Marco,
Simply include pipes in your system and choose a pipe model that takes into account not only the thermal capacitance of the fluid but also that of the the pipe wall and insulation. As a nice approximation, you can also create one pipe that has the same volume as the volume of all the pipes that lead to the collectors and the same surface area as the surface area of all the pipes that lead to the collector. With a bit of work, you can also calculate the effective insulation thickness that gives you the same thermal resistance. Repeat the process for the pipes returning from the collector array.
Jeff
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Jeff Thornton
President - TESS LLC
22 N. Carroll Street, Madison WI USA 53703
Office: (608) 274-2577 Fax: (608) 278-1475
www.tess-inc.com
E-Mail: thornton@tess-inc.com
On 10/10/2012 7:34 am, Marco Scarpellino wrote:
Dear all,
I am trying to simulate with TRNSYS a solar cooling system.
I am not able to simulate the thermal capacitance of the piping of the plant. I try to explain better what I mean: in the early morning, in the real condition, the pipe has a temperature equal to the ambient temperature, because of the stop of the plant during nighttime and the consequent temperature decrease. When the pump starts to run and the panels begin to work the temperature of the piping rises until it reaches the fluid working temperature. The energy that we produce with the solar thermal panels in the meantime is used to raise the temperature of the whole piping. How I can take into account this loss of energy?
I am at your disposal for any clarification you may need.
Thanks in advance for your help.
Best Regards,
Marco Scarpellino