What Is An Air-cooled Screw Chiller?

Air-cooled screw chiller is a kind of screw chiller. It takes air as cooling medium and realizes refrigeration cycle through screw compressor. Mainly used for air conditioning systems, industrial equipment and so on to provide low-temperature cooling water. The following is a detailed introduction from the working principle, structure composition, characteristics, application scenarios, etc.:
1.Principles of work
Core of the refrigeration cycle:
screw compressor are used to compress refrigerants (e.g. R134a, R410A, etc.) into high-temperature, high-pressure gases.
The high-temperature and high-pressure refrigerant gas enters the air-cooled condenser, which forces the air to flow, releasing heat into the external environment and condensing it into a liquid.
The liquid refrigerant throttles down through the expansion valve, goes into the evaporator, absorbs the heat of the cooling water (cooling water), evaporates into gas, and then returns to the compressor to complete the cycle.
Air-cooled cooling method:
Unlike water-cooled units, which use cooling water to circulate heat, air-cooled units exchange heat with the air through wings on the condenser's outer surface, discharging heat directly into the atmosphere without the need for additional cooling towers, water pumps and other ancillary equipment.
2.Main structural elements
Compressor:
Using Adopts screw compressor, the refrigerant is compressed by meshing and rotating nut, and the operation is smooth and efficient.
Air-cooled condenser:
Fin-type heat exchanger with an axial fan on the outside that forces air to carry heat through the finned heat exchanger.
Evaporators:
Usually a shell and tube heat exchanger cooling water flowing inside the tube and refrigerant evaporating and absorbing heat on the side of the tubular casing.
Throttling device:
Expansion valve (thermal or electronic expansion valve) are used to control the refrigerant flow and reduce pressure.
Control system:
Contains PLC or microprocessor to monitor temperature, pressure, operation status, automatic start and stop, energy regulation (e.g., 10% ~ 100% stepless regulation), and fault protection.
3.Characteristics (comparative advantages and disadvantages)
Strengths:
Convenient installation:
No need to install cooling towers, piping and water pump, saving engine room space, reducing installation costs and recycling, suitable for outdoor or rooftop installation (e.g., commercial building roof).
Widespread application:
It is highly adaptable to the environment and does not need water. It can be used in areas where water isscarce or where it is difficult to arrange cooling systems (e.g., remote factories and outdoor equipment).
Flexible operation:
High efficiency under partial load (such as good performance at 50% load). The speed of compressor or number of units can be adjusted by frequency conversion to meet the actual cooling requirements.
Simple maintenance:
The cooling water system has no scale and corrosion problem, which reduces the work of condenser cleaning and water quality treatment, and the maintenance cost is low.
High initial investment:
The compressor and heat exchanger of screw type air chiller is more expensive than that of the small piston screw units, but the investment is lower than that of water-cooled screw type air chiller of the same capacity (eliminating equipment such as cooling towers).
IV. INTRODUCTION Application scenarios
Commercial and civil buildings:
Central air-conditioning systems in small and medium-sized shopping malls, offices, hotels, hospitals, etc., are particularly suitable for places with no cooling water system or limited installation space (e.g. directly on the roof).
Industrial cooling:
Electronic equipment cooling (e.g., data center servers), plastic processing (injection molding machine mold cooling), food processing (cold storage cooling), etc., require flexible layouts that do not depend on water sources.
Special circumstances:
Cooling needs in water-scarce areas (e.g. factories in arid areas), temporary buildings or mobile refrigeration equipment (e.g. vehicle-mounted cooling systems).
V. Selection considerations
Cooling capacity requirements: Calculate the cooling capacity required based on the building load or the heat load of industrial equipment and consider redundancy (usually reserved for 10% ~ 20%).
Ambient temperature: In high-temperature areas, models (such as condensers designed to accommodate temperatures above 40°C) that can withstand high ambient temperatures need to be selected.
Noise control: If installed near a residential area, choose a low-noise model or have a noise shield installed.
Energy efficiency requirements: Variable frequency models, high energy efficiency under some load, in line with green building standards (e.g. LEED, national energy efficiency rating).
In short, air-cooled screw chillers have become a common choice for small and medium-sized refrigeration scenarios, especially in commercial buildings and industrial refrigeration, due to their anhydrous and flexible installation.