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Re: [TRNSYS-users] problem with sky temperature model



Isabelle,

Using Trnysys 16 with the Iisibat interface, I face one difficulty with the sky temperature model. Could you help me?

The warning message I receive is the following:

/** Warning at time : 6295.000000
Generated by Unit : 12
Generated by Type : 69
TRNSYS Message 317 : The sky temperature model has reported an inconsistency in the supplied INPUTS. The inconsistency has been fixed but should be investigated as it may lead to other problems. This error can be caused by a dew point temperature above the ambient temperature, a solar radiation value less than zero, or a cloud cover fraction less than zero or greater than one
Reported information : Not available



As indicated by the message, there are 4 conditions that can trigger that warning:
- Dewpoint temperature > dry bulb temperature. This is easy to check
with a plot of the difference between your inputs 2 and 1. If this is
the cause, using both temperatures from Type 33 should make sure the
inputs are consistent.
- Direct or diffuse radiation < 0 (bad connection for input 3 or 4, or
bad data file)
- Cloud cover < 0 (Bad connection for input 5 or bad data file)
- Cloud cover > 1: Bad connection, likely because you use the output
from Type 89 directly. Type 89 outputs the cloud cover in
percents (i.e. 0..100) while Type 69 expects them between 0 and 1. You
have to use an equation between the 2 types (let's just say this is
for "historical reasons").


I hope this helps,

Michaël Kummert

PS: A bug has just been found in TRNSYS 16.00.0037 and before: Type 89 for EPW and CWEC files outputs the cloud cover between 0 and 10, not 0 and 100. This will be fixed in the next release.

--
_________________________________________________________

Michaël Kummert

Solar Energy Laboratory - University of Wisconsin-Madison
1303 Engr Res Bldg, 1500 Engineering Drive
Madison, WI 53706

Tel: +1 (608) 263-1589
Fax: +1 (608) 262-8464
E-mail: kummert@xxxxxxxxxxxxx

SEL Web Site: http://sel.me.wisc.edu
TRNSYS Web Site: http://sel.me.wisc.edu/trnsys
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