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Trane TRG-TRC016-EN manual Part-LoadEfficiency Rating, notes, Types of Water Chillers, period one

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Part-Load Efficiency Rating

period one

Types of Water Chillers

notes

Part-Load Efficiency Rating

▲Integrated Part-Load Value (IPLV)

◆Weighted-average load curves

◆Based on an “average” single-chiller installation

◆Standard operating conditions

▲Non-Standard Part-Load Value (NPLV)

◆Weighted-average load curves

◆Based on an “average” single-chiller installation

◆Non-standard operating conditions

Figure 22

The IPLV predicts chiller efficiency at the ARI standard rating conditions, using weighted-average load curves that represent a broad range of geographic locations, building types, and operating-hour scenarios, both with and without an airside economizer. The NPLV uses the same methods to predict chiller efficiency at non-standard rating conditions. Although these weighted-average load curves place greater emphasis on the part-load operation of an average, single-chiller installation, they will not—by definition—represent any particular installation.

Additionally, ARI notes that more than 80 percent of all chillers are installed in multiple-chiller systems. Chillers in these systems exhibit different unloading characteristics than the IPLV weighted formula indicates. Appendix D of Standard 550/590–1998 explains this further:

The IPLV equations and procedure are intended to provide a single- number, part-load performance number for water-chilling products. The equation was derived to provide a representation of the average part-load efficiency for a single chiller only. However, it is best to use a comprehensive analysis that reflects the actual weather data, building load characteristics, operational hours, economizer capabilities, and energy drawn by auxiliaries, such as pumps and cooling towers, when calculating the chiller and system efficiency.

Here is the important part:

This becomes increasingly important with multiple-chiller systems because individual chillers operating within multiple-chiller systems are more heavily loaded than single chillers within single-chiller systems.

TRG-TRC016-EN

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Trane TRG-TRC016-EN Part-LoadEfficiency Rating, notes, Types of Water Chillers, period one, Integrated Part-LoadValue IPLV

Contents

TRG-TRC016-EN Air Conditioning Clinic Chilled-WaterSystemsOne of the Systems Series THE TRANE COMPANY Attn: Applications Engineering BUSINESS REPLY MAILBUSINESS REPLY MAIL 3600 Pammel Creek Road La Crosse WIChilled-WaterSystems Comment CardResponse Card One of the Systems SeriesThe Trane Company Chilled-WaterSystemsOne of the Systems Series A publication of A Trane Air Conditioning Clinic PrefaceChilled-WaterSystems period three Contentsperiod two Chilled-WaterSystem Design period fourTRG-TRC016-EN Types of Water Chillers notesperiod one Types of Water Chillersnotes period oneDriving Sources Types of Water ChillersTypes of Water Chillers Vapor-CompressionCyclenotes period oneTypes of Water Chillers Compressor Typesnotes period oneTypes of Water Chillers Variable-SpeedDrivesnotes period onenotes Condenser TypesAir-Cooledor Water-Cooled Types of Water Chillersnotes MaintenanceTower maintenance Freeze protection Makeup water Types of Water ChillersTypes of Water Chillers Low Ambient Operationnotes period oneTypes of Water Chillers Efficiencynotes period oneTypes of Water Chillers Comparisonnotes period oneTypes of Water Chillers Packaged Air-CooledChillernotes period oneTypes of Water Chillers Remote Evaporator Barrelnotes period oneTypes of Water Chillers Remote Air-CooledCondensernotes period oneTypes of Water Chillers Indoor Air-CooledCondensernotes period oneTypes of Water Chillers Absorption Refrigeration Cyclenotes period onenotes Absorption Chillers Offer ChoiceWaste heat recovery Cogeneration Types of Water ChillersTypes of Water Chillers Absorption Chiller Typesnotes period oneTypes of Water Chillers Equipment Rating Standardsnotes period oneTypes of Water Chillers Part-LoadEfficiency Ratingnotes period oneTypes of Water Chillers Standard Rating Conditionsnotes period oneTypes of Water Chillers Flow Rates and Temperaturesnotes period oneTypes of Water Chillers Flow Rates and Temperaturesnotes period onenotes ASHRAE/IESNA Standard 90.1–1999Electric Vapor-CompressionChillers Types of Water ChillersTypes of Water Chillers Water-CooledAbsorption Chillersnotes period onenotes ASHRAE Standard 15–1994Safety standard for refrigerating systems Types of Water ChillersChilled-WaterSystem Design period twoChilled-WaterSystem Design period twonotes period twoChilled-WaterSystem Chilled-WaterSystem DesignChilled-WaterSystem Design Load-TerminalControl Optionsnotes period twoChilled-WaterSystem Design Three-WayValve Controlnotes period twoChilled-WaterSystem Design Two-WayValve Controlnotes period twoChilled-WaterSystem Design Face-and-BypassDamper Controlnotes period twoChilled-WaterSystem Design Chiller Evaporator Flownotes period twoChilled-WaterSystem Design Single-ChillerSystemnotes period twoChilled-WaterSystem Design Multiple-ChillerSystemsnotes period twonotes Single PumpParallel Configuration Chilled-WaterSystem DesignChilled-WaterSystem Design Dedicated Pumpsnotes period twoChilled-WaterSystem Design Figure 43 shows an example of the pump–systemcurve relationship. When both pumps are operating, the system receives 100 percent of design flow. When only one pump is operating, the intersection of the pump’s performance curve with the system curve results in about 65 percent of design flownotes period twonotes Chillers Piped in SeriesSeries Configuration Chilled-WaterSystem DesignChilled-WaterSystem Design Equal Set Pointsnotes period twoChilled-WaterSystem Design Staggered Set Pointsnotes period twoChilled-WaterSystem Design Primary-SecondaryConfigurationPrimary-SecondaryDecoupled Configuration period twoChilled-WaterSystem Design Primary-SecondarySystem Rulesnotes period twoChilled-WaterSystem Design Production Loopnotes period twoChilled-WaterSystem Design Manifolded Production Pumpsnotes period twoperiod two Distribution LoopChilled-WaterSystem Design period two notesChilled-WaterSystem Design Primary-SecondarySystem RulesChilled-WaterSystem Design Varying Distribution Flownotes period twoChilled-WaterSystem Design Multiple Distribution Pumpsnotes period twoChilled-WaterSystem Design A variation of the multiple-pumpconfiguration is to use separate pumps to deliver water to specific, dedicated loads. An example is a chilled-watersystem serving a college campus. Separate distribution pumps supply water to the east A, west B, and central C portions of the campus. A primary advantage of this configuration is flexibility. Expanding the system can be achieved by simply adding another distribution pump to the existing plant and connecting it to the piping that runs to the new buildingnotes period twoChilled-WaterSystem Design Tertiary Pumpingnotes period twonotes Distribution Loop CharacteristicsHigher return-watertemperatures Chilled-WaterSystem Designperiod two notesChilled-WaterSystem Design Primary-SecondarySystem RulesChilled-WaterSystem Design System Operationnotes period twoChilled-WaterSystem Design Deficit Flownotes period twoChilled-WaterSystem Design Excess Flownotes period twoChilled-WaterSystem Design Control of Primary-SecondarySystemnotes period twoperiod two Types of Fluid Flow MetersChilled-WaterSystem Design Pressure-basedChilled-WaterSystem Design Temperature-BasedCalculationsnotes period twoSystem Variations period threeSystem Variations period threeSystem Variations period threeFuel Choice Options absorption thermal storageperiod three Chiller Efficiency ImprovementsSystem Variations Low-FlowSystemsnotes Greater Focus on System EfficiencyTrend Toward Lower Flow Rates System VariationsSystem Variations Low-FlowSystemsnotes period threeSystem Variations Variable-Primary-FlowSystemsnotes period threeSystem Variations Critical VPF System Requirementsnotes period threeSystem Variations Preferential Chiller Loadingnotes period threeSystem Variations Sidestream Configurationnotes period threenotes Heat-RecoveryChillerHeat Recovery System VariationsSystem Variations Heat-RecoveryChiller Optionsnotes period threeSystem Variations Heat-RecoveryChiller Efficiencynotes period threeSystem Variations Control of a Heat-RecoveryChillernotes period threeSystem Variations Asymmetric Designnotes period threeSystem Variations Swing Chillernotes period threeperiod three notesSystem Variations Swing ChillerSystem Variations “Free” Coolingnotes period threeSystem Variations Plate-and-FrameHeat Exchangernotes period threeSystem Variations Refrigerant Migrationnotes period threeSystem Variations Application Outside Range of Chillernotes period threeChiller-PlantControl period fourChiller-PlantControl period fourStart–stop Chilled-watertemperature control period fourChiller Controls notesHow to recover from an equipment failure What Is Important?When to turn a chiller on or off How to optimize system efficiencyChiller-PlantControl Chiller Sequencingnotes period fourChiller-PlantControl Temperaturenotes period fourChiller-PlantControl Flownotes period fourChiller-PlantControl Capacitynotes period fourChiller-PlantControl Chiller Rotationnotes period fourChiller-PlantControl When the system consists of chillers with different capacities, efficiencies, or fuel types, the question of which chiller to turn on or off next becomes more complex. Although each system requires a complete analysis, there are some general principles that apply to most systemsnotes period fournotes Heat Recoverypreferentially-loaded heat-recoverychiller Chiller-PlantControlChiller-PlantControl The variable-primary-flowsystem, introduced in Period Three, is designed to operate with variable flow through the chiller evaporators. Sequencing chillers in this type of system cannot be based solely on temperature, because in a properly-operatingsystem the supply- and return-watertemperatures will be nearly constant. Determining when to turn chillers on or off is not a simple task. For control stability and chiller reliability, the flow rates through the chillers, and the rate of flow change, must be kept within allowable rangesnotes period fournotes System Failure RecoveryFailure Recovery and Contingency Planning Chiller-PlantControlChiller-PlantControl Contingency Planningnotes period fourLoad-confirmationtimer System TimersSystem Tuning Staging-intervaltimerChiller-PlantControl Unload Before Startnotes period fourChiller-PlantControl Soft Loadingnotes period fourChiller-PlantControl Chilled-WaterSet Point Controlnotes period fourChiller-PlantControl System Optimizationnotes period fourChiller-PlantControl Chilled Water Resetnotes period fourChiller-PlantControl Condenser-WaterTemperaturenotes period fourperiod four Control of Condensing PressureChiller-PlantControl Chiller-PlantControl Operator Training and Supportnotes period fourChiller-PlantControl Operator Interfacenotes period fourChiller-PlantControl ASHRAE Guidelinenotes period fourReview period fiveReview period fiveParallel configuration Series configuration period fiveReview—PeriodTwo notesnotes Review—PeriodThreeHeat recovery Asymmetric design ReviewContingency planning System tuning Review—PeriodFourChiller sequencing Failure recovery notesnASHRAE Handbook – Refrigeration Reviewperiod five nASHRAE Handbook – Systems and EquipmentQuestions for Period QuizQuestions for Period Questions for Period 9Why does a variable-primary-flowVPF system require a bypass in the system?Quiz Questions for PeriodAnswers Answers 12Sequencing 13Decreases; increasesGlossary Glossary decoupled system See primary-secondarysystemGlossary swing chiller A smaller-capacitychiller used in a multiple-chillersystem. It is alternated on and off between the larger chillers operation to serve as a smaller, incremental step of loading notesGlossary The Trane Company