Commonly used air conditioning systems are divided into full air systems and air-water systems
1. All air system
A complete central air-conditioning system should consist of four parts: air handling equipment, conveying equipment, cold and heat sources, control systems, and adjustment systems.
The composition of the all-air air-conditioning system includes,
Air treatment part: The air treatment part of the centralized air conditioning system is an air treatment room including various air treatment equipment, which can purify and filter the air and heat and humidify the air. It is called an air conditioning box (referred to as an air conditioning box). ).
Outside the delivery department: The air delivery part mainly includes fans (usually located in the air-conditioning box), air ducts, air outlets and other equipment and accessories; the cold and hot water delivery part mainly includes water pumps, water pipes and accessories.
Cold and heat sources: mainly include refrigeration units (chillers, air-cooled heat pump units, etc.), heat exchangers, cooling towers, etc.
Outside the auxiliary system department: it is used to keep the temperature, humidity, pressure and wind speed and other parameters within the required range and prevent these parameters from exceeding the set value, and at the same time, it can provide economic operation mode as required, that is, stop or stop in a predetermined program. Start the equipment and provide corresponding system output according to load changes and needs.
1. Primary return air system
The fresh air and return air are mixed in the air treatment equipment, and then sent to the room by the fan after the coil cooling (or heating). After the room absorbs (or releases) the heat and humidity load, it is discharged outside, and part of it is recycled as the return air. . This system can not only provide a certain amount of fresh air to the room to meet the hygiene requirements of indoor personnel, but also use return air as much as possible to save energy.
2. Secondary air return system
The secondary return air system divides the return air into two parts. The first part is directly mixed with fresh air and then cooled and heat-treated through the coil, while the second part is mixed with the treated air for a second time. The equipment and management of the secondary air return system tends to be complicated, and it is mainly used in technological air-conditioning projects such as constant temperature and humidity or purification air-conditioning.
3. Variable air volume air conditioning system
Variable air volume air-conditioning system is a full-air air-conditioning system that adjusts the indoor temperature by changing the indoor air volume. Its air supply status remains unchanged. The variable air volume air conditioning system can automatically adjust the air volume according to changes in indoor load and reduce fan energy consumption. , Improve the efficiency of equipment and systems. The system is more complicated, and the initial investment is relatively high. It is mainly suitable for newly-built intelligent office buildings.
2. Air-water system
The central air-conditioning user system is also a cold or heat distribution system composed of a pipeline system and a terminal device, which reasonably distributes the cold and heat to each room according to the size of the load.
The water system of central air-conditioning includes cold (hot) water system, cooling water system and condensate water system.
Chilled water system: The cold water returned from the air-conditioning equipment passes through the water collector, decontamination device, and circulating water pump, and enters the chiller unit during the prime period. It absorbs the cold energy evaporated by the refrigerant, reduces its temperature to cold water, and then enters the water separator for delivery. It enters the surface cooler or cooling coil of the air conditioning equipment, exchanges heat with the processed air, and then returns to the chiller for circulating cooling.
Hot water system: It mainly bears the heat required by air-conditioning equipment in winter to heat the air. The hot water circulation system needs to include a heat source.
Cooling water circulation system: The cooling water that enters the condenser of the chiller absorbs the heat released by the refrigerant in the condenser to increase its temperature, and then enters the outdoor cooling tower to dissipate heat and cool down, and it is cyclically cooled by the cooling water circulating water pump, and the refrigerant is continuously taken away by condensation and released Heat to ensure the refrigeration cycle of the chiller.
Condensate drain system: a water pipe that drains the condensed water formed on the surface of the air conditioner’s surface cooler due to condensation.
