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Sound Attenuators
A sound attenuator, or duct silencer, sound trap, or muffler, is a noise control acoustical treatment of Heating Ventilating and Air-Conditioning (HVAC) ductwork designed to reduce transmission of noise through the ductwork, either from equipment into occupied spaces in a building, or between occupied spaces. In its simplest form, a sound attenuator consists of a baffle within the ductwork. These baffles often contain sound-absorbing materials. The physical dimensions and baffle configuration of sound attenuators are selected to attenuate a specific range of frequencies. Unlike conventional internally-lined ductwork, which is only effective at attenuating mid- and high-frequency noise, sound attenuators can achieve broader band attenuation in relatively short lengths. Certain types of sound attenuators are essentially a Helmholtz resonator used as a passive noise-control device. Configuration Generally, sound attenuators consist of the following elements: * An inner perforat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muffler
A muffler (North American and Australian English) or silencer (British English) is a device for reducing the noise emitted by the exhaust of an internal combustion engine—especially a noise-deadening device forming part of the exhaust system of an automobile. Description Mufflers are installed within the exhaust system of most internal combustion engines. The muffler is engineered as an acoustic device to reduce the loudness of the sound pressure created by the engine by acoustic quieting. The noise of the burning-hot exhaust gas exiting the engine at high speed is abated by a series of passages and chambers lined with roving fiberglass insulation and/or resonating chambers harmonically tuned to cause destructive interference, wherein opposite sound waves cancel each other out. An unavoidable side effect of this noise reduction is the restriction of the exhaust gas flow, which creates back pressure, which can decrease engine efficiency. This is because the engine exha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Concert Halls
A concert hall is a cultural building with a stage that serves as a performance venue and an auditorium filled with seats. This list does not include other venues such as sports stadia, dramatic theatres or convention centres that may occasionally be used for concerts. ::''The list is organised alphabetically by geo-political region or continent and then by country within each region''. Africa Egypt Morocco South Africa Asia Armenia Azerbaijan China Georgia Hong Kong India Iran Israel Indonesia Japan Kazakhstan Lebanon Macau Malaysia North Korea Oman Philippines Singapore South Korea Syria Taiwan Thailand Turkey Vietnam Europe Albania Austria Belgium Bulgaria Croatia Czech Republic Denmark Estonia Finland France Germany Greece Hungary Iceland Ireland (Republic of) Italy Latvia Luxembourg Netherlands Norway Poland Portugal Romania Russia Serbia Slovakia Slov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duct (flow)
Ducts are conduits or passages used in heating, ventilation, and air conditioning (HVAC) to deliver and remove air. The needed airflows include, for example, ''supply air'', ''return air'', and ''exhaust air''. Ducts commonly also deliver '' ventilation air'' as part of the supply air. As such, air ducts are one method of ensuring acceptable indoor air quality as well as thermal comfort. A duct system is also called ''ductwork''. Planning (laying out), sizing, optimizing, detailing, and finding the pressure losses through a duct system is called ''duct design''. Materials Ducts can be made out of the following materials: Galvanized steel Galvanized mild steel is the standard and most common material used in fabricating ductwork because the zinc coating of this metal prevents rusting and avoids cost of painting. For insulation purposes, metal ducts are typically lined with faced fiberglass blankets (duct liner) or wrapped externally with fiberglass blankets (duct wrap). When ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cooling Tower
A cooling tower is a device that rejects waste heat to the atmosphere through the cooling of a coolant stream, usually a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or, in the case of ''dry cooling towers'', rely solely on air to cool the working fluid to near the dry-bulb air temperature using radiators. Common applications include cooling the circulating water used in oil refineries, petrochemical and other chemical plants, thermal power stations, nuclear power stations and HVAC systems for cooling buildings. The classification is based on the type of air induction into the tower: the main types of cooling towers are natural draft and induced draft cooling towers. Cooling towers vary in size from small roof-top units to very large hyperboloid structures (as in the adjacent image) that can be up to tall and in diameter, or rectangu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Background Noise
Background noise or ambient noise is any sound other than the sound being monitored (primary sound). Background noise is a form of noise pollution or interference. Background noise is an important concept in setting noise levels. Background noises include environmental noises such as water waves, traffic noise, alarms, extraneous speech, bioacoustic noise from animals, and electrical noise from devices such as refrigerators, air conditioning, power supplies, and motors. The prevention or reduction of background noise is important in the field of active noise control. It is an important consideration with the use of ultrasound (e.g. for medical diagnosis or imaging), sonar, and sound reproduction. Other uses In astronomy, background noise or cosmic background radiation is electromagnetic radiation from the sky with no discernible source. In information architecture, irrelevant, duplicate or incorrect information may be called background noise. In physics and telecommunicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Turbine
A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the direction of flow: * a rotating gas compressor * a combustor * a compressor-driving turbine. Additional components have to be added to the gas generator to suit its application. Common to all is an air inlet but with different configurations to suit the requirements of marine use, land use or flight at speeds varying from stationary to supersonic. A propelling nozzle is added to produce thrust for flight. An extra turbine is added to drive a propeller (turboprop) or ducted fan (turbofan) to reduce fuel consumption (by increasing propulsive efficiency) at subsonic flight speeds. An extra turbine is also required to drive a helicopter rotor or land-vehicle transmission (turboshaft), marine propeller or electrical generator (power turbine). Greater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compressor
A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. The main distinction is that the focus of a compressor is to change the density or volume of the fluid, which is mostly only achievable on gases. Gases are compressible, while liquids are relatively incompressible, so compressors are rarely used for liquids. The main action of a pump is to pressurize and transport liquids. Many compressors can be staged, that is, the fluid is compressed several times in steps or stages, to increase discharge pressure. Often, the second stage is physically smaller than the primary stage, to accommodate the already compressed gas without reducing its pressure. Each stage further compresses the gas and increases its pressure and also temperature (if inter cooling between stages i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fan Coil Unit
A fan coil unit (FCU), also known as a Vertical Fan Coil-Unit (VFC), is a device consisting of a heat exchanger (coil) and a fan. As part of an HVAC system found in residential, commercial, and industrial buildings using ducted split air conditioning or with central plant cooling, a fan coil unit is often connected to ductwork and a thermostat to regulate the temperature of one or more spaces as well as assisting the main air handling unit for each space if used with chillers. The thermostat controls the fan speed and/or the throughput of water to the heat exchanger using a control valve. Owing to their simplicity and flexibility, fan coil units can be more economical to install than ducted 100% fresh air systems (VAV) or central heating systems with air handling units or chilled beams. Various unit configurations are available, including horizontal (ceiling mounted) or vertical (floor mounted). Noise output from FCUs, like any other form of air conditioning, is principally ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Handler
An air handler, or air handling unit (often abbreviated to AHU), is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. An air handler is usually a large metal box containing a blower, heating or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to a ductwork ventilation system that distributes the conditioned air through the building and returns it to the AHU. Sometimes AHUs discharge (''supply'') and admit (''return'') air directly to and from the space served without ductwork Small air handlers, for local use, are called terminal units, and may only include an air filter, coil, and blower; these simple terminal units are called blower coils or fan coil units. A larger air handler that conditions 100% outside air, and no recirculated air, is known as a makeup air unit (MAU) or fresh air handling unit (FAHU). An air handler designed for outdoor use, typical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Architectural Acoustics
Architectural acoustics (also known as building acoustics) is the science and engineering of achieving a good sound within a building and is a branch of acoustical engineering. The first application of modern scientific methods to architectural acoustics was carried out by the American physicist Wallace Sabine in the Fogg Museum lecture room. He applied his newfound knowledge to the design of Symphony Hall, Boston. Architectural acoustics can be about achieving good speech intelligibility in a theatre, restaurant or railway station, enhancing the quality of music in a concert hall or recording studio, or suppressing noise to make offices and homes more productive and pleasant places to work and live in. Architectural acoustic design is usually done by acoustic consultants. Building skin envelope This science analyzes noise transmission from building exterior envelope to interior and vice versa. The main noise paths are roofs, eaves, walls, windows, door and penetrations. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Koppers
Koppers is a global chemical and materials company based in Pittsburgh, Pennsylvania, United States in an art-deco 1920s skyscraper, the Koppers Tower. Structure Koppers is an integrated global producer of carbon compounds, chemicals, and treated wood products for the aluminum, railroad, specialty chemical, utility, rubber, steel, residential lumber, and agriculture industries. It serves customers through a comprehensive global manufacturing and distribution network with facilities located in North America, South America, Australasia, China, and Europe. Koppers operates three principal businesses: Performance Chemicals, Railroad and Utility Products and Services, and Carbon Materials and Chemicals. History In 1912 immigrant German engineer Heinrich Koppers founded Koppers Company in Chicago, Illinois. In 1915 the organization moved to Pittsburgh, Pennsylvania. The company founder's interest in the company was bought out by Pittsburgh financier Andrew Mellon, who became a large ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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