[TRNSYS-users] Collector SRCC test data - Aperture or gross area

[Jeff Thornton]

Janeet, 

Each of the collectors you specified has a gross area of 5.24 square
meters - so with a total area of 42 square meters that means you have 8
collectors. How can you have a string of 5 collectors in series with 8
collectors? In series means that the same molecule of water flows
through 5 collector modules one right after each other. 

You chose efficiency mode 2 - which means your efficiency equation is
based on Tave-Tamb. But the SRCC document clearly lists the efficiency
as Tin-Tamb. Change your efficiency mode to 1. 

<Assuming TRNSYS uses gross areas and average temperatures.> 

Not sure what that means. And don't assume - verify. The TRNSYS
efficiency equation can use of three modes; inlet, average or outlet and
you need to set this correctly. As for gross area - the model wants the
area consistent with the efficiency equation. So if your efficiency is
based on gross area then gross area should be used. 

If you have access to the TESS Libraries I strongly suggest you use Type
538 for the evacuated tube model. It's a significant upgrade over Type
71. 

Did you create an external data file for the IAM's based on the
published data from the certification? Or did you just use a default
external file? 

Jeff 

---
Jeff Thornton
President - TESS LLC
3 N. Pinckney Street, Suite 202, Madison WI USA 53703
Office: (608) 274-2577 Fax: (608) 278-1475
www.tess-inc.com
E-Mail: thornton at tess-inc.com

On 07/15/2020 11:25 pm, janeet anand via TRNSYS-users wrote: 

> Dear Experts, 
> 
> Currently working on a project to simulate an absorption chiller fed from a solar collector. 
> 
> For the solar collector I am using type 71(ETC) of 42m2 collector area. Also attached the SRCC test certificate for the same. Problem is I am getting unacceptable high Outlet fluid temperatures eg. Tin=60 Tou=150 @ flow rate=250. Same is the case if I use test data from the Keymark test and further the outputs do not match with the outputs for the SRCC data. 
> 
> Please could you advise if the parameters are specified correctly and the assumptions mentioned are in line with what is required by TRNSYS. Assuming TRNSYS uses gross areas and average temperatures. 
> 
> 1. NUMBER IN SERIES _5_ - (Solar array design calculated for required flow and outlet temp) 
> 2. COLLECTOR AREA _42 m^2_ (Total gross collector array area, Trnsys will internally calculate nos in parallel) 
> 3. FLUID SPECIFIC HEAT _4.190 kJ/kg.K_ (water)
> 4. EFFICIENCY MODE _2_ - (Tavg based on SRCC ISO efficiency equation note (P)=Ti-Ta)
> 5. FLOW RATE AT TEST CONDITIONS _71.64 kg/hr.m^2_ (SRCC Test mass flow rate .0199*3600-assumption is it is based on gross area and not aperture area )
> 6. INTERCEPT EFFICIENCY_ 0.398_ - (SRCC ISO eff. equation- SI units η= 0.398 - 0.62210(P/G) - 0.01611(P²/G). However solar keymark test data mentions 0.734)
> 7. NEGATIVE OF FIRST ORDER EFFICIENCY COEFFICIENT _2.24 kJ/hr.m^2.K_ (SRCC .6221*3.6. However, solar keymar test data mentions 5.5044 )
> 8. NEGATIVE OF SECOND ORDER EFFICIENCY COEFFICIENT _0.058_ kJ/hr.m^2.K^2 (SRCC .01611*3.6. However, solar keymark test data mentions 0.0166 ) 
> 9. LOGICAL UNIT OF FILE CONTAINING BIAXIAL IAM DATA _37_ - (TRNSYS assigned)
> 10. NUMBER OF LONGITUDINAL ANGLES FOR WHICH IAMS ARE PROVIDED _11_ - (external data file prepared as per SRCC data)
> 11. NUMBER OF TRANSVERSE ANGLES FOR WHICH IAMS ARE PROVIDED _11_ - (external data file prepared as per SRCC data) 
> 
> Thank you for your time in advance. 
> 
> Regards, 
> Janeet 
> 
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> TRNSYS-users at lists.onebuilding.org
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