[TRNSYS-users] dynamic data invalid data points

Jeremy Osborne j.osborne at student.unsw.edu.au
Tue Feb 16 07:08:52 PST 2010


Thank you all for your input, I found a neat solution that could easily be
implemented from a combination of your responses.

Simply make the invalid (unavailable data points) massive numbers and then
use TYPE581 (an interpolater) and an equation to read the same data file and
the equation to switch the chiller off using a less then statement if the
data is also massive (i set used control = lt(data, 1.22) since the max
possible output of valid data was 1.2).

Not the greatest but much better then an 50 individual equations specifying
ranges of the data.

TYPE107/680 (same component) is programmed incorrectly for another reason
not taking into account the actual capacity of machine to work out the
required energy input. Therefore used an modified version of type677
combining the data files S1 and S2 into the same reader because the broad
chiller capacity is dependent of 3 independent variable TempHW, TempCW, and
TempCHWsetpoint. To more accurate adding TempHW, TempCHWsetpoint to the last
data file would be best since the required input is also dependent on these.
One other fix to type677 was to make the frac of design cap also dependent
on the actual capacity of operation not only the designed capacity.

Kind regards,

Jeremy Osborne






On Mon, Feb 8, 2010 at 5:22 AM, Jones Marcus <Marcus.Jones at ait.ac.at> wrote:

>  Could you use an equation instead of changing the fortran code? Something
> like (CW greater than 24C) AND (HW less than 85) AND (Tset less than 7)
> THEN (control signal = 0)? Equations are useful for quick fixes if you don’t
> want to recompile the fortran type.
>
>
>
> Marcus
>
>
>
> *MARCUS JONES, MSc*
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> Energy Department
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> -----Original Message-----
> *From:* Jeremy Osborne [mailto:j.osborne at student.unsw.edu.au]
> *Sent:* February 8, 2010 7:08 AM
> *To:* trnsys-users at cae.wisc.edu; techsupport at tess-inc.com
> *Subject:* [TRNSYS-users] dynamic data invalid data points
>
>
>
> Dear All,
>
> I am modeling a BROAD single effect absorption chiller using type680. This
> uses the catalog data lookup approach. Not all data points are available for
> all operation conditions, for example, with cooling water (CW) in of 30C,
> Set point Temp 7C, and hot water (HW)  input of 85C there is no capacity
> data point because it is below 50%, however there is a data point available
> at CW of 24C, set point temp of 7C and HW input of 85C so we need to have
> the 85C included in the data file.
>
> The problem is what to put as the data point in these invalid points?
>  Zero (0) works for most, as it just turns the chiller off, but a problem
> occurs when the conditions are between an invalid and a valid data point
> because the dynamic data point interpolates between the 0 and the real value
> leading to unrealistic data.
>
> There needs to be a way to switch the chiller off when an any invalid data
> point is used.
>
> One solution is to add another 0, Zero point very close to each side of the
> point, for example(not exact), do 85, 89.9, 90.....  = capacity 0, 0,
> 0.74.....
>
> This would minimize the interpolation chance, however not great and
> pointful to create the data file.
>
> Another solution would be to put NA or something in the data file for the
> invalid points, and change the fortran code to recognize this and switch the
> chiller off. Similar to the errorif  function in Excel.
> However my fortran is very limited and i couldn't find anything on the web.
>
>
> Has anyone found a better solution or can help with this?
>
> Kind regards,
>
> Jeremy
>
>
>
>
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