Air-cooled scroll chillers adopts Kano cycle principle and adopts scroll compressor and air chiller technology to realize refrigeration. Its working process can be divided into four core stages: compression, condensation, throttling and evaporation, supported by intelligent control and safety protection mechanisms. Here are the details:
I. Core Components
Scroll Compressor
It is composed of a fixed stator and a rotating rotor, which compress the refrigerant gas through two parts of meshing motion. It has the characteristics of high efficiency, low noise and low vibration.
Air-cooled Condenser
Using the fintube structure, forced airflow of the fan dissipates heat of the high-temperature, high-pressure refrigerant gas into the environment.
Expansion Valve (Throttling Device)
Adjust the flow of refrigerant, reduce the pressure of high-pressure liquid refrigerant, form a low-temperature, low-pressure gas-liquid mixture.
Evaporators
Refrigerant absorbs heat from cooled media (e.g., cooling water) to achieve a cooling effect.
Control System
Monitors temperature, pressure and other parameters, automatically adjust compressor speed and fan speed to optimize energy efficiency.
Safety gear
Includes high/low pressure protection, overload protection and antifreeze protection to ensure safe operation.
ii. Working Processes
1. Compression Process
Start point: Low-temperature, low-pressure refrigerant vapor (usually gaseous and close to evaporation evaporation temperature) from the evaporator outlet.
Action: Steam is sucked into scroll compressor, and the rotating rotor engages the the stator, gradually compressing the refrigerant.
Results: Refrigerants are compressed into high-temperature, high-pressure gases (temperatures can reach 70-90°C depending on the refrigerant type).
2. Condensation Process
Starting point: hightemperature, high pressure gas from compressor outlet.
Effect: Gas enters the air-cooled condenser, where heat exchange takes place, forcing air to pass through the finned tubes.
RESULTS: The refrigerant releases heat into the air and condenses into a high-pressure liquid (near ambient temperature with constant pressure).
3. Throttling Process
Start point: High-pressure liquid refrigerant from the condenser outlet.
Action: Liquid passes through the expansion valve; the reduced cross-sectional area of the the valve results in a rapid decrease in refrigerant pressure. Results: A low-temperature, low-pressure gas-liquid mixture is formed (temperature may be below 0°C and the pressure close to evaporation pressure).
4. Evaporation Process
Start point: Low temperature, low pressure, gas-liquid mixture at the outlet of the expansion valve outlet.
Role: The mixture enters the evaporator, absorbs heat from the cooling medium (e.g., chilled water) and vaporizes the liquid.
Results: The temperature of the cooling medium decreases (e.g., chilled water from 12°C to 7°C) and the refrigerant becomes a low-temperature, low-pressure vapour.
Cycle: The steam returns to the compressor to start a new cycle.
III. Key Auxiliary Systems
Air Circulation System
The condenser fan forces air over the fin tube and accelerates heat dissipation. Fan speed can be automatically adjusted according to condensing pressure to optimize energy efficiency.
Water Circulation System (Chilled Water Side)
Refrigerant in evaporator absorbs heat from cold water and lowers temperature. Cooling water is pumped to end-user equipment (e.g., air treatment units, fan coil units) to provide cooling.
Control System
Temperature control: Adjust the frequency of compressor and the opening of expansion valve opening to maintain the cooling water outlet temperature stable.
Energy Efficiency Optimization: using frequency conversion technology to reduce compressor speed and save energy under some load conditions.
Fault diagnosis: monitor parameters in real time and trigger alarm or shutdown protection when abnormal situation is found.
IV. INTRODUCTION Examples of work
Take, for example, a 50kW air-cooled scroll chiller:
Evaporator side: Chilled water temperature drops from 12°C to 7°C with a flow rate of about 8.6 m3/h.
Compressor: Compress 7°C, 0.5 MPa vapor to 75°C, 2.0 MPa gas.
Condenser: The gas is cooled in a the finned tubes and expelled as a 35°C, 2.0 MPa liquid.
Expansion valve: Liquid pressure reduced to 0.6 MPa, temperature reduced to 2°C.
Evaporator: 2°C liquid refrigerant absorbs heat from cold water, evaporates and completes the cycle.
V. Advantages and characteristics
Easy Installation: No cooling tower or water pump is required, saving space and initial investment.
High Adaptability: Suitable for areas with limited or poor water water quality resources. Stable operation: Scroll compressors has no reciprocating motion, low vibration and long service life.
Energy saving: Variable frequency technology dynamically adjusts output to reduce energy consumption.
VI. INTRODUCTION Application Scenarios
Commercial buildings: central air conditioning systems for office buildings, shopping malls, hotels, etc..
Industrial applications: Used in electronic equipment cooling, plastic molding, plating and other industrial processes.
Special Environments: Areas with limited or poor water resources, such as deserts and islands.