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Hi TRNSYS Users,
I have a question regarding the possibility of running multiple multizone building s simulation which interact with a district network. Since it is not possible to model multiple multizone buildings in one project, I was wondering if it would be possible to correlate multiple models using a piece of external code or not? As far as I know, it is not possible to gain access to output text files from a model, unless the modelling is terminated. I was thinking about writing the files to type 25 in one model and use type 9 to read it in another model.
I would appreciate it if anyone who has experience with this problem would respond to this message.
Thanks
In case it is not possible, how would it be possible to extract data from the the building side temperature and mass flow rate profile and feed it into the network side of the system, considering the fact that the models are highly dynamic and the return/supply temperature from/to building's heat pump is not constant?
I'm not sure if this is the answer to your question, but it is possible to include multiple multi-zone buildings in a single .b18 file.
ShamsoddinGhiami Topic starter
11/09/2024 10:10 am
Thanks @yuichiyasuda for your response and suggestion.
You are absolutely right about. It is possible to sketch multiple multizone buildings in a single .bui file. However, since too many buildings are in the system, many of them identical, it would not be efficient to model each and every building in a single SketchUp model as different systems are needed to be integrated into each building.
@shamsoddinghiami and @yuichiyasuda This is a great topic. We have been doing a lot of work on district and ambient loop systems recently. The method that we use is to generate the building loads in a first step either using Type56 or more often using other energy modeling software tools altogether. We then get their hourly heating, cooling, and water heating requirements into one or more data files, read them into a TRNSYS simulation using Type9 and then impose them on the appropriate points in the distribution network using the "flowstream loads" components that are in the TESS Loads and Structures library.
kind regards,
David
ShamsoddinGhiami Topic starter
21/10/2024 7:06 pm
Thanks @davidbradley for your response.
Just one question which is a bit tricky to model in the network side of the project. Each end-user building is connected to a tank which is a medium between the building and network.
On the building side of the project, the tank temperature was controlled by an external flow (which is expected to be provided by the network with 8000 kg/hr water flow at 16C) and would be connected to the network (as you said by type 682). However, designing the network in a way that provides the flow rate a the same temperature of 16C is not an easy task as the fluid temperature is affected by the pipeline heat dissipation due to external weather condition.
Moreover, the controller (for instance type2) has a dead band that set a fluctuating water temperature to the load. It is therefore not possible to have an accurate network design for the system.
Would you please give me a hint on this issue.
Thanks @davidbradley for your response.
Just one question which is a bit tricky to model in the network side of the project. Each end-user building is connected to a tank which is a medium between the building and network.
On the building side of the project, the tank temperature was controlled by an external flow (which is expected to be provided by the network with 8000 kg/hr water flow at 16C) and would be connected to the network (as you said by type 682). However, designing the network in a way that provides the flow rate a the same temperature of 16C is not an easy task as the fluid temperature is affected by the pipeline heat dissipation due to external weather condition.
Moreover, the controller (for instance type2) has a dead band that set a fluctuating water temperature to the load. It is therefore not possible to have an accurate network design for the system.
Would you please give me a hint on this issue.
@shamsoddinghiami It is a bit hard to give an answer simply because there are dozens of different ways that the system could be designed. I'll try to give some general ideas...Type2 is mainly appropriate for situations in which you have on/off pumping. In most network systems, many if not all the flows are variable so as to maintain a temperature difference across each load. If you know what the building loads are and you know the temperature difference that you want to maintain then you can calculate the required flow that the network has to provide. If you are seeing big drops in temperature between the supply and the building (more than a few tenths of a degree C) then perhaps the flow rates are too low or there needs to be more insulation on the network piping. If the tanks are providing a small hydraulic buffer between the network and the building then one thing you could try is to put variable speed pumping on the building side (by knowing the load and the desired delta T) and a thermostat on the tank (Type2 could be used in this case). Your network would then have to provide liquid to the tank at a temperature colder (assuming that you are dealing with a cooling load) than 16C whenever the tank temperature rises above the deadband. Maybe when the tank gets to 17C you'd turn on the 8000kg/h until the tank returns to 15C. That strategy assumes that the load can be met with temperatures anywhere between 15 and 17C. If that is not the case and the load must be supplied with 16C then you'd need to add a tempering loop on the building side so that some return water is mixed in with the tank water so that the supply temperature to the building stays at 16C. There are tempering valve controller models in the TESS Control library.
I hope something in there proves helpful!
david
ShamsoddinGhiami Topic starter
28/10/2024 7:22 pm
@davidbradley
Are there any limitation on the instances of Type 682 within a single project? I used two of them in the project (one for heating load and one for the cooling load) and the cooling load is not considered in the model.
Thanks
Shams
@shamsoddinghiami no, there is not a limitation on the number of instances of Type682 that can be in a project.
