Hi John,
Isn't it "simply" a matter of the derating coil heat transfer and
pumping efficiencies, based on the percentage of glycol concentration?
Of course, deriving the derating factors is the not so simple part...
and probably the general solution would be to define a parametric
relationship between the glycol concentration and the coil and pumping
efficiencies.
Glycol manufacturer's data should have plenty of info on the derating
factors, perhaps even a parametric equation that can be utilized in BDL.
Well that was the easy part... hope it helps!
Brandon Nichols, PE
Hi Folks:
I am running into a few office/data center buildings where the main
office areas are cooled by conventional chillers and the data
center/server areas are conditioned by either Liebert type package units
or 40% glycol-to-water mix chillers (colder climates that still need
servers cooled). Naturally, both units will be on the same electric
meter.
The standard DOE-2 does not model glycol cooling, and a commercial
building does not need the refrigeration version of eQuest. Usually, I
know the kw/ton (or the moral equivalent) of the glycol cooling source.
But glycol/water does not have the same heat absorption properties as
straight shot water to follow the load.
I am trying to insure I am showing the correct energy used by these
units, as I believe the LEED now includes the process loads within the
Base and Proposed models to certify the level of LEED obtained.
Does anyone have any "tricks" they have used?
John R. Aulbach, PE, CEM