Screw Type Cold Water Chiller Type:
Screw chillers can be categorized into water-cooled and air-cooled types based on their cooling methods. Water-cooled chillers use a cooling tower water circulation system for heat dissipation, while air-cooled screw chillers utilize finned air heat dissipation.
Key Selection Points for Screw Chiller:
1. The main control parameters of a screw-type chill water unit include the coefficient of performance (COP), rated cooling capacity, input power, and refrigerant type.
2. The selection of a chilled water unit should be based on the cooling load and application. For refrigeration systems with long operating times at low load conditions, it is advisable to choose multi-head piston or screw compressor units for ease of adjustment and energy savings.
3. When selecting a chilled water unit, prioritize those with higher performance coefficient values. According to statistics, the chilled water units typically operate at full load for less than 1/4 of the total running time throughout the year. The operating time proportions at 100/75/50/25% loads within the total running time are approximately 2.3%, 41.5%, 46.1%, and 10.1%, respectively. Therefore, when choosing a chilled water unit, it's advisable to opt for models with flatter efficiency curves. Additionally, consider the load adjustment range of the chilled water unit during design selection. Multi-head screw-type chilled water units have excellent part-load performance and can be selected based on actual conditions.
4. When selecting a chilled water unit, attention should be given to the nominal operating conditions. The actual cooling capacity of the chilled water unit is related to the following factors:
a) Cold water outlet temperature and flow rate;
b) Inlet water temperature, flow rate, and dirtiness factor for cooling water.
5. When selecting a chilled water unit, pay attention to the normal operating range of the model, primarily the current limit of the main motor, which is the current value of the shaft power under nominal operating conditions.
6. When selecting the design, attention should be given to: The outlet temperature of the chilled water should not exceed 15℃ under the nominal operating flow rate, and the outdoor dry bulb temperature of the air-cooled unit should not exceed 43℃. If it is necessary to exceed these ranges, it is important to check whether the compressor's operating range allows it and whether the power of the main motor is sufficient.
