[TRNSYS-users] Type 71: Input 5, Incident Diffuse Radiation

[Matt Duffy]

José,

My colleague just brought a good point to my attention.  You may also sum
together the sky diffuse radiation and the ground-reflected diffuse in an
equation and connect that to the "incident diffuse radiation" in Type71. 
That would be better practice since the ground-reflected diffuse is
non-zero.

Best regards,

Matt Duffy



----- Original Message -----
From: "Matt Duffy"
Sent: Wed, August 20, 2008 13:34
Subject:Re: [TRNSYS-users] Type 71: Input 5, Incident Diffuse Radiation


José,

The "sky diffuse radiation on tilted surface" is the output of Type109
that you connect to the input of "incident diffuse radiation" to Type71.
Please make sure that the units match.  The ground reflected radiation is
usually minimal unless there is a significant amount of snow  that is
reflecting radiation towards the collector surface.  That is why some of
the general collector component models ignore ground reflectance.  Please
refer to Duffie and Beckman for more detailed information.

Best regards,

Matt Duffy



----- Original Message -----
From: José Luis Corrales Ciganda
Sent: Fri, August 15, 2008 8:09
Subject:[TRNSYS-users] Type 71: Input 5, Incident Diffuse Radiation


Dear TRNSYS Users:

I have a question concerning the use of Type 71 for the simulation of a
Evacuated Tube Collector Field.

There are two inputs to this Type passing the radiation data: the total
incident radiation and the incident diffuse radiation. I´m trying to use
radiation data computed with Type 109.
I have linked the "total radiation on tilted surface" output of Type 109
with the "Incident Radiation" input. But I have doubts concerning the
input 5 of Type 71, "Incident diffuse radiation". I don´t know if I should
link it with the "sky diffuse radiation on tilted surface" output from Typ
109 or with the "ground reflected diffused radiation on tilted surface". I
tried to find out how the type 71 uses this input, but i didn´t find it.
Why is this "incident diffuse radiation" necesary? It is the total
incident diffuse radiation on the tilted surface? Or only the sky diffuse
or the ground reflected radiation?

Maybe I am a litlle bit confused with the terms used.

I will appreciate any answer from, thank you in advance.

Kind Regards,

José L.




*********************************************

Technische Universität Berlin

José Luis Corrales Ciganda / Sekr. KT 2

Institut für Energietechnik

Marchstrasse 18

10587 Berlin

Tel.:      +49 30 314 22126

Fax.:    +49 30 314 22253

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