Types of Chillers – Exploring Chiller Technologies & Working Principle

The kind of chiller to use is one of the most important decisions you will make when designing or upgrading a process cooling system.

Remember, the efficiency of a chiller has a direct impact on your energy costs, stability in your processes and the quality of your products.

In case you are wondering which type of chiller systems to install in your factory – we will classify the different options available by cooling method, compressor type, capacity, application and temperature range.

What Is A Chiller?

A chiller is an industrial or commercial cooling system that cools liquid, with mostly water or glycol, by incorporating a refrigeration cycle. Such chilled liquid is then pumped out overheat exchangers or other equipment cooling systems.

Although chiller systems feature unique designs, their main aim is to remove undesired heat and maintain optimal temperatures for various processes.

We can essentially categorize chillers based on their principle of vapor-compression principle and refrigeration cycle.

But more importantly, it is worth noting that these chillers have these key elements:

• Evaporator: responsible for ensuring the refrigerant takes away heat from the process fluid.
• Compressor: the device that pushes and pumps the refrigerant inside the chiller system.
• Condenser: responsible for releasing the absorbed heat via air or water.
• Expansion valve: greatly reduces the pressure of the refrigerant just before it is redirected back into the evaporator.

As you can see, this is simply a giant-scale refrigerator you can use to cool your industrial processes or HVAC systems. Their main purpose is to maintain efficient operation temperatures and safeguard equipment.

Types of Chillers

We can categorize chillers in several ways depending on their cooling method, the compressor used, and their temperature range. We also consider their capacity or application specialization.

Let us go through each category, detailing its working principles and all they entail:

· By Cooling Method

Air-cooled Chillers

The cooling mechanism for air cooled chiller combines both condenser coils and fans to cool the air to ambient temperatures. Heat contained in the process liquid is absorbed by the refrigerant, which then dissipates it into the air contained in the condenser.

Advantages

• You can easily install it with the option of a cooling tower and water supply eliminated
• It will cost you less to maintain it as compared to water-cooled systems
• Works well if you are operating a small facility or require an outdoor installation.

Disadvantages

• They have a fairly poor performance when you subject them to extremely hot environments.
• There may be unpleasant noise generated by the fans
• They generate a high load per square foot when we compare them to other chillers having the same capacity.

Applications

They are the preferred chiller for medium-sized commercial places such as data centers and small manufacturing plants. They also work well if your location has problems with accessing water or has poor-quality water.

Water Cooled Chillers

Just as the name suggests, they use water as the cooling fluid. The water achieves this inside a condenser by absorbing the heat, then releasing it in a cooling tower.

Advantages

• You will incur less wastage, especially if you are using a large-capacity chiller
• Your chiller achieves an extended lifespan due to constant operations
• Its quiet and seamless operations make it appropriate for indoor applications

Disadvantages

• You have to install it together with a cooling tower and regular water treatment
• Its maintenance and installation are a bit costly
• You have to supply it with a regular and quality supply of water

Applications

If your cooling demands are high, such as in hospitals or large office buildings, then this is your best bet. The efficiency of this chiller is very high in such situations and can meet your demand.

Here is a side by side comparison:

· By Compressor Type

Scroll Compressor Chillers

The scroll chillers involve a combination of two spiral scrolls, which are interlocked with one of them stagnant. The other one moves to allow refrigerant compression to be realized efficiently and smoothly.

Advantages

• It has a compact design that offers a smooth operation
• Works well in light to medium load cooling
• Its compact design means it has fewer moving components, minimizing maintenance

Disadvantages

• It is unable to maintain loads above 200 tons
• It is not fit for applications having heavy industrial loads

Applications

• Due to its limited capacity, you can only apply it in HVAC and small buildings such as labs. Such buildings have moderate cooling loads that can easily be sustained.

Screw Compressor Chillers

The design of these chillers contains two helical screws rotors that serve the purpose of compressing the refrigerant. This design offers you an extremely smooth operation that is vibration-free with excellent pressure control.

Advantages

• Screw chillers are extremely efficient, especially if you are dealing with heavy loads
• It can handle variable loads very well
• Its durability makes it suitable if you are operating a continuous industrial activity

Disadvantage

• It has a very high initial cost
• Maintenance and running costs tend to be on the upper side

Application

You can use it best in facilities with large-capacity systems, such as data centers and process cooling plants.

· By Temperature Range

Standard Temperature Chillers (5°C to 30°C)

One of the most common chillers you will find in the market and commonly used in our homes and industrial processes. They apply either the R134 or R410A refrigerants to provide your room with conditions close to ambient.

Application

Commonly used in food and beverage production. You will also find it in the cooling of HVAC and also in general machinery.

Low Temperature Chillers /Glycol Chiller (0°C to -35°C)

These chillers employ either propylene glycol or ethylene glycol to ensure that no freezing takes. They are also referred to as glycol chillers. This is most common in applications that require temperatures below zero.

Advantages

• Works well in extremely low temperatures.
• Removes any form of ice accumulation in the system.

Disadvantages

• You are required to constantly monitor and control the glycol concentration
• Constantly running the pumps increases your operational costs

Application

With its freeze prevention, you can use it best in food freezing applications. However, it is also used in laser cooling systems, chemical plants, and in breweries.

· By Chiller Capacity

0.8kW to 20kW (Small Capacity Chillers)

They are usually very small, portable, and compact, meaning you can easily install them and require minimal maintenance. We mostly use them in cooling electronics and small machinery.

20kW to 200kW (Medium Capacity Chillers)

We mostly use these chillers in HVACS, hospitals, and factories with medium temperature reduction requirements. Their balance between capacity and efficiency ensures you achieve the best cooling performance.

200kW to 1750kW (Large Capacity Chillers

You will find them commonly used in commercial towers or large-scale industrial plants with extreme cooling demands. Since such applications work around the clock, they require water cooling, centrifugal, or the screw model for maximum energy efficiency.

· By Application Specialty

Industrial Water Chiller

Employed mostly in industrial settings such as those that deal with injection molding, food processing, and more. They ensure that process water temperature is maintained at a constant for stable production and to prevent the equipment from overheating.

Specialty Application Chillers

These chillers are customized to serve specific cooling requirements, such as:

• Welding/Laser/Lab/MRI Chillers: Ensure that heat build-up is eliminated in these high-precision equipment by providing a stability temperature within +/- 0.1°C
• Industrial Oil Cooling Chillers: Mostly used in machines having oil as their coolant, such as hydraulic systems or CNC machining, to maintain viscosity and oil temperature.
• Stainless Steel Chillers: Their design has a corrosion-free, full stainless steel construction recommended for both food-grade and pharmaceutical processes.
• Glycol chillers: For large-scale digital signage, an LED display cooling system using glycol chillers maintains optimal operating temperatures even in high ambient heat.

Process Specific Chillers

• Mold Temperature Chillers: Ensure temperature during molding to ensure uniform quality parts and reduce the process time.
• Cooling and Heating Chillers (Dual Function): Serve as chillers and heat pumps to ensure the process temperature is regulated at a desired level. This is very common in chemical industries, pharmaceuticals, and testing laboratories.

Comparing Vapor Compression Chillers vs Vapor Absorption Chillers

How to Choose the Right Chiller System

When settling for the right chiller for your applications, a combination of operational and technical issues comes into play. Let us dive into some of them and how they impact your choice:

Cooling Requirements

You must have a clear understanding of your process requirements and whether they require intermittent or continuous cooling. You can do this by first calculating your total heat load.

Assess Your Operating Environment

Factors such as the availability of water, surrounding humidity, and temperature should be taken into account. If your application area is hot and dry, go for an air cooling system; otherwise, settle for a water cooling system for large-scale or humid applications.

Temperature Range Requirements

If you are operating a chemical or beverage application that requires a sub-zero operating environment, your best bet is a low-temperature glycol chiller. For comfort cooling, just go for the conventional chiller systems.

Compare Service Life

When purchasing a chiller, cheaper prices do not directly translate to low operational costs. Always factor in its energy consumption, maintenance costs, and the impact of its downtime.

Installation Requirements

If you want to install an air-cooled chiller, you will require a lot of space to allow for air movement. As for the water-cooled ones, you will require space for cooling towers, pumps, and a mechanical room.

Future Expansions

Go for chiller designs that accord you an expansion capability. Additionally, install systems that you can easily expand with your plant’s growth.

Conclusion

Settling for the best chiller is both a technical and business decision since it impacts the cost, efficiency, and reliability of your operations. Chillers play an important role in maintaining stable temperatures for refrigeration applications. For temperature-controlled warehouses, cold storage racking help improve storage efficiency and protect temperature-sensitive goods. Aligning your process requirements with your long-term objectives ensures you acquire a chiller system that gives your plant peak performance.

FAQs

What are the main components of chiller systems?

Primary parts include an expansion valve, a compressor, an evaporator, and a condenser.

Which gas is used in chillers?

Some of the commonly used refrigerants include R32, R134a, R410A, and R407C.

How do you calculate chiller capacity?

Use the formula:

Chiller Capacity (kW) =  Flow rate (L/s) x Temperature difference (°C)

                                                                   1000

What is the lifespan of a chiller?

The lifespan varies according to technology and design however, it can range from 15 to 25 years.

What is the function of chillers?

They take heat out of areas or processes by re-circulating cooled fluid through heat exchangers to keep the temperature as required.