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Ethan,<br>
There are two ways of conditioning a Type56 thermal zone: energy rate
control and temperature level control and I think that what is
happening in your simulation is that the two are getting mixed. When
you work in energy rate control, you define the temperature of the zone
and you calculate the amount of energy that is required to meet that
set point. Because you predefined the set point, you are in essence
assuming that your HVAC system is able to meet that set point. When you
work in temperature level control, the zone becomes just another
component in the system; its temperature and humidity are a result of
both ambient and the systems that try to keep them at set point. In
your simulation, you have defined a set point and then are modulating
the capacity of the cooling system at the same time. I think what you
want to do is one of the following:<br>
<br>
Define the set point and allow the capacity to be unlimited and
calculate the cooling loads, then afterwards, impose those loads on
your CCU and make sure that it can meet them at all times.<br>
<br>
or<br>
<br>
Define a thermostat model (Type23 perhaps) that monitors the cabin
temperature and Type56 ventilation inputs (T, RH, and ach). Have the
thermostat command your CCU and pass its outlet temperature, flow rate,
and RH to the Type56 model. The temperature in the cabin will oscillate
around the set point a bit (as it would in reality) as it turns fans up
and down.<br>
<br>
I hope that helps,<br>
David<br>
<br>
<br>
Ethan Lust wrote:
<blockquote cite="mid:000b01c8d22b$a7eef060$f7ccd120$@edu" type="cite">
<pre wrap="">Hello,
I am trying to simulate the operation of a climate control unit (vapor
compression air conditioner and electric resistance heater) in a small
closed space. The climate control unit (CCU) (Type 202 and the accompanying
DLL7) is an original component created from manufacturer's data. Prior to
the heater and air conditioning code within the Type202.f code, there is a
switch that keeps the air conditioner and heater from operating
simultaneously. The climate control unit is operated via a PID controller
(Type 23). In addition, the space also has an internal heat load due to
some electronics, hence the three type 9a components and the Type 41c.
If the heat from the CCU is input into Type 56 through the heating function
in TRNBuild and the cooling output from the CCU is attached likewise, there
are a number of points over the course of the TMY2 year at which the program
"bogs down" and stops with the calculations though no error message is
produced. Occasionally an error message will pop up stating that there are
6 errors (no matter how many I have set to allow within the control cards),
which all relate to temperature divergence at a wall, according to the list
file. I have tried increasing the convergence tolerance with no luck.
If the cooling portion is removed, the program proceeds fine, with or
without the internal loads attached.
I have sought help for a similar problem, to which I was suggested to
decrease the cooling output and/or decrease the time interval to aid in
convergence. I've tried reducing the cooling input to very low values (the
DLL I'm sending has it cut in half) with no luck. The current time interval
is a dreadfully slow 5 seconds.
I have also tried connecting the cooling output of the CCU to the Type 56
using the gain function (using a negative value as input) with the same
result.
Attached are the project, bui, component (fortran and proforma) files and
the DLL.
Please help!
Thanks,
Ethan Lust
University of Maryland
</pre>
<pre wrap="">
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