Screw chiller and centrifugal chiller are equipment that we often encounter. Below, Oumal Refrigeration will take you to understand the difference between centrifugal chiller and screw chiller?

What is a screw chiller?

The compressor adopts a screw type, hence the name screw chiller. The refrigerant coming out of the evaporator of the unit is a gas; after adiabatic compression by the compressor, it becomes a high-temperature and high-pressure state.

The compressed gas refrigerant is isobarically cooled and condensed in the condenser. After condensation, it changes into liquid refrigerant, and then expands to low pressure through the throttle valve and becomes a gas-liquid mixture.

The liquid refrigerant under low temperature and low pressure absorbs the heat of the cooled material in the evaporator and becomes a gaseous refrigerant again. The gaseous refrigerant re-enters the compressor through the pipeline and starts a new cycle. These are the four processes of the freezing cycle. It is also the main working principle of screw chiller.

2. What is a centrifugal chiller?

The biggest difference from the screw chiller is that it uses a centrifugal compressor.

It is a cooling system that uses the principle of centrifugal force to remove heat from the inside of the fluid. It is composed of centrifugal refrigeration compressor, evaporator, condenser, main motor, air extraction recovery device, lubrication system, control cabinet and starting cabinet. Some of these components are assembled in a decentralized manner, but most are "assembled" units in which each component is put together. The units are divided into fully enclosed, semi-enclosed and open types.

Both centrifugal and screw chillers are types of refrigeration systems commonly used for cooling in various applications. While they serve a similar purpose, there are some key differences between the two different chillers:

Working Principle:

Centrifugal Chiller: Centrifugal chillers use a rotating impeller and centrifugal force to compress and cool the refrigerant.

Screw Chiller: Screw chillers use two rotating screws (male and female) to compress and cool the refrigerant.

Capacity:

Centrifugal Chiller: Centrifugal chillers are typically available in larger capacities, ranging from several hundred tons to several thousand tons of refrigeration.

Screw Chiller: Screw chillers are available in a wide range of capacities, but they are generally suitable for smaller to medium-sized applications.

Energy Efficiency:

Centrifugal Chiller: Centrifugal chillers are known for their high energy efficiency, especially at full load conditions. They are designed to provide efficient cooling for large-scale applications.

Screw Chiller: Screw chillers also offer good energy efficiency, but their efficiency may vary based on operating conditions and load levels.

Operating Characteristics:

Centrifugal Chiller: Centrifugal chillers are often used in applications with varying loads and where precise temperature control is required. They can handle load variations effectively and provide good part-load performance.

Screw Chiller: Screw chillers are suitable for applications with relatively constant loads, as they are generally more efficient at full load conditions. They are commonly used in commercial and industrial settings.

Maintenance and Service:

Centrifugal Chiller: Centrifugal chillers typically require specialized maintenance and service due to their complex design and construction.

Screw Chiller: Screw chillers are relatively easier to maintain and service compared to centrifugal chillers, primarily due to their simpler design and fewer moving parts.

It's important to note that the selection between centrifugal and screw chillers depends on various factors such as cooling requirements, capacity, energy efficiency goals, load characteristics, and budget considerations. Consulting with a professional HVAC engineer or chiller manufacturer can help determine the most suitable chiller type for specific applications.

A screw chiller, also known as a screw compressor chiller, is a type of water chiller utilized for cooling applications in various industries, including injection molding. The semi-hermetic screw compressor is the core components of a screw chiller.  It operates based on the principle of a rotary screw compressor, which is a positive displacement compressor. The screw compressor consists of two interlocking helical rotors that compress the refrigerant gas to raise its pressure and temperature.

According to different heat dissipation methods, screw chillers are divided into air-cooled screw chillers and water-cooled screw chillers. Under the same cooling capacity requirement, the purchase cost of water-cooled screw chillers is lower than that of air-cooled screw chillers. As far as chiller installation is concerned, air-cooled screw chillers are easier to install.

Here are some key features of a screw chiller:

Cooling capacity: Screw chillers are available in a wide range of cooling capacities to meet the specific requirements of injection molding machines. They can handle high cooling loads efficiently, making them suitable for industrial applications. Oumal screw water chiller cooling capacity from 100kw to 1000kw.

Air cooled screw chiller cooling capacity from 90kw to 600KW.

Energy efficiency: Screw chillers are known for their energy efficiency. They can achieve high cooling capacities while consuming relatively less electrical power compared to other types of chillers.

Temperature control: Screw chillers offer precise temperature control, allowing for stable and consistent cooling of the process water used in injection molding machines. This helps maintain the desired temperature for optimal molding conditions. Oumal screw chillers use Siemens PLC controller. Intelligent control, simple operation.

Reliability and durability: Screw chillers are robust and designed for continuous operation in demanding industrial environments. They are built with durable components and feature advanced control systems to ensure reliable and trouble-free performance.

Modular design: Many screw chillers have a modular design, which allows for easy scalability and flexibility. This means that multiple units can be combined to provide higher cooling capacity if needed, making them suitable for expanding operations or varying cooling requirements.

Advanced control options: Screw chillers often come with advanced control options, such as microprocessor-based controllers or touch screen interfaces. These controls provide intuitive operation, real-time monitoring, and the ability to set and adjust various parameters for optimal performance and energy savings.

Noise reduction: Screw chillers are designed with noise reduction features to minimize the operating noise levels. This is important in industrial settings where noise can be a concern.

Overall, screw chillers offer efficient and reliable cooling solutions for injection molding machines, helping to maintain consistent process temperatures and optimize the production of high-quality plastic parts.