[esp-r] Re: Zone Conrol Model

[Jon Hand]

A recent question about setting surface temperatures:  below are
a series of questions about how to fix the exterior surface temperature
within a model.  The core issue is that the temperature of a surface
facing the outside in ESP-r (and most other simulation tools) is 
the <<result>> of the various flux exchanges at the outside face.

The 1st attempt used timestep data - but that data is used for
controlling the zone air temperature to a specified point not
for forcing the outside face temperatures to a fixed value.  It might
be that the documentation on this type of temporal entity is
not as clear as it could be.

The 2nd attempt is clever, however it would probably fail even
if there were no issue with the number of zones.  The details
of one or two of the control loops would be necessary to
confirm the mode of failure.  

Essentially a zone control allows
you to sense the temperature at a surface and inject or extract
flux near the outside face of the surface - but one would require
a separate loop for each surface in the zone and ESP-r would
not let you have more than one zone control loop associated
with each zone.  There is no existing ideal zone control that
could control the temperature of multiple surfaces.

A point of strategy - if you are exploring a control that is
experimental and/or new to you confirm that it works first
on a shoe-box model. 

The second point of strategy is to consider the reason for
fixing the outside surface temperatures - 18 zones
seems much larger than one would typically find in an
emperical test chamber (where it is occassionally necessary
to fix boundary conditions).  There are techniques which can
be used to encourage the outside surface temperature to be
close to a known temperature, but such techniques have
not been used in an 18 zone model.  

To plan an appropriate strategy the community is going to need 
to know more about what it is that you are trying to represent.

-ESRU

-----Original Message-----
From: esp-r-bounces at lists.strath.ac.uk on behalf of Ali fallahi
Sent: Mon 10/15/2007 3:38 AM
To: esp-r at lists.strath.ac.uk
Subject: [esp-r]  Zone Conrol Model
 
Dear All,

I have a question regarding the control model in ESP-r. I wanted to
assign surface temperatures changing in a fixed frequency ( 24 surface
temperatures per day)  to external surfaces of 18 zones. I did this in
two ways but I couldn't succeed.

1- I used Shorttime step (temporal) model and SETPTTT to define the
surface temperature profile for one day and timestep of one. Then I
associated this index to a control loop. After simulation I just got
zero surface temperature!! As I understood SETPTTT uses control law 11
to match sensed/recorded temperature. I changed heating and cooling
capacity and sensor's parameter , but again i got the same zero
surface temperature.

2- I tried to assign the surface temperatures using zone control
model. However, with the current version 11.3  it's possible just to
have 8 control periods for one control loop. Therefore, I changed the
code (MBCDP in building.h  from 8 to 100). I could include all my
temperature profile this way (24 periods per loop and more than 18
contol loops) and I used control law 1; however, results show that
ESP-r just considers the first 12 control loops and doesn't take into
account the other 6 control loops. Thus, I could assign the surface
temperatures just to 12 zones.

I would be pleased if someone could advise me how to assign 24 surface
temperatures ( changing in a fixed frequency )  to 18 external
surfaces.

Best Regards,
Ali Fallahi

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