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Re: [TRNSYS-users] Heating pipes model




David,

Thanks for your explanation. But my real concern is whether Type 31/709 is suitable as a model for heating pipes in a greenhouse, since I do not have Type 604.

Kind regards,
Knut Erik



David Bradley <bradley@tess-inc.com>

05/14/2009 08:05 PM

To
knut.erik.enerstvedt@niva.no
cc
thornton@tess-inc.com, trnsys-users@engr.wisc.edu
Subject
Re: [TRNSYS-users] Heating pipes model





Knut Erik,
Type31 and 709 take an overall UA for losses from the pipe. Where Type604 goes a bit farther is to calculate the loss coefficient based on some natural convection correlations. I think it also separates out convection and radiation and accounts for the thermal mass of the pipe and insulation.
Kind regards,
David


knut.erik.enerstvedt@niva.nowrote:

Jeff,


Thank you for answering my question.


However, I can't seem to find Type 604 in the TESS Hydronics library. Instead, I see that Type 604 is listed among the individual TESS components. Do you think it would be possible to use Type 31 or Type 709 (TESS Hydronics) instead, connecting the "environment losses" output as GAIN in Type 56, or is this a bad idea since I can not separate conective and radiative gains?


Kind regards,
Knut Erik



"Jeff Thornton" <thornton@tess-inc.com>

05/12/2009 07:21 PM

Please respond to
thornton@tess-inc.com


To
knut.erik.enerstvedt@niva.no, trnsys-users@engr.wisc.edu
cc
Subject
Re: [TRNSYS-users] Heating pipes model







<I need to model heating pipes commonly found in greenhouses. The pipes
are in loops located 15 cm above the floor, 1 m above the floor, along the
walls and somewhat below the ceiling. Hot water flows in the pipes and
heats up the greenhouse. I use Type 56 to model the greenhouse, but have
not yet succeded in finding a model for the heating pipes. Does anyone
know an appropriate model for the heating pipes and how to use it in
combination with Type 56? >

We use the Type 604 model (TESS Hydronics) which accounts for the
convective and radiative heat transfer to the zone.  Then simply set up a
new "gain" inside of Type 56 and set the radiative and convective gains as
inputs to Type 56.  Then make the connections from Type 56 to the pipe
(zone temperature and effective surface temperature) and from the pipe to
Type 56 (radiative heat transfer and convective heat transfer).

Jeff


Jeff Thornton
President - TESS, LLC

22 North Carroll Street - Suite 370
Madison WI 53703 USA

Phone: 608-274-2577
Fax: 608-278-1475
E-mail:
thornton@tess-inc.com
Web:
www.tess-inc.com


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