What is Ductless Air Conditioning?

A system for artificially treating the temperature, humidity, cleanliness and air velocity of indoor air. Some places can get air with a certain temperature, humidity and air quality to meet the requirements of users and production processes and improve labor hygiene and indoor climate conditions.

Chinese name: Air Conditioning System
Equipment: Air treatment equipment

Method: Man-made approach to indoor air
Purpose: Improved industrial hygiene and indoor climate

Classification of air-conditioning system

Centralized air conditioning system

All air processing equipment (fans, filters, heaters, coolers, humidifiers, dehumidifiers, refrigeration units, etc.) are concentrated in the air-conditioning room, and after the air is processed, they are sent to the air-conditioning rooms by air ducts. The heat and cold sources of this air conditioning system are also centralized. It handles a large amount of air, runs reliably, and is easy to manage and maintain, but the machine room covers a large area.

Semi-concentrated air conditioner

The air processing equipment concentrated in the air-conditioning room only processes a part of the air, and there are also air processing equipment in the dispersed air-conditioned rooms. They either process indoor air in situ, or replenish air from centralized processing equipment. The induction system, fan coil + fresh air system are typical examples of such semi-centralized air conditioning systems.

Local air conditioning system

This system is to disperse the air treatment equipment in the air-conditioned room, so the local air-conditioning system is also called decentralized air-conditioning system. Various air conditioners commonly used fall into this category. The air conditioner concentrates indoor air processing equipment, indoor fans, etc., and the cold and heat sources and the refrigerant output system in a single box. Decentralized air conditioners only deliver hot and cold carriers to the room, and wind is processed in fan coils in the room.

Air conditioning system inspection

How to check the used car air conditioning system?

The air-conditioning system of a car is a relatively complicated system. The air-conditioning filter can be said to be the most important air-conditioning component. It mainly cleans the air dust, pollen, and bacteria. These are mainly to the interior of the air-conditioning system create pollution. During the maintenance of the air-conditioning refrigeration system, we must thoroughly clean the air-conditioning filters. We can use air ducts to clean the dust. If the air-conditioning filters cannot be cleaned effectively, the owner can replace them. Air conditioning filter.

When inspecting the air conditioner, mainly check the condenser of the air conditioner, and clean the surface of the evaporator. If there is too much dust, it must be cleaned in time, and compressed air should be blown out. During the inspection, the performance of various switches and control elements must be checked, the reliability of their performance, and whether the air conditioner is deficient in fluorine. If the refrigerant of the vehicle is insufficient, this may cause the air conditioner to promote the original refrigeration. Role, if the refrigerant is filled, then you must pay attention to the use of refrigerant, can not be leaked, you can also observe the components of the surface of the compressor to effectively deal with, mainly the surface of the compressor, the hose And the oil traces of the joint assembly department will be processed in time. Through comprehensive judgment, it can be shown whether there is a leak in its system. If it happens, it can be repaired in time. The above is the treatment method of the air conditioner in the car.

Air-conditioning system division

Air conditioning system by medium

All-air system: This system is the air-conditioned room's heating and cooling load is entirely borne by the treated air. The centralized air-conditioning system is an all-air system.

All-water system: This system is the cooling and heating load of the air-conditioned room. It does not solve the ventilation problem of the room and is generally not used alone. Fresh air fan coils belong to this all-water system.

Air-water system: This system is the air and water load of the air-conditioned room is borne by both air and water. Fan coil plus fresh air system is such a system.

Refrigerant system: The cooling and heating load of the air-conditioned room of this system is directly borne by the refrigerant of the refrigeration system, and the local air-conditioning system belongs to this category.

Air conditioning system by type

Direct evaporation system: The refrigerant evaporates directly in the cooling coil, and absorbs the heat of the air outside the coil. It is suitable for occasions where the air conditioning load is not large and the air conditioning room is relatively concentrated.

Indirect cooling system: The refrigerant evaporates and absorbs heat in a dedicated evaporator to cool the chilled water (also known as refrigerant water). The chilled water is transported by a water pump to a dedicated water-cooled surface cooler to cool the air. It is suitable for occasions with heavy air-conditioning load, scattered rooms or high requirements for automatic control. ^[1]

Air-conditioning system

DC system: also known as the new air-conditioning system. The air processed by the air conditioner is fresh air, which is sent to each room for heat and humidity exchange and is discharged to the outside without return air ducts. This system has good sanitary conditions, high energy consumption, and poor economy, and is used in workshops where harmful gases are generated. Laboratory, etc.

Closed system: All the air processed by the air conditioning system is recirculated, and the system is not supplemented with fresh air. The system has low energy consumption and poor sanitary conditions, and needs to regenerate oxygen in the air and have a carbon dioxide suction device. Such as air conditioning for underground buildings and submarines, etc.

Hybrid system: The air processed by the air conditioner is a mixture of return air and fresh air. It has both the advantages of DC type and closed type, and is widely used, such as air-conditioning systems in hotels, theaters and other places.

Energy-saving control method for air-conditioning system of air-conditioning system

At present, the main forms of air-conditioning air systems in China are fixed air volume all air systems, fan coils and fresh air systems, and variable air volume all air systems. From the perspective of parameter adjustment, the existing energy-saving control methods of air conditioning air systems mainly include variable air volume control, Variable supply air temperature and humidity control and variable fresh air ratio control.

Variable air volume energy-saving control method for air conditioning system

Variable air volume is the primary adjustment method in various energy-saving control methods of the wind system. Among them, the variable air volume control method with the supply air static pressure as the control reference quantity is the main control and adjustment method. The method of resetting the setting value of the static pressure of the supply air using the valve position of the terminal variable air volume box as a reference has been used in actual systems in the 1990s. The core idea of this method is to use the valve position of the variable air volume box as a control reference value, and adjust the fan speed by frequency conversion to maintain the required static air supply pressure reset value to ensure that at least one terminal of the variable air volume box air valve is fully open. This method has achieved good energy-saving effects in practice, but the biggest problem is the looseness between the valve stem and the valve position sensor. Because the existing actuator lacks a self-diagnosis link, the feedback valve position information cannot reflect the valve's The true opening degree brings about the problem of miscontrol.

Energy-saving control method for variable air temperature and humidity of air conditioning system

On the basis of variable air volume control, optimizing the supply air temperature and humidity and achieving optimal control of surface coolers, heaters, and humidifiers is an important method to further reduce the energy consumption of air conditioning systems; variable air supply temperature is also a constant air volume air conditioning system Commonly used important energy-saving adjustment methods. The core idea of variable supply air temperature control is to adjust the opening of the chilled water or hot water valve of the heat exchanger of the air-conditioning unit to maintain the set value of the supply air temperature; adjust the humidification amount of the humidifier of the air-conditioning unit to maintain the set value of the supply air humidity. How to set the supply air temperature and humidity set value is the key to change the supply air temperature and humidity control.

Energy-saving control method for changing air ratio of air conditioning system

The control of the fresh air ratio is the adjustment control of the economizer (consisting of the fresh air valve, return air valve, and exhaust valve) of the air conditioning unit. When the outdoor heat value is lower than the indoor heat value, it can be adjusted by the fresh air ratio and using the fresh air cooling capacity. Reduce the energy consumption of artificial cooling. In addition, the adjustment of the fresh air ratio should also meet the control requirements of indoor CO ₂ concentration.

Energy-saving control method of air-conditioning system of air-conditioning system

The above-mentioned control and adjustment methods of variable air volume, variable supply air temperature and humidity, and fresh air ratio are not only embodied in the variable air volume all-air air-conditioning system, but also cover a single control loop adjustment method of almost all air-conditioning system forms. Therefore, studying the control reference model optimization selection and its adaptive optimization setting method of the single control link mentioned above has important academic significance and application value for solving the common control adjustment problem of air-conditioning air system.

However, for any specific air conditioning air system, there is a strong coupling relationship between variable air volume, variable supply air temperature and humidity, and fresh air ratio. The decoupling control and coordinated control between the control loops of the air conditioning air system are Another key issue for achieving energy-saving control of wind systems. ^[2]