Re: [TRNSYS-users] Type 15-2: Relationship between data arrangements, simulation times and convergence

[David BRADLEY <d.bradley@tess-inc.com>]

Ciarán,
  Option 1) is incorrect. Type15 is intended to be used with year-long weather files that have a 1-hour data interval. The component knows from the simulation start and stop time what day of the year it is, so if you trick it by setting the simulation start time to hour zero and rearrange the weather file to start in the middle of the year, what the Type calculates about the sunup and sundown times and what the data file says is happening are not going to match at all. Option 2 is the only correct one.
Best,
 David
 

On 11/12/2012 06:32, Flynn Ciaran wrote:

Hello,

 

I have a couple of questions concerning the relationship between the arrangement of data in TMY2 weather files, TRNSYS simulation times and convergence errors. I tried looking at the source code but I could not figure out the answer..
I am running a simulation for one year, using Type 15-2 for weather, starting at 1h on July 1^st and ending at 24h on June 30^th. This leaves me with two options:
1) Either I rearrange the tm2 file to start at 1h on the 1^st of July and end at 24h on June 30^th, and set the simulation start and stop times to 0 and 8760h respectively, or
2) Either I leave the weather file as it is and set the simulation start and stop times at 4344h and 13104h respectively.

 

When I use a provided weather file (e.g. CA-BC-Vancouver-718920.tm2) and set the simulation time step at 0.1h, I get the following:

 

	Failed convergence time steps	Time steps where: calculated total horizontal radiation > horizontal extraterrestrial radiation	Time steps where: direct normal radiation > solar constant	Time steps where: calculated horizontal beam radiation > total horizontal radiation
1)	7719	10664	124	3498
2)	6424	-	-	13

 

So my question are:

-          Why is TRNSYS giving different error messages if the same weather data are used ? (I believe that there are no other types in my file that could explain the reason for this)

-          What parameters do the radiation values calculated by TRNSYS depend on and how are they calculated?

-          What is the best approach in this situation (minimal radiation errors)?

 

Thanks a lot,

Ciarán

 

 

 

 

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