[TRNSYS-users] Cpc - type 74_ variation of acceptance angle

[Aditi Garg]

Yes. It is right that typer 74 is based for a constant aperture area. I
would like to know what should one change in the parameters so that results
should not contradict the theoretical fact of temperature increase with
higher GCR.



On Tue, Oct 1, 2019 at 9:39 AM Arian Bahrami via TRNSYS-users <
trnsys-users at lists.onebuilding.org> wrote:

> Hi,
>
> The type 74 is based on constant aperture area not based on absorber area.
> So when you increase the half acceptance angle when the aperture area is
> fixed it means that the CPC performance approachs flat plate performance so
> you got higher output. The notation you are using here is when the absorber
> area is fixed and as GCR increases when the absorber area is fixed, the
> output would be higher due to the fact the aperature area would be higher
> in this case.
>
> Arian
>
>
> Sent from Yahoo Mail for iPhone
> <https://overview.mail.yahoo.com/?.src=iOS>
>
> On Monday, September 30, 2019, 9:44 AM, Aditi Garg via TRNSYS-users <
> trnsys-users at lists.onebuilding.org> wrote:
>
> Dear all
>
> I am working with type 74 (cpc-solar collector). I am using it in a small
> circuit for water heating purpose. I had tried to vary the half acceptance
> angle parameter for cpc (30-65 degrees). Theoretically, with an increase in
> half acceptance angle value, the geometrical concentration ratio (GCR) will
> decrease and related by correlation, GCR=1/SIN (half acceptance angle).
>
> Now, the results indicate that with an increase in half-acceptance angle,
> the collector outlet temperature is increasing. However, it also means that
> with decreasing GCR, the temperature is increasing. This contradicts the
> theoretical fact that temperature increase with an increase in GCR.
>
> Besides, in the mathematical reference given in volume-4, page 552, the
> correlation for useful heat gain, the overall heat loss coefficient (UL) is
> also not divided by GCR. Generally, in concentrating collectors, the heat
> losses are divided by GCR.
>
>
> Any help regarding this doubt will be appreciated.
>
> Thanks
> Best regards
> Aditi
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