[TRNSYS-users] solar collector

[saja al-rifai]

Hello,

I'm simulating different types of solar collector. I want to investigate the effect of collector slope on useful energy. but if I increase the collector slope when I use the flat plate collector type 1b, the useful energy from collector decreased and the maximum useful energy occurred at 0 deg angle (horizontal), even though the latitude for my region 32 deg, which meaning the useful energy should be increase and not decrease at angles near the latitude angle .
but when I used the evacuated tube type 71, the useful energy increased with angle.
I returned to the TRNSYS mathematical reference, flat plate and evacuated tube collectors used the same thermal model and different IAM model. 
in case of flat plate collectors the IAM for both sky and diffuse radiation depends on the collector slope, if collector slope increase the effective sky and diffuse angle decrease, resulted in decrease the IAM, collector efficiency and useful energy. these results according to TRNSYS mathematical description.
 practically, the useful energy should be increase for flat plate as evacuated tube if the collector slope increase.   
does someone have an idea about this issue? 

saja
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