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Hello. I modeled a domestic hot water system in TRNSYS and I use Type 14 for a daily profile but it would be cumbersome to do an annual profile with it. Fortunately, I understand in the documentation that Type 41 may be used to take into account the seasonal variability of the DHW demand I have not been able to understand the use of Type 41 as described in the Mathematical Reference. I present here a simple case:
1/ I have 4 profiles during the year, one for each season: summer, winter, spring and fall. During each season, I have the same profile for the 5 working days and another one for the 2 weekend days. I don't care about special holidays. How do I proceed with Type 41?
2/ Alternatively, is it possible to provide a text file to TRNSYS, with a profile for the whole year (e.g. one column for the time, from 0 to 8760, and a value for the flow)?
3/ Alternatively, if I proceed with type 14 on a weekly basis, after a first week for instance, would I save the status of the system in order to launch the following weeks (with a new type 14 profile) and so on, for the 52 weeks? This actually means a new Type 14 for each season and the status of the system should be saved to start the following season.
Thank you.
Ken,
1) If you want to use Type 41 to do this, I would first build the eight daily profiles you want (weekday winter, weekend winter, weekday spring, weekend spring, etc.) as Type 14 forcing functions. Then I would write something like the following in an equation block:
IsWinter = LT(Time,2190) IsSpring = GE(Time,2190)*LT(Time,4380) IsSummer=GE(Time,4380)*LT(Time,6570) IsFall=GE(Time,6570) WeekdayDraw = IsWinter*WinterWeekday + IsSpring*SpringWeekday + IsSummer*SummerWeekday + IsFall*FallWeekday WeekendDraw = IsWinter*WinterWeekend + IsSpring*SpringWeekend + IsSummer*SummerWeekend + IsFall*FallWeekend
'Time' is a variable TRNSYS already recognizes as the hour of the year, you don't have to connect it or do anything else to define it. Connect 'WinterWeekday', 'WinterWeekend', etc. from the outputs of their respective forcing functions, and connect 'WeekdayDraw' and 'WeekendDraw' to their corresponding inputs in Type 41. You probably want to tweak those start and stop hours for each season, and I should note that this won't repeat annually if you want to run a simulation longer than 8760 hours ... still, it should give you a good starting point for what you're trying to accomplish.
(LT = "less than", GE = "greater than or equal to" - these and other logic functions are explained in the TRNEdit documentation, under "Available mathematical functions". You can also reference this post I wrote on the forum about using equation blocks to write IF statements).
2) Yes, you can provide a text file to TRNSYS with the profile for the whole year. Use the Type 9 data reader (also in the Utilities library) to do that. That may actually be easier than building eight forcing function profiles and wiring them up through the equation block and through Type 41 to get exactly the profile you want.
Ken Topic starter
08/06/2023 11:07 am
@a_weiss
Dear a_weiss , thank you very much for your detailed suggestions. I have just implemented the second solution (use of Type 9) and it works perfectly. So, my issue is solved.
I however wonder what could be the interest of the solution with Type 41 since it is very easy to generate a file to be read by Type 9. Thanks.
A_Weiss 08/06/2023 1:54 pm
@ken Depends on the situation. If you had a profile that you only wanted to run on weekdays, and be 0 on weekends and/or holidays, it would be very easy to connect that profile to the 'weekday' input of Type 41 and leave the weekend/holiday input unconnected at 0. That may be easier than manually copy/pasting the profile in a spreadsheet program and keeping track of weekday/weekend/holiday days while doing so. But there's no right or wrong way to do it, as long as the solution works for your situation. Flexibility is one of the major selling points of TRNSYS!
