Humidifier

Ultrasonic humidifier

In the process of breathing, animals (including humans) consume atmospheric oxygen and enrich it with carbon dioxide. In rooms, this is mainly corrected by ventilation . If the temperature of the outside air is significantly higher than the temperature of the air in the room, then with cooling its relative humidity rises. If necessary, reduce the relative humidity using dehumidifiers . If the outside air is much colder than comfortable, it is heated, which leads to a decrease in relative humidity. This is because heating raises the temperature, but does not increase the amount of moisture in the air. For example, at an outdoor temperature of −10 ° C and a relative humidity of 80%, the absolute humidity is 1.68 g / m³. If this air is heated to 20 ° C (indoors), then its absolute humidity, that is, the amount of water, will not change, but relative to the maximum absolute humidity at this temperature (17.3 g / m³) it will be 9.71%, which significantly below a comfortable level. According to various estimates, the ideal relative humidity in a living room is 30–45% (for the cold season), 30–60% (for the warm season), ^[1] and for a child with a respiratory infection (according to Komarovsky ) - 70 - 80% ^[2] . Drying the air causes increased evaporation of moisture from anywhere: from the skin and from the human body and pets, indoor plants, from covering walls, furniture, musical instruments, parquet, books, paintings and other objects made from hygroscopic materials, which is harmful to the health of inhabitants and safety items. Overmoistening of air can lead to deformation of objects made of hygroscopic materials (as a result of absorption of moisture from the air), to a violation of the thermoregulation mechanisms of warm-blooded animals (including humans), and to condensation on objects cooled below the dew point (for example, glass windows facing street).

To increase the relative humidity, air humidifiers are used. If the humidifier is equipped with a hygrostat, then it can raise the humidity to a predetermined level. Humidification occurs when water evaporates. The evaporation rate increases with increasing water temperature, water surface area and / or with a decrease in relative humidity. Since the purpose of humidification is to increase relative humidity, only the increase in water temperature ( steam humidifiers ) and the increase in the surface area of ​​evaporation, as well as a combination of these two methods, make sense. In turn, an increase in the evaporation surface is achieved by creating a water-air aerosol (nozzle and ultrasonic humidifiers ) or by moistening hydrophilic surfaces of complex shape ( traditional humidifiers and air washers ).

The history of air conditioning dates back thousands of years - constructions were used in Persia (the so-called " wind catchers " - the first documentary evidence of their appearance dates back to the 4th millennium BC), which provide cooling and humidification of the air in the room. However, the first independent devices for humidification appeared at the end of the XIX century. In 1897, a nozzle chamber was patented in the United States - an apparatus for humidifying, draining and cooling air with water. Since 1906, they began to apply the method of regulating air humidity by the moisture content of the nozzle chamber ^[3] .

The first company to produce humidifiers for the home was the Swiss company Plaston (trademarks Boneco and Air-O-Swiss). From 1969 to the present day is a leader on the market for HVAC equipment, having in its arsenal all types of humidifiers (traditional, ultrasonic and steam), as well as air washing. On the basis of the Boneco company - the Plaston factory, devices for the Electrolux company are also manufactured (humidifiers of the 35th and 55th series, air washers of the 65th and 75th series) .

According to GOST 22270-76 ^[4] , humidifiers can be of various types:

• Nozzle - water is sprayed by nozzles under air pressure.
• Rotary - water is sprayed by a rotating disk.
• Film - air humidification occurs in contact with the wetted surface of the nozzle.
• Porous - humidification occurs due to the evaporation of water from the surface of a moist porous material.
• Boilers - humidification occurs due to evaporation and boiling of water, organized with the help of a heating element.
• Steam - water vapor from a central or own source is supplied directly to the air stream.

The following types of humidifiers are currently available for sale:

• Traditional - correspond to porous (according to GOST).
• Air washing is a cross between film (according to GOST) and porous (according to GOST).
• Steam - corresponds to the boiler (according to GOST).
• Ultrasonic - like atomizer (according to GOST) and rotary (according to GOST) water is sprayed, but the ultrasonic emitter serves as a sprayer.
• High-pressure nozzles - water is sprayed like nozzles (according to GOST), but without the use of compressed air.

Traditional Humidifiers

In cold (adiabatic) humidifiers, the fan drives the air through a wet filter (humidifying cartridge), as a result of which the air is slightly cooled (the heat of evaporation of water is taken from the air) and humidified.

The performance of such humidifiers greatly depends on the relative humidity (the higher it is, the lower the evaporation rate) and temperature (the higher the temperature, the more intense the humidification). Thus, the relative humidity is automatically maintained at the optimum level. Ideally, cold humidifiers should run on distilled water, otherwise the humidifying cartridge will clog and will have to be replaced frequently.

Air Wash

"Air washing" is a modification of the traditional humidifier circuit. The moisturizing element is a drum of hydrophilic discs slowly rotating around a horizontal axis. Below the axis of rotation, the discs are immersed in water and get wet, and above it, they are blown by the air stream created by the fan and dry out, moistening the air. If there are dust particles in the air stream, then they with some probability adhere to the wet surface of the disk and are washed off when the disk segment is immersed in the water of the humidifier’s working volume. Thus, the airflow leaving the humidifier is cleaner and wetter than the incoming air.

You can use tap water to fill the “air wash”, the quality requirement is one: the water should not have an undesirable odor. If you intentionally add aromatic essential oils to the water, the humidifier will work like an aroma lamp , but the effectiveness of aromatization is significantly lower than that of full aroma lamps.

In addition to humidification, these devices carry out air purification .

Advantages of air washers:

• low power consumption;
• do not moisten the air;
• simultaneous cleaning and moisturizing;
• do not require consumables (filters and cartridges), except for tap water;
• safe for children.

The disadvantage is the inability to increase humidity above normal, which is necessary in greenhouses and botanical gardens. Regular water refilling is insufficient for sanitary reasons - dangerous microorganisms and fungi can develop in the water. The system must be washed.

Productivity of cold humidifiers is 3.5-17.5 liters per day. Power consumption - 3-60 watts. There are industrial models that are permanently connected to the water supply and sewage systems and have high performance.

Steam humidifiers

Steam humidifiers are similar in principle to electric kettles. For intense evaporation, the water in them is heated to a boil. Steam humidifiers must have a hygrostat (air humidity sensor), which turns off the device when the specified humidity is reached, otherwise the humidity in the room can significantly exceed the optimal level. Using steam humidifiers, you can raise the humidity in the room to a state of saturated steam and in addition to that, in turn, will lead to the formation of fog (water condensed in air) and dew (water condensate on hard surfaces). The fog and dew from the steam humidifier actually consist of distilled water , since it was formed from steam , therefore, with a decrease in the relative humidity in the room, such condensate evaporates without residue.

Advantages:

• The ability to quickly raise the relative humidity in the room to 100%.
• Water, evaporating, is purified from non-volatile impurities.
• If you add essential oils to the water of the working volume of the humidifier, you get an electric aroma lamp .

Disadvantages:

• Large power consumption. Their productivity can be from 7-16 liters per day with a power consumption of 300-600 W and above for large industrial models.
• Raise the room temperature. If the room temperature is lower than comfortable, then this will not be a disadvantage.

Ultrasonic Humidifiers

Ultrasonic humidifiers - are considered the most effective of the existing humidifiers. Such humidifiers create fog , knocking tiny droplets of water from the surface of the water using ultrasonic vibrations obtained by a piezoelectric emitter. This is an ultrasonic range in the 5 MHz region. Fog spreads over the volume of the room by natural air currents or forced (for example, using fans ). After some time (depending on the relative humidity of the air in the room), the fog particles in the process of natural evaporation turn into steam , which leads to an increase in relative humidity. A certain amount of fog can settle on solid surfaces before evaporation. Since the fog particles were obtained from the water in the humidifier mechanically, they contain everything that was contained in the water of the humidifier’s working volume - hardness salts , microorganisms and their spores, etc. After evaporation of the fog, everything that was dissolved or suspended in it water component, - either becomes a dry residue, or is deposited on the emitter, - significantly reducing its service life.

Ultrasonic humidifiers have these advantages over other (some) types:

• the ability to increase humidity to high values;
• leaving steam temperature no more than 20 ° C (provided that the humidifier is not equipped with an additional element for heating water ).
• low noise level ;
• built-in water heaters are possible.

Typical performance of ultrasonic humidifiers is 7-12 liters per day. Power consumption - 40-50 W (in the presence of an element for heating water, the power may exceed 125 W).

Disadvantages:

• Increased requirements for quality and purity of water, it is recommended to use distilled water ;
• Fog (steam) from the humidifier may contain all components of the tank fluid, including hardness salts , microorganisms and their spores , etc.
• A small tank of water, usually 3 to 4 liters. With a consumption of 300-400 ml / h, water will be spent in less than 10 hours;

High Pressure Nozzle Humidifiers

High pressure nozzle humidifiers work by spraying water in the nozzles . Sometimes such nozzles are called fogging nozzles. Most often, water is supplied under pressure from 30 to 85 bar, and the higher the pressure, the smaller the droplets of water obtained after spraying. Nozzles can be installed both directly in the room and in the ventilation duct (usually the duct method is not used for domestic systems, but is used for large industrial or commercial buildings). In the channel spraying method, non-vaporized droplets should be captured by special droplet eliminators. When directly sprayed into the room, droplets of water quickly evaporate in the air, if the nozzle performance and room parameters are selected correctly. Due to the evaporation of water droplets and a decrease in temperature (as a result of heat absorption during evaporation ), the relative humidity increases.

With nozzle humidification, all substances that were dissolved in water remain in droplets of water. Therefore, water before spraying must undergo filtration, disinfection and demineralization using reverse osmosis , and in some cases deionization, otherwise dissolved salts will form a characteristic coating on objects and surfaces.

Advantages:

• Low power consumption.
• High performance, can cater for many rooms with individual humidity settings.
• Hygiene, since water does not come in contact with air before spraying.
• Connection to a constant source of water, no need to top up water.
• Simple service.

Disadvantages:

• Water quality requirements, the need for pre-filtration if the filter is not built into the humidifier.
• High price.
• The complexity of installation.
• The air temperature decreases due to evaporation of water.

Industrial air humidifiers are more powerful air humidifiers compared to the household range. This technique is designed for a long service life with constant operation.

Updating air masses, incl. the air flow (open doors or open windows) reduces the humidifier's efficiency, which was achieved by the device, even during its long work.

• Aerosol generator

• The best humidifier for baby's health was selected on the site HI-TECH MAIL.RU June 1, 2016