- Hot summer 2013
- Modern air conditioning systems
- Technological and comfort air conditioners
- Central and local air conditioning systems
- Autonomous and non-autonomous air conditioners
- Direct-flow and recirculation systems
- Air conditioners with qualitative and quantitative control
- Classes and air pressure of air conditioners
- Single-zone and multi-zone installations
- Simplified air conditioner classification
- Instead of an epilogue
In this article: the purpose of air conditioners; types of air conditioning units; technological and comfortable air conditioners; how central and local air conditioning systems differ; that it is an autonomous and non-autonomous air conditioner; recirculation and direct-flow installations; qualitative and quantitative regulation; classes of air conditioners and the air pressure they develop; air conditioning systems designed for one and several zones; simplified classification of air conditioners.
Three decades ago, it was possible to completely get rid of the summer heat only in offices and halls of state institutions, whose buildings were equipped with duct ventilation and air conditioning systems that were not provided for residential high-rise buildings. For houses and apartments, the trading network offered Azerbaijani household air conditioners – bulky window monsters, with compressors roaring at low tones, during which the window panes vibrated. A couple of decades ago, BK ousted split-systems, the outer blocks of which “decorate” the facades of houses at the present time. Meanwhile, there are many more varieties of air conditioning units than two or three types – we will study how they are classified.
Hot summer 2013
Let the cold season still continue in Russia today and the thermometer outside the window stubbornly does not want to rise above +10 degrees – spring, and then summer weather will certainly happen in some one and a half to two months. And it will no longer be the winter cold that will pester the household, but the exhausting heat that has come to replace it, completely erasing from memory the impressions of the January cold, which, it would seem, cannot be forgotten.
It’s time to take care of the appliance, thanks to which the atmosphere of your home will be strikingly and for the better different from the street one – it’s time to choose an air conditioner, and choose it without following the colorful lectures of managers and sellers of outlets who want to sell the goods more profitably, but consciously, after weighing everything “for “And” against “.
In order to facilitate the buyers’ difficult task of choosing a split system and provide real information about these devices, with this material, the portal begins a series of articles devoted to household air conditioners.
Modern air conditioning systems
Air conditioning devices are designed to create certain air parameters (several or all) – humidity, cleanliness, temperature, speed and directions of movement – inside a closed room, as well as to maintain them at a given level in an automatic mode. The purpose of using such devices is to create a favorable working environment for people or technology..
The arrangement of the equipment that prepares air and its transportation to consumers is carried out in one common block or divided into two blocks – devices in one- and two-block configuration are called air conditioners or, in other words, air conditioning systems.
Despite the fact that there is no single classification system for air conditioning installations, since their characteristics and circuit diagrams are quite diverse, air conditioners produced today are divided into the following types:
- depending on the consumer – technological and comfortable;
- by location – local and central;
- depending on the presence or absence of a built-in source of cold or heat – autonomous and non-autonomous;
- according to the principle of conditioned air supply – recirculating, direct-flow and combined;
- according to the method of regulating the air parameters at the outlet of the air conditioner – one-pipe (qualitative regulation) and two-pipe (quantitative regulation);
- depending on the ability to maintain the specified climatic conditions in the room, air conditioning systems can be of the first, second and third classes;
- depending on the air pressure developed by the air conditioning ventilation units, there are high, medium and low pressure models;
- according to the number of simultaneously served local (isolated from each other) rooms, air conditioning systems are subdivided into single- and multi-zone.
Technological and comfort air conditioners
Technological air conditioning units are used to maintain the sanitary and hygienic characteristics of the air in production facilities. Comfort air conditioners provide a wide range of climatic characteristics of the air, they are intended for residential, public and administrative buildings.
Central and local air conditioning systems
Local air conditioning units are installed indoors where certain climatic conditions are required; their models can be based on both autonomous and non-autonomous air conditioners. Systems of this type are used in residential and office buildings in order to maintain the required air characteristics, which differ from the conditions suitable for most other premises for any reason – they are most often used in rooms saturated with heat sources (for example, in server rooms), as well as in large halls (restaurants and cafes, supermarkets, classrooms, etc.). These air conditioners are used in buildings where the central air conditioning system was not originally included in the project. The main advantage of local air conditioners is the simplicity of their installation, repair and dismantling..
Central air conditioning systems receive from the outside not only electricity, but also cold and heat – in the first case, circulating cold water or refrigerant acts as a carrier, in the second, this task is assigned to hot water, steam or electricity. The central unit is located outside the serviced halls (on the roof, in the basement or not far from the facade of the building), depending on its capacity, it is able to maintain a uniform climate in all internal rooms of the building at once, to serve an impressive hall, for example, a production workshop, a theater hall, circus, indoor stadium. When building central air conditioning units, non-autonomous air conditioners of standard configuration are used. Their advantages – the air conditioning system, which prepares the air for all premises of the building, is located in one place, which facilitates its maintenance and repair, the ability to minimize noise and vibration emanating from the installation for consumers inside the building by acoustic treatment of air ducts. The disadvantages of central air conditioners are associated with the impressive dimensions of their installations, the need for extensive work on the installation of air ducts.
Autonomous and non-autonomous air conditioners
Autonomous air conditioners do not need any other source of energy, except for electric – they are equipped with their own compressors that pump freon (for example, window, floor, cabinet and cassette air conditioners, split systems, etc.). During the operation of such units, recirculated or direct-flow air is passed through the evaporator of the compressor unit and cooled, after which it enters the room. In addition to cooling, some models of stand-alone units are capable of heating a room by blowing air into the electric heaters built into the air conditioner or an evaporator of a compressor operating in a reversible mode on the principle of a heat pump.
Non-autonomous air conditioning units are capable of either supplying air (central air conditioning) or supplying air and water to the serviced premises, while water acts as a transport for cold or heat (chiller-fan coil unit).
Direct-flow and recirculation systems
Recirculating air conditioners use only indoor air or with an admixture of outside air (no more than 40% of the air volume in the room) – in the second case, they are called combined. Any split system is a popular representative of such installations. Direct-flow air conditioning units do not consume air from the room, operating only on the outside air supplied to the room after its pretreatment (for example, window air conditioner).
Air conditioners with qualitative and quantitative control
The widespread one-pipe central air conditioning units supply the prepared air to the serviced premises through one common channel, during operation monitoring the air condition in the rooms using sensors installed in each room, which allows for high-quality regulation of climatic parameters. Quantitative regulation, which constitutes the principle of operation of two-pipe climatic systems, consists in the simultaneous transportation of cold and hot air to each room through two channels with the introduction of an air mixture into the room through mixing valves. The proportions of cold and hot air are determined based on the data reported to the installation by sensors installed in each room. Due to the complex regulation, two-pipe air conditioners are rarely used..
Classes and air pressure of air conditioners
Classes for air conditioning units are assigned on the basis of SNiP 2.04.05-91 *:
- the first class includes air conditioners capable of providing for the technological process the parameters established by the standards;
- to the second class – ensuring sanitary and hygienic and technological standards at the optimal level;
- to the third class – providing air conditioning parameters at a minimum level within the established standards.
Depending on the power of the fans with which the air conditioners are equipped, there are high pressure systems (more than 300 kg / m2), medium (100-300 kg / m2) and low (no more than 100 kg / m2).
Single-zone and multi-zone installations
Single-zone central air conditioning systems are intended for large-area premises – large cinemas, auditoriums, etc., in the air volume of which heat and humidity are distributed with relative uniformity. Such installations are usually equipped with heat exchangers and chambers for mixing air (recirculated and once-through). Multi-zone air conditioners are used in a large room or several with a small area, in which sources of excess heat are located unevenly. They are economically more profitable than equipping each service area with a local air conditioning unit, however, they are not able to maintain the specified climatic parameters with high accuracy..
Simplified air conditioner classification
If we classify air conditioners only according to user, simplified characteristics, then they can be divided into three groups: household (international designation – RAC), semi-industrial (PAC) and industrial (Unitary).
Household models include air conditioning units capable of providing specified climatic parameters in rooms with an area of no more than 100 m2, those. in the rooms of an apartment, private house, office, small shop or cafe. The RAC group includes window, mobile installations, split systems with one and several indoor hair dryers, whose power does not exceed 8 kW.
The power of semi-industrial air conditioners – cassette, duct, floor, ceiling and column – is from 8 to 20 kW. Medium power units (10 to 15 kW) presented in this group are used for air conditioning in rooms with an area of about 300 m2. PAC air conditioners are widely used in office buildings, for which household appliances seem to be suitable, but their capacity is insufficient due to a large number of heat sources (equipment and people), or due to the flow of warm air from the street.
Industrial air conditioning systems have a capacity of 20 kW or more, these include central air conditioning units, chiller-fan coil units, precision air conditioners, etc. They are used in residential, public and administrative buildings, supermarket and sports complexes, production workshops with an area of 300 m2.
Instead of an epilogue
From the next article, the second of the series “about air conditioners”, you will learn about the following types of air conditioning units – ceiling, cassette, duct, precision, roof and column. Do not rush to make your choice in favor of one or the other air conditioner model – it is quite possible that after reading the contents of the entire series of articles on climate control equipment or part of it, you will reconsider your opinion in favor of a more profitable and more efficient device.