Complete Guide to Screw Chillers: Principles, Types  and other points

If you’re looking for a high-performance chiller but are unsure whether a screw chiller is right for you, this article will provide you with a clear introduction. It will help you quickly understand the working principle, features, and applications of screw chillers—making it easier for you to make an informed and confident decision.

what is screw chiller​?

As the name suggests, a Screw Chiller is a type of chiller that uses a screw compressor to achieve cyclic refrigeration. Its core component—the screw compressor—compresses gas through the rotation of two intermeshing screws, offering advantages such as high efficiency, smooth operation, and suitability for long-term continuous use.

With high power output, strong cooling capacity, compact structure, low noise, and a service life exceeding 100,000 hours without failure, screw chillers perform exceptionally well in industrial cooling applications. They are widely used in high-load, long-cycle operations across industries such as chemicals, pharmaceuticals, machinery manufacturing, and new energy.

Compared with other types of chillers, the most distinctive feature of a Screw Chiller lies in the structure and working principle of its compressor. The type and quality of the compressor directly determine the overall performance and applicable scenarios of the chiller. Therefore, choosing the right compressor form—open-type, semi-hermetic, or fully hermetic—not only affects the initial investment but also has a significant impact on long-term system efficiency and economic performance.

Types of screw chiller

Based on differences in function and performance, screw chillers can be categorized into three main types:

1. Open-Type Screw Chiller

The open-type screw compressor connects the motor to the compressor via a coupling. A reliable shaft seal is incorporated in the chiller system to effectively prevent refrigerant and lubricant leakage at the source. Its simple structure allows for easy maintenance and makes it ideal for projects where initial cost is a major consideration.

2. Semi-Hermetic Screw Chiller

This type is an upgraded version of the open-type chiller. It uses an intermediate flange instead of a coupling to connect the compressor and motor, further reducing leakage risk. The innovative design uses the refrigerant to directly cool the motor, eliminating the need for a cooling fan, thus reducing noise and enhancing operational stability.

3. Hermetic (Fully Enclosed) Screw Chiller

In a fully hermetic design, the compressor and motor are sealed within the same housing, achieving a completely leak-free configuration. This structure eliminates any possibility of refrigerant or oil leakage, ensures low-noise operation, and delivers a significant boost in cooling capacity.

Under standard conditions (evaporation temperature: -15°C, condensation temperature: 30°C), the cooling capacity of a fully hermetic screw chiller can theoretically exceed 3500 kW, making it highly suitable for large-scale industrial cooling applications in sectors such as chemical processing, pharmaceuticals, and machinery manufacturing.

Summary

From open-type to fully hermetic designs, our screw chillers have undergone continuous improvement in key areas:

1.Noise Reduction: Evolved from fan-based noise control to refrigerant-cooled motors and finally to sealed silent designs

2.Leak Prevention: Ongoing optimization of shaft seals and structural connections minimizes refrigerant and oil leakage risks

3.Cooling Capacity Enhancement: Particularly significant in fully enclosed models, meeting the demands of high-load conditions

Classification by Cooling Method

Screw chillers can also be classified based on their cooling method into air-cooled and water-cooled types. These two types differ significantly in terms of operating principles, environmental adaptability, and overall performance. The table below highlights their respective features and advantages:

Difference Point	Air Cooled Chiller	Water Cooled Chiller
Cooling Medium	Air	Water
Cooling Equipment	Fan	Cooling Tower
Environmental Limitations	Applicable to both water sparse and water rich areas	Needs a moist environment to grow
Climate Suitability	Works well in icy conditions	More efficient in warmer areas
Application Scale	Small-medium scale applications: factories	Industrial installations and commercial buildings widespread use at scale
Cooling Capacity	Usually, from several kW to a few hundred kW	Hundreds of kW to a few MW
Efficiency	Relatively lower	Generally higher
Service Life	15 to 20 years	20 to 30 years
Water Consumption	Low	High
Heat Transfer Method	Ambient air flow	Air (moist air flow) and water spray
Maintenance & Installation Costs	Usual (average, no cooling tower, medium construction)	High (need cooling tower and water treatment)
Space Requirement	Larger footprint	Smaller footprint
Installation Location	Typically outdoors	Typically indoors

screw chiller components

Like other types of chillers, screw chillers mainly consist of four core components that form a complete refrigeration cycle system:

 Compressor

 Condenser

 Expansion Valve

 Evaporator

These four components work together to complete the refrigeration cycle of heating and vaporization, condensation and liquefaction, heat dissipation, and evaporation, achieving stable and reliable temperature control.

Additionally, depending on the cooling method and temperature control requirements, the external accessories of screw chillers differ and are mainly divided into two types:

1.Air-Cooled Screw Chiller

 No cooling tower required

 Equipped with fans to dissipate heat through air condensation

 Compact structure and easy installation, suitable for places with limited water resources or good outdoor air cooling conditions

2.Water-Cooled Screw Chiller

 No fans required

 Requires a cooling tower, using circulating cooling water to achieve condensation and cooling

 Suitable for high-load continuous operation scenarios, generally more energy-efficient than air-cooled types

Screw chiller working principle

The screw compressor consists of two helical rotors (male rotor and female rotor) and can provide an almost constant flow rate.
The operation of a screw chiller compresses the refrigerant gas by direct volumetric compression between the two rotors, turning it into vapor.
The detailed process is shown in the following diagram/video.

Screw chiller capacity range

What is chiller capacity?

Capacity  is a key parameter that measures the cooling capability of a chiller. It represents the amount of heat the equipment can remove from a process or space per unit time. Common units are kilowatts (kW) or refrigeration tons (RT). This indicator directly determines whether a chiller is suitable for a specific industrial application and is a core reference when selecting a unit.

How large is the capacity of a screw chiller?

Screw chillers are typically used in large-scale applications that require high cooling capacity, featuring high power, high efficiency, and stable long-term operation. Even basic models available on the market usually offer cooling capacities ranging from several hundred to several thousand kW.

At LNEYA, our current standard screw chillers cover a capacity range from 9 kW to 936 kW, meeting most industrial cooling demands with a balanced focus on performance and energy efficiency.

Why do we focus on screw chillers under 1000 kW?

Although we have the technical capability to develop chillers with capacities above 1000 kW, the screw compressors we use mainly fall within the medium power segment. This enables us to provide mid-to-large industrial chillers with the best cost-performance ratio and efficiency.

Choosing screw chillers over 1000 kW with high power would lack competitiveness in terms of price and cost, resulting in lower value for customers.

Screw chiller life expectancy

Generally, the service life of a screw chiller is between 10 to 20 years. However, this is not absolute. The lifespan of a chiller depends not only on the quality of its components and design but also heavily on the level of maintenance by the user. The higher the quality of the chiller and the better the maintenance performed, the longer its service life will be.

Recommended screw chillers