In the case without the forcing function, there are 700W/m2 of solar radiation incident on the collector surface at all times. In the case with the forcing function there is whatever amount of solar radiation that the forcing function determines there to be. Please bear in mind that when you change the units of an input, TRNSYS does not perform any automatic unit conversions. The Type expects to receive a value in the default units (kJ/h.m2 in this case). If your forcing function is giving a value, that value is being interpreted by Type538 as being given in kJ/h.m2.
kind regards,
David
============================================Hi there,
I'm working on solar water heating system.I wanted to test the performance of the weather file before using it, by replacing it with the generic forcing function type 14h to keep the beam radiation on the tilted surface of component type 538 . I compared the outlet temperature with and without the forcing functions type 14h.
I plotted the output temperature on the online printer,but the model without the forcing function gave an output temperature of 20.8 degrees while output temp. of the model with the forcing function was 15.8 degrees. Find screenshot of the two above. What is the reason for the difference in the output temperature of the models?
Regards
Idris
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-- *************************** David BRADLEY Principal Thermal Energy Systems Specialists, LLC 22 North Carroll Street - suite 370 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