A dehumidifier is generally an electrical device that reduces and maintains moisture levels in the air, usually for health or comfort reasons, or to remove the musty smell and to prevent mold growth. It can be used for household, commercial, and industrial applications. Large dehumidifiers are also used in commercial buildings such as indoor ice rinks, swimming pools, as well as factories or storage sheds to control moisture levels.
Video Dehumidifier
Overview
With their operation, dehumidifiers extract water from the process air passing through the internal airspace of the unit. There are mainly two types of dehumidifiers, namely dehumidifiers and dehumidifiers.
Condensate-reducing uses a cooling system to collect water known as condensate, which is usually gray water but can sometimes be reused for industrial use. Some manufacturers offer a filtration system usually based on reverse osmosis to convert the condensate into potable water. Some designs, such as ionic membrane dehumidifiers, remove excess water in the form of vapor rather than liquid form. The efficiency of dehumidifiers can vary greatly.
Drying dehumidifiers (also known as absorption reducers) bind water from air using hydrophilic materials such as silica gel. Inexpensive domestic units contain disposable hydrophilic substance cartridges, gels, and powders. Larger commercial units contain a hot air recovery system to remove moist air from outside the room.
Maps Dehumidifier
Dehumidification of thermal condensation
These methods depend on the withdrawal of air on a cold surface. Since the saturated water vapor pressure decreases with decreasing temperature, water in the air condenses on the surface, separating water from the air.
Cooling (electric)
Electric coolant dehumidifiers are the most common type of dehumidifiers work by drawing moist air over the cooled evaporator with the fan. There are 3 main types of evaporators. They are rolled tubes, fins and tubes, and microchannel technology.
The cold evaporator coil from the cooling device condenses water, which is removed, and then air is reheated by the condenser coil. The air that is now moist and reheated is released into the room. This process works most effectively at higher ambient temperatures with high dew point temperatures. In cold climates, the process is less effective. The highest efficiency is achieved above 20 Â ° C and 45% relative humidity. This relative humidity value is higher if the air temperature is lower..
This type of dehumidifier is different from the standard air cooler ie the evaporator and the condenser are placed in the same air path. The standard AC transfers heat energy outdoors because the condenser coil releases heat outside. However, since all dehumidifier components are in the same space , no heat energy is eliminated. In contrast, the electric power consumed by the dehumidifier remains in the room as heat, so the room is actually heated, just as the electric heater draws the same amount of power.
In addition, if the water is condensed indoors, the amount of heat previously required to vaporize the water is also released back into the room (latent heat of evaporation). The dehumidification process is the opposite of adding water to a room with an evaporative coolant, and instead releasing heat. Therefore, the dehumidifier in the room will always warm the room and reduce the relative humidity indirectly, as well as reduce the humidity more directly, by condensing and removing water.
Warm and humid air is drawn into unit A in the diagram above. This air enters the crossflow plate heat exchanger (B) where a substantial proportion of reasonable heat is transferred to the cold supply air flow. This process brings the extracted air closer to saturation. Air is then flowed into the courtroom from an extract fan (C) in which some of it can be rejected outward. Rejected amounts may vary and are either determined by law on the requirements of fresh air, or by the requirement to maintain a fresh, odor-free environment. The air balance then enters the evaporator coil from the heat pump in which it is cooled and the moisture condenses. This process generates large amounts of latent energy into the cooling circuit. Fresh air is then introduced to replace the extracted amount and the mixture is discharged by the supply fan (G) to the crossflow plate exchanger (B) where it is heated by air extract from the pond. This pre-heat air then passes through the heat pump condenser (F) where it is heated by the latent energy removed during the condensation process and the energy input to the compressor. The warm, dry air is then thrown into the room.
Conventional air conditioning
Conventional air conditioners are very similar to electric dehumidifiers and act as dehumidifiers when cooling air. However, in the air conditioning, the air passes through a cold evaporator coil and then straight into the room. It is not reheated by passing the condenser, as in the cooling dehumidifier. Instead, the refrigerant is pumped by the compressor to the condenser that is located outdoors to be conditioned, and heat is then released into the outside air. Conventional air conditioners use extra energy that exhausts the outside air, and new air can have more humidity than the room needs, like a billiard room that has retained moisture high in the air.
Water that condenses on the evaporator in the air conditioner is usually diverted to remove water extracted from the conditioned space. Newer higher-efficiency window units use condensed water to help cool condenser coils by evaporating water into the outside air, while older units just let water drip out.
Spray Dehumidifiers
When the water cools below the atmospheric dewpoint, the atmospheric water will condense onto it faster than water evaporating from it. Spray dehumidifiers mix cold water spray and air to capture atmospheric moisture. They also capture pollutants and contaminants such as pollen, whose goal is sometimes called "air purifiers".
Emergency smoke reduction
Because the window AC units have condensers and expansion units, some of them can be used as emergency dehumidifiers by sending their heat exhaust back into the same room with cooled air instead of the outside environment. If the condensate from the cooling coil is dried away from the room due to drip from the cooling coil, the result is a dryer but slightly warmer room air.
However, many window air conditioners are designed to discharge condensate water by evaporating back into the exhaust air stream, which cancels the moisture degradation caused by the condensation of water vapor on the cooling coil. To be effective as a dehumidifier, air coolers must be designed or modified so that most or all of the condensed water is dried in liquid form, not vaporized again. Even if the condensate is dried, the modified air conditioner is still less efficient than a single multipurpose tool with a design optimized for dehumidification. Dehumidifiers are designed to drain the air directly onto the cooling coil and then the heating coil in an efficient pass through the device.
In addition, most air conditioners are controlled by thermostats that feel the temperature, not humidistats that feel moisture and are usually used to control dehumidifiers. The thermostat is not designed to control moisture, and controls it badly if at all.
Ice Stacking
Under certain temperature and humidity conditions, ice can form on dehumidifier cooling evaporator coils. The accumulation of ice can block the flow of air and eventually form a solid block that wraps the coil. This buildup prevents dehumidifiers from operating effectively, and can cause water damage if condensed water drips from ice accumulation and not into the collection tray. In extreme cases, ice can damage or distort mechanical elements, causing permanent damage.
Better quality dehumidifiers may have ice or ice sensors. This will turn off the engine and allow the ice covered rolls to warm and melt the ice. Once thawed, the machine will automatically restart. Most ice sensors are simple thermal switches and do not directly sense the presence or absence of ice accumulation. An alternative design feels blocked air flow and closes the cooling coils in the same way.
thermoelectric dehumidifiers
Thermoelectric dehumidifiers use a Peltier heat pump to cool the surface and condense moisture from the air. The design is simpler and has the benefit of being quieter than a dehumidifier with a mechanical compressor. However, due to the relatively poor Coefficient of Performance, this design is mainly used for small dehumidifiers. Ice buildup can be a problem, similar to a problem with the descending cooler.
Absorption/drying dehumidification
This process uses a special moisture absorbent material called a desiccant, which is exposed to air to be conditioned. The saturated material of moisture is then transferred to a different location, where it is "refilled" to repel moisture, usually by heating it. The desiccant can be mounted on a belt or other means to transport it during the operating cycle.
Dehumidifiers that work in accordance with the absorption principle are particularly suitable for high humidity levels at low temperatures. They are often used in various sectors in industry because humidity levels below 35% can be achieved.
Due to the lack of dehumidifiers the compressor dryer parts are often lighter and quieter than compressor lowers. Drying dehumidifiers can also operate at lower temperatures than dehumidifiers compressors because the unit has no coils that can not extract moisture from the air at lower temperatures.
Dehumidification of ionic membranes
Ionic membranes can be used to move moisture in or out of enclosed cages, operating at the molecular level without involving visible fluid.
The solid electrolyte polymer membrane (SPE) is a low steady state dehumidifier for a closed area where treatment is difficult. The electrolytic process results in a dehumidifying capacity of up to 0.2 grams/day from a space of 0.2 mà (7 cu ft) to 58 grams/day from 8mÃ,³ (280 cu ft). SPE systems generally do not have high dehydration capacity, but because moisture is removed through electrolysis, the process is maintenance free. This process also requires very little electrical energy to operate, using no moving parts, making the ionic membrane stationary in operation and highly reliable for long periods of time. SPE reducers are commonly used to protect sensitive electrical components, medical equipment, museum specimens, or scientific equipment from a humid environment.
SPE consists of a proton-conductive protective polymer electrolyte and a porous electrode with a catalytic layer composed of precious metal particles. When the voltage is applied to the porous electrode attached to the membrane, the water vapor on the anode side (dehumidifying side) dissociates into hydrogen ions (H) and oxygen. Hydrogen ions migrate through the membrane to be disposed at the side of the cathode (water-emptying) where they react with oxygen in the air, producing water molecules (vapors), discharged.
Condensate
Disposal
Products that use condensation technology have traditionally used a cold surface where moisture in warm air is condensed. Today a warm condensation technology based on the concept of saturated steam in a closed environment allows to reduce air humidity at temperatures below zero. It is a technology that is very energy efficient and equally efficient in all temperatures.
Most portable dehumidifiers are equipped with a condensate receptacle, usually with a float sensor that detects when the container is fully loaded, to turn off dehumidifier and prevent overflow of collected water. In a warm and humid environment, these buckets will generally be filled with water in 8-12 hours, and may need to be emptied manually and replaced several times per day to ensure continuous operation.
Many portable dehumidifiers can also be adapted to connect the output of condensate drops directly to the drain through the hose. Some dehumidifier models can be tied to a pipeline or use a built-in water pump to empty themselves as they collect water. Alternatively, a separate condensate pump can be used to move collected water to a disposal site when gravity drainage is not possible.
The central air-conditioning unit usually needs to be connected to the drain, since the quantity of condensate water generated by the system can be very large from time to time. If condensate water is directed to a sewer system, it must be trapped properly. Otherwise, the back pressure may allow the smell or culvert to enter the building. Condensate should not be directed to the home septic system, since large central air conditioning systems carry water that does not need to be maintained by a septic system. If the height of the air handler (containing the evaporator) is above ground level or in the attic of the house, the condensate line can also often be diverted to the rain gutter. Air handlers located in the basement of a house require a condensate pump to pump water up to the ground.
Potability
Generally, dehumidifier water is considered a rather clean type of greywater: unsuitable for drinking, but acceptable for watering plants, though not garden vegetables. The health problem is: [ a better reference is needed ]
- Water may contain traces of metal from solder and other metal parts, most significantly causing (which is quite harmful), but also copper, aluminum, or zinc. Metal footprints can be dangerous if used on edible plants, as they can accumulate. However, water can be used for irrigation of plants that can not be eaten.
- Various pathogens, including fungal spores, can accumulate in the water, mainly because they are stagnant. Unlike in the production of distilled water, water is not boiled, which will kill pathogens (including bacteria).
- Like distilled water, most beneficial minerals do not exist.
Food-grade dehumidifiers, also called atmospheric water generators, are designed to avoid toxic metal contamination and to keep all contact surfaces clean. These devices are primarily intended to produce pure water, and moisturizing effects are seen as secondary to their operations.
Maintenance
If condensate water is handled automatically, most dehumidifiers require very little maintenance. Due to the volume of airflow through the apparatus, the dust buildup must be removed so as not to block airflow; many design features removable and washable air filters. The trays and containers of condensate collection may need to be cleaned occasionally to remove the buildup of debris and prevent drainage drainage, which may cause water leakage and overflow.
Apps
The relative humidity in the dwelling should range from 30 to 50%.
Home and work
Dehumidification in buildings can control:
- a buildup of excessive sweat that can not evaporate in the humid air
- condensation dripping from cold water pipes
- warping and sticking furniture and doors
- mushrooms and fungi, which can cause laundry, books, and furniture to develop mustiness
- moth clothes, lice, cockroaches, woodworms, centipedes, and dust mites, which thrive in humid conditions
Basements, Crawling Room, Kitchen, Bedroom, Bathroom, Spa or Indoor Swimming Pool Area, Warehouse, Workshop
Industrial process
Dehumidifiers are used in industrial climatic chambers, to reduce relative humidity and dew point in many industrial applications from wastewater treatment plants and fresh water to indoor growing spaces where moisture control is essential.
Some industries include:
- Milling and machining
- Food packaging and processing
See also
- Air ionizer, different device for air cooler
- The atmospheric water generator, the machine that extracts pure drinking water from the air
- Food dehydrator, a device to lower water content in food, to prevent spoilage
- Humidifier, a tool that improves air humidity
- Thermoelectric Cooling
References
Further reading
- Energy Star Dehumidifiers Qualified table lists removal rates and efficiency. Long Island Authority, January 2011.
- Product Certification Program AHAM Dehumidifier. Association of Household Appliances Manufacturers.
External links
- Dehumidifier is reminiscent. US Consumer Product Safety Commission.
Source of the article : Wikipedia
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