[TRNSYS-users] Type 8b strikes back

[Diego Alejandro Arias]

Hi Stefan,
I am afraid that you found a bug.
An error occurs when you have this set of conditions: when you use any  
non-zero value as dead band, and when you only have one instance of  
Type8 in your simulation.  The problem is that this is the default  
condition, so you will be likely to experience it all the time.
In other words, the problem occurs because the set point for cooling  
(in the source code: TC) is saved between time steps.  This variable  
is used in the intermediate calculations as the adjusted cooling set  
point, taking into account the dead band.

I have two possible fixes:
- Elegant fix: in the source code, comment out lines 133 and 144:
!10    IF(INFO(1).NE.IUNIT) THEN
         !recall the UNIT and TYPE number
         IUNIT = INFO(1)
	  ITYPE = INFO(2)
         !read parameter values
         ISTK = JFIX(PAR(1)+0.1)
         ISTG = JFIX(PAR(2)+0.1)
         TMIN = PAR(3)
         TC   = PAR(4)
         TH1  = PAR(5)
         TH2  = PAR(6)
!	ENDIF
This means that Type8 will read the parameters at each iteration.

- Not so elegant fix: add another Type8 to your simulation, even if it  
does nothing in your simulation.

Best regards,

Diego


Quoting Stefan de Kool <S.deKool at chri.nl>:

> Dear all,
>
>
>
> I have a problem with type 8b in Trnsys 16. It gives strange values, see
> simple test case attached. I had this problem before in trnsys 15 but upon
> Diego's kind advice I put a Type 93 (value recall) before type 8b to use the
> temperature of the prev timestip. This worked well. But now the problem
> emerges again in T16 and type 93 does not help this time.
>
>
>
> I tried changing about every paramter, to no avail. Also changing the no. of
> oscillations permitted doesn't work.
>
>
>
> Any suggestions?
>
>
>
> Regards
>
>
> Stefan de Kool
>
>
> Cauberg-Huygen Raadgevende Ingenieurs BV
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