What Is Humidity Calculation?

Humidity, a physical quantity that indicates how dry the atmosphere is. At a certain temperature, the less water vapor in a certain volume of air, the drier the air; the more water vapor, the more humid the air. The dryness and humidity of the air is called "humidity". In this sense, physical quantities such as absolute humidity, relative humidity, comparative humidity, mixing ratio, difference in saturation, and dew point are commonly used to express it; if the weight of water vapor in wet steam is expressed as a percentage of the total weight (volume) of the steam, it is called Is the humidity of the steam. The comfortable humidity of the human body is: the relative humidity is less than 70%.

Humidity, generally at

Data inversion products

Humidity is an indicator of the humidity of the climate.

Air humidity has important uses in many aspects. It is mainly an important value in theory in atmospheric science, meteorology, and climatology, but its role in practical applications is relatively small.

Humidity Meteorology Hydrology

When it rains, the air humidity is very high. In meteorology and hydrology, humidity is an important data that determines evaporation and transpiration. It plays a decisive role in the generation of different climatic zones. Water vapor in the atmosphere is also essential in the water cycle. Water can quickly move on the surface of the earth through water vapor. Water forms precipitation, clouds, and other phenomena in the atmosphere, which determine the weather and climate of the earth.

In weather forecast, relative humidity is more commonly used. It reflects the possibility of rain and fog. In hot weather, high relative humidity makes humans (and other animals) feel hotter because it prevents the evaporation of sweat. Humans can work out the heat index.

Humidity Medicine

The relationship between air humidity and respiration is very close in medicine. Under a certain humidity, oxygen can easily enter the blood through the alveoli. The average person feels most comfortable at a relative humidity of 45-55%. The relative humidity in an overheated, unventilated room is generally low, which may cause skin irritation and irritation to the mucous membranes. Excessive humidity affects people's ability to regulate body sweat, and people feel sweltering. In general, people feel better in high temperature but low humidity (such as desert) than in low temperature but high humidity (such as rain forest). The humidity of the anesthetic gas is very important when anesthesia is performed by breathing. The anesthetic gas used in medicine is generally stored under anhydrous conditions. If humidity is not added during use, it will cause evaporation and water loss in the human lung.

Humid air is bad for the human body at any temperature.

Studies have shown that when the humidity is too high, the amount of pineal hormone secreted by a pineal gland in the human body is also large, so that the concentrations of thyroxine and epinephrine in the body are relatively reduced, and the cells will be "lazy". Will be listless and sluggish. Working and living in a place with high humidity for a long time, it is also prone to suffering from paralysis. When the humidity is too small, evaporation will accelerate, and dry air will easily deprive the human body of water, dry the skin, and stimulate the nasal mucosa. When invaded, it is easy to induce respiratory diseases. In addition, too much or too little air humidity is conducive to the reproduction and spread of some bacteria and viruses. Scientific determination shows that when the air humidity is greater than 65% or less than 40%, the germs multiply and breed the fastest, and when the relative humidity is 45% -55%, the germs die faster.

Relative humidity usually affects the human body in conjunction with air temperature and air pressure. Modern medical meteorological research shows that the relative humidity that is more suitable for the human body is: when the room temperature is 25 ° C in summer, it is more comfortable to control the relative humidity at 40% -50%; when the room temperature is 20 ° C in winter, the relative humidity is controlled to 60% -70%. Due to the effects of high temperature, low pressure, and high humidity in summer, human sweat is not easy to be discharged, and it is not easy to evaporate after sweating, so it can cause irritability, tiredness, and loss of appetite; in winter, the humidity is sometimes too small, and the air is too dry, which may cause Mucosa infection of the upper respiratory tract and cold. According to scientific experiments, when the diurnal change of temperature is greater than 3 ° C, the diurnal change of air pressure is greater than 10 hPa, and the diurnal change of relative humidity is greater than 10%, the incidence of arthritis will increase significantly.

High-temperature indicators of human death are also strongly related to air humidity. When the temperature and humidity reach a certain limit, the body's heat cannot be emitted, and the body temperature will rise, so that the body's heat resistance limit is exceeded, and the person will die. Therefore, China s standard for severe weather is that the maximum temperature in the south of the Yangtze River is higher than 40 ° C, or the maximum temperature is 35 ° C, and the relative humidity is greater than 60%; the maximum temperature in the north of the Yangtze River is 35 ° C, or the maximum temperature is 30 ° C. At the same time, the relative humidity is greater than 65%.

In summer, when humidity increases and water vapor tends to be saturated, it will inhibit the human body's heat dissipation function, making people feel very stuffy and irritable. In winter, when humidity increases, heat conduction will be accelerated about 20 times, making people feel colder and depressed. Patients with arthritis due to damage to the joint synovium and surrounding tissues at the affected site weaken their ability to resist external stimuli and cannot adapt to intense cooling, which exacerbates the condition or aches. If the humidity is too small, due to the large loss of water in the upper respiratory tract mucosa, people feel dry mouth, even sore throat, hoarseness and nosebleed, and induce a cold. Investigation and research also show that when the relative humidity is above 90%, 25 will make people feel like 30 . Dry air can absorb sweat at the same rate as sweat produced by the human sweat glands, making us feel cool. However, because the humid air is already full of water, it is unable to absorb water again, so sweat has to accumulate on our skin, causing our body temperature to rise continuously, and our heart is overloaded. ^[4]

Air humidity is a meteorological element that indicates the water vapor content and the degree of humidity in the air. The ground air humidity refers to the air humidity at the prescribed height (that is, 1.25 to 2.00 meters in China, and 1.5 meters in China). It is measured by instruments such as wet and dry bulb thermometers and hygrometers installed in the louver (basic station regularly observes 4 times a day, and base station observes 24 times a day). There are three basic forms, namely water vapor pressure, Relative humidity, dew point temperature. Water vapor pressure (formerly known as absolute humidity) indicates the pressure of the water vapor portion of the air. The unit is in hundred-pascal (hpa), which is a decimal. Temperature at saturation.

Humidity Biology

Air humidity is a very critical quantity in biology, especially in ecology. It determines the composition of an ecosystem. Switching of stomata on plant foliage and plant breathing. Some animals, such as snails, can only absorb oxygen if their skin has a certain humidity.

Humidity storage and production

The humidity in the warehouse where the fruit is stored determines its ripeness. Excessive humidity in a metal storage warehouse can cause corrosion. Many other goods such as chemicals, tobacco, wine, sausages, wood, art, integrated circuits, etc. must also be stored at a certain humidity or at a humidity of zero. Therefore, many warehouses, museums, libraries, computer centers and certain factories (such as the microelectronics industry) have air-conditioning devices to control indoor humidity.

Humidity Agriculture and Forestry

Too low humidity in misty forests can cause soil and plant water loss and reduce yield in agriculture.

Humidity is also a very critical quantity in the forestry and forestry industries. In sawmills, people often water the logs that have accumulated there. The wood itself has its own humidity, and in the air its humidity gradually approaches the surrounding humidity. The change in humidity in this wood will cause a change in the volume of the wood, which is very critical for the forestry industry. ^[5]

Generally, when the wood is stored, the air can directly contact with it in all directions, so as to prevent the wood from deforming or mold. When paving the floor, it is best to leave the floor wood in the house for a day or two to make it the same humidity as the house. Otherwise, the floor wood may stretch or shrink after laying. ^[6]

Humidity building

Dew point is a very important quantity in building physics. If the temperature inside a building is not the same, the water that flows from the high temperature part into the humid air of the low temperature part may condense. Mold may occur in these places, and this must be taken into account when designing the building. In addition, relative humidity is an important indicator for measuring the indoor thermal environment of buildings. When the subjective thermal sensation of the human body is neutral, the wind speed is no more than 0.15m / s and the relative humidity is 50%. It is also a benchmark for indoor thermal environment design.

Humidity Static and Humidity

The more dry the air, the more likely it is to generate static electricity. Relative humidity (RH) has a direct effect on the performance of the surface's accumulated charge. The higher the relative humidity, the shorter the storage time of the object, and the method of reducing the surface charge (because the relative humidity increases) can be recombined or conducted. As the relative humidity increases, the electrical conductivity of the air also increases.

As the air gradually dries (the percentage of relative humidity decreases), the change in the ability to generate static electricity is certain and obvious. At a relative humidity of 10% (very dry air), a charge of 35kV can be generated when walking on a carpet, but it will drop sharply to 7.5kV at a relative humidity of 55%. The optimal range of relative humidity in the working environment is 30% -50%. Some clean places generally require relative humidity of 50%. Due to the presence of components that are more sensitive to the effects of corrosion and humidity, other environments require lower relative humidity.

Humidification and dehumidification

Humidification

Centrifugal humidification principle

Centrifugal humidifier works:

The centrifugal humidifier uses a high-speed motor to drive the composite impeller to generate a vacuum. The water in the water storage tank is pressurized by a water absorber to the composite atomizing impeller under the effect of atmospheric pressure. The water is converted into a fine mist with a diameter of 5um and passes through the lower air duct. The breeze is sent to the fog outlet, where the high-speed air current of the upper inlet and the air outlet merge together to form a high-speed aerosol sprayed into the air. The aerosol and the residual heat in the air are in contact with each other to completely vaporize to achieve the purpose of humidification.

Polar humidification principle

Working principle of electrode steam humidifier:

When the tap water enters the humidifying bucket, the water level gradually rises. The electrodes of the humidifier are energized. When the water level passes through the electrodes, the current between the electrodes forms the current loop through the conductivity of the water, and the water is heated to boiling to output clean steam. With the steam output, the water level gradually decreases. At this time, the water inlet valve is turned on, and the water is re-injected until the proper water level is reached, and steam continues to be generated.

When the concentration of minerals in the humidification bucket becomes higher and higher, the drain valve opens automatically to drain the waste water, the humidifier replenishes fresh water again, and continues the humidification work process.

Using tap water with too high or low conductivity may cause excessive loss of humidification bucket or insufficient humidification capacity

Ultrasonic humidifier principle:

The ultrasonic humidifier is based on the principle of high-frequency ultrasonic vibration. The water is atomized into fine particles of 1-5 microns, and the water mist is diffused into the air by the wind device, so as to achieve the purpose of uniformly humidifying the air. Its characteristics are: high humidification intensity, uniform humidification, and high humidification efficiency; energy saving and power saving; super long service life; automatic humidity balance and automatic protection without water; both functions of medical atomization, cold compressing bath surface, and cleaning jewelry; disadvantages There are certain requirements for water quality.

The humidifier mainly relies on the atomizing sheet to work. You can make a simple humidifier by connecting the power supply to the centrifugal humidifying atomizing sheet. This is not true because it has a vacuum atmospheric pressure and you cannot do it. Therefore, the voltage cannot be mentioned. ^[7]

Dehumidification

Dehumidifier working principle:

The core structure of the rotor dehumidifier is a continuously rotating honeycomb drying rotor. It is the most critical part of the dehumidifier to absorb moisture. It is composed of a special glass fiber carrier containing a little metal titanium and activated silica gel. The structural design can not only attach the hygroscopic agent to a maximum extent, increase the surface area where the humid air and the hygroscopic agent contact each other, improve the working efficiency of the dehumidifier, but also have high strength, which can be well applied to various complicated working environment.

On both sides of the runner, a partition made of highly sealed silicone rubber divides the entire surface into two sectors: a 270-degree processing sector; a 90-degree regeneration reduction sector.

When the dehumidified humid air (called processing air) enters the processing area, the water vapor in the humid air is adsorbed by the active silica gel in the runner to obtain dryness, and the dried air is sent out by a blower. As the absorption of moisture increases, the processing sector gradually becomes saturated. In order to maintain its stable dehumidification performance, it is necessary to regenerate and reduce the hygroscopic agent in the runner. At this time, the rotor tending to be saturated is slowly driven into the regeneration area by the motor to start the regeneration process.

The regenerated air (usually taken from the outdoor or computer room) is heated to 100 ~ 140 degrees, and then blown into the regeneration area in reverse. At high temperature, the moisture absorbed in the runner is desorbed. During the process, a large amount of sensible heat is lost, and the temperature of the sensible heat is reduced to become humid air saturated with moisture, which is guided to the outdoor by the fan to complete the water transfer. After the regenerative dehydration, the runner regains its strong moisture absorption capacity. Driven by the motor, it turns into the work area for dehumidification.

The above-mentioned dehumidification and regeneration processes occur simultaneously, the air is continuously dried, the runner is continuously regenerated, and iterates over and over again, thereby ensuring a constant and constant working state of the dehumidifier. The rotating speed of the runner is 8 ~ 12 rpm, and the required power is very small. The parameters of the air at the outlet of the dehumidifier depend only on the parameters of the inlet air and the control of the regeneration energy. ^[8]