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Dear Christoph, Thank you for response! But we need to be more clear: When we set: · boundary conditions = IDENTICAL · AIR temperature in zone is about 24 C · Temperature of inlet water (active layer) is about 18 C (and outlet almost 19 C) · Convective heat transfer coefficient on back surface is set FLOOR Then temperature on back surface is about 26 C. In other words Tso is higher than Tsi and water temperature, while there is no internal heat gains. Why? Kind regards, Karol From: hotline [mailto:hotline@Transsolar.com] Dear Karol and Katarzyna, If boundary conditions = IDENTICAL, the surface temperatures of the active wall Tsi and Tso will only be identical, if: - Wall construction is symmetrical - Convective heat transfer coefficients (front and back) are the same Best __________________________________________________________________________________________________ Christoph Stetter M.Eng. Transsolar Energietechnik GmbH Curiestraße 2 70563 Stuttgart Transsolar: KlimaEngineering- Technologien für energieeffizientes Bauen und Nutzerkomfort in Gebäuden Stuttgart – München – New York – Paris Geschäftsführer :Diplom-Ingenieur Matthias Schuler, Diplom-Ingenieur Thomas Auer, Diplom-Physiker Stefan Holst, Diplom-Betriebswirt Dieter Schnelle Eingetragen beim Amtsgericht Stuttgart HRB 23347, Steuernummer: 99073/00911,USt-IdNr.: DE 152272639 Von: TRNSYS-users [mailto:trnsys-users-bounces@lists.onebuilding.org] Im Auftrag von Karol Bandurski via TRNSYS-users Dear Users and Developers, We would like to model active layer as component of TABS. Now our model is one zone with active layer in ceiling. Adiabatic condition/IDENTICAL for all internal partition and set. We have one external wall. 1) We would like to keep neighborhood zones in the same AIR temperature. But when we set boundary condition to IDENTICAL over TABS, then outer surface of this partition has higher temperature then indoor air temperature and active layer water temperature… -Why? 2) The situation is better if we set convective heat transfer coefficient, on outer surface of TABS to 0.001. If we understand, it is mean direct contact between air and surface. So if there are adiabatic/identical condition: outer SURFACE temperature of TABS has the same temperature as AIR inside modelled zone. But our aim is to keep identical inside and outside AIR temperature, not SURFACE temperature… How we can do it? Kind regards, -------------------------------------------------------------------- Karol BANDURSKI M. Sc. Faculty of Civil and Environemntal Engeneering Division of Heating, Air Conditioning and Air Protection Poznan University of Technology https://www.researchgate.net/profile/Karol_Bandurski www.put.poznan.pl/~karol.bandurski |