht-----
  > Von: EnergyPlus_Support@xxxxxxxxxxxxxxx
  > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]Im Auftrag von Michael J.
Witte
  > Gesendet: Montag, 10. Juli 2006 21:10
  > An: EnergyPlus_Support@xxxxxxxxxxxxxxx
  > Betreff: Re: [EnergyPlus_Support] moisture simulation with MTF or EMPD
  >
  >
  > The MTF model would probably not be appropriate for this task. Note the
  > cautions about using it over a wide range of conditions in the Input
  > Output
  > Reference (p. 73, pdf p. 110) and the Engineering Reference (p. 24, pdf
  > p.
  > 56).
  >
  > The best option within EnergyPlus would be the EMPD model, however, you
  > may not
  > be able to find the appropriate coefficient data for this model for the
  > specialized material you are studying.
  >
  > Mike
  >
  > On 7 Jul 2006 at 6:14, hatt_hans wrote:
  >
  > > We would like to do an ep simulation for a magazine which stores
  > > important documents. To balance the relative humidity in the magazine
  > > we would like to use clay o calciumsilicat panels at the inside
  > > surfaces. With these materials we would like to store the moisture
from
  > > the summer to the winter period. Should we use the MTF or EMPD model
  > > for simulation? How can we get the needed parameters for clay and
  > > calciumsilicat. In the moisture.idf file we have found already some
  > > materials, which were very helpful.
  > >
  > > Thanks a lot for help.
  > >
  > > Hans, Lenum AG
  > >
  > >
  > >
  > >
  > >
  > >
  > >
  > > The primary EnergyPlus web site is found at:
  > > http://www.energyplus.gov
  > >
  > > The group web site is:
  > > http://groups.yahoo.com/group/EnergyPlus_Support/
  > >
  > > Attachments are not allowed -- please post any files to the
appropriate
  > folder
  > > in the Files area of the Support Web Site.
  > >
  > > EnergyPlus Documentation is searchable. Open EPlusMainMenu.idf and
  > press
  > the
  > > "search" button.
  > >
  > > Yahoo! Groups Links
  > >
  > >
  > >
  > >
  > >
  > >
  > >
  > >
  > >
  >
  > ========================================================
  > Michael J. Witte, GARD Analytics, Inc.
  > EnergyPlus Testing and Support
  > EnergyPlus-Support@xxxxxxxx
  >
  >
  >
  >
  >
  >
  > [Non-text portions of this message have been removed]
  >
  >
  >
  >
  > The primary EnergyPlus web site is found at:
  > http://www.energyplus.gov
  >
  > The group web site is:
  > http://groups.yahoo.com/group/EnergyPlus_Support/
  >
  > Attachments are not allowed -- please post any files to the appropriate
  > folder in the Files area of the Support Web Site.
  >
  > EnergyPlus Documentation is searchable. Open EPlusMainMenu.idf and press
  > the "search" button.
  >
  > Yahoo! Groups Links
  >
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  >






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