Welcome to the TRNSYS Users Forum.
The forum is a place where people can interact and have discussions about different topics involving the use of the TRNSYS software package. Here you can post topics for discussion or questions on using TRNSYS and get advice from other users or TRNSYS experts. This forum is not intended for detailed technical support. Users should contact their distributor’s hotline for such assistance.
Some tips for success on using the forum:
- Follow the Forum Rules posted in Forum Administration.
- There are categories for different types of topics and questions. Post your topic or question into the proper category.
- Before posting a topic or question search the existing topics (and the TRNSYS Users listserv archive) to see if a similar topic or question has already been answered.
- Use a descriptive topic name. Don’t use attention getting subjects, they don’t get attention and only annoy people.
- State the version of TRNSYS and which add-ons your are using.
- Include enough specific details for your topic of question to be answered. Just posting “Why am I getting an error?” without describing the specific error and what you are trying to do when you get the error will not receive a response that fixes your issue.
- Remember when people help you, they are doing you a favor. Be patient, help people out by posting good descriptions of what you need help with, and be polite even if a response does not solve your issue.
- Moderators may edit your post for clarity or move your topic to a more appropriate category.
TRNSYS documentation recommends a multiplication factor of 5-10xAir capacitance for a furnished air node. ASRAE, European standards recommend adjusting the capacitance of furnished Airnode based on model calibration (capacitance of furniture to minimize RMSE of simulation and observed zone temperature). Is there anyway to dynamically change the capacitance of an airnode and find the optimum one using algorithms available in TRNOPT? To my knowledge air node capacitance in TRNSYS cannot be dynamically changed. Any comments on this will be highly appreciated. Thanks.
TimMcDowell 06/06/2023 3:59 pm
@tm-abir-ahsan Since the zone capacitance cannot be exposed as an input to the Type56 building model it cannot be changed by TRNOpt. There are other optimization options available (like using GenOpt directly or Python scripting) that involve modifying the building input file directly and running the simulations. These processes take a deep knowledge of the structure of the building input file (see the Multizone Building volume of the TRNSYS documentation set) and how the optimization processes modify files and execute simulations. A first step would be to run your simulation at a high and low value of capacitance and see how those results compare to your measured temperatures. This may lead you to conclusions on the capacitance without needing a full blown optimization.
Hi Tim, Thanks for your help. I would request TRNSYS to include this modification so that users can calibrate their model which I believe is a common practice.
DavidBradley 16/06/2023 3:09 pm
@tm-abir-ahsan
There is a model of a lumped capacitance in the TESS Loads and Structures library (Type963). It can be coupled to Type56 to model a varying amount of thermal capacitance in a zone and because it is its own Type, it can also be exposed to TRNOpt.
kind regards,
David
Hi David, That was super helpful. Thank you so much, I will use that one then!
