Centrifugal Chiller

What is the Centrifugal Chiller？

Centrifugal chillers are refrigeration equipment that use centrifugal compressors in the refrigerant cooling cycle. The centrifugal compressor serves as the heart of the vapor compression refrigeration system, driving the refrigerant cycle and ensuring continuous and stable cooling. Thanks to the high efficiency and capacity of centrifugal compressors, you can use centrifugal chillers for cooling medium to large commercial and industrial projects.

How the Centrifugal Chiller Works？

Two cycles exist in centrifugal chillers, including the heat exchange between the water and the heat-generating equipment/area and the cooling cycle of the refrigerant.

Heat Absorption

When you run a centrifugal chiller, you can adjust the cooling programme you need via the control panel. The pump will immediately deliver water to the area that needs to be cooled, then exchange heat with the heat source and subsequently carry the heat to the evaporator. The water transfers the heat to the refrigerant in the evaporator and the re-cooled water is then transferred to the heat source again to absorb the heat.

Evaporation

When water enters the evaporator with heat drawn in from the outside, the refrigerant inside the evaporator rapidly absorbs the heat from the water, lowering the temperature of the water. The re-cooled water is returned to continue the cycle of heat exchange to achieve rapid cooling of equipment or the environment, while the refrigerant is rapidly converted from a liquid to a gaseous state after absorbing heat.

Compression

The centrifugal compressor serves as the heart of the cooling cycle and provides the power to circulate the refrigerant. The refrigerant is converted into a gaseous state at low pressure. The centrifugal compressor generates centrifugal force with its high-speed rotating impellers, which rapidly draw in the gaseous refrigerant and transform it into a high-pressure state, helping it to enter the condenser smoothly.

Condensation

The refrigerant entering the condenser exchanges heat with air or water to dissipate heat quickly. Air-cooled centrifugal chillers exchange heat with ambient air, while water-cooled centrifugal chillers exchange heat with chilled water in a cooling tower. The cooled refrigerant will recondense to a liquid state.

Expansion

Refrigerant that has been recondensed to a liquid state is under high pressure and it is difficult to absorb heat again. The expansion valve further transforms the refrigerant into a low-temperature, low-pressure state so that it can effectively absorb heat again and quickly transform into a gaseous state. The refrigerant enters the evaporator again for the next cycle.

Main Types of Centrifugal Chillers

Maglev Centrifugal Chillers

The Magnetic Levitation Centrifugal Chiller is an advanced centrifugal chiller that utilises magnetic levitation technology. It achieves oil-free, friction-free, and mechanical contact-free operation, resulting in higher energy efficiency. This also allows the magnetic levitation centrifugal chiller to have a longer service life than ordinary centrifugal chillers, while greatly reducing the noise and vibration generated by the operation. In addition, its lighter weight and tighter construction allow you to use it in scenarios with tight space constraints.

Water-Cooled Centrifugal Chiller and Air-Cooled Centrifugal Chiller

Centrifugal chillers can be divided into water-cooled centrifugal chillers and air-cooled centrifugal chillers according to the different methods of heat dissipation of refrigerant in centrifugal chillers.

• Air-Cooled centrifugal chiller: The refrigerant in an air-cooled centrifugal chiller transfers heat to the ambient air in the condenser to dissipate heat. It requires a fan to blow ambient air onto the exposed condenser for efficient heat transfer during operation. It is a relatively simple structure with low initial and maintenance costs. However, it does not perform well in high-temperature environments because it relies on ambient air for its cooling efficiency. And the fan makes it more noisy.
• Water-cooled centrifugal chiller: The refrigerant in a water-cooled centrifugal chiller transfers heat to water in a condenser to dissipate the heat. Therefore, it does not require a fan but a cooling tower to provide water. The superior heat transfer efficiency of water makes it a more efficient cooler and unaffected by ambient air. However, it has a higher initial cost and is more complex to maintain. And you’re better off using it in an environment where water is plentiful.

Closed, Semi-hermetic and Open Centrifugal Chiller

To achieve a wider range of applicability, centrifugal compressors are also available in open, hermetic and semi-hermetic centrifugal chillers to meet different installation requirements. These differences lie in the way the centrifugal compressor and motor are mounted, with the most common being the semi-hermetic type, which mounts the compressor and motor closed. Whereas the open type installs them separately, the closed type installs them sealed from the entire unit.

Advantages of Centrifugal Chillers

Superior Performance

Centrifugal compressors have more efficient operating speeds, allowing them to compress more refrigerant in less time, resulting in improved cooling efficiency and greater capacity. This allows it to withstand the cooling demands of larger loads, meeting the needs of heavy-duty and large-scale projects. In addition, it allows for longer runs, less downtime and better reliability.

High Energy Efficiency

Centrifugal compressors provide better cooling in terms of capacity and cooling efficiency with the same amount of energy. Low energy costs make it a cost-effective choice for large and long-term projects. You can also choose centrifugal chillers with variable speed drives to reduce unnecessary energy losses and further reduce energy costs.

Low Maintenance Costs

On the one hand, centrifugal compressors are more compact than other types of compressors and therefore take up less space. On the other hand, their low operating friction and high durability reduce component damage and do not require regular lubrication. This not only extends their service life but also reduces maintenance costs.

Quiet Operation

Centrifugal compressors create less friction during operation, which reduces noise and vibration, resulting in smoother operation. This provides a more comfortable environment for customers and employees in a variety of commercial and industrial applications, resulting in improved operations and productivity.