[TRNSYS-users] Max heat load calculation

[Matt Duffy]

Dear Marshall,

Unfortunately, I have not used the max heat load calculation function in
TRNBuild, but it most likely sounds like some directory is not referenced
properly or permissions issues with windows. On the other hand, when I
wish to see the max heating load from my simulation throughout the course
of the year, I integrate (Type24) the output of TRNBUILD/Type56 NTYPE 30,
QHEAT, hourly (kJ/hr --> kJ) and print the results (Type25). I then open
the results in Excel and search for the maximum value. Although this might
seem like quite the caveman approach, it seems to work just fine.

For your next issue, please reference wikipedia or any heat transfer text.

# thermal resistance (R value) = t/k, measured in K·m**2·W**−1;
where "t" is the thickness(m) and "k" is the thermal conductivity (W/mK)

Please note that when you define layers for your walls they can be either
"massive" or "massless". The massless layer is simply a resistance
(R-Value in SI units). You obviously do not define a thickness for a
resitive, "massless" layer as the heat transfer is going to be a function
of the wall area; however, for the "massive" layer and to answer your
question, it is required that you define a thickness for each layer of
your wall in the TRNBUILD "wall typemanager". Yes, you can either grab a
wall or a layer from the provided libraries. The "wall typemanager" will
specify the appropriate thicknesses of each layer.

For reference

R-1 (1 h ft^2 F/ BTU) = 0.048919 h m^2 K / kJ

1 h m^2 K / kJ = 3.6 m^2 K / W




Best regards,

Matt Duffy


----- Original Message -----
From: "Marshall L Sweet/sweetml/O/VCU" <sweetml at vcu.edu>
Sent: Wed, June 17, 2009 11:15
Subject:[TRNSYS-users] Max heat load calculation

Hello TRNSYS users,

I have two questions:

1.
I am trying to use the "Max heat load calculation" feature in TRNBUILD. 
Everything
appears to work fine until the last stage where a window appears displaying
"Calculation Terminated" and I have to choose "No" or "Run TRNSYS".  I
click the
"Run TRNSYS" button and then I get an error that says "File C:\Program
does not
exist".  I have checked and rechecked the directories under the OPTIONS \
SETTINGS
menu and my file directory for TRNSYS is correct.  The folder where I have
my TYPE
56 shows that maxheatload files (.b16, .bld, .d16) have been created.
What is the problem?  Is there another way to set up the simulation?

2.
I am using the American library for my walls, layers, and windows in
TRNBUILD.  I am
curious to know how the conductivity for layers are calculated.  Say I
want to use
R-13 insulation, what would be the corresponding conductivity?  Does R-13
already
exist in the library?  When I try converting from English units (R-13 = 13
ft^2 F h
/ BTU) to SI units and inverting to obtain the U value I am left with an
extra meter
in the denomonator (ie. kJ/(h k m^2)).  Does TRNBUILD use some standard
length to
eliminate a meter unit?

Thanks,

Marshall

Graduate Student
Dept. of Mechanical Engineering
Virginia Commonwealth University

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