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Hooman, I doubt that Type2 is doing the wrong thing. It might be worth reading the reference manual section on Type2 if my reply does not make sense but my guess is that early in the morning there is enough solar energy to heat up the stagnant collector fluid above the Type2 turn on temperature difference. However, as soon as the pump starts flowing the outlet temperature drops again because there is not enough solar to maintain the outlet temperature of flowing liquid above the temperature difference. The controller probably oscillates back and forth between the possible decisions (pump on vs pump off) and cannot converge so it "sticks." In your case it sticks in the pump-off position so you see a bit temperature spike until there is enough solar radiation to maintain the outlet temperature above the turn-on temperature difference. If you are using Type1 then it is important to be aware that this collector model ignores the thermal capacitance of the collector materials themselves as well as that of the fluid contained in the collector. As a result the collector reacts to changes very fast (sometimes unrealistically fast). You could use Type539 from the TESS Solar library if you have access to it. That collector model accounts for the capacitance of the collector itself. Also make sure that you are using a reasonably short timestep (1-5 minutes) and that there is not some unrealistic mismatch between the size of the tank, the area of the collector array and the flow rate of the pump. kind regards, David
On 09/15/2018 04:48, Hooman Azad 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 |