Use and maintenance of central air-conditioning chillers

Use and maintenance of central air-conditioning chillers

At present, central air-conditioning refrigerators are widely used, especially in shopping malls and other places with a large number of people. The article introduces the principle of refrigeration of central air-conditioning chillers, system classification, use and maintenance of central air-conditioning chillers.

　　The use of central air-conditioning chillers simplifies the procedures for large-scale enterprises to manage and control systems. Generally, large-scale enterprises will centralize the operating systems of each link for management. This is the current development trend of the central operating system of large enterprises, and the central air-conditioning chiller is different from the single air conditioner used in the home. The central air-conditioning chiller has higher requirements on the scope of refrigeration and maintenance.

　　 1. The refrigeration principle of central air conditioning refrigerator

The cooling principle of central air-conditioning chiller is based on the principle that when the liquid evaporates, the surrounding heat is obtained. Under normal air pressure, water must reach 100 degrees Celsius to evaporate. However, in a vacuum environment, water can boil and evaporate without reaching 100 degrees Celsius. If it is in a closed environment with a low pressure of 6mmHg, the water to find the tissue needs to reach 4 degrees Celsius to boil and evaporate. Lithium bromide refrigerators currently adopted by most companies use this principle for cooling. Lithium bromide is a substance with very strong water absorption capacity. This lithium bromide refrigerator uses water as a refrigerant and lithium bromide as an absorbent. Lithium bromide is a white crystal of salt, which is very easy to fuse with water, has strong stability and will not deteriorate. The key is that it is a non-toxic chemical substance and will not be harmful in use.

　　 Lithium bromide absorption refrigerator is mainly composed of generator, condenser, evaporator, absorber, heat exchanger, circulating pump and so on. During the operation of the lithium bromide absorption refrigerator, after the lithium bromide aqueous solution in the generator is heated by the heating medium water, the water in the solution continuously volatilizes; as the water volatilizes, the concentration of the lithium bromide aqueous solution continues to increase and enters the absorber; water The steam enters the condenser, and when it encounters the cooling water of the condenser, the temperature drops and gradually condenses. It becomes high-pressure and low-temperature liquid water; when the liquid water in the condenser enters the evaporator through the throttle valve, it rapidly expands and evaporates, and absorbs a large amount of heat from the refrigerant water during the evaporation process, thereby achieving the purpose of cooling and cooling.

　　 2. System classification of central air-conditioning chillers

　　 1. Water-cooled cold water (heat pump) air conditioner

　　 Water-cooled cold water (heat pump) air conditioners are divided into piston type, screw type, centrifugal type, scroll type, direct-fired lithium bromide absorption type

　　 and other forms. Three types of centrifugal type, screw type and direct-fired type are commonly used. Screw-type and centrifugal-type water chillers are commonly used in various hotels and shopping malls. They are a common form of traditional central air conditioning. It is generally in the form of single cooling. Direct-fired chillers are mainly used in areas where electricity is scarce or gas and fuel prices are low. At the same time, it can provide sanitary hot water and heating water. In addition, there are some forms of heat recovery air conditioning, which are widely used in hotels, saunas, hospitals and other places that require hot water for a long time. This form of heat recovery in summer is generally 15% of the cooling capacity, and hot water can be obtained for free, which can basically meet the hot water required by the hotel, and generally only requires a one-year investment payback period. However, in winter and transitional seasons, when the amount of air conditioner is small, it cannot be used. There are also water (ground) source heat pumps, which are more suitable for areas with abundant groundwater resources or near lakes and seawater. The water source heat pump is 10%-20% more energy-saving than traditional air conditioners. It can simultaneously meet the needs of heating in winter and cooling in summer. However, it cannot be used if the temperature in winter is lower than 0℃.

　　 2. Air-cooled cold water (heat pump) air-conditioning form

　　 According to the compressor, it can be divided into scroll type, piston type, screw type, etc. Commonly used are screw type and scroll type. Parts of large buildings or small comprehensive buildings use this form more often. The comprehensive energy efficiency ratio of both cooling and heating is about 3.0. Other forms include: total heat recovery, partial heat recovery, and air-cooled and hot water units with partial heat recovery. Saunas, hotels, hospitals and other places that require hot water for a long time use this form more.

　　3, water-cooled air-conditioning form

　　According to the classification of compressors, it can be divided into scroll type, piston type and other types, and scroll type is often used. The main form is: water-cooled cabinet machine. Due to the low cost and operating cost of this form, the general factory uses this form more. But its noise is relatively large, if it is used in commercial projects, it is necessary to install noise-absorbing facilities. There is also a water ring heat pump, which is composed of small units with a lot of sweat, and is installed in the equipment room or on the ceiling. This decentralized management saves energy. However, because the compressor is installed indoors, the noise is relatively large, which affects people's normal work and life. In addition, the decentralized units have increased maintenance work.

　　 4. Air-cooled air-conditioning form

　　 This form generally uses scroll compressors. The main form is a split machine. Other forms include: frequency conversion central air conditioning system, frequency conversion unit air conditioner, unit unit air conditioner unit, special air cooler for cold storage, three-in-one heat pump system, freezer, etc. The advantages of the frequency conversion central air-conditioning system are that the location is flexible, easy to control and billing, and there is no restriction on the use time. In some cases, the use and operation costs are very low. But there are also shortcomings. Its cost is relatively high, and it also has to place the camera outdoors, which affects the layout of the building to a certain extent. The three-in-one heat pump system has the functions of dehumidification and heating, and is usually used in the design of swimming pools. And the overall efficiency of this system is relatively high, the hotel's constant temperature swimming pool, sauna baths, etc. will adopt this system form. .

　　 3. Common problems and maintenance in the use of central air-conditioning refrigerators

　　 1. The running noise is loud

　　The design, noise reduction measures and installation of the central air-conditioning will affect the noise level of the central air-conditioning chiller. And during operation, if the impeller of the fan collides or the bearing is damaged, it will affect the excessive noise. Too much operating noise will affect people's normal life and cause economic losses to users. Air-conditioning noise mainly includes pneumatic, mechanical and electromagnetic noise. Pay attention to the craftsmanship during the installation process, check the airflow of the flyport, adjust the valve, and improve the noise reduction measures to reduce the noise of the central air-conditioning refrigerator.

　　2, the water system is blocked

　　 The water system clogs the normal operation of the British gas refrigerator system. The main reason for the blockage of the water system is that other substances enter the pipeline or the pipeline at the water inlet is aging and cracked. If the cooling effect of the air conditioner deteriorates, you can check whether it is the cause of the blockage of the central air conditioning water system. In the case of Zezhong, you only need to open the water filter of the water supply pipe to check and clear the blockage.

　　3, slow indoor cooling

The slow cooling is because the air supply volume of the air conditioner chiller is less than the design value, the number of air changes is small, the system with secondary air return, the secondary return air volume is too large, the central air conditioning system has many rooms, and the air volume is unevenly distributed. Please check whether the fan model meets the design requirements, whether the impeller steering is correct, whether the belt is slack, open a large air supply valve, eliminate the factor of insufficient air volume, and reduce the secondary return air volume, and adjust the air volume distribution in each room.

　　4. The measured air volume of the central air-conditioning system is less than the design air volume

This situation is because the actual resistance of the central air-conditioning system is greater than the design resistance, the air volume of the fan is reduced, the central air-conditioning system is blocked, the fan cannot reach the design capacity, or the impeller rotates in the wrong direction, and the belt slips, resulting in poor system wind operation. The air volume is reduced.

　　 5. Easy to form scale

　　The water or cooling water of central air-conditioning mostly comes from ordinary tap water. The cooling water is recycled for a long time, and the blockage is the cause of water scaling under heating, flowing, and evaporating conditions. The scale generated in the condenser and evaporator of the central air-conditioning reduces the heat exchange efficiency of the central air-conditioning chiller and increases the energy consumption. The most important thing is that the corrosion of these scales easily affects the safe operation of the central air-conditioning equipment. The service life of the equipment is shortened, and the cost of maintaining the equipment is increased. Users can use high-frequency electromagnetic to remove scale, or install a water softener to soften the water and prevent the generation of scale.

　　6. ​​Fungi and algae are produced in the water system

　　The production of these fungi and algae plants is mainly due to the cooling water in the central air-conditioning system. The environment of these cooling water is suitable for the reproduction of fungi and algae plants. Five poisonous algaecides can be used to remove algae. In addition, electronic descaling agents can also be used to achieve the effect of algae and sterilization, while also removing scale.

　　 Fourth, concluding remarks

　　 In summary, through the introduction of the refrigeration principle of central air conditioning refrigerators and the classification of refrigeration systems, a detailed description of various refrigeration systems, the advantages and disadvantages of various systems, and the applicable places and fields are made. As well as the common problems and maintenance and repair measures of central air-conditioning refrigerators in use. It can be seen that the application of central air-conditioning refrigerators is very wide, and various refrigeration systems that adapt to social needs have been designed according to the characteristics and needs of different regions and fields. And there are targeted solutions for use and maintenance.