Chilled-Water System | Trane TRG-TRC016-EN guide

period two

Chilled-Water System Design

notes

Chilled-Water System

air-cooled chiller

pump

coil

control valve

Figure 32

This period focuses on the chilled-water side of the system; that is, the water that flows through the chiller evaporator and out through the load terminals. Specifically, we will review methods of load-terminal control and various multiple-chiller system configurations. These topics apply to systems using both air-cooled and water-cooled chillers.

Fundamentally, the function of the chilled-water system is to transport the cooling fluid from the chillers to the load terminals and back to the chillers. Assuming that the distribution system is adequately sized, we will concentrate on the hydraulic interaction between the load terminals and the chillers.

TRG-TRC016-EN

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Image 34

Trane TRG-TRC016-EN manual Chilled-Water System

Contents

Air Conditioning Clinic Chilled-Water Systems Business Reply Mail Comment Card One of the Systems Series One of the Systems Series Publication Trane Company Preface Contents Iii Types of Water Chillers Water systems Driving Sources Compressor-driven heat-driven Vapor-Compression Cycle Vapor-Compression Water Chillers Compressor Types Scroll Reciprocating Helical-rotarycentrifugal Variable-Speed Drives Air-Cooled or Water-Cooled Condenser TypesAir-Cooled or Water-Cooled Condensing Maintenance Low Ambient Operation Efficiency Comparison Packaged Air-Cooled Chiller Packaged or Split Components Remote Evaporator Barrel Remote Air-Cooled Condenser Indoor Air-Cooled Condenser Absorption Refrigeration Cycle Absorption Water Chillers Absorption Chillers Offer Choice Absorption Chiller Types Single-effectdouble-effect Direct-fired Equipment Rating Standards Equipment Rating StandardsAir-Conditioning & Refrigeration Institute ARI Integrated Part-Load Value Iplv Part-Load Efficiency RatingNon-Standard Part-Load Value Nplv Standard Rating Conditions Evaporator Condenser Rating Chiller type Flow rate Flow Rates and Temperatures QBtu/hr = 500 ⋅ flow rate ⋅ ∆T ARI conditions Low-flow conditions Electric Vapor-Compression Chillers ASHRAE/IESNA StandardEnergy Standard Water-Cooled Absorption Chillers Chiller type Capacity Ashrae Standard Chilled-Water System Design Chilled-Water System Components Chilled-Water System Load-Terminal Control Options Load-Terminal Control Three-Way Valve Control Two-Way Valve Control Face-and-Bypass Damper Control Three-way modulating valve Chiller Evaporator FlowConstant flow is most common Variable flow is possible Single-Chiller System Multiple-Chiller Systems Redundancy Part-load efficiency Parallel Configuration Single Pump Dedicated Pumps Percent flow Series Configuration Chillers Piped in Series Equal Set Points Staggered Set Points Primary-Secondary Configuration Primary-Secondary Decoupled Configuration Primary-Secondary System Rules Bypass pipe should be free of restrictions Production Loop Manifolded Production Pumps Distribution Loop Bypass pipe should be free of restrictions Load terminals should use two-way modulating control valves Varying Distribution Flow Variable-speed control riding the pump curve Multiple Distribution Pumps Distribution Tertiary Pumping Distribution Loop Characteristics Primary-Secondary System Rules System Operation Primary-Secondary System Operation Deficit Flow Excess Flow Control of Primary-Secondary System Pressure-based Types of Fluid Flow MetersTurbine and impeller Vortex Magnetic Ultrasonic Temperature-Based Calculations Electric Utility Deregulation Alternate Fuel Choice Fuel Choice Options Indirectly-coupled, gas-engine chillers Chiller Efficiency Improvements Low-Flow Systems Greater Focus on System Efficiency Trend Toward Lower Flow Rates Low-Flow Systems Variable-Primary-Flow Systems Variable-Primary-Flow Systems Critical VPF System Requirements Preferential Chiller Loading Preferential Loading Sidestream Configuration Heat-Recovery Chiller Heat Recovery Heat-Recovery Chiller Options Heat-recovery Auxiliary Dual condenser Condenser Heat pump Heat-Recovery Chiller Efficiency Mode Control of a Heat-Recovery Chiller Unloadingwith Different chiller Capacities Asymmetric DesignAsymmetric Design Different chiller Swing Chiller Chiller Free Cooling Free CoolingAirside economizer Waterside economizer Plate-and-Frame Heat Exchanger Refrigerant Migration Application Outside Range of Chiller Application Outside the Operating Range of the Chiller Chiller-Plant Control Chiller Controls What Is Important? Chiller Sequencing Chiller Sequencing Temperature Flow Capacity Chiller Rotation Small electric Chiller largeelectric chiller Heat Recovery Variable-Primary-Flow Systems Maintain flow of chilled water Keep it simple System Failure RecoveryFailure Recovery and Contingency Planning Notify the operator Allow the operator to intervene Contingency Planning Load-confirmation timer System TimersSystem Tuning Staging-interval timer Unload Before Start Soft Loading Chilled-Water Set Point Control System Optimization System Optimization Pros Chilled Water ResetCons Condenser-Water Temperature Tower Control of Condensing Pressure Operator Training and Support Operator Interface Operator Interface Ashrae Guideline Review-Period One Vapor-compression water chillers Review-Period Two Load-terminal control Review-Period Three Review-Period Four For more information, refer to the following references Quiz 109 Answers 111 Glossary 113 114 115 Trane Company