For chillers in EnergyPlus I have to provide the data “Minimum Unloading Ratio”. It is defined in the following way: “The minimum unloading ratio is where the chiller capacity can no longer be reduced by unloading and must be false loaded to meet smaller cooling loads”.
In some cases (e.g. System 8) in the baseline systems the cooling is supplied by chillers.
As performance data for the baseline model I have to respect the EER value and the IPLV value that are indicated in Table 6.8.1C.
I have simulated two models in EnergyPlus: the first one with “Minimum Unloading Ratio” = 0.25 and the second one with “Minimum Unloading Ratio” = 0. The calculated IPLV seems unaffected by the “Minimum Unloading Ratio”.
What “Minimum Unloading Ratio” shall I consider in the baseline model? A typical value (0.2? 0.25?)? The same value of the proposed model? Or zero?
Regards
P.S.: in my question I have mentioned EnergyPlus, but I think that a parameter similar to the “Minimum Unloading Ratio” could exist also in other software
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
March 23, 2016 - 11:41 am
We think it should be zero since the baseline is not based on any kind of typical value associated with a particular chiller.