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TESS is pleased to announce the availability of a newly implemented model of a two-pipe VRF air handler.
The component models an air source heat pump in which a single outdoor unit serves multiple indoor units. In a two-pipe configuration the indoor units must all either be in heating mode or cooling mode. A mixed mode in which some indoor units are in heating mode while others are in cooling mode is not possible. Not all the indoor units need to be active; some may simply be OFF. As is the case for many of the TRNSYS HVAC components, the performance of the VRF air handler is based on a performance map.
The component is being offered as an individual component for the time being. More information is available by visiting:
https://trnsys.com/tess-libraries/individual-components.php.html
hello
Is there a tutorial on how to develop a VRF heat pump model in TRNSYS?
@oumaima The new Type (Type1254) includes a documented example. I would not really call the example a tutorial because while the documentation explains the details of the completed example, it doesn't really take you step by step through setting up a model. I can share the documentation with you if you'd like. Please email me directly: techsupport@tess-inc.com
kind regards,
David
Hello David,
I have sent you an email about this type1254. I am interested in know about if the model is simplified based on manufacturer curves or if it is a more detail model based on physics. I would like to see the documentation before to buy this new component. Would be possible?
Francisco, For some reason I did not receive the email but I think I found yours so I will send you the documentation. I am afraid that the model is based on performance data from manufacturers and not on physics.
David
Don't worry David, I have paid this type and I am happy with how it works. Only one question, the number of zones served by the heat pump is limited to 10?
This could be a limitation in VRF applications with high power heat pumps which serve more than 10 zones.
@franciscofh Francisco, the 10-zone limit is a soft one; it can be modified by editing the proforma and recompiling the code with a different limit. If you need a version with a higher limit, please let me know and I can make it for you.
kind regards,
David
@davidbradley perfect! Great news! I can modify the type without problems. Thank you for your help
Hello, @davidbradley, I have some problems with the 2-Pipe Variable Refrigerant Flow model type1254. I bought this model 4 months ago and yesterday I tried to simulate the example provided and the typical error of Invalid floating point operation appeared.
Do you have the same problems with this type?
Thank you
@franciscofh, could you please send the project *.tpf, the data files it is using, and any other files needed in order to run the model (even if you didn't modify anything) to TESS's hotline? I don't get that error when I run the example and would like to see if I do with your version. If you don't have TESS's hotline email address, it can be found at https://trnsys.com/contact/index.html
kind regards,
David
@davidbradley, thank you for your support but I finally got the model to work properly. I checked the code and there were some equations where there could be a division by zero. Now the model works well.
Kind Regards,
Francisco
Hello,
Sorry again. I have checked that although the VRF model type1254 can be simulated, the results of the example provided are not accurate. The air temperatures of the zones are not conditioned by the VRF model because the air flow rate output of the type is always 0. I have checked in the code that the parameter corresponding to "Rated indoor unit air flow rate for zone i" is used for the calculation of this output but the value of the parameter is zero although I set a value in the proforma.
Please, can you check it?
Thank you
Hi again,
I have found a problem with the type and the variable
Type (unitSpecs) :: indoorUnit(nMaxZones)
which unitSpecs is defined before as:
Type unitSpecs
Double Precision :: lpsAir = 0.d0
...
End Type
If for exameple indoorUnit(i)%lpsAir is defined as a parameter, the value of the parameter which is set in the proforma is not assigned in this variable and it always takes the initial value defined at the beggining of the model. However, if indoorUnit(i)%lpsAir is defined as an input, there is no problem, and the results are well calculated. I have carefully checked it.
Please, can you tell me something about this? The solution could be changing these parameters with the variable indoorUnit(i)%... to inputs but I don't know if it could be another better solution.
Thank you for your support.
Francisco
@franciscofh could you please send the project (*.tpf) and any files required in order to run the project to techsupport@tess-inc.com. If there is a bug in the code, I will need to run a project that causes the problem in order to find a solution.
kind regards,
David
