#19 Wrong electricity demand for cooling?

[Alex]

Hi,
when trying to recalculate the electricity demand for water cooled chiller, my manual results do not match those of EINSTEIN. My steps:

1. Cooling production own calculation = Cooling production EINSTEIN calculation.
2. I'm calculating the parameters (EERfullload, EERpartload) per hand. In this particular case, I know that the part-load of my equipment is 1 (the chiller is only working at 100%, and this only 3 days in a week).
3. In the results of the CCheck, I see that EINSTEIN has calculated a "Mean utilisation factor" of 0,418.
4. If I use this value (0.418) instead of 1 (100%) for the PLR, then my calculation match that of EINSTEIN.
5. In the code, I found this lign: "#TODO: change part-load function back to the real one once consistent solution between ccheck and simulation results has been found".
   Might this be part of the problem?

Cheers
Alex

[Jan Ries]

Hi,

I'm not sure what the wrong values are as I don't know the calculations. But perhaps it's a mix up of nomenclatura.

To the user it is meant in the following way:
The part-load factor is the internal name of a parameter of a process and of a parameter of an equipment. It is the mean of the load factors of the process while running, such that running the process over its whole running time with this load, would create the same demands. Or it is telling how much time of the whole year (365 days) a equipment has to run on 100% to cover the demands on the pipes it is connected to. The latter meaning can be seen in the GUI for equipments under the name of "mean utilisation factor".

Therefore perhaps the PLR you are meaning, the one in the Chiller module is, is the mean utilisation factor of the equipment (about 0.43 for 3 days a week at load 100%) and not of the process (1 if it runs on 100% whenever it runs).
Yes the chiller module code

[Alex]

Hi,
well, the PLR that is needed for the calculation needs to be calculated every hours in respect to the nominal cooling power of the chiller, it's not the mean utilisation factor.
I'll forward you the description of the model from the technical manual, maybe it will make things clearer.
CHeers
Alex

[Jan Ries]

Sorry, correct the PLR is the utilisatzion factor for each time slice. But again the PLR values are the part load of the equipment (ca. 3/7 as a mean if you run 3 days out of 7 with full nominal power) not of the process (1).

If you send me the numbers of your case I can perhaps understand better what is expected.

[energyXperts.NET]

As a bug should be solved with Advanced Training example AT03. Feature request added for future improvements of part load correction function.