[esp-r] Re: adjustment of specific heat capacity of air to model effect of furniture

[Achim Geissler]

Dear Leen

Probably using the "hanging surface" approach for furniture in a zone is
quite a bit easier. No obscure factors involved. Use a material like "wood"
or the like (whatever the furniture is made of) and even place the surfaces
such that the wireframe looks good (also good for export to radiance for
nice client-oriented pictures).

What happens in regard to ventilation heat loss if you use a factor on the
capacity of air? Furniture will show a (slight) time lag in getting rid of
excess heat, the air will not ... just one point that comes to mind.

Regards
Achim


-----Original Message-----
From: esp-r-bounces at lists.strath.ac.uk
[mailto:esp-r-bounces at lists.strath.ac.uk] On Behalf Of Leen Peeters
Sent: Dienstag, 24. Februar 2009 19:39
To: Leen Peeters; esp-r at lists.strath.ac.uk
Subject: [esp-r] Re: adjustment of specific heat capacity of air to model
effect of furniture

Ok, some further searching in the code gave me this (which is in
esrubld/mstmsc, line 394 and following)

C *********************************************************************
C CPair01 calculates the specific heat capacity of dry air (J/kg K)
C as a function of temperature ( C ) (Marieke 1994, Ham 1984)
C *********************************************************************
      FUNCTION CPair01(TC)
      COMMON/OUTIN/IUOUT,IUIN

      CPair01=1006.0+TC/200.0+TC*TC/7.5E3
      IF(CPair01.LT.0.0)then
        call edisp(iuout,'CPair01: negative specific heat capacity.')
        call epwait
        call epagend
        STOP
      endif
      RETURN
      END


But then remains ... with what factor to adapt it?

________________________________________
From: esp-r-bounces at lists.strath.ac.uk [esp-r-bounces at lists.strath.ac.uk] On
Behalf Of Leen Peeters [Leen.Peeters at mech.kuleuven.be]
Sent: 24 February 2009 19:27
To: esp-r at lists.strath.ac.uk
Subject: [esp-r] adjustment of specific heat capacity of air to model effect
of furniture

Dear all,

I was checking the code in order to find the exact location to adjust the
heat capacity of air in order to model the effect of furniture in a zone.
Is there a standard way to do so? In BCL22 I saw it was stated as AIRCAP,
but that does seem to appear in that controller only...

The ASHRAE fundamentals do not mention the topic 'furniture', I know the
TRNSYS people use an increase of the air capacity with a factor 5 to 10 as a
rule of thumb, but is there no general guidance for that?

Thanks!

Leen

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