Introduction
Water-cooled chillers are key for controlling temperature in industrial and commercial settings. They provide a reliable way to manage unwanted heat in large applications. Water-cooled chillers use water to absorb and release heat, making them, in some cases, more efficient than using air-cooled chillers as a standalone solution, which use air to cool. They are well-suited for settings where energy efficiency, high cooling capacity and long-term operational stability are critical.
These systems are widely used in:
- HVAC applications for large buildings
- Manufacturing processes that require precise temperature regulation
- Data centres where continuous cooling is essential for optimal performance
Water-cooled chillers can be more energy efficient than air-cooled ones. This makes them a better choice for facilities focusing on sustainability and saving money.
At Aggreko, we understand that every cooling challenge is unique. Whether supporting temporary cooling needs during peak demand or providing long-term, scalable solutions, our expertise ensures businesses stay operational, efficient and resilient. With many years of experience, we provide flexible and high-performance cooling solutions. We help customers understand cooling technology. Our goal is to ensure they get the right system for their needs.
Working Principle of a Water-Cooled Chiller
Water-cooled chillers work on the fundamentals of heat exchange and the refrigeration cycle, efficiently removing heat from a process or environment. These systems use a refrigerant to absorb and transfer heat, with water helping to cool things down.
Unlike air-cooled chillers, which release heat directly into the surrounding air, water-cooled chillers use a cooling tower to disperse excess heat.
Key Stages in Operation
1. Heat absorption at the evaporator: the refrigerant extracts heat from the circulating water, cooling it for recirculation.
2. Refrigeration cycle: the compressor, condenser and expansion valve work together to regulate refrigerant pressure and temperature.
3. Heat rejection through the cooling tower: water transfers heat from the condenser to the cooling tower, where it is released.
Water-Cooler Chiller vs Air-Cooled Chiller
The primary difference between water-cooled and air-cooled chillers lies in their heat rejection method.
Air-cooled chillers use fans to blow heat into the air. This makes them simpler to install but less efficient when demand is high.
Water-cooled chillers use a cooling tower for heat dissipation, which offers greater efficiency, especially in large buildings, industrial plants and data centres. Although they require additional infrastructure, such as cooling towers and water treatment systems, they offer better long-term performance and energy savings in the right conditions.
By understanding the working principle of water-cooled chillers, businesses can make informed decisions about their cooling requirements, balancing efficiency and capacity with operational needs.
How a Water-Cooled Chiller Works
Water-cooled chillers work in a cycle that removes heat from a building or system. This keeps things cool and efficient. By understanding how each component functions and interacts within the system, businesses can optimise performance, improve efficiency and reduce operational costs.
Key Components and Their Functions
Evaporator - absorbs heat and cools water
The evaporator is the starting point of the cooling cycle. Warm water from the building or process enters the evaporator, where it transfers heat to the refrigerant.
As the refrigerant absorbs heat, it evaporates from a liquid into a gas. This cools the water, which is then recirculated to maintain desired temperatures.
Compressor - increases refrigerant pressure and temperature
The compressor is responsible for pressurising the refrigerant gas, increasing its temperature and preparing it for heat rejection in the condenser.
This is an important step as the pressure difference drives the refrigerant through the system. Common compressor types include centrifugal, screw and reciprocating compressors, each suited to different capacity requirements.
Condenser - transfers heat to the cooling water
The high-pressure, high-temperature refrigerant gas moves into the condenser, where it releases heat to the cooling water circulating from the cooling tower.
As the refrigerant loses heat, it condenses back into a liquid, ready to be cycled again.
Expansion valve - regulates refrigerant flow
The expansion valve plays an important role in reducing the pressure and temperature of the liquid refrigerant before it re-enters the evaporator.
By precisely controlling the refrigerant flow, the expansion valve ensures efficiency and prevents operational issues like flooding or freezing.
Cooling tower - removes excess heat from the system
The cooling tower is an external unit that helps release the heat absorbed from the condenser water.
It expels heat into the atmosphere, typically using evaporation and air movement. Then, it sends the cooled water back to the condenser to start the process again.
Water-Cooled Chiller How it Works: A Detailed Breakdown
1. Flow of refrigerant and water through the system
- The cycle begins with warm water from the facility entering the evaporator, where the refrigerant absorbs heat and cools the water.
- The refrigerant, now a gas, is compressed to increase its pressure and temperature.
- The high-temperature gas enters the condenser, where it releases heat into the cooling water that flows to the cooling tower.
- The refrigerant condenses into a liquid, passes through the expansion valve, and enters the evaporator again to restart the cycle.
2. Interaction between different components
- The chiller’s efficiency depends on coordination between the evaporator, compressor, condenser, and cooling tower.
- Properly maintained refrigerant levels, clean heat exchanger surfaces and optimal compressor performance ensure effective heat transfer and cooling capacity.
3. Efficiency considerations and common operational challenges
- Regular maintenance, water treatment to prevent scaling, and optimising part-load operation can improve efficiency.
- Poor water quality can lead to fouling in heat exchangers, inefficient cooling towers can reduce heat rejection efficiency, and improper refrigerant levels can impact performance.
- Routine system checks, using variable-speed devices (VSDs) on compressors and pumps, and selecting the right chiller size for the load can solve these issues.
Importance of Understanding the System Layout
A well-planned chiller system layout ensures:
- Optimised performance: proper component placement improves cooling efficiency
- Simplified maintenance: clear access to key parts allows for easier servicing
- Energy savings: correct system design reduces operational costs
By understanding the system layout, businesses can ensure smooth installation, effective troubleshooting and optimal system efficiency.
Water-Cooled Chiller Cooling Capacity
Cooling capacity is an important factor when selecting a water-cooled chiller, as it determines the system’s ability to maintain optimal temperatures for industrial, commercial and HVAC applications. Understanding how cooling capacity is calculated, what it influences, and the typical capacity ranges available helps businesses choose the right system for their needs.
What is Cooling Capacity, and Why is it Important?
Cooling capacity refers to the amount of heat a chiller can remove from a system over a given period. It is typically measured in kilowatts (kW), British Thermal Units per hour (BTU/h) or tons of refrigeration (TR).
Selecting the appropriate cooling capacity ensures efficiency, prevents underperformance, and reduces unnecessary energy consumption.
Industries such as manufacturing, data centres and commercial buildings require different capacity levels to maintain operational stability.
What Affects Cooling Capacity?
- Load requirements: the total heat generated by equipment, lighting and occupancy
- Ambient conditions: temperature, humidity and climate variations influence chiller performance
- Water flow rate: the volume of water passing through the chiller affects heat absorption
What Affects Cooling Capacity?
Typical tonnage and power output:
- Small systems: 10-100 kW (3-30 TR)
Suitable for small commercial buildings and HVAC applications.
- Medium systems: 100-1000 kW (30-300 TR)
Used in hospitals, shopping centres and manufacturing plants.
- Large industrial systems: 1000+ kW (300+ TR)
Found in data centres, heavy manufacturing and large district cooling plants.
Application-based capacity selection:
- HVAC cooling for buildings: medium to large chillers with high efficiency
- Industrial processes: requires precise temperature control with scalable chiller configurations
- Data centres: high-capacity chillers with redundancy to ensure uptime
Selecting the correct cooling capacity is essential for energy efficiency, cost-effectiveness and operational reliability. By calculating and evaluating the required capacity, businesses can ensure optimal performance for their cooling needs.
Conclusion
Water-cooled chillers play a key role in industrial, commercial and HVAC cooling, offering reliable and energy-efficient temperature control. By using water and a cooling tower for heat rejection, they deliver greater efficiency and performance compared to air-cooled systems, particularly in large-scale applications.
At Aggreko, we specialise in providing high-performance, flexible cooling solutions for unique industry needs. Whether you require temporary cooling for peak demand periods or a long-term, scalable chiller system, our expertise ensures your operations run smoothly and efficiently. We help businesses make informed decisions, ensuring they invest in the right solution to meet their cooling challenges today and in the future.