NPLVNonstandard Part-Load Value (cooling towers)
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When you compare the COP or NPLV of the chillers only, the water-cooled units are obviously much more efficient.
The report of NPLV as replicating in the brown planthopper, as a non-pathogenic infection (Nakashima & Noda 1995), suggests that DcRV may also be non-pathogenic to D.
IPLV and NPLV [AHRI 2003] are terms coined by the Air Conditioning, Heating, and Refrigeration Institute (AHRI), sometimes promoted as the method to analyze and compare chiller performance.
NPLV is calculated in exactly the same way, except at chilled water and condenser water conditions differing from these defined values.
Geister & Thompson argue that IPLV or NPLV do not accurately represent a chiller plant's operating characteristics, particularly in chiller plants with more than one chiller.
D = -0.147 + 7.04E-06 x CDD65 - 0.124 x NPLV + 0.0038 x WB + 0.00133 x APPROACH + 0.00217 x RANGE
The middle chart illustrates the type of chiller performance data that must be provided by manufactures if simulation modeling is to be accomplished; as stated above, peak-load performance and NPLV numbers (Geister 2009) are not adequate for simulation modeling.
Needless to say, the low NPLV chiller is frequently used during cooling season.
The NPLV value is much larger than these CSE values.
First, it is important to recognize that AHRI's IPLV and NPLV evaluation methods were created to help compare the unloading characteristics of similar chillers--not to infer economic savings.
So, while variable-speed drives can offer significant savings in the right application for centrifugal chillers, they give the perception of efficiency gains when the IPLV/ NPLV formula is applied--a recipe for selling more drives, and not necessarily offering real energy savings.
IPLV/ NPLV methodology makes sense when determining minimum efficiency requirements such as in the Standard 90.1 or IECC efficiency standards (Figure 10, p.