Centrifugal Water Chillers A Trane Air Conditioning Clinic

Centrifugal Water Chillers A Trane Air Conditioning Clinic © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Chilled Water System © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

centrifugal absorption helical-rotary © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Centrifugal Water Chillers © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Centrifugal Water Chillers period one Components © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

components of a Centrifugal Water Chiller compressor motor condens er control panel © American Standard Inc. 1999 starter evaporator Air Conditioning Clinic TRG-TRC 010 -EN

Compressor © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Impeller blades © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Centrifugal Compressor volute diffuser passage impeller passages © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

centrifugal compressor Energy Conversion velocity refrigerant enters diffuser refrigerant enters volute static pressure refrigerant enters impeller path through compressor © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Multistage Compressor © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Condenser refrigerant vapor baffle cooling tower water © American Standard Inc. 1999 tube bundle liquid refrigeran Air Conditioning Clinic TRG-TRC 010 -EN

expansion device Orifice Plates orifice plates to evaporator H 1 © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

expansion device Orifice Plates orifice plates to evaporator H 2 © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

2 -stage chiller Economizer refrigerant vapor to second stage of compression orifice liquid refrigerant from condenser © American Standard Inc. 1999 liquid refrigerant to evaporator Air Conditioning Clinic TRG-TRC 010 -EN

3 -stage chiller Economizer refrigerant vapor to third stage of compression refrigerant vapor to second stage of compression liquid refrigerant to evaporator orifice liquid refrigerant from condenser orifice © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Evaporator tube bundle liquid refrigerant chilled water return liquid distributor © American Standard Inc. 1999 eliminator orifice system Air Conditioning Clinic TRG-TRC 010 -EN

Motor motor gear-drive impeller motor impellers direct-drive gears © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Hermetic Motor Cooling stator rotor © American Standard Inc. 1999 liquid refrigerant drain Air Conditioning Clinic TRG-TRC 010 -EN

Controls and Starter control panel © American Standard Inc. 1999 starter Air Conditioning Clinic TRG-TRC 010 -EN

Starters line power control power wiring starter control power wiring unit-mounted remote-mounted © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Centrifugal Water Chillers period two Refrigeration Cycle © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

2 -stage centrifugal chiller Refrigeration Cycle 2 -stage compress or economiz er condense r evaporato r © American Standard Inc. 1999 expansion devices Air Conditioning Clinic TRG-TRC 010 -EN

pressure Pressure-Enthalpy (p-h) Chart 5 psia subcooled liquid A mixture of liquid and vapor B [0. 034 MPa] © American Standard Inc. 1999 15. 5 Btu/lb [201. 0 enthalpy k. J/kg] superheated vapor 92. 4 Btu/lb [380. 4 k. J/kg] Air Conditioning Clinic TRG-TRC 010 -EN

2 -stage centrifugal chiller pressure Refrigeration Cycle Pc P 1 Pe © American Standard Inc. 1999 6 expansio n devices 8 9 condens er economizer 5 7 evaporat or enthalpy 4 2 -stage 2 compress or 3 1 Air Conditioning Clinic TRG-TRC 010 -EN

2 -stage centrifugal chiller pressure Refrigeration Cycle Pc P 1 Pe © American Standard Inc. 1999 6 expansio n devices 8 condens er economizer 5 7 9 evaporat or C B enthalpy 2 -stage 2 compress or 3 10 4 1 A Air Conditioning Clinic TRG-TRC 010 -EN

Refrigerant Operating Pressures pressure HCFC 22 atmospheri c pressure © American Standard Inc. 1999 HFC 134 a HCFC 123 temperature Air Conditioning Clinic TRG-TRC 010 -EN

Low-Pressure Chillers compressor suction elbow evaporator © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Purge System © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Purge Operation purge tank to chiller vent line purge evaporat or coil refrigera nt vapor from condens er to condenser © American Standard Inc. 1999 filtration canister filter drier Air Conditioning Clinic TRG-TRC 010 -EN

Centrifugal Water Chillers period three Compressor Capacity Control © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Inlet Vanes inlet vanes impeller © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Multistage Compressor impellers inlet vanes © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Impeller R Vr Vt © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Impeller Dynamics Vr µ refrigerant flow rate R Vt rotation al speed © American Standard Inc. 1999 Vr Vt µ rotational speed × diameter refrigera nt flow rate Air Conditioning Clinic TRG-TRC 010 -EN

Compressor Unloading R Vt full load © American Standard Inc. 1999 Vr R Vr Vt part load Air Conditioning Clinic TRG-TRC 010 -EN

Surge Vr R Vt © American Standard Inc. 1999 Vr < static pressure Air Conditioning Clinic TRG-TRC 010 -EN

pressure difference Compressor Map © American Standard Inc. 1999 e g r su 90 75 51 10 14 25 36 63 vane position (degrees) refrigerant flow rate Air Conditioning Clinic TRG-TRC 010 -EN

Operating Point pressure difference operatin g point © American Standard Inc. 1999 refrigerant flow rate Air Conditioning Clinic TRG-TRC 010 -EN

compressor map for a 2 -Stage Compressor pressure difference operatin g point © American Standard Inc. 1999 e g r su 90 75 51 10 14 25 36 63 vane position (degrees) refrigerant flow rate Air Conditioning Clinic TRG-TRC 010 -EN

compressor map for a 2 -Stage Compressor pressure difference A © American Standard Inc. 1999 e g r su 90 B C 75 51 10 14 25 63 36 unloading line refrigerant flow rate Air Conditioning Clinic TRG-TRC 010 -EN

power consumption Adjustable-Frequency Drives inlet vanes only AFD + inlet vanes load © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Centrifugal Water Chillers period four Maintenance Considerations © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Maintenance Considerations s Operating log s Mechanical components s Heat-transfer surfaces s Fluid analysis © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

operating log ASHRAE Guideline 3 s Chilled water inlet and outlet temperatures and pressures s Oil pressures, temperature, and levels s Chilled water flow s Addition of refrigerant s Evaporator refrigerant temperature and pressures s Addition of oil s Evaporator approach temperature s Vibration levels s Condenser water inlet and outlet temperatures and pressures s Condenser water flow s Condenser refrigerant temperature and pressures s Condenser approach temperature © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

maintenance considerations Mechanical Components s Required maintenance u Compressor u Controls: s and motor: no maintenance required no maintenance or calibration required Recommended maintenance u Visually inspect overall unit u Inspect safety controls and electrical components u Tighten electrical connections u Check © American Standard Inc. 1999 for leaks Air Conditioning Clinic TRG-TRC 010 -EN

maintenance considerations Mechanical Components s Other design-specific requirements u Change oil when oil analysis dictates u Replace oil filter periodically u Replace filter drier periodically u Clean oil strainers annually u Check shaft alignment annually u Check coupling annually u Replace shaft seal every 2 to 4 years u Compressor © American Standard Inc. 1999 teardown inspection every 5 to 10 years Air Conditioning Clinic TRG-TRC 010 -EN

maintenance considerations Heat Transfer Surfaces s Recommended maintenance u Use a qualified water treatment specialist u Clean condenser tubes as needed u Clean u Test © American Standard Inc. 1999 water-side strainers tubes every 3 years Air Conditioning Clinic TRG-TRC 010 -EN

Fluid Analysis s Oil analysis u Conduct annual analysis to verify system integrity u Measure oil pressure drop to determine if filter needs changing u Measure s charge Refrigerant charge u Conduct u Inspect © American Standard Inc. 1999 analysis of refrigerant purge system Air Conditioning Clinic TRG-TRC 010 -EN

Oil Analysis s Why perform regular oil analysis? u Helps reduce maintenance costs u Detects problems without compressor disassembly u Extends service life of oil charge u Reduces environmental problems related to oil disposal u Helps maintain compressor efficiency and reliability u Helps © American Standard Inc. 1999 lower refrigerant emissions Air Conditioning Clinic TRG-TRC 010 -EN

Centrifugal Water Chillers period five Application Considerations © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Condensing Temperature Control A pressure difference C © American Standard Inc. 1999 e g r su 90 75 B 51 10 14 25 unloading line 36 63 vane position (degrees) refrigerant flow rate Air Conditioning Clinic TRG-TRC 010 -EN

condensing temperature control Cooling Tower Bypass 40°F [4°C ] cooling tower bypass 55°F [13°C ] © American Standard Inc. 1999 diverting valve 65°F [18°C] condenser Air Conditioning Clinic TRG-TRC 010 -EN

evaporator water flow Constant or Variable Flow chilled water pump evaporator variable speed drive © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

variable evaporator water flow Limitations s Maintain minimum and maximum water flow rates through the chiller evaporator s Rate at which the evaporator water flow changes must be kept below the corresponding limit to: u Maintain u Keep the chiller on line u Protect © American Standard Inc. 1999 the chilled water set point control the chiller from damage Air Conditioning Clinic TRG-TRC 010 -EN

Short Evaporator-Water Loops load chilled water pump evaporator © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Short Evaporator-Water Loops load tank chilled water pump © American Standard Inc. 1999 evaporator Air Conditioning Clinic TRG-TRC 010 -EN

Heat Recovery heatrecovery condenser cooling tower water standard condense r © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Heat-Recovery Chiller Options heat-recovery (dual) condenser fullsize condenser auxiliary condenser heat pump u Second, u Large u Preheating u No extra condenser u Controlled loads u Large base heating loads or continuous u Moderate operation hot water temperatures u High hot water temperatures u Uncontrolled u Degrades u Improves loads heating smaller size condenser u High hot water temperatures chiller efficiency © American Standard Inc. 1999 efficiency chiller u Controlled u Chiller efficiency preserved Air Conditioning Clinic TRG-TRC 010 -EN

Free Cooling air-side economizer u Most efficient u Requires strainer cycle u Coldest water temperatures plate-and-frame heat exchanger u Potential fouling limited to heat exchanger larger outdoor air, u Potential fouling return, and in chilled water u Requires additional exhaust duct loop heat exchanger, systems piping, valves, and u Requires controls additional piping, valves, and u Can operate controls simultaneously with chiller © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

free cooling Refrigerant Migration from compress or condenser to compress or © American Standard Inc. 1999 evaporato r Air Conditioning Clinic TRG-TRC 010 -EN

equipment certification standards ARI Standard 550/590 s Purpose u Establish definitions, testing, and rating requirements s Scope u Factory designed and prefabricated water chillers u Vapor-compression refrigeration u Air-cooled and water-cooled condensing © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

equipment certification standards ARI Standard 550/590 s Standard rating conditions u Common u Fouling s system conditions for published ratings factor Integrated Part Load Value (IPLV) u Part-load u Based on an “average” single-chiller installation u Standard © American Standard Inc. 1999 efficiency rating operating conditions Air Conditioning Clinic TRG-TRC 010 -EN

Centrifugal Water Chillers period six Review © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Review—Period 1 compressor motor condens er control panel © American Standard Inc. 1999 starter evaporator Air Conditioning Clinic TRG-TRC 010 -EN

pressure Review—Period 2 Pc P 1 Pe © American Standard Inc. 1999 6 expansio n devices 8 9 condens er economizer 5 7 evaporat or enthalpy 4 2 -stage 2 compress or 3 1 Air Conditioning Clinic TRG-TRC 010 -EN

Review—Period 3 impellers inlet vanes © American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN

Review—Period 4 s Maintenance considerations u Operating log u Mechanical components u Heat-transfer u Fluid © American Standard Inc. 1999 surfaces analysis Air Conditioning Clinic TRG-TRC 010 -EN

Review—Period 5 s Application considerations u Condensing u Constant u Short temperature control or variable evaporator-water flow evaporator-water loops u Heat recovery u Free cooling u Equipment © American Standard Inc. 1999 certification standards Air Conditioning Clinic TRG-TRC 010 -EN

© American Standard Inc. 1999 Air Conditioning Clinic TRG-TRC 010 -EN