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  • Water-cooled Systems in Industrial Air Compressors

    | Deniz Arda Soylu

    Water-cooled Systems in Industrial Air Compressors

    As much as 90% of the mechanical energy consumed during the compression process in industrial air compressors is transformed into heat energy, and this provides an increase in the temperature of the pressurized air. Depending on the temperature and humidity of the ambient air that enters the system during pressurization, a specific amount of water mass becomes part of the system. To prevent condensation and protect customer equipment when supplying the compressed air produced by the compressor, it's crucial to cool the compressed air and drain the resulting condensate before the supply process. The high mass air flow rate provided per unit of energy consumed in industrial air compressors expresses high energy efficiency. The cooling system directly impacts the energy efficiency of the compressor. For this reason, cooling systems have been developed in different methods in particular for compressor operating conditions today. Water-cooled systems are considered a suitable alternative when it is aimed to perform the cooling function required for the compressor as well as to gain the heat energy generated.

    Water-cooled compressors used in industrial air compressors can be examined under 3 titles in the application;

    Open systems that do not require water circulation

    Open systems that require water circulation

    Closed systems that require water circulation

    Open Systems that Do Not Require Water Circulation

    In open systems that do not require water circulation, cooling is provided by an external water supply connection. Local mains water, lakes, and any fresh or salty water source can be used as cooling water for this system. The cooling water used during cooling leaves the system as wastewater at the compressor outlet. To control the air temperature provided, thermostats and similar equipment are employed in these systems. Open systems have the advantage of being low cost of installation. The purity of spring water used as cooling water in open systems is a critical concern to be considered. When assessing the purity of the spring water, choosing filtration elements and materials that are suitable for the operating conditions prevents blockages that can impede cooling efficiency and the passage of substances that may harm the cooling line equipment. Along with filter selection, it's essential that the filter is easily serviceable, enabling periodic changes and cleaning.

    Open Systems that Require Water Circulation

    In open systems that require water circulation for water-cooled compressors, the cooling water serves to cool the compressed air within the compressor through recirculation within the system. The cooling water absorbs heat in this process and must release heat to be reused as cooling water within the system. In this system, the cooling water, which absorbs heat during the cooling process, is directed to an external water tower circuit via a pump and is reduced to approximately 2°C below the ambient temperature and redirected to the system as cooling water. As the water volume decreases due to evaporation and heat dissipation in the water tower over time, the system is fed from an external water source. One drawback of this system is the potential contamination of the cooling water over time depending on the quality of the ambient air. In cold weather conditions when the compressor is not operating, draining the water from the water tower becomes a crucial consideration to prevent the cooling water from freezing.

    Closed Systems that Require Water Circulation

    Closed systems that require water circulation incorporate external heat exchanger equipment to cool down the heated cooling water during its return to the system following the cooling process. In applications, the heat exchangers employed are typically either air-cooled or water-cooled. After pressurization, the coolant that receives the increased compressed air during cooling is cooled to 5°C above the coolant in an external heat exchanger equipment before being redirected to the system for circulation. In the application of cooling cooling water using an external liquid-cooled heat exchanger, plate-type heat exchangers are a common choice. Given the characteristics of the coolant used in this application, materials with high corrosion resistance should be selected. In situations where access to external water is restricted, cooling is achieved through forced heat transfer by means of a fan. In scenarios where cooling water is chilled by ambient air, glycol is introduced into the cooling water to prevent freezing during cold weather conditions. In this application, when sizing the heat exchanger, the thermophysical properties that change with the added glycol are taken into consideration. Closed systems demanding water circulation offer benefits such as extended service intervals and reduced maintenance expenses.

    Within the DALGAKIRAN Kompresör product range, you can find choices for water-cooled system alternatives. When the essential equipment is provided for water-cooled systems, specifically engineered plate, and tubular-type heat exchangers for the compressor model ensure increased energy efficiency with minimal pressure loss and reduce operational costs.