AIR COOLED CHILLER NOISE CONTROL SOLUTIONS

AIR COOLEDCHILLERNOISE CONTROLSOLUTIONS

NOISEPROBLEMSNOISE PATHSAddressing each noise pathfrom an air-cooled chiller is notas simple as merely addingattenuation or isolation.6There are many noise paths from air-cooled chillers (seeFig. 1 for examples) that, if not treated correctly, can leadto noise problems. When addressing each noise path,ventilation requirements, pressure drop considerations,space constraints, aesthetics, location, supporting structure,and materials of construction need to be considered.AIR COOLEDCHILLERSAir-cooled chillers arerefrigeration machinesthat remove heat fromcooling loads usingchilled water andreject this heat intothe atmosphere usingrefrigerant.THEY ALL HAVE fans, condenser coils,and compressors. Air-cooled chillersare used to provide cooling for humancomfort and electronic equipment aswell as industrial process applicationsaround the world.Nearly all air-cooled chillers arelocated outdoors to allow adequateairflow through the condenser heatexchanger coils. Air-cooled chillers areoften placed adjacent to or on top ofbuildings to minimize the amount ofspace they take up and to reduce theamount of piping required to connect toassociated equipment.1Vibro-AcousticsAir-cooled chillers can also create noise and vibrationproblems for building occupants. Harsh tonal noiseassociated with chillers can pass through standardwindows and vibration can transmit through the buildingstructure. When a chiller is placed next to a building itsnoise will be reflected from adjacent surfaces, combiningwith noise directly from the machine and creating higherlevels of noise—which can travel farther and be heard bymore people—causing more discomfort and annoyance.The result in occupant annoyance could lead to codeviolations and subsequent financial penalties.Since most air-cooled chillers are outside, any noisereduction solution needs to be designed to withstandwind loads as required by local building codes. Properdesign of both the silencers and their attachmentswill need to be performed by a licensed professionalengineer in that jurisdiction.AirAir1AirCompressors are a primary noise source in chillers.Large air-cooled chillers can have multiple compressorsto help provide good turn-down ratios to meet part-loadconditions. The combination of multiple compressorschanging speeds and turning on and off makes the noisemore irritating as the sound level goes up and down andtones continuously vary in intensity.Condenser fans often account for more than half of theoverall sound level. Most chillers cycle the fans on and offto match cooling load, varying the noise levels. Reducingor eliminating noise requires consideration of complicatingfactors including the relatively low capacity of condenserfans to accommodate additional pressure drop as theymove large amounts of air. Any silencers placed in theair path must ensure airflows are maintained.3Air2Air Cooled Chiller54Fig. 1 Air Cooled Chiller Noise PathsAIR COOLED CHILLER NOISE PATHS1Noise from compressors2Noise from inlet side of condenser coils3Noise from discharge side of condenser fans4Noise radiated into the building5Vibration path radiated noise6Noise reflected off the ground and adjacent surfacesTypically, aircooled chillerfans can handleno more than0.25" staticpressureAir Cooled Chiller Noise Control Solutions2

Targets problemAIR COOLEDCHILLERNOISE CONTROLSOLUTIONVibro-Acousticsprovides ano-obligationapplicationengineeringLay-In service toanalyze projectspecific chillersystem design andprovide an optimalsolution.Discharge SilencersTo reduce noise transmissionVibro-Acoustics’ discharge silencers reduce noise transmissionthrough air exhaust openings of the chiller.Targets problems12Intake Silencers/LouversTo reduce noisetransmissionVibro-Acoustics’ intakesilencers reduce noisetransmission fromcompressors and air flow atthe intake of the chiller.3Vibro-AcousticsTargets problem4Vibro-Acoustics provides aerodynamic calculations stampedby a Professional Engineer. The maximum recommendedcombined pressure drop including system effects for both intakeand discharge silencers is 0.25” wg or less.Acoustic PanelsTo reduce noisetransmissionVibro-Acoustics acousticpanels reduce noisetransmission while formingan enclosure aroundthe chiller to ensuremaintenance access andmaintain manufacturerrecommended clearancesTargets problemWE PROVIDE a noise controlsolution that integrates withthe system and addresses allnoise sources and paths sothat the project’s sound criteriaare achieved.The chiller noise control solutionenables the consulting engineerto place a solution that willwork with the selected chillerand consider energy efficiency.Solutions will be designedkeeping the air flow and staticpressure limitations in mindwith designs that do not nullifychiller manufacturer’s warranties,or greatly reduced chillerperformance. Building ownerscan run their chillers withoutdisrupting neighbors, occupantsor violating noise by-laws andregulations. What the engineerand contractor receive is anintegrated solution to addressmultiple areas of concern with asingle source responsibility.36Absorption PanelsVibro-acoustics Absorptionpanels reduce soundreflection from hardsurfaces. They can beinstalled on existing wallswith relative ease.Targets problemsSeismic and wind rated support structureVibro-Acoustics enclosure comes complete withstructural elements to ensure that it is rated as perproject specific wind and seismic ratings. Seismicand wind calculations stamped by a state licensedProfessional engineer are available upon request.45Acoustic Isolation PlatformTo reduce radiated noise and vibrationVibro-Acoustics Acoustic Isolation Platforms canbe used with air cooled chillers to reduce thevibration transmitted through the structure and theradiated noise through the roof.Air Cooled Chiller Noise Control Solutions4

Vibro-acoustics application engineers offercreative and pragmatic solutions to overcomechallenges, such as:Stringent noise criteriaProximity to property linesLow available pressure dropsRequired clearances around chillers forair flow and maintenance accessENSURE NOISE &BY-LAW COMPLIANTSOLUTIONS BY TAKINGADVANTAGE OFOUR APPLICATIONENGINEERING SERVICESChiller withbarrier onlyChiller withsilencer and louverContact your local Vibro-Acoustics sales representative or getin touch with us to find out more about our generator noisecontrol solutions and Lay-In Service. Call 1-800-565-8401, oremail info@vibro-acoustics.com.5Vibro-Acoustics

LIT-CHI-001VIBRO-ACOUSTICS355 Apple Creek Blvd.Markham, ON L3R 9X7 CanadaT 416-291-7371TF 1-800-565-8401E info@vibro-acoustics.comvibro-acoustics.comNOISE CONTROL

Air Cooled Chiller Air Air 2 Air Air 6 AIR COOLED CHILLERS Air-cooled chillers are refrigeration machines that remove heat from cooling loads using chilled water and reject this heat into the atmosphere using refrigerant. THEY ALL HAVE fans, condenser coils, and compressors. Air-cooled chillers are used to provide cooling for human comfort and electronic equipment as well as industrial process .