[TRNSYS-users] Accuracy of simulation / deviation from output and input fluid temperatures

[lukas.spitalny at tu-dortmund.de]

Dear all,

I've modeled a building heating simulation with following main elements: a heat pump (type401) connected to a  stratified storage tank (type4a), and a building (type56) connected to the storage tank. The types are connected with single speed pumps (type114) (pump efficiency and motor efficiency is set to 1, heat loss fraction 0). The heat transfer into the building is realized by active layer in type56. Actually the simulation works, but if I look in the plotted results (type65c excel file) there are deviations in the input and output temperatures of the fluids. For example the input temperature of the active layer differs from the output of the connected single speed pump (which are directly connected). The deviations are quite low (3 places after the decimal point for example 33.0716522857412 and 33.0703189827348). However, I'm wondering why there is a deviation because the output value should be the same as the input value?! Since I'm simulating in one minute time steps I got a significant error in the energy balance about one percent. In the control cards I've have already set the "tolerance integration" and "tolerance convergence" to 0.0001. Does anyone has an advice how I can choose this problem?

Thank you very much in advance for an advice.

Kind regards

Lukas Spitalny

--
Lukas Spitalny, M. Sc.
Research Associate

TU Dortmund University
Institute of Energy Systems, Energy Efficiency and Energy Economics
Emil-Figge-Str. 68
44227 Dortmund

Phone: +49 (0)231 / 755-4305
Fax: +49 (0)231 / 755-4338
Mail: lukas.spitalny at tu-dortmund.de<mailto:lukas.spitalny at tu-dortmund.de>
www.ie3.tu-dortmund.de<http://www.ie3.tu-dortmund.de/>



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