What Is a Chiller?

A chiller is a vital piece of industrial equipment used in refrigeration and air conditioning, serving various applications across workshops, industries, commercial spaces, and residences. Its primary function is to cool water to temperatures ranging from +1 to +7 degrees Celsius in a single cycle. Chillers are employed for cooling equipment, processes, and spaces, with their capacity and type selected based on the volume of cold water required.

In essence, a chiller is an industrial device that generates cold water and transfers it to equipment such as air conditioners, fan coils, and cold water heat exchangers. It receives water at a certain temperature and cools it using refrigerants like Freon or ammonia to the desired level, ensuring it remains above freezing point. For applications requiring sub-zero temperatures, ethylene glycol is used instead of water, as it has a freezing point of about -12 degrees Celsius.

A chiller is a device that regulates temperature by circulating a flowing liquid, typically water. The temperature of this liquid is controlled through the refrigeration cycle.

 Main Components of a Chiller

The chiller comprises several essential components, each serving a specific function crucial to the cooling process. Understanding these components is vital for grasping the chiller’s operation. Here are the main components:

1. Compressor: The compressor is the heart of the chiller. It compresses the refrigerant, transforming it into a high-temperature, high-pressure gas. Compressors come in various types, such as screw or piston, which significantly influence the chiller’s efficiency and cost.
2. Condenser: Responsible for condensing the refrigerant from a gas to a liquid, the condenser also cools it down (subcooling). Condensers can be water-cooled or air-cooled, with different types affecting the overall chiller classification.
3. Expansion Valve: This modular valve rapidly decreases the pressure of the liquefied refrigerant from the condenser to the evaporator, transforming it back into a gas. This process cools the water or fluid within the evaporator. Expansion valves come in electronic and thermostatic types, with electronic valves offering higher accuracy at a higher price point.
4. Evaporator: The evaporator facilitates the transfer of heat from water to refrigerant. As the refrigerant evaporates within the evaporator, it absorbs heat from the water, thus reducing its temperature. Evaporators come in plate and shell and tube types, with plate types typically offering higher efficiency.

 How Does a Chiller Work?

Chillers operate by utilizing the refrigeration cycle to cool the water required by various equipment. In essence, the chiller functions by using a refrigerant to transfer heat from water or ethylene glycol to the surrounding environment. The process begins as the low-pressure refrigerant gas enters the compressor, where its pressure and temperature are significantly increased. Subsequently, the refrigerant travels to the condenser, where it releases heat at constant pressure and undergoes a phase change from gas to liquid. Next, the liquid refrigerant enters the evaporator through the expansion valve. 

the refrigerant drops during evaporation, it absorbs heat from the water, effectively cooling it. Finally, the refrigerant, now carrying the absorbed heat, returns to the compressor to begin the refrigeration cycle anew. Through this process, the water is thoroughly cooled, typically reaching temperatures as low as +4 degrees Celsius, before being circulated for use, while the heated refrigerant continues its cycle within the chiller.

 Chiller Technical Specifications

The technical specifications of chillers vary depending on factors such as type, application, and model. However, when selecting a chiller, it’s essential to consider certain key specifications to ensure it meets your requirements effectively. Here are some important technical specifications to consider:

1. Cooling Capacity: This indicates the chiller’s ability to remove heat from the fluid and is typically measured in kilowatts, BTU/hr, or tons of refrigeration.
2. Cooling Method: Determine whether the chiller is designed for cool water or air-cooled operation based on your specific needs.
3. Minimum Water Temperature: Consider the lowest temperature the chiller can achieve to ensure it meets your cooling requirements.
4. Electrical Panel Type: Evaluate the automation capabilities of the chiller’s electrical panel to meet operational needs.

5. Expansion Valve Type: Choose between thermostatic or electronic expansion valves based on performance and control requirements.
6. Dimensions and Installation: Assess the size of the chiller and whether it’s suitable for indoor or outdoor installation based on available space and environmental conditions.
7. Quality of Components: Consider the brand and quality of parts used in the chiller to ensure reliability and longevity.
8. Compressor Type: Evaluate the compressor type (scroll, piston, or screw) and brand to ensure compatibility with your application and performance requirements.
9. Manufacturing Standards: Verify that the chiller complies with relevant manufacturing standards to ensure safety and quality.
10. Price and Terms: Consider the overall cost of the chiller, including warranty, terms of sale, and after-sales service, to make an informed decision.

Ultimately, the technical specifications of the chiller should align with your specific needs and operational constraints. For instance, if your application requires fluid temperatures below +1 degree Celsius, ethylene glycol may be necessary instead of water. Additionally, if water availability is limited, an air-cooled chiller may be preferable.

 Chiller Usage Types

Chillers serve various purposes across different sectors within the air conditioning industry. Broadly speaking, chiller usage types can be categorized into the following two categories:

Air Conditioning Systems: Chillers are extensively used in air conditioning systems for commercial, industrial, and residential purposes. They play a crucial role in regulating indoor temperature by cooling water or another intermediate fluid, which is then circulated through the building to remove heat and maintain comfortable conditions.

Industrial Applications: Chillers find widespread use in industrial settings for various cooling applications. They are employed in manufacturing processes, food and beverage production, pharmaceuticals, plastics processing, and more. In industrial applications, chillers are utilized to cool equipment, machinery, or products to specific temperatures required for production processes.

Overall, regardless of their specific structures, all chillers share the common task of reducing and controlling the temperature of water or another intermediate fluid, such as ethylene glycol. They provide efficient cooling solutions wherever cold water or chilled fluid is needed, catering to diverse requirements across different sectors and applications.

Utilizing Chillers in Air Conditioning Systems

In air conditioning systems, chillers play a pivotal role in regulating temperatures. They facilitate the cooling process by circulating water or a cooling fluid like ethylene glycol through heat exchangers such as fan coils or air conditioners. This cooled liquid then absorbs heat from the air in the designated space, effectively reducing its temperature. Subsequently, the now-warmed liquid returns to the chiller to undergo the cooling process anew. Chillers designed for air conditioning applications typically offer a cooling capacity ranging from approximately 50 kW to 21 MW, with notable examples produced by companies like YORK.

 Utilizing Chillers Across Industrial Applications

In industrial settings, chillers find widespread application across various sectors and processes. They are integral for cooling equipment, machinery, and even laboratory setups. Industries benefiting from chiller usage encompass a wide spectrum, including casting, food processing, pharmaceuticals, plastics and molding, paper manufacturing, cement production, vacuum systems, X-ray apparatus, semiconductor fabrication, and power generation turbines.

Industrial chillers may be configured centrally, serving multiple cooling requirements simultaneously. Alternatively, they can be employed individually for distinct cooling needs. Each approach offers its unique set of advantages and drawbacks, depending on factors such as operational requirements, scalability, and resource allocation.

Types of chillers, comparison of types of chillers

There are different categories for chillers, but in general, chillers can be divided into two general categories: compression chillers and absorption chillers. Each of these two categories will be divided into different subcategories. Of course, some people consider another category called mini chiller for all kinds of chillers. But this classification is not correct; Because mini chillers are low capacity chillers that are used for light residential applications and are usually compression type.

A piston or compression chiller uses a compressor and refrigerant compression to cool air conditioning devices. But in absorption chillers, there is no compressor and the water in these chillers is cooled using a generator. In this section, we introduce the types of absorption chillers and compression chillers and compare them.

 Types of Chillers

 Compressor Type

Scroll Chiller: Utilizes scroll compressors, ideal for residential or small industrial settings due to their compact size and lower capacity.

Air-Cooled Scroll Chiller

An air-cooled scroll chiller rejects heat directly to ambient air through fin-tube or microchannel coils, so it doesn’t need a cooling tower, make-up water, or water treatment. That makes it a practical choice for residential buildings, small shops, and compact sites without water infrastructure. It has a small footprint and low sound, and in inverter or multi-compressor configurations it can modulate capacity to follow the load.

Select the unit for the site’s summer design temperature and provide clearances that prevent hot-air recirculation. To keep performance stable, keep condenser coils clean, and routinely verify chilled-water flow and the intended temperature difference across the evaporator so capacity doesn’t fall off in hot weather and leaving-water temperature stays steady.

Water-Cooled Scroll Chiller

A water-cooled scroll chiller pairs a hermetic scroll compressor with a shell-and-tube condenser, rejecting heat through a cooling tower. Its key difference from screw and piston units is capacity control: there is no slide valve and no cylinder unloading; capacity is adjusted either continuously with an inverter on a single compressor or stepwise by staging multiple compressors. Typical applications are small to mid-range plants where a compact footprint and low sound are valued. Service is usually module replacement rather than a full overhaul, which shortens downtime.

For stable operation, design to the site’s tower temperature, maintain correct condenser-water flow and keep heat exchangers clean to avoid elevated condensing pressure. Verify chilled-water flow and design delta-T in the hydronic circuit. All compressor types are sensitive to liquid return, so proper superheat and circuit design are required to keep the evaporator stable and the leaving-water temperature steady.

Screw Chiller: Features high efficiency and capacity ranging from 60 to 500 tons of refrigeration, suitable for high-end industrial and residential applications with variable capacity control.

Water-Cooled Screw Chiller

The water-cooled screw chiller uses a screw compressor and a shell-and-tube condenser to reject heat via a cooling tower. The result is high efficiency, very low chilled-water temperature fluctuation, and low operating sound. It’s a stable, cost-effective choice for medium to very high capacities in production lines, hospitals, data centers, and office–commercial complexes.

Capacity control is available so the unit can match the project’s cooling load. For lasting performance, ensure proper cooling-tower water quality and descaling practices, adequate plant-room space, and correct chilled-water flow and ΔT are considered in design and execution.

Air-Cooled Screw Chiller

An air-cooled screw chiller uses a screw compressor and a fin-tube or microchannel condenser to reject heat directly to ambient air. It eliminates the need for a cooling tower, make-up water, and water treatment, removing water-related risks such as scaling, corrosion, and Legionella. Performance depends on outdoor dry-bulb temperature, so selection must be based on the site’s summer design point (commonly 35–46 °C). As ambient temperature rises, condensing pressure increases and both instantaneous capacity and efficiency fall. Proper placement in open areas such as rooftops or service yards, adequate clearances to prevent hot-air recirculation, and compliance with site noise limits are essential. Capacity control is available to match the cooling load. To maintain stable operation, keep condenser coils clean and regularly verify chilled-water flow and design ΔT in the hydronic circuit.

Piston or Reciprocating Chiller: Utilizes piston compressors with capacities ranging from 5 to 40 tons of refrigeration, suitable for achieving desired capacity by using multiple compressors.

Water-Cooled Piston Chiller

A water-cooled piston chiller uses a reciprocating compressor and a shell and tube condenser to reject heat through a cooling tower, which means it requires make-up water and regular water treatment. Capacity control is weaker than a screw chiller because it is stepped via cylinder unloading, so part-load operation can show greater temperature swing and lower efficiency. Typical available capacities are lower than screw machines, and mechanical vibration and noise should be managed with proper anchoring and isolation.

Its strengths are straightforward service and lower maintenance cost, with spare parts commonly available. For reliable operation, size to the site’s tower design temperature, maintain correct condenser water flow and water quality to prevent scaling and high condensing pressure, and verify chilled-water flow and design delta-T in the hydronic circuit.

Air-Cooled Piston Chiller

An air-cooled piston chiller uses a reciprocating compressor and a fin-tube or microchannel condenser to reject heat directly to ambient air, eliminating the cooling tower. Capacity control is stepped via cylinder unloading, so at part load you can expect larger chilled-water temperature swing and more frequent cycling than with a screw unit. Because reciprocating compressors run with higher discharge temperatures, ensure adequate subcooling, a properly sized liquid receiver, and a crankcase heater to prevent refrigerant migration. Vibration is pulsating and must be managed with proper mounting and isolation. Available capacities are typically lower than screw machines. Selection should be based on the site’s summer design temperature, with clearances that prevent hot-air recirculation.

This chiller is a good fit when simple service and easy parts availability are priorities. Reliable operation depends on keeping condenser coils clean, regularly verifying chilled-water flow and design delta-T, monitoring superheat and oil condition, and checking condenser fan operation and staging. For small to mid-size projects without water infrastructure, an air-cooled piston chiller can be a practical, cost-effective choice in terms of upfront and maintenance costs.

4. Centrifugal Chiller: Known for its high efficiency, low energy consumption, and long lifespan, primarily used in specialized projects due to its relatively higher cost.

 Condenser Type

1. Water-Cooled Chillers: Utilize a cooling tower to dissipate heat from the refrigerant by circulating water, offering higher efficiency but requiring water for operation.
2. Air-Cooled Chillers: Installed in open environments, utilize a coil and fin condenser to dissipate heat directly to the surrounding air, suitable for humid areas and environments with simple piping requirements.

 Refrigerant Type

Refrigerants can be from the Freon family (R-22, R-134A, R-404A) or ammonia (R717). Freon refrigerants are commonly used in mini chillers and those with smaller capacities for residential air conditioning. Ammonia refrigerants offer better thermodynamic properties, reducing both initial purchase cost and electricity consumption, making them ideal for high-capacity applications.

 Types of Absorption Chillers

Absorption chillers utilize thermal energy (hot water or steam) to produce cold and are categorized based on performance and energy consumption:

1. Performance-based Classification: Includes single-effect and double-effect chillers.
2. Energy Consumption-based Classification: Includes direct flame and indirect flame chillers, with direct flame chillers operating directly with the flame for cooling.

Absorption chillers have fewer moving parts compared to compression chillers, resulting in lower maintenance and repair requirements. They are virtually vibration-free and produce less noise. However, they require a constant supply of hot water or steam from a boiler for operation.

 Comparison of Absorption Chiller and Compression Chiller

When deciding between absorption and compression chillers, it’s essential to compare their features and suitability for specific applications. Here’s a comparison between the two types:

Coefficient of Performance (COP): Compression chillers typically have a COP ranging from 3.5 to 6, depending on the compressor type. In contrast, absorption chillers have a COP of around 1.4 in similar conditions, indicating lower efficiency.

Weight and Dimensions: Absorption chillers are larger and heavier compared to compression chillers of the same capacity, occupying more space.

Chiller Price: Absorption chillers are generally more expensive than compression chillers due to their larger size and specialized requirements.

Energy Consumption: Absorption chillers tend to consume more energy and water compared to compression chillers.

Noise Production: Absorption chillers produce less noise during operation than compression chillers.

In summary, absorption chillers may be suitable for specific applications such as hospitals where steam boilers are available and noise reduction is critical. However, due to their lower efficiency, higher cost, and larger dimensions, compression chillers are often the more technically and financially viable option for around 90% of applications.

Chiller Price Factors and Considerations

Determining the price of a chiller involves several factors, and each model may vary in cost. Here are some considerations to keep in mind when estimating the price of a chiller:

1. Type of Chiller: Whether it’s a condensation or absorption chiller will significantly impact the price.
2. Chiller Capacity: The cooling capacity of the chiller, measured in tons or kilowatts, plays a key role in determining its price.
3. Type of Compressor: Different types of compressors, such as scroll, screw, or piston, can affect the cost of the chiller.
4. Condenser Type: The type of condenser, whether air-cooled or water-cooled, will influence the price.
5. Quality of Parts: The quality and brand of components used in the chiller can affect its price and overall performance.
6. Manufacturer Brand: Well-known brands may command higher prices due to their reputation and reliability.
7. Energy Consumption: Chiller models with higher energy efficiency ratings may come at a premium price but can offer long-term savings on operating costs.
8. Device Efficiency: The overall efficiency and performance of the chiller can impact its price.
9. Dimensions and Weight: Larger and heavier chillers may be more expensive due to their size and installation requirements.

Considering these factors before making a purchase is crucial. Consulting with experts in the field can help you choose the best chiller model that meets your specific needs and budget. Feel free to contact us for a free consultation to explore your options further.