Fan coil working principle and definition
Dezhou Lai Sen Environmental Technology Co., Ltd. fan coil unit is also called the terminal equipment of central air conditioner.It is mainly composed of motor, cooling tube and water pan.
The role of the motor
Blow the wind from the water inlet to the cold doubt pipe. The wind comes out of the water outlet and it is cold wind.
The role of the cold doubt pipe: circulate the cold water on the central air conditioning host
The role of the water tray: collect the water evaporated from the side of the cold suspect pipe, and then flow away through the drain pipe
It is a device that consists of a pipe and a fin that can introduce a flowing medium, and then allows the fan to force the air flow through to achieve the purpose of heating or cooling.
The fan coil unit is mainly composed of low-noise motor and coil.
The fan sends indoor air or outdoor mixed air through a surface cooler to cool or heat it, and then sends it into the room to reduce or increase the indoor temperature to meet people's comfort requirements. The cold (hot) medium water in the coil is supplied centrally from the machine room.
Fan coil is an ideal end product of central air-conditioning. Fan coil is widely used in hotels, office buildings, hospitals, commercial and residential, scientific research institutions. In order to meet the design and selection of different occasions, the types of fan coils are: horizontal concealed (with return air box) fan coils, horizontal surface-mounted fan coils, vertical concealed fan coils, vertical surface-mounted fan coils , Cassette two outlet fan coil, Cassette four outlet fan coil and wall-mounted fan coil.
The fan coil unit is mainly composed of low-noise motor and coil. The fan sends indoor air or outdoor mixed air through a surface cooler to cool or heat it, and then sends it into the room to reduce or increase the indoor temperature to meet people's comfort requirements. The cold (hot) medium water in the coil is supplied centrally from the machine room.
The main features of fan coil unit The fan coil body is exquisite in structure, compact, sturdy and durable, beautiful in appearance and elegant.
The fan coil adopts a high-quality galvanized sheet shell, and the condensate water pan is integrally formed by a molding process. There are no welding seams, welding points, and fire-resistant insulation materials are connected to the water pan as a whole.
Fan coils are small in size: The body design is lightweight. Drain pipes and lines are easy to install, and the left and right takeover and return air modes can be changed at any time to match the site conditions. The unit can be installed in any space.
High efficiency of fan coil: Advanced tube expansion technology ensures close contact between copper tubes and aluminum foil of the heat exchanger, and good heat transfer performance; Low noise of fan coil: Reasonable fan and airflow structure design, high-quality sound-absorbing and thermal insulation materials, Make the unit noise lower than the national standard 1-3dB (A); Low energy consumption of the fan coil: The fan and the heat exchanger are reasonably matched, and the three-stage adjustable air volume makes the fan use the least power.
Fan coil unit is a widely used terminal equipment in the purchase of central air conditioners. The full name of the specification is the central air conditioner fan coil unit, which can be simply classified as follows:
The central air-conditioning fan coil is divided into five types: horizontal concealed, horizontal exposed, vertical concealed, vertical exposed, and cassette;
Horizontal fan coils can be divided into: ultra-thin, ordinary;
Cassette fan coil can be divided into ordinary type and luxurious type according to the presence or absence of condensate pump;
The central air-conditioning fan coil can be divided into: 0Pa, 12Pa, 30Pa, 50Pa, 80Pa, etc., which refers to the external static pressure; the central air-conditioning fan coil can be divided into two rows according to the number of rows: three rows tube;
There are also two regulations and four regulations: two regulations, that is, ordinary fan coils are cooled by cold water in summer, and heated by hot water in winter;
Four-control fan coils are mostly used in some luxurious places, which can take hot and cold water at the same time, that is, some rooms can be cooled according to needs, and some rooms can be heated. Attention should be paid to the selection of fan coils: In foreign fan coil samples, generally the air volume and cooling capacity under different static pressures outside the machine are given to facilitate user selection. Although some foreign concise samples only give the nominal air volume, its meaning is different from the Chinese standard. It generally refers to the air volume value under a certain static pressure outside the machine. Therefore, foreign fan coils with similar nominal air volume will have higher air volume than domestic units. Out of 20% ~ 50%. It should also be emphasized that when using concise foreign samples, it must be noted that foreign companies often implement different standards, and there will be some differences in the meaning of nominal air volume. Therefore, it is best to use the latest samples with complete data, or ask the supplier to provide the air volume and cold value of the product under different static pressure outside the machine to determine the reliability.
Development of various types of fan coils:
When selecting a fan coil unit, in addition to the cooling capacity to meet the calculation of the cold load requirements, it also needs to meet the matching of its sensible and latent heat to meet the requirements of the room heat-humidity ratio. And other requirements. As the application range of fan coil units continues to expand, the types of air-conditioned rooms they serve will also increase. The central air-conditioned rooms with different properties and different use requirements have different heat-humidity ratios, and the matching of cooling and air volume should not be static. Even for rooms with the same air-conditioning requirements and net volume, different cooling loads will be caused due to differences in weather conditions, orientation, or envelope structure. Obviously, fan coils with different structural characteristics must be used to meet the different needs of the room. However, most of the fan coils currently used are three rows of tubes, and the same form of eight tubes in each row cannot obviously meet the requirements of different rooms. Even if the cooling load meets the requirements, it may lead to excessive room temperature gradients and fluctuations in low-load rooms due to insufficient air volume and ventilation times, reducing the accuracy and comfort of air-conditioning; if units with the same air volume are used, high-load rooms may cause Insufficient cooling does not guarantee temperature and humidity requirements. Therefore, different types of fan coils should be used for air-conditioned rooms with different conditions and requirements.
Some experts advocate the development of two rows of fan coils, which can reduce the temperature difference of the air supply and increase the number of ventilations, which will help improve the accuracy and comfort of the air conditioner. Under the same cooling capacity, using a small temperature difference and a large air volume to supply air will achieve better air conditioning effects than a large temperature difference and a small air volume; the coil adopts a variety of waterway designs. At present, the three-row pipe coils produced in China, regardless of length, use the same three-in-three-outlet waterway. In order to reduce water resistance and increase cooling capacity, coils of different lengths must use different waterway designs. For example, Carrier's 2 × 8 coils use three different waterways: two-in, two-out, three-in, three-out, and four-in, four-out. The nature of these assumptions is to meet the different processing requirements of the room, the specific choices depend on the application.
The fan coil mainly relies on the forced action of the fan to make the air be heated as it passes through the surface of the heater, thus strengthening the convection heat exchanger between the radiator and the air, which can quickly heat the air in the room. The fan coil is the end device of the air conditioning system. Its working principle is that the air in the room is continuously recirculated in the unit, so that the air is cooled (heated) after passing through the cold water (hot water) coil to keep the room temperature constant. Usually, it is sent into the room after being processed by a new fan unit to meet the demand for fresh air volume in air-conditioned rooms.
However, because this heating method is based on convective heat exchange only, which does not allow the best level of comfort indoors, it is only suitable for places where people stay for a short time, such as offices and hotels, and not for ordinary residences. Due to the increase of the fan, the cost of construction and operation is increased, and the maintenance and management of the equipment is more complicated.
Fan coil control mostly uses local control schemes, which are divided into simple control and temperature control. Simple control: Use the three-speed switch to directly control the three-speed conversion and start-stop of the fan. Temperature control: The STC series thermostat automatically controls the opening and closing of the STV series electric two / three-way valve according to the comparison and calculation of the set temperature and the actual detected temperature; the three-speed conversion of the fan. Or directly control the three-speed conversion and start-stop of the fan, so as to achieve the purpose of constant temperature by controlling the system water flow or air volume. The fan coil is used as the terminal equipment of the central air conditioner, and its quality determines the indoor air conditioning effect. The performance is mainly the guarantee of the amount of cold (hot) supply, the guarantee of the amount of air supply, the numerical value ratio of noise, the leakage of condensate, and the rationality of the design of electrical appliances and sheet metal parts.