An evaporative cooler (also cold swamp , desert cooler and wet air conditioner ) is a device that cools the air through evaporation water. Evaporative cooling differs from general air conditioning systems, which use vapor compression or absorption cooling cycles. Evaporative cooling works by utilizing the large enthalpy of water evaporation. The temperature of dry air can drop significantly through the transition phase of liquid water to water vapor (evaporation). It can cool the air using less energy than cooling. In a very dry climate, evaporative air cooling has the added benefit of air conditioning with more moisture for the comfort of building occupants.
The cooling potential for evaporative cooling depends on wet bulb depression, the difference between the temperature of the dry bulb and the temperature of the wet bulb. In a dry climate, evaporative cooling can reduce energy consumption and total equipment for conditioning as an alternative to compressor-based cooling. In a climate not considered dry, indirect evaporative cooling can still take advantage of the evaporative cooling process without increasing moisture. Passive evaporative cooling strategies offer the same benefits of a mechanical evaporative cooling system without the hassle of equipment and require ducts.
Video Evaporative cooler
Overview
The early form of evaporative cooling, wind catcher, was used in ancient Egypt and Persia thousands of years ago in the form of a wind ax on the roof. They catch the wind, pass under underground water in an qanat and throw the cooled air into the building. The modern Iranians have widely adopted the evaporative coolant powered ( coolere ÃÆ' Â ¢ bi ).
Evaporative coolants are the subject of a number of US patents in the 20th century; much of this, beginning in 1906, suggests or assumes the use of higher (wooden wool) bearings as an element to carry large volumes of water in contact with moving air to allow evaporation to occur. A typical design, as demonstrated in the 1945 patent, includes a water reservoir (usually with a level controlled by a floating valve), a pump to circulate water over a higher bearing and centrifugal fan to draw air through the cushion and into the house. These designs and these materials remain dominant in evaporative coolers in Southwest America, where they are also used to increase moisture. In the United States, the use of the term "cold swamp" may be caused by the smell of algae produced by the initial unit.
Externally installed evaporative coolers (car coolers) are used in some cars to cool interior air - often as an aftermarket accessory - until modern vapor compression air conditioning becomes widely available.
Passive evaporative cooling techniques in buildings, such as evaporative cooling towers, have been developed and studied in the last 30 years. In 1974, William H. Goettl invented "Evaporative Cooling and Evaporative Cooling" in Arizona after realizing that evaporative cooling technology works better in dry climates rather than moisture but a combination unit would be more effective. In 1986, two researchers at the Universities of Arizona, Tucson, W. Cunningham and T. Thompson, built the first passive evaporative cooling tower in Tucson, AZ. Performance data from this experimental facility form the basis of today's evaporative cooling tower design guidelines, developed by Baruch Givoni.
Maps Evaporative cooler
Physical Principles
Evaporative coolers lower air temperatures using the evaporative cooling principle, unlike ordinary air conditioning systems that use vapor compression refrigeration or absorption refrigerators. Evaporative cooling is the conversion of liquid water into steam using heat energy in the air, resulting in a lower air temperature. The energy required to evaporate water is taken from the air in a reasonable form of heat, which affects the temperature of the air, and converted into latent heat, the energy present in the moisture component in the air, while air remains in the air. constant enthalpy value. This plausible heat conversion to latent heat is known as the isenthalpic process because it occurs at a constant enthalpy value. Evaporative cooling therefore causes a decrease in air temperature in proportion to a reasonable reduction in heat and an increase in humidity proportional to the increase in latent heat. Evaporative cooling can be visualized using psychrometric charts by finding the initial air conditions and moving along the constant enthalpy line to a higher humidity state.
A simple example of natural evaporative cooling is sweat, or sweat, which is secreted by the body, the evaporation that cools the body. The amount of heat transfer depends on the rate of evaporation, but for every kilogram of water vaporized 2,257 kJ of energy (about 890 BTU per pound of pure water, at 95 ° F (35 ° C)) transferred. The rate of evaporation depends on the temperature and humidity of the air, which is why sweat accumulates more on a humid day, because it does not evaporate fast enough.
The cooling of vapor compression uses evaporative cooling, but steam evaporates in a closed system, and then compressed is ready to evaporate again, using energy to do so. Simple evaporative cooling water is evaporated into the environment, and does not recover. In the interior chamber cooling unit, the evaporated water is introduced into the chamber together with the air now cooled; in the evaporative tower, the evaporating water is carried out in the airflow.
Other types of phase-change cooling
The closely related process, sublimation cooling differs from evaporative cooling because the phase transition from solid to vapor, rather than liquid to vapor, occurs.
Sublimation cooling has been observed to operate on a planetary scale on the planetoid Pluto, where it has been called the anti-greenhouse effect.
Another application of the phase change to cooling is the "self-cooling" drink can. A separate compartment inside the tin contains a dryer and a liquid. Just before drinking, the tab is drawn so that the dryer contacts with the liquid and dissolves. Because it absorbs some heat energy called latent heat of fusion. Evaporative cooling works by the phase of fluid change into vapor and latent heat of evaporation, but the cooling itself can use change from solid to liquid, and latent heat of fusion to achieve the same result.
Apps
Prior to the advent of cooling, evaporative cooling was used for thousands of years. A porous pottery vessel will cool the water by evaporation through its walls; frescoes from about 2500 BC show slaves fanning water jars to cool rooms. A ship can also be placed in a bowl of water, covered with a damp cloth dipped in water, to keep milk or butter as fresh as possible.
Evaporative cooling is a common form of refrigeration building for thermal comfort because it is relatively inexpensive and requires less energy than other forms of cooling.
The figures showing the Salt Lake City weather data represent a typical summer climate (June to September). The colored lines illustrate the potential for direct and indirect evaporative cooling strategies to expand the range of comfort in the summer. This is mainly explained by the combination of higher airspeed on one side and high indoor humidity when the region allows a direct evaporative cooling strategy on the other. An evaporative cooling strategy that involves air humidification should be carried out in dry conditions where increased moisture content remains below the recommendation for occupant comfort and indoor air quality. Passive cooling towers do not have the control that traditional HVAC systems offer to residents. However, additional air movement provided into space can improve occupant comfort.
Evaporative cooling is most effective when relative humidity is on the lower side, limiting its popularity to dry climates. Evaporative cooling significantly increases the internal moisture level, which desert residents can appreciate when moist air returns to hydrate dry skin and sinuses. Therefore, assessing typical climate data is an important procedure for determining the potential for evaporative cooling strategies for buildings. The three most important climate considerations are dry-bulb temperature, wet ball temperature, and wet ball depression during the summer design day. It is important to determine whether wet bulb depression can provide adequate cooling during the design day of summer. By reducing wet-ball depression from the temperature of the outer balls, one can estimate the approximate temperature of the air leaving the coolant evaporate. It is important to consider that the ability for exterior dry-bulb temperature to achieve wet-bulb temperature depends on the saturation efficiency. A general recommendation for applying direct evaporative cooling is to apply it in places where the wet-bulb temperature of the outdoor air does not exceed 22 ° C (71.6 ° F). However, in the Salt Lake City example, the upper limit for direct evaporative cooling on the psychrometric chart is 20 Ã, Â ° C (68Ã, Â ° F). Although this value is lower, this climate is still suitable for this technique.
Evaporative cooling is particularly suitable for climates where hot air and humidity are low. In the United States, the western/mountain state is a good location, with evaporative coolers prevalent in cities like Denver, Salt Lake City, Albuquerque, El Paso, Tucson, and Fresno. Evaporative air conditioners are also popular and suitable for the southern part of Australia. In dry and dry climates, the installation and operating costs of evaporative coolers can be much lower than coolant cooling, often 80% or more. However, evaporative cooling and steam compression conditioning are sometimes used in combination to produce optimal cooling results. Some evaporative coolers can also serve as a moisturizer in the heating season. Even in areas that are mostly dry, short periods of high humidity can prevent evaporative cooling from an effective cooling strategy. Examples of these events are the rainy season in New Mexico and southern Arizona in July and August.
In locations with moderate humidity, there are many cost-effective uses for evaporative cooling, in addition to their extensive use in dry climates. For example, industrial plants, commercial kitchens, laundry, dry cleaners, greenhouses, cooling premises (loading docks, warehouses, factories, construction sites, athletic events, workshops, garages, and enclosures) and confinement farms (poultry, pigs and dairy farms ) often use evaporative cooling. In a very humid climate, evaporative cooling may have little benefit of thermal comfort beyond the increased ventilation and air movement it provides.
Another example
Trees cultivate large amounts of water through the pores in their leaves called stomata, and through this evaporative cooling process, forests interact with the climate on a local and global scale.
Evaporative cooling is commonly used in cryogenic applications. The steam above the cryogenic liquid reservoir is pumped away, and the liquid continues to evaporate as long as the liquid vapor pressure is significant. Evaporative cooling of ordinary helium forms a 1-K pot, which can cool at least 1.2 K. Helium-3 evaporative cooling can provide temperatures below 300 mK. These techniques can be used to make cryocoolers, or as components of lower-temperature cryostats such as coolant. As the temperature decreases, the vapor pressure of the liquid also falls, and the cooling becomes less effective. This sets the lower limit for the temperature that can be achieved with the given fluid.
Evaporative cooling is also the last cooling step to achieve the ultra-low temperatures required for Bose-Einstein condensation (BEC). Here, so-called forced evaporative cooling is used to selectively remove high-energy ("hot") atoms from an atomic cloud until the remaining clouds are cooled below the BEC transition temperature. For a cloud of 1 million alkali atoms, this temperature is about 1? K.
Although the robotic spacecraft uses almost exclusively thermal radiation, many manned spacecraft have short missions that allow open cycle evaporative cooling. Examples include Space Shuttle, Apollo Command/Service Module (CSM), Lunar Module and Portable Life Support System. The Apollo CSM and Space Shuttle also have a radiator, and Shuttle can evaporate ammonia and water. The Apollo spacecraft uses a sublimator, compact and mostly passive device that discharges waste heat in moisture (steam) that is released into space. When liquid water is exposed to a vacuum, it boils violently, bringing enough heat to freeze the remaining ice covering the sublimator and automatically adjust the flow of the feed water depending on the heat load. The water released is often available in a surplus of fuel cells used by many manned spacecraft to generate electricity.
However ice crystals from urine are discarded, water etc., which fly through space at orbital speeds, have been found for spacecraft "sand blasts".
Design
Most designs make use of the fact that water has one of the highest evaporation rates (latent heat of evaporation) known from any common substance. Therefore, the evaporative coolant uses only a small portion of the vapor compression energy or absorption air conditioning system. Unfortunately, except in very dry climates, a one-stage (direct) coolant can increase relative humidity (RH) to levels that make the occupants uncomfortable. The two-stage evaporative coolant and indirectly keep the RH lower.
Direct evaporative cooling
Direct evaporative cooling (open circuit) is used to lower the temperature and increase the air humidity by using latent heat of evaporation, converting liquid water into water vapor. In this process, the energy in the air does not change. The warm, dry air is converted into cool, moist air. The heat from the outside air is used to evaporate water. RH increases to 70 to 90% which reduces the cooling effect of human sweat. Humid air must be constantly released outward or the air becomes saturated and evaporation stops.
The mechanical unit direct evaporative cooler unit using fan to draw air through a wet membrane, or pad, which provides a large surface area to evaporate water into the air. Water is sprayed on the top of the pad so it can drip into the membrane and constantly keep the membrane saturated. Any excess water dripping from the bottom of the membrane is collected in a pan and recirculated back upward. Direct one-way evaporative coolers are usually small because they consist of membranes, water pumps, and centrifugal fans. The mineral content of urban water supply will cause scaling of the membrane, which will lead to a blockage of membrane life. Depending on the mineral content and evaporation rate, regular cleaning and maintenance is required to ensure optimal performance. Generally, the air supply from the one-stage evaporative coolant needs to be drained directly (one-way flow) due to high air supply humidity. Several design solutions have been devised to harness energy in the air such as directing the exhaust air through two double-pane glass windows, thereby reducing the solar energy absorbed through the glass. Compared to the energy required to achieve a cooling load equivalent to a compressor, a one-stage evaporative coolant consumes less energy.
Passive Direct evaporative cooling can occur in anywhere that evaporative cooled water can cool the space without fan help. This can be achieved through the use of fountains or more architectural designs such as evaporative downdraft cooling towers, also called "passive cooling towers". The design of the passive cooling tower allows outside air to flow through the top of the tower built inside or next to the building. The outer air comes into contact with the water inside the tower through the wet or mister membrane. As the water evaporates in the outside air, the air becomes cooler and less buoyant and creates a downward flow in the tower. At the bottom of the tower, the outlet allows the cooler air to go inside. Similar to mechanical evaporative coolers, the tower can be an attractive low energy solution for hot and dry climates because they only require a water pump to raise water to the top of the tower. The energy savings from using direct passive evaporator cooling strategy depend on climate and heat load. For dry climates with large depressions of spheres, cooling towers can provide sufficient cooling during the design conditions of the summer to zero net. For example, a 371 m² (4,000à ftÃ,²) retail store in Tucson, Arizona with a reasonable heat gain of 29.3 kJ/h (100,000 Btu/h) can be cooled entirely by two passive cooling towers providing 11890 mÃ, Misalnya/h (7,000 cfm) respectively.
For the Zion National Park Visitor Center, which uses two passive cooling towers, the cooling energy intensity is 14.5 MJ/mÃ,² (1.28 kbtu/ft;), which is 77% smaller than typical buildings in the western United States using 62.5 MJ/mÃ,² (5.5 kBtu/ftÃ,²). A field performance study in Kuwait revealed that the power requirement for evaporative coolants is about 75% lower than the power requirements for conventional air conditioning unit packages.
Indirect evaporative cooling
Indirect indirect cooling (closed circuit) is a cooling process that uses direct evaporative cooling in addition to some type of heat exchanger to transfer cold energy into the supply air. The humid air cooled from the direct evaporative cooling process has never been in direct contact with the conditioned air supply. The moist air stream is released outside or is used to cool other external devices such as solar cells that are more efficient if kept cool. One indirect cooling manufacturer uses a cycle called Maisotsenko that uses multi-step heat exchangers that can reduce the product air temperature to below the temperature of the wet bulb, and can approach the dew point. Although no moisture is added to the incoming air, the relative humidity (RH) rises slightly in accordance with the RH-Temperature formula. However, relatively dry air due to indirect evaporative cooling allows the sweat of the population to evaporate more easily, increasing the relative effectiveness of the technique. Indirect Cooling is an effective strategy for a hot-humid climate that is unable to increase the moisture content of air supply due to indoor air quality and human thermal comfort issues. The following graph illustrates a direct and indirect evaporative cooling process with changes in temperature, moisture content and relative humidity.
Passive indirect inductive cooling strategies are rare because these strategies involve architectural elements to act as heat exchangers (eg roofs). This element can be sprayed with water and cooled by water evaporation on this element. This strategy is rare due to high water use, which also introduces the risk of water intrusion and sacrifices the building structure.
Two-stage evaporative cooling, or indirectly
In the first stage of the two cooling stages, the warm air is indirectly cooled without adding moisture (by passing in a heat exchanger cooled by evaporation outside). In the immediate stage, the previously cooled air passes through a water-soaked pad and takes moisture during cold. Since the air supply has been previously cooled in the first stage, less humidity is transferred in the immediate stage, to achieve the desired cooling temperature. The result, according to the manufacturer, is colder air with RH between 50-70%, depending on climate, compared to traditional systems that produce about 70-80% relative humidity in air conditioning.
In hybrid designs, direct or indirect cooling has been combined with vapor compression or AC absorption to improve overall efficiency and/or to reduce the temperature below the wet ball limit.
Materials
Traditionally, evaporative cold bearings consisted of higher (aspen wood fibers) in the containment net, but more modern materials, such as some melamine plastics and papers, which came in were used as cold pad media. Modern rigid media, generally 8 "or 12" thick, adds more moisture, and thereby cools the air over typically thinner Aspen media. Another material that is sometimes used is corrugated cardboard.
Design considerations
Water usage
In a dry and semi-arid climate, water scarcity makes water consumption a concern in the design of cooling systems. From 420938 L (111,200 gal) installed water meter consumed during 2002 to two passive cooling towers at Zion National Park Visitor Center. However, these concerns are handled by experts who note that electricity generation typically requires a lot of water, and evaporative coolers use much less electricity, and thus water is comparable overall, and cost less overall, compared to chillers.
Shading
Allowing direct exposure to the sun bearing media increases the rate of evaporation. However, sunlight can degrade some of the media, in addition to heating up other elements of the evaporative cooling design. Therefore, shade is recommended in most applications.
Mechanical system
In addition to the fans used in mechanical evaporative cooling, the pump is the only other mechanical equipment required for evaporative cooling processes in both mechanical and passive applications. Pumps can be used for water recirculation to a wet media pad or provide water at very high pressure to the mister system for passive cooling towers. The pump specifications will vary depending on the evaporation rate and area of ​​the media pad. Zion National Park Visitor Center uses a 250 W (1/3 HP) pump.
Exhaust
The open drain and/or window must be used at all times to allow air to continuously exit from the air-conditioned area. Otherwise, the pressure develops and the fan/blower in the system can not push much air through the media and into the air-conditioned area. The evaporative system does not work without exhausting the continuous air supply from the air-conditioned area to the outside. By optimizing the 'cooled air' inlet placement, along with the layout of the home alleys, doors and windows of related spaces, the system can be used most effectively to direct cooled air to the required area. A well-designed layout can be very effective at scavenging and expelling hot air from the desired area without the need for a ventilation system above the ceiling. Continuous airflow is essential, so windows or exhaust ventilation should not limit the volume and air ducts introduced by evaporative cooling machines. We must also pay attention to the direction of the wind from the outside, as a strong southern wind will slow or limit the tired air from the south-facing window. It is always best to have a window against open wind direction, while the window against the wind is closed.
Different types of installations
General installation
Typically, home and industrial evaporative refrigerants use direct evaporation, and can be described as a metal or a closed plastic box with a ventilated side. The air is driven by a centrifugal fan or blower, (usually driven by an electric motor with pulleys known as sheaves in HVAC terminology, or direct axial fan), and a water pump is used to wet the evaporative cooling pad. The cooling unit can be mounted on the roof (down draft, or downflow), or outer wall or window (side draft, or horizontal flow) of the building. To cool, the fan draws ambient air through the vents on the side of the unit and through the wet pads. The heat in the air evaporates water from the constantly muffled bearings to continue the cooling process. Then cooled, moist air is sent to the building through a vent on the roof or wall.
Since the cooling air comes from outside the building, one or more large vents must exist to allow air to move from the inside out. Air may only be allowed to pass through the system once, or the cooling effect will decrease. This is because the air reaches saturation point. Often 15 or more hourly air changes (ACH) occur in the space served by an evaporative coolant, a relatively high level of air exchange.
Evaporative cooling towers
Cooling towers are structures for cooling water or other heat transfer media to ambient near-ambient temperature bulb. The wet cooling tower operates on the principle of evaporative cooling, but is optimized to cool water rather than air. Cooling towers can often be found in large buildings or in industrial locations. They transfer heat to the environment from coolant, industrial process, or power cycle Rankine, for example.
The atomizer system
The drizzle system works by forcing water through high pressure pumps and tubes through a brass mist nozzle and stainless steel which has a hole of about 5 micrometers, resulting in a fine micro-fog. Water droplets that create a mist are so small that they evaporate instantly. Flash evaporation can reduce the ambient air temperature by 35 Â ° F (20 Â ° C) in just seconds. For core systems, it is ideal to install a fog line of about 8 to 10 feet (2.4 to 3.0 m) above the ground for optimal cooling. Drizzle is used for applications such as flower plots, pets, livestock, cages, insect control, odor control, zoo, veterinary clinics, refrigeration products, and greenhouses.
Drizzle fans
Fog fan is similar to humidifier. A fan blows water fog into the air. If the air is not too moist, the water evaporates, absorbs heat from the air, allowing the drizzle fan to also work as an air conditioner. Fog fans can be used outdoors, especially in dry climates. It can also be used indoors.
A small portable battery-powered drizzle fan, consisting of electric fans and hand-operated handmade water pumps, is sold as a new item. Their effectiveness in everyday use is unclear.
Performance
Understanding the cooling performance of yawning requires an understanding of psychrometric. Evaporative cooling performance varies due to changes in external temperature and humidity level. The housing cooler should be able to lower the air temperature to 3 to 4 Â ° C (5 to 7 Â ° F) from the temperature of the wet bulb.
It's easy to predict cooler performance than standard weather reporting information. Because weather reports usually contain dew and relative humidity, but not wet ball temperatures, psychrometric charts or simple computer programs should be used to calculate wet ball temperatures. After the temperature of the wet bulb and dry ball temperature is identified, cooling performance or leaving coolant air temperature can be determined.
Evaporative media efficiency typically ranges from 80% to 90%. The most efficient system can reduce the dry air temperature to 95% of the wet-bulb temperature, the most inefficient system reaches only 50%. The efficiency of evaporation drops very little over time.
The common aspen bearing used in residential evaporative coolers offers approximately 85% efficiency while the CELdek evaporation medium type offers efficiency & gt; 90% depending on airspeed. CELdek media is more commonly used in large commercial and industrial installations.
Sebagai contoh, di Las Vegas, dengan hari desain khas musim panas sebesar 42 ° C (108 ° F) dry ball kering dan suhu ball basah basah or  ± 19  ° C (66 ° F) atau sekitar 8% kelembaban relatif, suhu udara yang meninggalkan pendingin perumahan denote efisiensi 85% akan menjadi:
- Ã, = 42à , ° CÃ, - [(42 Ã,  ° C Ã,â € "19à , ° C ) Ã, ÃÆ'â € "85%] = 22,45Ã,  ° C atau 72,41à , ° F
However, one of two methods can be used to estimate performance:
- Use the psychrometry graph to calculate the temperature of the wet bulb, then add 5-7Ã, Â ° F as described above.
- Use a rule of thumb that estimates that the wet ball temperature is approximately equal to the ambient temperature, minus one third of the difference between ambient temperature and dew point. As before, add 5-7Ã, Â ° F as described above.
Some examples clarify this relationship:
- At 32Ã, Â ° C (90Ã, Â ° F) and relative humidity of 15%, air can be cooled to nearly 16Ã, Â ° C (61Ã, Â ° F). The dew point for this condition is 2 Ã, Â ° C (36Ã, Â ° F).
- At 32Ã, Â ° C and 50% relative humidity, air can be cooled to about 24Ã, Â ° C (75Ã, Â ° F). The dew point for this condition is 20Ã, Â ° C (68Ã, Â ° F).
- At 40 ° C (104 ° F) and 15% relative humidity, air can be cooled to nearly 21 ° C (70 ° F). The dew point for this condition is 8Ã, Â ° C (46Ã, Â ° F).
( Cooling examples taken from the June 25, 2000, Idaho University publication, "Homewise" ).
Because evaporative coolers are best in dry conditions, they are widely used and most effective in arid desert regions such as the southwestern US and northern Mexico.
The same equation shows why evaporative coolants are of limited use in very humid environments: for example, a hot August day in Tokyo may be 30 ° C (86 ° F) with 85% relative humidity, 1,005 hPa pressure. It gives a dew point of 27.2 Â ° C (81.0 Â ° F) and a wet ball temperature of 27.88 Â ° C (82.18 Â ° F). According to the formula above, at 85% cooling efficiency can be cooled down to just 28.2 ° C (82.8 ° F) which makes it quite impractical.
Comparison with AC
Comparison of evaporative cooling to coolant-based cooling air:
Benefits
Cheaper to install and operate
- Estimated cost for professional installation is about half or less of the central air conditioner.
- The estimated operating cost is 1/8 of the cooling air conditioner.
- There is no power surge when turned on due to lack of compressors
- Power consumption is limited to fans and water pumps, which have relatively low current draws at start-up.
- The working fluid is water. No special refrigerants, such as ammonia or CFC, are used which can be toxic, expensive to replace, contribute to ozone depletion and/or subject to strict permissions and environmental regulations.
Ease of installation and maintenance
- Tools can be installed by mechanically inclined users at a much lower cost than cooling equipment that requires special expertise and professional installation.
- Only two mechanical parts in the most basic evaporative coolant are fan motors and water pumps, both of which can be repaired or replaced at low and frequent costs by mechanically inclined users, eliminating costly service calls to HVAC contractors./li>
Air ventilation
- The frequent and high volumetric flow rate of air travel through buildings dramatically reduces the "air age" in the building.
- Evaporative cooling improves humidity. In dry climates, this can improve comfort and reduce the problem of static electricity.
- The pad itself acts as a rather effective air filter when properly maintained; it is capable of removing various contaminants in the air, including urban ozone caused by pollution, regardless of the very dry weather. A cooling-based refrigeration system loses this capability when there is not enough moisture in the air to keep the evaporator wet while providing frequent condensation droplets to wash away dirt from the air.
Losses
Performance
- Most evaporative coolers can not lower air temperatures as much as cooling air conditioning.
- The high dew (moisture) condition decreases the cooling capability of the evaporative coolant.
- There is no dehumidification. Traditional air conditioning removes moisture from the air, except in very dry locations where recirculation can cause moisture buildup. Evaporative cooling adds moisture, and in humid climates, drought can increase thermal comfort at higher temperatures.
Convenience
- The air supplied by the evaporative coolant generally has a relative humidity of 80-90% and can cause the interior moisture level as high as 65%; very humid air reduces the rate of moisture evaporation from the skin, nose, lungs, and eyes.
- High humidity in the air accelerates corrosion, especially in the presence of dust. This can greatly reduce the life of electronics and other equipment.
- High humidity in the air can cause water condensation. This can be a problem for some situations (eg, electrical appliances, computers, papers, books, old wood).
- Odor and other outside contaminants may be blown into the building unless adequate filtering already exists.
Water usage
- Evaporative coolers require constant water supply to soak the pads.
- High water mineral content (hard water) will leave the mineral deposits on the pads and the inside of the cooler. Depending on the type and concentration of minerals, possible safety hazards during replacement and removal of bearing waste may be present. The bleed-off and purge pump system can reduce but not eliminate this problem. Installation of inline water filters (drinking water refrigerator/ice maker) will drastically reduce mineral deposits.
Maintenance frequency
- Any rusty or corrosive mechanical component needs to be cleaned or replaced regularly due to high humidity environments and potentially heavy mineral contents in areas with hard water.
- Evaporative media should be replaced regularly to maintain cooling performance. The wooden wool pads are cheap but require replacement every few months. High-efficiency rigid media are much more expensive but will last for several years in proportion to water hardness; in areas with very hard water, rigid media can only last for two years before unacceptable mineral scale accumulation decreases performance.
- In areas with cold winters, evaporative coolers should be dried and frozen to protect the drains and cooler than freezing and then freeze them before winter.
Health hazards
- Evaporative coolers are a common place for mosquito breeding. Many people consider improper cooling as a threat to public health.
- Fungi and bacteria can be dispersed into the interior air of an untreated or damaged system, causing Sick Building Syndrome and adverse effects for people with asthma and allergies.
- Wood wool from dry cushioned pads can be burned even by small sparks.
See also
- Architectural techniques
- Building engineering
- Car cooler
- Coolgardie is safe Australian Food Cooler using Evaporative Refrigeration
- Cooling tower
- Dehumidifier
- Humidifier
- HVAC (Heating, ventilation, and air conditioning)
- Pot-in-pot refrigerator
References
External links
- Holladay, April (2001). "The swamp cooler cools the air with evaporation". Ask Ask Weekly Q & amp; Column of science . USAToday.com . Retrieved 2006-07-14 . Ã,
- PATH Tech Inventory: Two Evaporative Cooler Stages
- evaporative cooler
- PATH Tech Inventory: Evaporative Cooler
- Evaporative cooling
- Indirect Coolapado's Indaporative Cooling
- Innovative Technologies Evaporate and Enhance Heatly Improve Air Conditioning
- Evaporative Cooling on the plane - described in 1934 Flight
- Dengue and Cooler
Source of the article : Wikipedia
0 Comments