Panel Brushless
Air handler
Air handler components
Blower/fan
Air handlers typically employ a large squirrel cage blower driven by an AC induction electric motor to move the air. The blower may operate at a single speed, offer a variety of set speeds, or be driven by a Variable Frequency Drive to allow a wide range of air flow rates. Flow rate may also be controlled by inlet vanes or outlet dampers on the fan. Some residential air handlers (central ‘furnaces’ or ‘air conditioners’) use a brushless DC electric motor that has variable speed capabilities.
Multiple blowers may be present in large commercial air handling units, typically placed at the end of the AHU and the beginning of the supply ductwork (therefore also called “supply fans”). They are often augmented by fans in the return air duct (“return fans”) pushing the air into the AHU.
Heating and/or cooling elements
Air handlers may need to provide heating, cooling, or both to change the supply air temperature depending on the location and the application.
Smaller air handlers may contain a fuel-burning heater or a refrigeration evaporator, placed directly in the air stream. Electric resistance and heat pumps can be used as well. Evaporative cooling is possible in dry climates.
Large commercial air handling units contain coils that circulate hot water or steam for heating, and chilled water for cooling. Coils are typically manufactured from copper for the tubes, with copper or aluminium fins to aid heat transfer. Cooling coils will also employ eliminator plates to remove and drain condensate. The hot water or steam is provided by a central boiler, and the chilled water is provided by a central chiller. Downstream temperature sensors are typically used to monitor and control ‘off coil’ temperatures, in conjunction with an appropriate motorised control valve prior to the coil.
Filters
Air filtration is almost always present in order to provide clean dust-free air to the building occupants. It may be via simple low-MERV pleated media, HEPA, electrostatic, or a combination of techniques. Gas-phase and ultraviolet air treatments may be employed as well.
It is typically placed first in the AHU in order to keep all its components clean. Depending upon the grade of filtration required, typically filters will be arranged in two (or more) banks with a coarse-grade panel filter provided in front of a fine-grade bag filter, or other ‘final’ filtration medium. The panel filter is cheaper to replace and maintain, and thus protects the more expensive bag filters.
The life of a filter may be assessed by monitoring the pressure drop through the filter medium at design air volume flow rate. This may be done by means of a visual display, using a pressure gauge, or by a pressure switch linked to an alarm point on the building control system. Failure to replace a filter may eventually lead to its collapse, as the forces exerted upon it by the fan overcome its inherent strength, resulting in collapse and thus contamination of the air handler and downstream ductwork.
Humidifier
Humidification is often necessary in colder climates where continuous heating will make the air drier, resulting in uncomfortable air quality and increased static electricity. Various types of humidification may be used:
Evaporative: dry air blown over a reservoir will evaporate some of the water. The rate of evaporation can be increased by spraying the water onto baffles in the air stream.
Vaporizer: steam or vapour from a boiler is blown directly into the air stream.
Spray mist: water is diffused either by a nozzle or other mechanical means into fine droplets and carried by the air.
Ultrasonic: A tray of fresh water in the airstream is excited by an ultrasonic device forming a fog or water mist.
Wetted medium: A fine fibrous medium in the airstream is kept moist with fresh water from a header pipe with a series of small outlets. As the air passes through the medium it entrains the water in fine droplets. This type of humidifier can quickly clog if the primary air filtration is not maintained in good order.
Mixing chamber
In order to maintain indoor air quality, air handlers commonly have provisions to allow the introduction of outside air into, and the exhausting of air from the building. In temperate climates, mixing the right amount of cooler outside air with warmer return air can be used to approach the desired supply air temperature. A mixing chamber is therefore used which has dampers controlling the ratio between the return, outside, and exhaust air.
Heat recovery device
A heat recovery device heat exchanger of many types, may be fitted to the air handler between supply and extract airstreams for energy savings and increasing capacity. These types more commonly include for:
Cross Plate Heat exchanger: A sandwich of plastic or metal plates with interlaced air paths. Heat is transferred between airstreams from one side of the plate to the other. The plates are typically spaced at 4 to 6mm apart. Can also be used to recover coolth. Heat recovery efficiency up to 70%.
Thermal Wheel: A slowly rotating matrix of finely corrugated metal, operating in both opposing airstreams, heat is absorbed as air passes through the matrix in the exhaust airstream, during one half rotation, and released during the second half rotation into the supply airstream in a continuous process. Can also be used to recover and coolth. Heat recovery efficiency up to 85%. Wheels are also available with a hydroscopic coating to provide latent heat transfer and also the drying or humidification of airstreams
Run around coil: Two air to liquid heat exchanger coils, in opposing airstreams, piped together with a circulating pump and using water or a brine as the heat transfer medium. This device, although not very efficient, allows heat recovery between remote and sometimes multiple supply and exhaust airstreams. Heat recovery efficiency up to 50%.
Heat Pipe: Operating in both opposing air paths, using a confined refrigerant as a heat transfer medium. The ‘pipe’ is multiple sealed pipes mounted in a coil configuration with fins to increase heat transfer. Heat is absorbed on one side of the pipe, by evaporation of the refrigerant, and released at the other side, by condensation of the refrigerant. Condensed refrigerant flows by gravity to the first side of the pipe to repeat the process. Heat recovery efficiency up to 65%.
Controls
Controls are necessary to regulate every aspect of an air handler, such as: flow rate of air, supply air temperature, mixed air temperature, humidity, air quality. They may be as simple as an off/on thermostat or as complex as a building automation system using BACnet or LonWorks, for example.
Common control components include temperature sensors, humidity sensors, sail switches, actuators, motors, and controllers.
Vibration isolators
The blowers in an air handler can create substantial vibration and the large area of the duct system would transmit this noise and vibration to the occupants of the building. To avoid this, vibration isolators (flexible sections) are normally inserted into the duct immediately before and after the air handler and often also between the fan compartment and the rest of the AHU. The rubberized canvas-like material of these sections allow the air handler to vibrate without transmitting much vibration to the attached ducts.
The fan compartment can be further isolated by placing it on a spring suspension, which will mitigate the transfer of vibration through the floor.
Major manufacturers
Carrier Corporation (also makes Bryant and Payne brands)
Citizen Industries
Daikin Industries (also makes McQuay International)
Engineered Air (North America)
Flkt Woods
Johnson Controls (also makes York International brand)
Lennox International
Nortek (makers of Huntair, Nordyne, Temtrol, Ventrol, and other brands)
Rheem (also makes Ruud)
Robatherm GMBH
Trane
Weger Air Solutions (Europe)
Zamil Air Conditioners (Middle East)
Haakon Industries Inc.
See also
HVAC
Thermal comfort
Indoor air quality
Categories: Heating, ventilating, and air conditioning | Mechanical engineeringHidden categories: Articles lacking sources from January 2008 | All articles lacking sources
About the Author
I am a professional editor from
Chinese Manufacturers
, and my work is to promote a free online trade platform.
http://www.chinaqualitycrafts.com/ contain a great deal of information about
dog leash light
,
orthopedic pet bed
welcome to visit!
Solar Fountain Pond Water Pump Panel Brushless
|
|
Solar Panel Power Water Pump Brushless Submersible Fountain Pond Garden Watering $19.98 |
|
|
Solar Panel Power Brushless Submersible Pond Fountain Pool Water Pump $17.36 |
|
|
150L/H Solar Panel Power Brushless Submersible Fountain Pool Water Pump $17.35 |
|
|
Solar Panel Power Water Pump Brushless Submersible Garden Fountain Pool $17.34 |
|
|
12V DC Brushless Water Pump for Solar Panel DC50-1215 $36.69 |
|
|
New Brushless Water Pump for Solar Panel 12V 650mA 3.5M $26.59 |
|
|
7V Solar Fountain Pond Water Pump Panel Brushless H $21.66 |
|
|
6pcs Solar Panel Power Brushless Submersible Pond Fountain Pool Water Pump $84.00 |
|
|
6pcs 150L/H Solar Panel Power Water Pump Brushless Submersible Fountain Pool $83.99 |
|
|
6pcs Solar Panel Power Brushless Submersible Pond Fountain Pool Water Pump $84.00 |
|
|
6pcs 150L/H Solar Panel Power Water Pump Brushless Submersible Fountain Pool $83.99 |
|
|
6V 1.5W 160L/H Solar Panel Power Water Pump Brushless Submersible Fountain Pool $25.99 |
|
|
20Watt 12V poly solar panel with solar brushless fountain, solar pump system $100.00 |
|
|
Solar Panel Power Brushless Submersible Pond Fountain Pool Water Pump $17.88 |
|
|
150L/H Solar Panel Power Brushless Submersible Fountain Pool Water Pump $17.56 |
|
|
Solar Panel Power Brushless Submersible Garden Fountain Pool Water Pump $17.66 |
|
|
18.8W 1.57A 2M DC CPU Brushless Water Pump Solar Panel Powered F Cooling System $36.90 |
|
|
3 Watt Solar Powered Water Fountain Pump $129.10 3 Watt Solar Powered Water Pump No need to worry about skyrocketing electric rates! operate day and night with water valve and timer work everyday automatically by preset working time. Water lift Max: 5 Feet Water flow max: 100G/H…. |
|
|
Windmax HY400 500 Watt Max 12-Volt 5-Blade Residential Wind Generator Kit $649.00 Advantages of 5-blade wind turbines over 3-blade wind turbines 1) 5-blade wind turbines will greatly improve annual energy production in low wind conditions. For areas with average wind speeds of 11 MPH (5m/s). If you compare annual energy output to conventional 3-blade wind turbine, there is an increase of annual energy output of more than 60%. 2) 5-blade wind turbines will dramatically improve … |
|
|
Windmax HY1000-5 1,000 Watt Max 24-Volt 5-Blade Residential Wind Generator Kit $1,099.00 Advantages of 5-blade wind turbines over 3-blade wind turbines 1) 5-blade wind turbines will greatly improve annual energy production in low wind conditions. For areas with average wind speeds of 11 MPH (5m/s). If you compare annual energy output to conventional 3-blade wind turbine, there is an increase of annual energy output of more than 60%. 2) 5-blade wind turbines will dramatically improve t… |
|
|
Niles FM1 (FG01215) Cabinet Cooling Module $299.95 The Niles FM-1 Cabinet and rack system cooling module was developed to address the growing need for cabinet and rack system cooling, and it does so in a quiet, low profile and unobtrusive fashion. This single-rack fan design will draw up to 150 cubic feet… |
|
|
HYT TR-50 5Watt UHF Repeater $995.00 Double Your On Site Two Way Radio Range! The smallest portable repeater; Exquisite industrial design the best choice of business consumer and amateur hobbyist.Durable die-cast chassis, easily assembled & disassembled; Diverse applications for residence security management, hotel & restaurant, entertainment spot, construction, manufacturing, etc…. |
|
|
Niles FM1R RACK MT COOLING FAN $379.00 … |
|
|
Tascam CD-500 CD Player $470.00 Need a great CD player? Here she is! The TASCAM CD-500 offers reliable playback in a high-quality slot-loading design. Tons of pro features are here, including a special brushless motor for enhanced reliability. Whether you’re installing it at the venue or putting it to work in the studio to reference mixes, you’ll appreciate the performance the TASCAM CD-500 delivers!… |
|
|
Tascam CD-500 Single Rackspace CD Player $579.95 Need a great CD player? Here she is! The TASCAM CD-500B offers reliable playback in a high-quality slot-loading design. Tons of pro features are here, including a special brushless motor for enhanced reliability. Whether you’re installing it at the venue or putting it to work in the studio to reference mixes, you’ll appreciate the performance the TASCAM CD-500B delivers! This model features balanc… |
|
|
Rule 24 Marine Rule 360 Marine Bilge Pump (360-GPH, 12-Volt) $12.67 Rule Submersible Bilge Pumps give you BIG value for your dollar! Rule submersible bilge pumps have set the standard for the industry for many years. They are the first choice of yachtsmen and commercial fishermen throughout the world. More innovations in bilge pump design have come from Rule Industries than any other manufacturer. Totally submersible; Compact, efficient, maintenance-free; Silent r… |
This entry was posted on Sunday, January 22nd, 2006 at 11:21 pm and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.