Marion, Could you explain what kind of heat or mass transfer exist by Virtual surface: 1. Radiation? 2. Convection? 3. Mass transfer? 4. Neither? – virtual surface is perfect insulator If 1-3 : how values of these magnitude are calculated? Regards ------------------------------------------------ Karol Bandurski MSc. Institute of Environmental Engineering Poznan University of Technology From: Marion Hiller [mailto:hiller@transsolar.com] David and Joke, the coupling airflows between two airnodes belonging two different zones are defined by adjacent surfaces (walls/windows). Coupling airflows between two airnodes of the same thermal zone can be defined in the regime. A new button coupling becomes active. Concerning the false ceiling problem of Joke, do you use the detailed radiation modes? I assume not because you do have a shading and the distribution isn’t that important anymore, right? If you use standard radiation mode I suggest that your airnode “false ceiling” doesn’t cover the whole Ceiling area, but only 70 %. The remaining separating vertical surface between the airnode false ceiling and room could be defined as a resistance wall with a high conductivity. Virtual surfaces are defined in Trnsys3D, but they don’t exist in the thermal model. Thus no heat transfer through the virtual surface can be calculated. Virtual surfaces are defined for creating closed volumes for airnodes such that the volume calculation of the airnode is performed correctly. Best, Marion Dipl.-Ing. Marion Hiller Geschäftsführer: Dipl.Ing. Matthias Schuler, Dipl.Ing. Thomas Auer, Dipl.Phys. Stefan Holst, Prof. Dipl.-Ing. Bleicher Von: David BRADLEY [mailto:d.bradley@tess-inc.com] Joke, David, Thanks for the answer. But the problem is that it isn't a 100% false ceiling but about 70%. So what do I do with the "air - air contact" between the two zones. Does Trnsys takes this into account when I model it with a virtual surface in google sketchup or do the airnodes then have to belong to the same thermal zone? Greetings, Joke Van: David BRADLEY [d.bradley@tess-inc.com] Joke, Dear all, Can anyone help me what’s the best way to simulate a suspended false ceiling? The goal is to simulate a class room where the comfort is assured by using night ventilation. However for acoustic reasons we need a false ceiling. I want to know the percentage of suspended false ceiling is possible in order to have still enough inertia from the concrete ceiling. Is the best way just to define two different types of ceiling (1. A concrete ceiling and 2.a false ceiling (concrete + air layer + false ceiling)) or has anyone another idea? Is it possible to draw for example some obstructions in Google sketch up and then to define 3 air nodes in trnsys. One air node above the suspended false ceiling; one air node in the middle of the room and one air node representing the opening window? Will it take into account the less availability of the inertia of the concrete ceiling? Hoping for an answer, Joke De Beuckelaer project engineer mep VK HEALTHCARE | BUILDINGS | INDUSTRY | INFRA Value by design VK ENGINEERING Avenue Clemenceaulaan 87, 1070 Bruxelles Brussel, Belgium ALWAYS LOOKING FOR GREAT PEOPLE ****DISCLAIMER**** _______________________________________________ TRNSYS-users mailing list TRNSYS-users@cae.wisc.edu https://mailman.cae.wisc.edu/listinfo/trnsys-users -- *************************** David BRADLEY Principal Thermal Energy Systems Specialists, LLC 22 North Carroll Street - suite 370 Madison, WI 53703 USA
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P:+1.608.274.2577 F:+1.608.278.1475 d.bradley@tess-inc.com
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