During the operation of a screw air compressor, air is continuously compressed, which generates a large amount of heat. If this heat is not removed effectively, it can affect the normal operation of the compressor. Therefore, the cooling system is an essential part of a screw air compressor.
Simply put, the main purpose of the cooling system is to control the heat generated during compressor operation and keep the equipment within a suitable operating temperature range. The design of the cooling system can vary depending on the compressor type and application requirements.
Today, screw air compressors on the market can mainly be divided into oil-lubricated screw air compressors and oil-free screw air compressors. These two types have different compression methods and cooling requirements, so their cooling system designs are also different.
For oil-lubricated screw air compressors, the lubricating oil not only provides lubrication and sealing, but also helps remove the heat generated during compression. Therefore, these compressors normally require cooling for both the lubricating oil and compressed air.
Oil-free screw air compressors use different technologies, with dry-type oil-free and water-injected oil-free being two common types.
Dry-type oil-free: These compressors generally use multi-stage compression, with intercooling and aftercooling to control the temperature rise during compression.
Water-injected oil-free: Treated water is injected into the compression chamber during the compression process. The water provides sealing and absorbs heat, helping reduce the temperature rise during compression. An external cooling system is then used to control the temperature of the circulating water.
In practical applications, oil-lubricated and oil-free screw air compressors have different areas of application. In general manufacturing, machining, automotive parts, metal processing, textile, packaging, and similar industries, compressed air is mainly used for pneumatic tools, automated equipment, production lines, and general process applications. For these applications, oil-lubricated screw air compressors can normally meet the required air supply needs and offer good suitability in terms of equipment configuration and operating cost.
In food and beverage, pharmaceutical, electronics manufacturing, medical, and some high-precision production processes, compressed air may come into direct or indirect contact with products, or the process may be more sensitive to oil contamination in the air. These applications usually place greater importance on compressed air quality, making oil-free screw air compressors a possible choice. In applications where oil contamination cannot be accepted, oil-free technology can reduce the risk of oil entering the compressed air system at the compressor source.
Of course, the industry alone does not determine which type of compressor should be used. Different production processes within the same industry can have different compressed air requirements. For example, general packaging equipment and production processes that have direct contact with products in a food factory may have different air quality requirements. Different production processes in an electronics factory may also have different requirements for air quality, pressure stability, and continuous operation. Therefore, the final selection should always consider the specific points of use and production conditions.
In addition to the difference between oil-lubricated and oil-free compressors, air cooling and water cooling are also two common cooling methods on the market. Air-cooled systems mainly use fans and ambient air to remove heat, making them relatively simple to install and operate. Water-cooled systems use cooling water to remove heat and can offer advantages in applications with specific requirements for temperature control, installation space, or continuous operation.
From the cooling system perspective, these two compressor technologies also have different requirements. Oil-lubricated screw air compressors need to effectively manage the heat generated in the lubricating oil and compressed air, while oil-free screw air compressors need to control the temperature rise during compression according to their specific oil-free technology. Therefore, the cooling system is not only related to heat removal, but is also closely connected to the compressor technology and its final application.
For this reason, the Cooling System should not be treated simply as an auxiliary component when selecting a compressor. The compressor type, operating pressure, air demand, ambient temperature, installation space, operating hours, and site conditions can all affect the cooling system selection.
At Dawos, we configure compressor solutions based on the customer’s actual pressure requirements, air demand, environmental conditions, and operating requirements. We consider the Air End, Cooling System, Oil-Air Separation System, and control system as a complete solution and select a suitable compressor configuration for each application.
A suitable cooling system is not simply about reducing temperature. It is about keeping the screw air compressor stable and reliable under its actual operating conditions.
In the following articles, we will take a closer look at the cooling systems used in oil-lubricated screw air compressors and oil-free screw air compressors, and explore the different cooling technologies and application characteristics of each.
