Channel humidifiers of the ventilation system. Supply and exhaust ventilation with humidification in a private house. First experience…. Supply air humidification methods

In apartments and individual rooms of cottages, ultrasonic humidifiers (including those with pre-heating water) and “air washers” are most often used. Ultrasonic models tend to be cheaper and perform better, but require regular replacement of the softening cartridge. If we consider humidifiers in terms of hygiene and ease of use, then the best choice there will be an "air wash". The typical capacity of a household humidifier (0.3-0.5 kg/h) is sufficient to service one room of 20-30 m².

However, no matter which humidifier you choose, once or twice a day you will have to pour water into its tank. If this type of operation of the humidifier does not suit you, you will have to purchase a more expensive semi-industrial humidifier that is connected to the water supply and sewerage. It is convenient to use such humidifiers as part of a ventilation system to humidify the air in the ventilation duct - this allows you to maintain the required humidity level in all rooms of an apartment or cottage without the need for constant maintenance. Next, we will talk about such systems using Carel equipment as an example, but first a little theory.

Humidifier Capacity Calculator

The calculator allows you to calculate the required performance of an air humidifier for an apartment, office or cottage (correction value Y used when calculating humidification for production processes is not taken into account). The calculation method is described below.

Method for calculating the performance of a humidifier

The performance of most household humidifiers lies in the range of 0.3-0.5 kg / h and therefore there is no need to select them according to this parameter. Commercial humidifiers have a capacity of 1 to 500 kg/h and for each object an accurate calculation of the moisture deficit is required. The following main parameters are taken into account in the calculation:

• Required humidity in the room (at a given temperature).
• Temperature and humidity of the outside air.
• Availability supply ventilation and its performance
• Room volume
• Other factors that may affect the required performance of the humidifier (presence of people, hygroscopicity and moisture content of materials, etc.).

Moisture deficit is calculated using the formula:

Q=+Y, where:

Q- the amount of moisture required to humidify the air in the room, kg / h;
L- in the presence of forced ventilation its productivity, m³/h

in the absence of forced ventilation L = V x N, where

V— room volume, m³;
N- air exchange rate (usually from 0.5 to 2.0);

1,17 - air density, kg / m³ (at a temperature of 21 ° C and a barometric pressure of 99 kPa);
X1– moisture content (absolute humidity) supply air under the worst conditions (usually in winter), g/kg;
X2— moisture content (absolute humidity) of humidified air in the room at a given temperature, g/kg;
Y- correction value that takes into account other factors (hygroscopic materials, etc.).

Air moisture content (absolute humidity) X1 and X2 is determined based on the given values ​​of temperature and relative humidity. To determine the moisture content, it is necessary to draw a line upwards from the set temperature (on the lower scale) until it intersects with the curve indicated by the required humidity level. From the point of their intersection to the right, a horizontal line is drawn, which, when crossing with the scale, will show the desired value of absolute humidity.

For example, at a temperature of 23°C and a relative humidity of 50%, 1 kg of dry air will contain 9 g of water (i.e. a moisture content of 9 g/kg). On the given id-diagram, the air temperature is limited from below by -10°C. Since the moisture content of cold air is very low, for approximate calculations, the moisture content X1 at temperatures below -10°C can be taken equal to 0.5 g/kg.

Typical moisture deficit values ​​for residential premises at an outdoor temperature of -20°C, an indoor air temperature and humidity of +22°C and 50%, respectively:

• Apartment with an area of ​​80 m² without forced ventilation at N = 1: Q = 2.1 kg/h
• Apartment of 80 m² with forced ventilation at L=350 m³/h: Q = 3.3 kg/h
• Cottage of 150 m² with forced ventilation at L=700 m³/h: Q = 6.6 kg/h
• Cottage of 450 m² with forced ventilation at L=2000 m³/h: Q = 18.8 kg/h

After the moisture deficit is calculated, you can proceed to the sequential selection of the type, series and model of the humidifier.

Classification of air humidifiers

In the previous sections, we have described the types of household humidifiers depending on their operating principle. For high performance humidifiers, more than general classification, based on the method of obtaining steam. All humidifiers are divided into two groups: isothermal and adiabatic.

• In isothermal (or steam) humidifiers, water is brought to a boil, and the resulting steam is supplied to the room. At the same time, the air temperature in the room remains almost unchanged (it can only slightly increase), since the energy spent on the evaporation of water goes to increase the enthalpy (latent energy) of the air. Since mineral salts and microorganisms do not get into the air when water evaporates, Carel isothermal humidifiers can be used not only in residential areas, but even in rooms with a sterile and antiseptic environment (hospitals, operating rooms, clean rooms in the electronics industry). The disadvantage of steam humidifiers is their high energy consumption (about 750 W/h of energy is required to produce 1 kg of steam), so their maximum steam output is limited to 180 kg/h.
• In adiabatic humidifiers, the evaporation of water occurs at room temperature, without the supply of additional energy (for example, "air washing" and ultrasonic models are adiabatic humidifiers). In industry, most commonly used spray-type humidifiers or atomizers, which spray a finely dispersed water suspension through special nozzles. During the phase transition of water from a liquid state to a gaseous state, heat is absorbed from the air, as a result of which its temperature decreases. Thus, adiabatic humidifiers can be used to simultaneously humidify and cool the air with minimal energy consumption. Due to low energy consumption, the capacity of series-produced adiabatic humidifiers can reach 500 kg/h, and on request it is possible to manufacture systems with a capacity of up to 5000 kg/h. Adiabatic humidifiers are used in cold rooms, in textile and paper production, printing houses and warehouses of finished products.

In the next two sections, we will discuss which types of humidifiers are recommended for different sites and look at the features of the popular Carel series of isothermal and adiabatic humidifiers.

(due to heating water with electricity, steam is formed, which enters the steam collector and then to ventilation duct) and adiabatic. , in turn, are divided into nozzles (humidification occurs by spraying water under pressure through special nozzles) and ultrasonic duct humidifiers. There are also honeycomb humidifiers (air passes through the wetted surface of the material and takes moisture with it). The latter type of humidifiers is less popular, as it has a large aerodynamic resistance and low humidity control accuracy.

Types of duct humidifiers

Duct humidifiers according to the type of ventilation duct to which they are connected are divided into:

humidifiers for round channels;

humidifiers for rectangular ducts.

Depending on the installation location, they are divided into:

• built directly into the ventilation duct;
• installed on the wall near the air duct with steam supply through the distribution pipe.

The length of the distribution tube is limited and usually does not exceed 5 meters. Therefore, if it is not possible to install a humidifier on the wall next to the ventilation duct, use a humidifier built directly into the duct.

Whether water treatment is necessary for a duct humidifier depends on its type (adiabatic or isothermal) and model. In most cases, it is recommended to install a water treatment with reverse osmosis filters in order to avoid scale formation (in steam humidifiers) and nozzle breakage (in adiabatic humidifiers). In more detail, whether your humidifier needs water treatment and if so, what kind - you can consult our engineer.

The humidity level is controlled by humidity sensors. Traditionally, 2 humidity sensors are installed: one in the supply ventilation duct, the second directly in the room itself.

Benefits of duct humidifiers for ventilation

Duct humidifiers can only be installed if there is already a duct system for ventilation. Since, along with ventilation, moist air from the room is also removed from the room, and usually drier air from the street comes in instead (this is especially true in winter) - for a comfortable microclimate, it is recommended to install duct humidifiers for ventilation systems. Otherwise, the relative humidity in the house in winter with ventilation running can drop to 10-20%.

The main advantages of duct humidifiers are:

the ability to increase air humidity in several rooms at once (no need to install one humidifier in each room);

hidden installation (usually the humidifier is installed either behind a false ceiling or in a utility room near the ventilation unit);

precise regulation and integration with the ventilation unit (automatic humidifier allows you to connect it to the system " smart House» and accurately control the microclimate parameters)

How to choose a duct humidifier

The main parameter when choosing a humidifier is:

duct humidifier cost

The main parameters that affect duct humidifier price is its performance, equipment, type and brand.

Only due to the competent choice of brand and manufacturer, you can save up to 40% of the cost. It is also equally important to choose the right humidifier for performance. Our specialist will calculate the required performance of the humidifier and help you decide on the model. The most popular brands of duct type humidifiers are: Breezart and carel.

According to the regulations in rooms with a permanent stay of people, it is necessary to maintain not only a certain temperature, but also humidity. Low humidity contributes to the accumulation of static electricity on metal objects. Increased - also unpleasant and leads to a feeling of stuffiness and condensation on surfaces.

Humidity is maintained by special devices - humidifiers. They are fundamentally divided into two different types, differing in the method of moistening - it can be adiabatic (isoenthalpic) or isothermal (Fig. 1, lines 1-3 and 1-2, respectively).

Adiabatic (isoenthalpic) humidification

Adiabatic humidification is the most common process of evaporation of water into the environment. This is how water in a glass evaporates over time, puddles on the roads disappear ...

The driving force behind the evaporation process is the difference in partial pressures of water vapor above the water surface (where it is large and almost equal to saturated vapor pressure) and in the ambient air (where it is lower, and the lower the drier the air).

The efficiency of adiabatic humidification depends on the area of ​​the wet surface and the speed of the air blowing over it. Therefore, the elements from which evaporation occurs in humidifiers using this method are either cloth or paper cassettes, or plastic discs on which water flows. These elements are built into the duct or blown by a separate fan.

From a physical point of view, the following happens: the air flow absorbs moisture, turning it into water vapor. The process of turning water into steam requires a huge amount of energy. The air gives off this energy to the water, as a result of which it cools. The total energy of the system (enthalpy) is practically unchanged, therefore the process is called isoenthalpic (adiabatic).

On the Id-diagram, this process is depicted by a straight line along the isoenthalpy to the right down (Fig. 1).

The adiabatic method of humidification is used in evaporative, splitting and ultrasonic humidifiers.

Isothermal Humidification

Isothermal humidification is the process of mixing water vapor with air flow.

The task of the humidifier is to prepare steam from water, but this time the energy needed to turn liquid into gas is not taken from the air, but from the mains. As a result, the air temperature practically does not change during humidification (which is why the method is called isothermal), and the electricity bill is a little bewildering, because a unit with a capacity of only 1 l / h consumes 700 W, and humidifying an apartment in winter requires about 3 kW.

On the Id diagram, the process line is directed along the isotherm to the right (Fig. 1).

The isothermal method of humidification is used in heating, infrared and electrode humidifiers.

From the point of view of terminology, we note that isothermal humidifiers are often called steam humidifiers, since they generate steam during their work. In turn, adiabatic humidifiers cannot be called steam humidifiers.

Types of Humidifiers

Let's take a closer look at each of the mentioned types of humidifiers:

Isothermal Humidifiers

Heating Humidifiers

In heating humidifiers, water is heated and boiled in a special tank, and the resulting steam is fed through a hose into an air duct, where it is evenly distributed through a tube with small holes along its entire length (steam distributor).

In this case, the generated steam must be superheated so as not to condense on the walls of the hose on the way to the duct.

Infrared Humidifiers

Infrared humidifiers are similar to heating humidifiers and differ only in the way the water is heated. AT this case lamps are used that heat water by means of infrared thermal radiation.

Electrode Humidifiers

Electrode-type humidifiers (Fig. 2) use the phenomenon of water dissociation to produce steam - its decomposition under the action of electric current. Two electrodes, an anode and a cathode, are lowered into a tank of water and voltage is applied to them. The current passing through the water heats it up and turns it into steam.

Electrode steam humidifiers are more efficient than heating and infrared ones. In addition, they are much safer: in the event of a lack of water, the electrical circuit breaks and the humidifier automatically turns off.

Adiabatic Humidifiers

Evaporative Humidifiers

In evaporative humidifiers, water is supplied to a special surface (usually paper or plastic) that is blown with air. When blown, the moisture gradually evaporates, thereby moistening the air.

Decomposing humidifiers

Split humidifiers use compressed air or a water pump high pressure for splitting water into small particles that are sent to the air stream and easily evaporate.

Ultrasonic Humidifiers

This is the most modern type of humidifier (Fig. 3). It uses a special membrane that vibrates at a high frequency. Water falling on the membrane is instantly sprayed and turns into a cloud of microparticles. The air passing through this cloud effectively absorbs moisture.

Note that for the last two types of humidifiers, pure water to avoid air pollution. Many manufacturers, in an effort to make splitting and ultrasonic humidifiers as safe as possible for humans, equip them with a number of features that solve this problem.

Pros, Cons and Applications

As already mentioned, the main difference between adiabatic and isothermal humidification is that in the first case, the energy of the air flow is spent on the evaporation of water, as a result of which it is cooled, and in the second case, electricity from the network is used. Therefore, where air cooling is not advantageous, isothermal humidification must be used.

For example, in winter, in the supply ventilation of an apartment, office or administrative building, the air taken from the street contains little water in absolute terms, and therefore, after heating, its humidity is only 10-15%. Humidification of freshly heated air by the adiabatic method will cool it and require another heating, which complicates the system. Therefore, it is recommended to use isothermal humidifiers in this case.

At the same time in summer outside air with a temperature of 28 °C and a humidity of 35% with the help of a household or duct adiabatic humidifier can be cooled to a quite comfortable temperature of 23 °C at a humidity of 60%. It should be noted here that humidification after 60%, although it leads to a subsequent decrease in air temperature, is not recommended, since high humidity causes a feeling of stuffiness and discomfort.

Another area of ​​application for adiabatic humidifiers is the cooling of the air entering the condenser in order to subsequently lower the condensing temperature in the refrigeration circuit as much as possible.

Such a need arises on hot days and carries several advantages at once. First, it avoids an accident refrigeration plant by high pressure. Secondly, a 1°C decrease in the condensing temperature increases the cooling capacity by 3%. Finally, if adiabatic air cooling for the condenser was included at the design stage of the installation, then this will save on capital investments: a less powerful condenser or drycooler will be required.

This system can be used in chiller condensers, compressor-condensing units, remote condensers, as well as in dry coolers and other coolers of the working substance (water, glycol solution, refrigerant) with outside air.

Isothermal humidification in the supply ventilation system

In supply ventilation systems for small and medium-sized objects, as a rule, isothermal humidification is used. In this case, the humidifier can be mounted separately (usually on the wall) or built into the air duct.

In the first case, the humidifier is in no way connected with ventilation and operates completely autonomously, independently generating required amount steam by controlling the power input, creating an air stream into which steam is introduced by built-in fans.

In the second case, the humidifier is directly connected to the operation of the supply ventilation system, and the steam is sprayed into the air duct, the air movement in which is provided by the supply fan. Accordingly, when ventilation is turned off, the humidifier must be turned off (as a rule, humidifiers have corresponding contacts).

Steam is supplied to the supply air duct using a linear steam distributor, steam to which is supplied through a hose (Fig. 4). The exact location of the linear steam distributor with references to the height of the air duct should be specified in accordance with the recommendations for installing the steam humidifier.

In the absence of a supply air duct, a fan unit is provided for installing a steam distribution pipe, which has connecting holes for a steam distributor and a fan to create an air flow. The advantages of this type of installation of a steam humidifier in comparison with a wall-mounted monoblock are the possibility of mounting the main and fan units at a distance from each other.

The steam humidifier can be controlled by both built-in and remote control.

Humidification sections in air handling units

In powerful ventilation units, adiabatic humidifiers are installed as optional sections. And here there are some peculiarities.

Already heated air must be supplied to the humidification section, and the parameters of this heating are determined from the following condition: the air after the heater must have such an enthalpy at which it can reach the required moisture content during humidification. For example, if the air is not heated enough, then when humidified, it will reach a state of saturation (φ \u003d 100%) before it receives the required amount of water.

A detailed study of this issue will reveal that the temperature in front of the humidifier must be noticeably higher than the temperature in the room (for example, 40 °C and 24 °C, as in the calculation example below).

Thus, in air handling units with a humidification section (also called central air conditioners), there are two heaters: before and after the humidifier (Fig. 5).

The humidifier is controlled from the panel of the central air conditioner. In this case, only the required values ​​​​of temperature and humidity are set, while the heating and humidifying sections are adjusted automatically.

Calculation example for an isothermal humidifier

Air handling unit data:

Humidity of the outside air (determined by the I d-diagram): φ out = 91%.

Parameters of the internal environment:

The enthalpy of air in the room (determined by the I d-diagram): i pom = 48 kJ / kg.

The air density in the room (determined by the I d-diagram): ρ pom \u003d 1.17 kg / m 3.

Thermodynamic data:

Calculation of the required steam output of the humidifier

Air enters the humidifier after the heater, so the air temperature is equal to the set temperature in the room (t pom). In this case, the heating process takes place at a constant moisture content, therefore, the moisture content of the heated air is equal to the moisture content of the outside (d out).

Air temperature after the heater: t load = t pom. T load = 24 °C.

Air enthalpy (determined by I d-diagram): i load = 25 kJ / kg.

Air humidity (determined by I d-diagram): φ load = 2%.

Air density (determined by the I d-diagram): ρ load = 1.17 kg / m 3.

As you can see, in winter, the air humidity after the heater is only 2% - this is precisely the reason for the need to equip the air handling unit with a humidifier. In its absence, extremely dry air will be supplied to the room. By the way, due to moisture release in the room (the use of water in the apartment, the moisture release of people and animals through sweat and breath), the humidity of the air, of course, is growing. As a rule, it is about 20% and the lower the lower the outside temperature.

The purpose of the humidifier is to increase the relative humidity of the air up to the set value (φ pom) without changing its temperature. Thus, the moisture content of the air must be increased from d load to d room.

d uvl \u003d d pom - d load.
dwl = 8.98 g/kg.

Required humidifier steam output:

P uvl \u003d 7.4 kg / h.

Thus, in a supply ventilation system with a flow rate G pr \u003d 700 m 3 / h, if it is necessary to humidify the air up to 50%, a water flow rate (humidifier steam output) of at least P humidifier \u003d 7.4 kg / h will be required.

Knowing the steam output of the humidifier, it is possible to estimate the power consumed by it. This estimate is based on the fact that a certain flow rate of water needs to be transferred to a gaseous state of aggregation (steam), that is, to spend the energy of a phase transition (the so-called latent heat of vaporization).

N SW = P SW ∙r water.

N uvl = 5.1 kW.

Express method for calculating the performance and power of a steam humidifier

The express method allows you to evaluate the steam output without complex calculations and the use of an I d-diagram.

P uvl [kg / h] \u003d 0.21 ∙ G [m 3 / h] ∙ φ [%] ∙ 10 -3,

where G and φ are, respectively, the supply air flow rate and the required humidity maintained in the room.

The given formula for the estimated calculation of steam production is valid only for the winter period; gives the best results at room humidity of 30 ... 70% and at any air flow.

The express method for calculating the power consumed by a steam humidifier is reduced to a simple formula and has practically no restrictions on use:

N ref [kW] = 0.7∙P ref [kg/h].

Calculation example for an adiabatic humidifier

Air handling unit data:

Supply air consumption: G pr \u003d 700 m 3 / h.

Options environment(standard design conditions):

Design pressure: Pcalc = 0.1 MPa.

Outside air temperature: t ext = -26 °C.

Enthalpy of outdoor air: i out = -25.1 kJ/kg.

Humidity of the outside air (determined by the I d diagram): φ out = 91%.

Parameters of the internal environment:

Temperature maintained in the room: t pom = 24 °C.

Humidity maintained in the room: φ pom = 50%.

The enthalpy of air in the room (determined by the I d diagram): i pom = 48 kJ / kg.

Air density in the room (determined by the I d diagram): ρ pom \u003d 1.17 kg / m 3.

Thermodynamic data:

Latent heat of vaporization: r water = 2500 kJ/kg.

Heat capacity of air c air = 1.005 kJ/kg∙°C.

Calculation of the required performance of the humidifier.

Air enters the humidifier after preheating. The power of the preheater is limited to a minimum value, so that the air after it, in the process of adiabatic humidification, can receive the amount of moisture required to achieve the moisture content d room. It can be seen from the I d diagram that, as a rule, the first heating stage should be more powerful than in a system with an isothermal humidifier.

For our example, we can take the temperature of the first heating t load = 40 °C. The heating process takes place at a constant moisture content, therefore, the moisture content of the heated air is equal to the moisture content of the outside (d out). Thus, air with parameters will enter the humidifier:

Air temperature after the heater: t load = 40 °C.

Air enthalpy (determined by I d-diagram): i load = 41.3 kJ / kg.

Air humidity (determined by I d-diagram): φ load = 1%.

Air density (determined by the I d-diagram): ρ load = 1.11 kg / m 3.

The purpose of an adiabatic humidifier is to increase the moisture content of the air to a predetermined value (d pom) in order to subsequently heat it up to the required temperature t pom and thus achieve the desired humidity φ pom.

Air enthalpy after humidification: i ad_uvl = i load i ad_uvl = 41.3 kJ/kg

Air temperature (determined from the I d diagram): t ad_uvl \u003d 17.4 ° C.

Air humidity (determined by I d diagram): φ ad_uvl = 75%.

Air density (determined from the I d diagram): ρ ad_uvl = 1.20 kg / m 3.

The difference between the moisture content of the air in the room and after the heater:

D uvl \u003d d ad_uvl - d load.

Dwl = 8.98 g/kg.

Required humidifier capacity:

P SWL = d SWL ∙G pr ∙ (ρ load + ρ pom)/2.

P uvl \u003d 7.4 kg / h.

The power for an adiabatic humidifier is not calculated, since the humidification process is isenthalpic and, accordingly, the energy costs are zero.

Now it remains to determine the power of the second heater, which is necessary for reheating humidified air to a given temperature t room:

N load2 \u003d c air ∙ G pr ∙ ρ pom ∙ (t pom - t ad_uvl).

N load2 = 1.5 kW.

findings

So under creation comfortable conditions It means not only maintaining the set temperature, but also controlling the humidity. Humidification issues in various aspects are important both in cold and in summer period of the year.

So, in winter, the moisture content of outdoor air is low (less than 1 g / kg) and after heating the air in the heaters, a dry stream is obtained at the outlet (relative humidity is not higher than 5%). Air humidification can be carried out by an adiabatic or isothermal method, depending on the type of ventilation equipment and other factors.

In summer, supply air humidification is practically irrelevant, except for the use of the cooling and humidification effect of adiabatic humidifiers in dry climates. However, of interest is the adiabatic cooling of the air cooling the outdoor units of air conditioning systems (chiller condensers, remote condensers, compressor-condenser units, dry coolers). This topic will be covered in more detail in future issues of the journal.

In addition, a separate topic is the use of precision air conditioners with built-in humidifiers, which is relevant for industrial and telecommunications facilities, such as data centers. This will also be covered in future releases.

Yury Khomutsky, technical editor of the magazine "Climate World"

The microclimate in the room depends largely on the level of humidity. Humidifiers help keep the humidity at the right level. For this purpose, large rooms are equipped with climate technology.

Climatic air humidifier is equipment that is able to maintain normal air humidity in large rooms or entire buildings. Channel-type humidifiers are equipped with:

• Living spaces.
• Production area.
• Museums.
• Greenhouses.
• Warehouses.
• Greenhouses.

Regulatory indicators

The humidity of the air should optimally correspond to the norms that differ for a person and objects of use. The following pH standards are valid:

1. A person needs 40-60%.
2. Plants and flowers in a greenhouse or conservatory need 55-75%.
3. Equipment and office equipment - 45-60%.
4. Furniture and musical instruments need 40-60%.
5. Books and art need 40-60%.

Insufficient humidity leads to deterioration of work and breakdown of equipment, impairs the growth of plants and reduces the life of books and works of art.

On the human body overdried air has a negative effect, causing tightness of the skin, decreased performance and deterioration of well-being. More serious consequences are manifested in the deterioration of immunity and constant colds. Duct humidifiers prevent such complications.

Installation and operation of duct humidifiers

Installation of duct humidifiers is carried out in the ventilation ducts of a room or house. Used to install a central air conditioning system. The devices can be used in air heating.

The principle of operation of channel-type humidifiers is quite simple. The air that enters the device undergoes a process of enrichment with water particles, after which it enters the ventilation duct. From the channel, enriched air enters the room and dilutes the main air masses. With this method, the air humidity indicator is maintained at a given level.

This article discusses various options creation climate system(based on Swegon Gold ventilation equipment of various standard sizes), key function which is to maintain the required values ​​of relative humidity.

The materials of the article were created on the basis of a pre-design feasibility study, the essence of which is to present to the customer, who is the owner of the business center, options equipment to create a system channel humidification air in the already created ventilation system of the business center using various Swegon Gold ventilation units.

We suggest that you familiarize yourself with a brief overview of the 4 types of duct humidification systems (advantages and disadvantages, design features, operation and installation), and in the summary table - with the main technical specifications and prices for this equipment.

• Comparative table of technical data and prices for duct humidification systems
• Since the operation of all proposed humidification systems is directly related to the use of water, to ensure the operation of all possible options for humidification systems at the facility, the issue of implementing a water treatment system was considered.

Initial data

Approximate selection of equipment was made on the basis of the following initial data:

• design outdoor air temperature during the cold season: -28°С;
• design temperature of internal air: +22...24°С;
• desired level of relative humidity in the supply air duct: 40-60%;
• data on the parameters of heat supply (kW), water supply (m³/h), electricity supply (kW) and the possibility of their use are not available.

Task

A duct humidification system is required as part of the Swegon Gold ventilation system.

The Swegon Gold RX-C series ventilation units installed at the site are equipped with highly efficient energy recuperators, i.e. most of the heat and cooling energy of the exhaust air is transferred to the supply air. This solution allows you to achieve a minimum consumption of energy resources. When retrofitting ventilation units of this type with humidification systems and reaching a relative humidity in the exhaust duct above 30%, frosting of the rotor will be observed, which in turn will lead to an emergency stop of the ventilation units (without the possibility of automatic restart).

Freezing of the heat exchanger occurs due to the fact that moist, warm exhaust air meets cold, dry supply air at the rotary heat exchanger, where moisture condenses and immediately freezes.

AT this moment all ventilation installations at the facility are as follows:

That is, they consist of a supply and exhaust monoblock unit, a water heater and a water cooler.

To ensure work existing system ventilation systems with humidification systems, it is necessary to retrofit ventilation units with preheating heaters.

The pre-heating heater allows already heated air to be supplied to the ventilation unit, which eliminates the risk of condensation. All options of humidification systems offered below include preheaters and their accessories.

We offer for consideration the following four solutions for the humidification system: , , , . A more detailed study of the issue can be made when developing a project or wiring diagram for a ventilation system with humidification selected by the customer.

Option #1 - honeycomb humidifier

Honeycomb humidifiers implement the process of adiabatic air humidification during the cold season. They can also be used during the warm season to reduce the load on the air conditioning system, as they provide direct and indirect air cooling.

The honeycomb humidifier consists of the following main elements:

• honeycomb humidifier cassettes;
• collector with nozzles;
• loading and unloading systems;
• pump;
• automation;
• stainless steel body.

The honeycomb humidifier looks like this (mounted in a ventilation unit or ventilation duct):

The principle of operation of such humidifiers is based on the contact method, i.e. the contact of air and liquid is achieved by wetting the surface of the humidifier during its irrigation. The air passes through the honeycomb of the humidifier and comes into contact with moisture, which impregnates the porous surface of the nozzle. This is the process of humidifying the air.

Simultaneously with humidification, the process of absorption of air heat occurs during the evaporation of moisture from the surface of the honeycombs. To compensate for the heat loss of the supply air after the humidifier during the cold season, it is necessary to reheat the air, i.e. to carry out the second heating (the first heating is carried out in the main heater of the ventilation unit, and it has already been installed at the facility).

Also, the second heating is necessary for the implementation of the humidity control system according to the “dew point” method. This method consists in influencing the water control valve or the control unit of the electric air heater and allows achieving the accuracy of maintaining the relative humidity in the supply air duct at the level of ± 1-2%.

Key Benefits of a Honeycomb Humidifier

• Low power consumption (energy is spent only on the operation of the pump - 50-270 W).
• The high value of the coefficient of efficiency of the process of heat and mass transfer.
• Compact design and small dimensions as there are no water droplets and no need for a droplet evaporation chamber.
• Small aerodynamic resistance.
• Higher allowable air velocities.
• The equipment can be used without water treatment (depending on water quality).
• It cleans the air from odors and dirt (dirt settles on the honeycombs, and then merges into the pan).

The main disadvantages of a honeycomb humidifier

• Possibility of formation of microorganisms in the pallet (with regular maintenance, the risk is eliminated and this is confirmed by a certificate).
• High air resistance occurring in the humidification chamber.

Option number 2 - steam humidifier

Steam humidifiers implement the process of isothermal (at constant temperature) air humidification during the cold season. The humidifier consists of the following main elements:

• steam distribution manifold;
• steam cylinder with electrodes;
• loading and unloading systems;
• automation;
• stainless steel body;
• steam pipelines.

Steam humidifiers look like this:

Steam humidifiers are mounted on the wall next to the ventilation unit, the steam distributor cuts into the air duct.

The principle of operation of such humidifiers is based on heating the water in the steam cylinder to a boil and the formation of steam. The steam is discharged through the steam lines to the steam distribution manifold, which evenly distributes the steam in the supply air flow.

Since the humidification process takes place without changing the temperature (unlike other options), therefore, there is no need for a second air heating. Maintaining a given relative humidity in the supply air duct is carried out by changing the amount of steam supplied. The accuracy of maintaining the humidity value is ±1%.

The main advantages of a steam humidifier

• Security High Quality processed air according to hygienic requirements.
• Less heat consumption in air heaters (no second heating).
• Flexible and precise control.
• Easy maintenance.
• High reliability.
• Can be used without water treatment (depending on water quality).

The main disadvantage of a steam humidifier is high power consumption (exceeds all other options).

Option number 3 - ultrasonic humidifier

Ultrasonic humidifiers implement the process of adiabatic air humidification during the cold season. The humidifier looks like this (mounted in a duct network in a special section):

The ultrasonic humidifier consists of the following main elements:

• external automation shield;
• fogging module with vibrators (stainless steel);
• external hydraulic part.

The principle of operation of such humidifiers is based on supersonic fogging. In the automation unit, an alternating current with low voltage and high frequency is created using a transformer. This signal is fed to a vibrator installed in the bath, which converts the signal into high-frequency vibrations.

Due to this, a “fog” (aerosol) is formed, which takes heat from the air and passes from a liquid state to a gaseous one. At the same time, the supply air is humidified.

Since the process of absorption of air heat takes place simultaneously with humidification, it is necessary to reheat the air, i.e. to carry out the second heating (the first heating is carried out in the main heater of the ventilation unit, and it has already been installed at the facility).

Maintaining the specified relative humidity in the supply air duct is carried out by the automation unit. The accuracy of maintaining the humidity value is ±1%.

Main advantages of ultrasonic humidifier

• Small power consumption.
• High accuracy of maintenance of the set value of humidity.

The main disadvantages of an ultrasonic humidifier

• High cost of equipment.

Option #4 - Water Mist Humidifier

Water mist humidifiers implement the process of adiabatic air humidification during the cold season.

The water mist humidifier is mounted on the wall next to the ventilation unit. Ramp with spray collectors is mounted in the air duct:

The humidifier consists of the following main elements:

• two-section control cabinet (electrical part and hydraulic part);
• distribution manifolds with nozzles;
• pipelines.

The principle of operation of such humidifiers is based on the spraying of water under high pressure through nozzles with a very small outlet.

A high-pressure piston pump is installed in the control cabinet (hydraulic part), which creates high water pressure in front of the nozzles.

System Composition and Operation Diagram of Water Spray Humidifier

Since, simultaneously with humidification, the process of heat absorption from the air takes place, the air must be reheated, that is, the second heating should be carried out (the first heating is carried out in the main heater of the ventilation unit, and it has already been installed at the facility).

Maintaining the specified relative humidity in the supply air channel is carried out by changing the number of revolutions of the high pressure pump and turning off part of the distribution manifolds. The accuracy of maintaining the humidity value in this system is ± 5%.

Key Benefits of Water Mist Humidifiers

• A controlled process of adiabatic humidification is implemented, which saves water and electricity.
• Compressed air is not used.
• High quality of the processed air, formation of microorganisms is excluded.
• Low power consumption.
• Low pressure loss.

Main Disadvantages of Water Spray Humidifiers

• High water pressure, special requirements for the piping system.
• High maintenance cost.
• High wear of the main elements.

Zone Adiabatic Humidifier

An adiabatic type humidifier with zone spraying does not belong to duct humidification systems and is presented in this review for additional consideration of the possibilities for implementing a humid microclimate.

In general, the essence of the operation of this humidifier lies in the fact that from the central unit of the system, under high pressure, water is supplied in tubes to nozzles located in different zones, from which water is sprayed in the form of a fine aerosol, which is a mist (water drops have an average size of 15 -40 microns, which evaporate very quickly, within a second).

Scheme of work

The humidification process is as follows:

1. The water supply is connected to a microcarbon filter.
2. Next, the water passes through the softening module (optional).
3. A microfilter is installed at the outlet of the softening module.
4. The prepared water is fed to the central module of the humidification system, where it is processed by the ultraviolet sterilization module and filtered according to the reverse osmosis principle, followed by re-treatment by the ultraviolet sterilization module.
5. The central module increases the pressure to 70 bar, after which the water high degree cleaning enters the ring line, and from there through the tee branches to the nozzle valves.
6. When the nozzle valves are opened, water under pressure is supplied to the nozzle tips, where it is sprayed until a fine mist is formed.
7. The resulting aerosol immediately evaporates in the surrounding air.

The main advantages of indoor mist humidifiers are:

• complete microbiological safety, protection against the spread of pathogens;
• the ability to accurately maintain humidity;
• the ability to set different humidity for different rooms;
• low power consumption.

The main disadvantages of room mist humidifiers are:

• high water pressure, special requirements for the piping system;
• the need for access to the nozzle installation areas for periodic maintenance.

Water treatment system

To maintain the working condition of all types of humidifiers at the facility, it is necessary to provide a set of equipment for water treatment. There is a proposal to create a water treatment system on a semi-industrial "osmosis", which can provide water of very high quality, which will increase the service life of humidifiers and simplify their maintenance.

Comparative table of the cost of duct humidification systems

The comparison table is a summary of the main technical data and costs of the humidification systems presented above. Technical data is presented for each of the four types of Swegon Gold RX30CKT, RX40CKT, RX60CKT, RX80CKT ventilation units, which are installed at the facility in different numbers.

Please note that in the table in the price column, not the prices of individual humidifiers are presented, but the cost of a set of equipment necessary to create a climate system with maintaining humidity in the winter season (excluding pipelines, power and control lines, fasteners and consumables), which includes the following elements and systems:

• prefilter, preheater, its accessories and automation,
• second heating heater, its accessories and automation,
• general control system,
• water treatment system,
• humidification system.

This table does not include the cost installation work and maintenance of humidification systems.

humidifier type	Consumed electricity	Prepared water consumption (kg/h)	Instant consumption of industrial water (kg/min)	Heat consumption for preheating and second heating, kW	Humidification system price (EUR)
Swegon Gold RX30CKT
		46,2	-	58,4	32 108
Steam humidifier (Carel)	40.0 kW (400 V, 50 Hz)	47,7	52,5	36,4	22 488
	2.8 kW (230 V, 50 Hz)	42,4	-	58,4	58 442
	0.475 kW (230 V, 50 Hz)	51,7	-	58,4	36 409
Swegon Gold RX40CKT
Honeycomb Humidifier (Munters)	0.05 kW (230V/400V, 50Hz)	50,4	-	77,8	41 120
Steam humidifier (Carel)	45.7 kW (400 V, 50 Hz)	63,5	52,5	48,5	28 811
Ultrasonic Humidifier (Carel)	3.66 kW (230 V, 50 Hz)	56,5	-	77,8	79 924
Water mist humidifier (Carel) *	0.275 kW (230 V, 50 Hz)	76,2	-	77,8	42 845
Swegon Gold RX60CKT
Honeycomb Humidifier (Munters)	0.05 kW (230V/400V, 50Hz)	92,4	-	107,1	51 818
Steam humidifier (Carel)	60.0 kW (400 V, 50 Hz)	87,4	105	66,7	37 418
Ultrasonic Humidifier (Carel)	5.02 kW (230 V, 50 Hz)	77,7	-	107,1	105 304
Water mist humidifier (Carel) *	0.475 kW (230 V, 50 Hz)	104,8	-	107,1	53 105
Swegon Gold RX80CKT
Honeycomb Humidifier (Munters)	0.05 kW (230V/400V, 50Hz)	109,2	-	126,5	54 027
Steam humidifier (Carel)	80.0 kW (400 V, 50 Hz)	103	105	78,8	46 776
Ultrasonic Humidifier (Carel)	5.9 kW (230 V, 50 Hz)	91,8	-	126,5	114 789
Water mist humidifier (Carel) *	0.475 kW (230 V, 50 Hz)	123,8	-	126,5	55 481

Note *

Due to the increased wear of the main elements of the water spray humidifier (nozzles, hoses, high pressure pump), it is necessary to have spare parts on site.

About prices for equipment complexes for humidification systems

The purpose of the comparison table is to guide consumers in the level of possible costs for a humidification system.

This information is not an estimate and contains data from open sources(recommended for sale prices by suppliers and manufacturers), that is, it does not contain possible discounts on equipment and materials, which are always discussed individually when making deliveries.

! Note to the customer

• Air humidification systems in building ventilation systems
• Reconstruction of the humidification system of the Veza ventilation unit: installation of a new evaporative humidifier with a circulating water supply system