Refrigeration 101: Understanding Process Chillers and Their Role in Industrial Settings
Industrial refrigeration provides the chilling force of process chillers and is essential to the smooth operation of some of the most important industries in the world.
The business of industrial refrigeration covers a gamut of processes from high temperature process chilling to low temperature freezers. Industrial refrigeration is a large business sector: Its importance and impact within industries such as food processing and construction cannot be underestimated.
Chillers are important for ensuring the right temperatures for the specific apparatus or tool in question. In fact, if the cooling process is not performed correctly, the entire refrigeration process is jeopardized. This can affect other important plant processes. By contrast, when everything is sufficiently cooled, everything runs optimally.
Did you know chiller systems are a major consumer of electrical usage in most industrial facilities? According to the U.S. Department of Energy, they use about 20 percent of the total electric power created in North America.
Due to the technical and complex nature, industrial refrigeration processes can present challenges to those who deal with their day-to-day functions. This specialized field deals with multiple levels of installations, parts, networks and, ultimately, costs.
Industrial Refrigeration Basics
Industrial refrigeration processes are a used in major industries from manufacturing and technology to food and chemicals. Industrial refrigeration also is an important part of any process where low temperatures must be maintained for cold storage. At the same time, process chillers play a big part in industrial cooling.
Before diving into the specifics, it is good to understand basic refrigeration processes. These include the refrigeration cycle process and how it transports heat energy from one place to another. Something else to understand are the key components of all refrigeration systems.
By its basic definition, refrigeration is the process of removing heat from a material, substance or space. With industrial processes, process chillers are used to remove heat from a specific process or material. The chillers utilize a refrigeration circuit that works using either a vapor compression or absorption system to cool or dehumidify air. The general principle of refrigeration is that liquid expanding into a gas removes heat from the local substance or space. A review of a simple refrigeration cycle and its components will help explain this.
The four key components in any refrigeration system include the compressor, condenser, expansion valve and evaporator.
There are four key components in any refrigeration system:
- Expansion valve.
During the refrigeration circuit, the refrigerant runs through a compressor. The compressor is the heart of any system and is usually powered by an electric motor. This process elevates the pressure of the refrigerant.
From the compressor, the refrigerant flows through a condenser. In the condenser, it changes from vapor form to liquid form and exudes heat. For air-cooled process chillers, the vapor is at a higher temperature than the air passing across the condenser. For water-cooled process chillers, the refrigerant vapor is at a higher temperature than the water passing through the condenser.
After the refrigerant passes through the condenser, it moves through the expansion valve (also referred to as a metering device) and drops in pressure.
The last step? The refrigerant moves to the evaporator, drawing heat and causing it to vaporize. The evaporator grabs heat from the area that needs to be cooled. Then, the refrigerant moves back to the compressor, and the cycle starts over again.
This describes the basic refrigeration cycle. For industrial applications, however, the process can become more complex. This is due to a few reasons:
With industrial applications, large loads running at long periods of time require significantly more resources in order to improve performance.
- Lower temperatures may be required, which require large volumes of insulation.
- With multistage cooling systems, several compressors and evaporators may be required.
As a result, with industrial refrigeration systems, other units and equipment are used. These may include:
- Liquid Receivers. These are units located near the condensers that receive and store the refrigerant charge.
- Suction Trap. The suction trap prevents liquid refrigerant from entering the compressor. It usually is located near the evaporator and compressor.
- Low Pressure Receivers. The low pressure receiver helps separate liquid from vapor, primarily used in liquid overfeed systems.
Now that the principles behind an industrial refrigeration system are understood, consider the applications in which chillers are used.
Chillers Use in Industrial Applications
Industrial refrigeration is used in many industries, from food processing, chemical, pharmaceutical and plastics manufacturing to construction.
Within these industries, water-cooled chillers play an important part in processes that require the cooling of a large amount of water. From small, one-ton units to large, thousand-ton sizes, water-cooled chillers range widely in size and are usually installed indoors. While they are efficient and last a long time, water-cooled chillers typically are more expensive due to the maintenance required.
Industrial refrigeration processes are used in major industries such as brewing, food processing, chemical and pharmaceutical manufacturing as well as construction.
Food processing is a large market for industrial refrigeration processes. From dairies and breweries to wineries and bakeries, cooling is essential in these applications. As an example, consider the dairy industry and one of its well-loved products: cheese.
Cheese is processed in five phases. They include:
- Preparation and processing of milk (intake).
- Pasteurization process.
- Water cooling (brining) process.
- Storage of product.
Cheese requires chilled process water — not only make the cheese itself but also to extend the life of the equipment being used. Chilled water also is critical for inhibiting the growth of bacteria and lowering energy costs overall. Refrigeration is required to process the cheese during the curing phase, where it may be held between 50 and 68°F (10 and 20°C) for some period of time.
A similar multi-stage process occurs in the wine and spirits industry. For instance, during the fermentation process, heat is removed. For beer, temperatures need to be kept between 45 and 55°F (7 and 13°C) in order to sustain the fermentation process. Refrigeration also is required to cool the beer storage area. Likewise, wine must be held in refrigerated storage at about 50°F (10°C). It also requires a cold stabilization process to precipitate potassium bitartrate. (To help this process along, wine must be chilled at about 25°F [-3°C] for 10 days.)
Another major application of refrigeration occurs within manufacturing plants, where cooling processes are required for environmental testing of extreme conditions. Examples include testing high and low temperatures, or high and low humidity readings. Refrigeration also may be required during the formulation of certain materials such as plastics and metals.
Within the construction industry, cooling processes are required to harden concrete, where the substances involved such as sand, cement, gravel and water are chilled. Refrigeration also would need to be applied to freeze wet soil, so excavations can safely occur.
Those in the chemical and pharmaceutical industries must meet certain legislative requirements — specific to refrigeration systems — so they have an important need for industrial refrigeration processes. From the condensation of gases to humidity control for certain chemicals, the need for large refrigeration plants is essential.
Industrial refrigeration is an important part of any process where low temperatures must be maintained. Process chillers play a big part in industrial cooling.
In conclusion, how do you know what chiller is the right one for your particular industry or application? Here are some things to consider:
- What is the importance of precise temperature control as part of the manufacturing process?
- Is there a large fluctuation of heat load requirements?
- Is the source of the cooling separate from rough environments?
Once you have a basic understanding of industrial refrigeration and how the cooling process works, it is easy to see how its application is essential to the smooth operation of some of the most important industries in the world. PC