Weihua, First, if you are using Trnsys18 then I would recommend that you work your way through some of the tutorials that are in the 09-Tutorials.pdf (..\Trnsys18\Documentation). There are a lot of issues in your email that are very fundamental to the correct use of Trnsys and that would be worth understanding well. The warnings
that you refer to are probably warnings about timesteps when the
simulated system did not converge. TRNSYS has a limit so that if
more than a certain number of warnings are generated, the
simulation will terminate with an error. You can adjust the
allowable number of warnings before the error but I would not
recommend you do so; non convergence issues should be corrected.
It is hard to tell you how to solve convergence problems; it depends on what you're simulating. The usual problems are that you do not have any enough thermal mass in the loops of a system. For instance if you have a Type1 solar collector, pump and heat exchanger model in a loop then those are all quasi steady state models and there is no thermal mass. The models will react unrealistically fast to external changes and may result in convergence problems. The other typical problem is too long a time step. Trnsys can only make one control decision per time step. If you are controlling a system with a 1 hour time step then the system will likely be unstable and have problems converging. I recommend using something between a 1 and 5 minute timestep. For your question about the active layer I would recommend that you refer to the Type56 manual to understand the limitations on the model. kind regards, David On 08/08/2018 19:48, 吕伟华 via
TRNSYS-users wrote:
-- *************************** David BRADLEY Principal Thermal Energy Systems Specialists, LLC 3 North Pinckney Street - suite 202 Madison, WI 53703 USA P:+1.608.274.2577 F:+1.608.278.1475 d.bradley@tess-inc.com http://www.tess-inc.com http://www.trnsys.com |