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How to select screw chiller
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2022/12/30 14:39:00 *
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Screw chiller is named as screw chiller because the key part of the compressor is screw chiller. It can be divided into water-cooled screw chiller and air-cooled screw chiller according to different heat dissipation modes.
1. The selection of screw chillers should be considered according to the cooling load and the aspects to be used. As for the refrigeration system with low load and long working hours, it is appropriate to select the multi-head screw compressor unit to facilitate conditioning and energy conservation, which is also known as the double-head screw refrigerator or the three-head screw refrigerator. With the change of load, the water chiller automatically confirms the capacity of the open compressor to ensure that the open compressor is in a good working condition, thus effectively saving electricity.
2. When selecting screw chillers, priority should be given to the units with higher function coefficient values. According to the previous material statistics, the normal refrigerating unit's operating time under load throughout the year accounts for less than 1/4 of the total operating time. The proportion of 75%, 50% and 25% load in different operation hours is about 2.3%, 41.5%, 46.1% and 10.1%. Therefore, the type of chiller with relatively flat power curve should be given priority when selecting chiller.
In addition, the adjustment scale of water chiller load should be considered in the design and selection. The multi-head screw chiller has excellent partial load function, and the screw chiller can be selected according to the factory practice.
3. When selecting screw chillers, pay attention to the nominal working conditions. The practical cooling capacity of the chiller is related to the following two points:
A. The chilled water outlet temperature and return water temperature of the refrigerator are also the inlet and outlet water temperature of the shell-and-tube evaporators;
B. The inlet water temperature, flow rate and fouling coefficient of the cooling circulating water of the refrigerator refer to the inlet and outlet water temperature of the condenser.
C. If the air-cooled screw refrigerator is selected, it is necessary to pay attention to the operating environment temperature and humidity, which directly affect the power and service life of the refrigerator.
D. Screw chillers used in special occupations, chemical industry, medicine, aerospace, machinery, aviation, chemical fiber and other professions with special requirements need to be clearly explained to the sales staff in advance, such as the chemical industry profession may need explosion-proof treatment of electrical appliances, shell-and-tube evaporators need anti-corrosion treatment, etc.
4. When selecting the screw chiller, you should pay attention to the normal operation field of this type of screw chiller. The main reason is that the current limit of the motor is the current value of the shaft power under the external working condition.
5. When designing and selecting screw chillers, attention should be paid to:,
The outlet temperature of the chilled water should not exceed 15 ℃, that is, the transpiration temperature should not be higher than the scale of the screw unit, otherwise the liquid return will be severe and liquid hammer will be formed. The outdoor dry-bulb temperature of air-cooled screw freezer is not appropriate to exceed 43 ℃.
If it is necessary to cross the above fields, we should understand whether the application field of the compressor can be allowed and whether the power of the auxiliary motor can be met.
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