[esp-r] Re: Air flow networks, temperature pick up of internal nodes

[Jon Hand]

A question about flow networks...

The use of additional flow nodes to support control actions or additional components
are sometimes called bookkeepping nodes. If there are, for example, 3 bookkeepping
nodes within a zone officex one option is to define them as internal nodes of unknown
pressure and when it asks whether it should be a fixed temperature or take the
temperature of another zone choose the relevant node.  The entry in the flow
network with a real node manager_a and a bookkeepping node man_book which
took the temperature of manager_a would look something like:

 Node         Fld. Type   Height    Temperature    Data_1       Data_2
 manager_a       1    0   1.5000       20.000       0.0000       40.501
 . . .
 man_book        1    0   1.5000        manager_a         0.0000       40.501

I just ran a quick simulation and plotted the temperatures of the nodes
and found that man_book was a flat line at 20C.  So there would appear
to be a bug in the graphing facility.

-Jon Hand
________________________________________
From: esp-r-bounces at lists.strath.ac.uk [esp-r-bounces at lists.strath.ac.uk] On Behalf Of Christian Anker Hviid [cah at byg.dtu.dk]
Sent: 23 October 2009 12:04
To: esp-r at lists.strath.ac.uk
Subject: [esp-r]  Air flow networks, temperature pick up of internal nodes

A question on air flow networks and internal nodes.

I have a network of nodes, some are associated with thermal zones, some are internal (acting as separators between two duct sizes).
I think that normally an internal node will track the temperature of the upstream node unless it is set to track the temperature of a specific node.
I use the former representation but when I plot the temperature of the internal nodes, the temperature is reset to zero.

Am I mistaken? Should I always manually set internal nodes to track upstream nodes? Or should I not worry too much of the temperature of internal nodes as they are represented in a special way?

I do not think the Cookbook is completely clear on this subject.



Best regards

Christian Anker Hviid
Industrial PhD candidate

DTU Byg
Technical University of Denmark
Brovej, building 118
DK-2800 Lyngby
Phone DTU: +45 4525 1886
Phone Alectia: +45 8819 1365
Mail: cah at byg.dtu.dk

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