The main control parameters of the screw chiller in the process of operation are the coefficient of refrigeration performance, the rated cooling capacity during operation, the input power and the refrigerant type to a certain extent, etc. The screw chiller should be effective. The selection is based on the cold load and the application. For a refrigeration system with a long time of low load operation, a multi-head piston compressor unit or a screw compressor unit should be used for adjustment and energy saving.
In the process of selecting the screw chiller, the unit with higher coefficient of performance value should be given priority to a certain extent. In operation, the chiller operates at 100% load throughout the year, accounting for about 1 of the total running time. /4 below. The operating time ratios of 100%, 75%, 50%, and 25% of the total operating time were approximately 2.3%, 41.5%, 46.1%, and 10.1%. Therefore, when selecting a chiller, priority should be given to models with a flatter efficiency curve.
The screw chiller should effectively consider the adjustment range of the chiller load during the design and selection process. The multi-head screw chiller has excellent partial load performance and can be selected according to the actual situation. When selecting a chiller, attention should be paid to the conditions of the nominal operating conditions.
The actual cooling capacity of the screw chiller is related to the following factors
1. Cold water outlet temperature and flow.
2. The inlet water temperature, flow rate and fouling coefficient of the cooling water.
3. In the process of selecting the chiller, the screw chiller should pay attention to the normal working range of the unit. When using the main motor, the current limit of the main motor is the current value of the shaft power under the nominal condition.
In the design and selection process of the screw chiller, it should be noted that under the nominal condition flow, the outlet temperature of the cold water should not exceed 15 °C, and the outdoor dry bulb temperature of the air-cooled unit should not exceed 43 °C. If it is necessary to exceed the above range, it should be understood whether the range of use of the compressor is allowed, and whether the power of the main motor is sufficient.
