Hey David, i saw that there is a Type 177 that was used by IEA - SHC task 25. This model is freely available at www.eta.tu-berlin.de, however the author at this site doesn't give the source code of the model. I realized that one of the four options under this type was specifically developed for Yazaki model WFC 10, the exact chiller model i am simulating. He suggests that we can get the source code from from www.iea-shc-task25.com, but i checked this source and it so happened that source code link is nolonger available since 2009. Could you be having an idea of how i can get this source code??? thanks
Martin,
I would recommend that you make a very simple project where the
chiller is subject to a known constant load with known constant
outdoor conditions. Hook up a Type65 online plotter to the chiller
and take a look at its performance under these known conditions;
once the model looks up the performance data in the data file, its
computations are really quite simplistic. You can verify them by
hand using the documentation in the 04-Mathematical Reference. This
will give you some confidence in your model.
One of the issues that often occurs in modeling absorption
chillers is that if you compute a building load and pass it directly
to the chiller then the chiller spends a lot of its time running at
a very very low part load. In reality, a chiller can't operate much
below 20% capacity so you have to make sure that this is reflected
in the data file. The data file should have near zero capacity and
near zero fraction of design energy input below about 20% PLR (part
load ratio). At one time, I think there was an error in the Type107
example data file that showed too large a capacity at very low PLR.
The more correct way to model the system would be to place the
chiller on its own primary loop and to place the load on a secondary
loop. The loops can be separated by a thermal storage tank whose
volume is equal to the volume of the primary and secondary loops.
The chiller operates to keep the primary loop cold and the secondary
loop draws off only as much as it needs to meet the load.
Kind regards,
David
On 12/19/2012 01:51, Martin Ssembatya
wrote:
Hello there,
I have been modelling a solar ooling system that uses one
of the YAazaki chiller models. I used type 107 for the
modelling of the absorption chiller partly because i did not
have satisfactory chiller performance data from the
manufacturer to model the chiller unit, but alos because i did
not have enough time and compiling language to create my own
model for this chiller. But on using type 107 for this
purpose, i am not getting satifactory results from my
simulation i.e. the chilling energy is always too low
compared to the rated capacity of the chiller regardless of
the season of the year, including summer periods with high
insolation values. Is there any one who could have created a
TRNSYS model for any Yazaki absorption chiller unit? If yes,
can you kindly help me with that model you created and to
use it in my simulation and see its effect on results. I
will be very grateful.
Martin,
A few years back, I was faced with modeling some greenhouses that
were covered by a plastic film. I ended up modeling them as a window
in Type56 and worked a lot in LBNL's WINDOW5 software to create a
glazing system that represented the plastic film. The process was no
different from creating any other new window for TRNBuild/Type56. I
wasn't entirely happy with the solution in part because of the
diffusion of the incoming solar caused by the plastic. However, it
was the best I could do at the time and the results were
defensible. At the time, I also looked for (and found) some models
of actual greenhouses that people had developed. None of them suited
the project very well but that might be a good avenue to pursue as
well.
Kind regards,
David
On 12/12/2012 02:26, Martin Ssembatya
wrote:
Hello there,
I am using TRNSYS 16 to estimate the total cooling requirement
of three temporally built structures. One of the structures is a
tent whose vertical walls contain like 50 percent plastic
transparent parts. How can i create a layer and define it to be
transparent to the incoming radiation?? I know that this must be
having a huge effect on the total cooling requirement. Can
someone please help me with some ideas how this can be done?!
Matthias,
I think the answer would depend a lot on the complexity of the
HVAC systems and on the level of detail to which you would need to
model them. The most comprehensive building models that I have done
are for LEED projects (proposed building, proposed mechanical
system, baseline (comparison) building, baseline (comparison) HVAC
system, and lots of report writing). These projects can range from
70 to 200 hours of time with most coming in around 100 to 150.
Again, though, that is modeling two buildings. To model just the one
proposed building, I think you would probably be in the range of 50
to 150 hours.
Some other thoughts for you, though (which I realize you didn't
request... ;-) ). Every model, every building simulation tool that
is out there is some simplification of a real process. The more
assumptions the model developer builds into the model, the simpler
the model is to implement but the less flexible it becomes. The
fewer assumptions that the developer builds in, the more flexible
the tool but the more complexity there is involved with implementing
a system model. I have found it helpful to think of building energy
modeling tools on a sliding scale where on one end are tools that
are relatively quick to use, which have a LOT of built-in
assumptions and which are therefore not very flexible. One the other
end are tools that are very flexible in terms of what you can model
but which are more time consuming to use. TRNSYS is definitely on
the "flexible but complex" end of that scale - intentionally so. If
you are trying to model a building that has some unusual features
(radiant floors, natural ventilation, double skin facades, complex
HVAC systems, etc.) in it then TRNSYS is a good tool to use, even
though it will require more hours to implement the model. If the
building has nothing but conventional envelope and systems then
there is no advantage to TRNSYS (or other tools like it); you will
spend an unnecessarily long time implementing the model. On the
other hand, it may be quick to implement a model in another software
but if the building has features that cannot be modeled by the other
software, you need to change to another, more comprehensive or
flexible tool.
Best,
David
On 12/12/2012 09:30, Matthias Maier wrote:
Hi TRNSYS-users,
I am studying electrical engineering at the Technical
University of Munich and currently I am writing my bachelor´s
thesis at the Institute for Energy Economy and Application
Technology. My subject is the comparison and assessment of
various building simulation programs. Background of this thesis
is the development of an automatized demand side management for
commercial buildings, in case of the emergence of a dynamic
electricity tariff in Germany. Therefor a whole thermal
simulation of the building and it´s HVAC systems would be
necessary.
One of my tasks is to estimate the costs for the implementation of
a building including its HVAC systems. For this reason I selected
an example building to estimate the costs for (added in the
attachment). Support referred me to this user service. I would be
very grateful if anyone could tell me how long it takes to
implement this example building including its HVAC to TRNSYS and
perform a high-resolution simulation (minute-basis) for a
eperienced user.