Carrier’s PLV Pro is a software tool that empowers consulting engineers to make objective and informed decisions about their chiller plant design that go beyond Full Load and IPLV metrics. Results are provided in a professional report or .csv format for further analysis. The tool is for professionals who need a quick and free-of-charge alternative to detailed energy modeling analyses.
Many engineers and facility managers know that full load and integrated part load value (IPLV) may not provide a complete and accurate picture of the performance of multi-chiller central plants in the real world, but they often fall back on them because detailed energy modeling analyses can be costly and time-consuming.Scott McDonough (Associate Director of Product Management, Carrier Commercial Global Equipment)
PLV Pro™ calculates custom PLV factors that can be incorporated into equipment specifications and can be used to calculate a custom part load value (CPLV) for water-cooled chillers in a plant. While the tool is fast and simple to use, it performs a detailed chiller plant analysis to derive the custom PLV factors.
What is Custom PLV?
A Custom PLV is an annual performance metric that is customized to local project conditions. It is conceptually similar to an integrated part load value (IPLV). However, the conditions used for an IPLV are based on a standard set of data and assumptions: average US weather data, a weighted average of common building load profiles, a plant containing a single chiller, and assumptions about standard cooling tower performance.
In contrast, a CPLV considers project weather conditions, an application-specific load profile, the number of chillers, staging control, flow rates, flow controls and cooling tower performance to generate weighting factors and entering condenser water temperatures (ECWTs) that are specific to your project.
A CPLV calculated in this way is an annual performance metric customized to your project conditions and therefore a better basis for evaluating performance of products being considered for the project.
What are Custom PLV Factors?
Just like an IPLV, a CPLV is a weighted average kW/Ton (or ikW/kW) calculated from chiller performance at four load points (100%, 75%, 50%, 25% chiller load) and corresponding ECWTs, combined with four weighting factors.
Custom PLV factors are derived using the same underlying principles that were originally used to derive the weighting factors and ECWTs for an IPLV, but the derivation for CPLV uses local project conditions.
How is a Custom PLV Calculated?
A CPLV is calculated with the same formula as an IPLV:
CPLV = 1 / [ (W100/A) + (W75/B) + (W50/C) + (W25/D) ]
where A, B, C, D are the chiller kW/ton or ikW/kW values for the 100%, 75%, 50%, and 25% load points, calculated at the four customized ECWTs. W100, W75, W50, and W25 are the four customized weighting factors for the 100%, 75%, 50% and 25% load points.
Key Program Calculations
PLV Pro calculates the custom PLV Factors using the following data and assumptions:
- Temperature bin weather data for the project location, customized for the operating schedule of the application’s building type.
- A building cooling load profile customized to the project location and building type. PLV Pro contains thousands of unique load profiles precalculated using Carrier’s Hourly Analysis Program (HAP) energy modeling software for all combinations of building type and location offered in the program. The profiles are normalized so they can be scaled to your project’s peak building load.
- A detailed chiller plant simulation accounting for weather, building load, and the chiller plant configuration and control.
- Multiple chillers in parallel. Chillers are assumed to be of equal capacity.
- Chillers sequenced on load or equally unloaded.
- User-specified design ECWT and minimum ECWT.
- User-specified evaporator and condenser flow rates.
- Constant primary evaporator flow or variable primary flow. Variable primary flow assumes turndown to 40% of design flow.
- User-specified design conditions for cooling towers including design wet-bulb and approach.
- A detailed thermodynamic model of cooling tower performance for accurate assessment of ECWTS for the given weather profile, load profile, and chiller plant operating conditions.
- Reports listing the custom PLV factors as well as explaining chiller plant operation, and documenting the derivation of the custom weighting factors and ECWTs.
Download PLV Pro™
About Carrier Founded by the inventor of modern air conditioning, Carrier is the world leader in high-technology heating, air-conditioning and refrigeration solutions.
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