The core problem of compressor oper
Detailed classification of commercial central air conditioning systems
Single cold type:
Inhale the hot and humid air in the room, condense the water vapor through the evaporator, and then send the dry, cool air into the room to cool down and reduce humidity.
hot and cold style:
can not only reduce temperature and humidity, but also heat and warm. Heating methods can be divided into heat pump type and electric heating type. When the heat pump air conditioner is used for heating, the outdoor air temperature must be above 5℃ to work normally.
Mobile:
The difference between it and the window air conditioner is that it adopts a water-cooling method, and the condensed water is discharged through a hose, and it can be moved at will in the room without installation.
Split:
It is composed of an indoor cabinet and an outdoor cabinet. The outdoor cabinet combines the compressor, condenser and axial fan in the refrigeration system.
Inverter air conditioner:
It is composed of a computer-controlled frequency converter and a frequency conversion compressor. It uses frequency conversion control technology to automatically select the cooling, heating and dehumidification operation modes of the air conditioner according to the ambient temperature, so that the room can quickly reach the required temperature in a short time, and In the state of low speed and low energy consumption, with a small temperature difference fluctuation, a fast, energy-saving and comfortable temperature control effect is realized.
Water cooling type:
is composed of indoor coils, and the outdoor unit can be a water-cooled screw or a cooling unit (this is also a single-cooling type). I won’t say anything about the unit. You should know the four major components.
Air-cooled:
Indoor coil, outdoor unit is air-cooled screw or modular unit.
The central air-conditioning system consists of a series of moving equipment (such as water pumps, fans and compressors) that drive fluid flow, various types of heat exchangers (such as fan coils, evaporators, condensers and intermediate heat exchangers, etc.) and connections Various devices are composed of pipes (such as air pipes, water pipes and refrigerant pipes) and valves. The system can generally be divided into the following five cycles:
1. Indoor air circulation;
2, cold water circulation;
3. Refrigerant circulation;
4. Cooling water circulation;
5. Outdoor air circulation.
Central air-conditioning system-main components
1. According to the medium used to bear the indoor heat and humidity load, it can be divided into:
1, all air system
2, full water system
3, air-water system
4, refrigerant system
2. According to the concentration of air treatment equipment, it can be divided into:
1, centralized
2, semi-centralized
Three, according to the source of the air to be treated can be divided into:
1, closed
2, DC type
3, hybrid type (primary return air and second return air)
The main components of the equipment are air-conditioning host (cold and heat source) fan coil unit, etc.
is essentially composed of air handling equipment, air conveying equipment, and air distribution equipment. There are also refrigeration systems, heating systems and automatic adjustment systems.
Air heat and humidity treatment equipment Air heat and humidity treatment equipment mainly heats, humidifies, cools, and dehumidifies air.
1) Water spray chamber. It is no longer used in civil buildings, but it is still widely used in air conditioning in textile factories and cigarette factories whose main purpose is to regulate humidity.
2) Surface heat exchanger. Coolers, heaters, and steam coils are collectively referred to as surface heat exchangers.
A. There are two types of coil surface heat exchangers: smooth tube and ribbed tube. According to different processing methods, the finned tube can be divided into wound tube, stringed tube and rolled tube.
In order to facilitate the use and maintenance, stop valves, check valves, filters, balance valves, pressure gauges and thermometers should be installed on the cold and hot coal pipelines. On the steam pipeline of the steam heater, a steam regulating valve and a steam trap are also provided. In order to ensure the normal operation of the surface heat exchanger, an air exhaust device (such as vertical and horizontal exhaust valves) should be installed at the high point of the water system, and a drain valve and a sewage valve should be installed at the low point.
B, electric heater. It has the advantages of compact structure, uniform heating, stable heat and convenient control. However, the electric heater uses high-grade heat energy, which is only suitable for use in some air conditioning units and small air conditioning systems. In large-scale air-conditioning systems that require high temperature accuracy, electric heaters are also commonly used to control local heating or as final heating.
There are two types of electric heaters commonly used: bare wire type and tube type.
In order to ensure safety, the design and installation of electric heating systems, especially when bare-wire electric heaters are used, must meet the following requirements:
①The electric heater should be installed in the air duct, and try not to put it in the air conditioner.
②The electric heater should be interlocked with the blower.
③The metal duct where the electric heater is installed should be well grounded.
④ The insulation materials of the air ducts within the range of 0.8m before and after the electric heater shall be insulated non-combustible materials.
⑤ Heat-resistant non-combustible material gaskets must be added between the air duct for installing the electric heater and the connecting flange of the front and rear air ducts.
⑥ For electric heaters that are concealed on the air duct in the ceiling, manholes should be opened on the ceiling relative to the electric heater.
⑦ An over-temperature protection device should be installed in the air duct behind the electric heater.
3) Commonly used air humidity treatment equipment.
Air humidification methods generally include water spray humidification (wet film humidification), high-pressure steam humidification, ultrasonic humidification, and far infrared humidification. The mixing process of using a steam boiler to turn water into steam and air is an isothermal humidification process.
A, isothermal humidification.
① Steam nozzle and dry steam nozzle.
②Dry steam humidifier.
③Electric heating humidifier.
B, isothermal humidification equipment.
There are compressed air sprayers, electric sprayers, and ultrasonic humidifiers that spray water directly into the air in air-conditioned rooms.
C, dehumidification of air.
①Frozen dehumidifier. It is more appropriate to use a refrigerated dehumidifier in places that require both dehumidification and heating. In places where the indoor humidity and heat production are large, it is best not to use a refrigerated dehumidifier.
②The chlorination process wheel dehumidifier. The chlorination rotary dehumidifier uses a special moisture-absorbing paper to absorb moisture in the air.
D. The most commonly used adsorbent for solid moisture absorption in air conditioning engineering is silica gel.
After the silica gel loses its moisture absorption capacity, it can be regenerated by heating, and the regenerated silica gel can still be reused.
Central air-conditioning system-the composition of the central air-conditioning system
1. Chiller:
This is the "refrigeration source" and "heart storage" of the central air conditioner. The circulating water to each room is "internally exchanged" by the chiller, and the temperature is reduced to "cooling water".
2, cooling tower:
is used to provide cooling water for the chiller.
3. External heat exchange system:
consists of two circulating water systems:
1) Chilled water circulation system
consists of a refrigeration pump and a frozen water pipeline. The chilled water from the chiller is pressurized by the chiller pump and sent to the chilled water pipeline, and heat exchange is carried out in the room to take away the heat in the room, which is the temperature drop in the room.
2) Cooling water circulation system
is composed of cooling pump, cooling water pipeline and cooling tower. The water chiller performs heat exchange, while cooling the water temperature, it will release a lot of heat. This heat is absorbed by the cooling water, and the temperature of the cooling water increases. The cooling pump presses the temperature-rising cooling water into the cooling tower, so that it exchanges heat with the atmosphere in the cooling tower, and then the cooled cooling water is sent back to the chiller. Such continuous circulation takes away the heat released by the chiller.
4, cooling fan:
There are two situations:
Indoor fan. Installed in the room where the temperature needs to be reduced, used to blow the air cooled by the chilled water into the room to accelerate the heat exchange in the room.
Cooling tower fan. It is used to reduce the water temperature of the cooling tower, and accelerate the dissipation of the heat brought back by the "return water" to the atmosphere.
The above is the system classification of commercial central air-conditioning.
