Re: [TRNSYS-users] Ambient temperature

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

Mihai,
  Type109 was found to have a number of issues and so was rewritten with the release of Trnsys17. If you are using a later version of Trnsys16, you might may have access to either Type933 or Type15 and I would highly recommend that you change to using one of these in place of Type109 since you are reading from a *.tm2 file. Type933 and Type15 are the same Type but were released at different times.
Kind regards,
 David

On 12/19/2014 04:49, Mihai T. wrote:

Hello!

I made a simulation in Trnsys to evaluate the heating demand for a office building. Now I need to compare the trnsys results with some results obtained using another method.

Please help me to find how TYPE 109 calculates „Ambient temperature” and how the correspondence with the solar radiation values at the correct time moments is ensured. I am asking you this because the ambient temperature used in simulation is not the same with ambient temperature from the weather data file (dry bulb temperature in the file '...\Trnsys16\Weather\Meteonorm\Europe\RO-Bucuresti-154200.tm2'). I cannot find this information in Trnsys Manual.

The problem found is that, if a shift is made (with 1/2h) to the dry bulb temperature (by averaging two values at 2 consecutive time moments in order to place the average values in the middle of the hour and to match the moment considered for solar calculations), the result is a mismatch between ambient temperature and solar radiation values (with 1 h difference).
I have performed the solar calculation using Perez model and I have found the same values as the ones calculated in trnsys, but with 1 hour shift (to have a correct match between temperatures and radiation the latter should be moved forward with 1 hour).

Please advise and give me some explanations on the calculation procedure used in trnsys.

Thank you for your support,
Mihai Toderașc

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David BRADLEY
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Thermal Energy Systems Specialists, LLC
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