What Is An Aftercooler?
An aftercooler is a device designed to cool compressed gases. In the automotive context, it’s also referred to as an intercooler. These coolers come in two types: air-cooled and water-cooled. Their primary function is to reduce the temperature of compressed gas to a level suitable for its intended use, particularly important in air compressors where compressed air contains high moisture levels. The aftercooler condenses this moisture and facilitates its removal while cooling the gas.
Uses of Aftercoolers
1. For Air Compressors
Aftercoolers are attached to the discharge port of air compressors to cool the compressed air. This process also condenses water vapor from the atmosphere, which is inherent in compressed air, requiring its removal to prevent equipment damage. Additional moisture reduction can be achieved through drying filters filled with desiccants like silica gel.
Cooling is also crucial to prevent equipment damage, paint bubbling, contamination, or freezing in applications using compressed air. Aftercoolers also convert oil mist in oil-injected compressors into a liquid form for removal. Some compressors integrate aftercoolers for a more compact design.
2. For Gas Compressors
For gases like nitrogen, oxygen, carbon dioxide, hydrogen, and methane, which reach high temperatures when compressed, aftercoolers ensure they are cooled to appropriate temperatures. Compressors dedicated to specific gases often have built-in aftercoolers.
Principle of Aftercoolers
1. Temperature Rise of Compressed Gas
Compression increases the velocity and reduces the distance between gas molecules, generating heat. The extent of this temperature rise is determined by the specific heat ratio, varying with the gas type. For example, ideal gases like helium, hydrogen, nitrogen, oxygen, air, and carbon dioxide have specific ratios influencing their temperature increase upon compression.
2. Cooling by Aftercooler
Air-cooled aftercoolers use air to cool the compressed gas, typically reducing the gas temperature by about 10 degrees Celsius compared to ambient air. Water-cooled aftercoolers, on the other hand, use water for cooling and are ideal when industrial water supplies or cooling facilities like towers are available. In automotive applications, water-cooled intercoolers use radiators to cool the water with air.
Other Information on Aftercoolers
Advantages of Aftercoolers
Cooling of Compressed Gas: Essential for applications sensitive to heat, such as in processing animal feed, baking mixes, or plastic granules. Removal of Moisture and Oil: Effective in protecting equipment from damage caused by moisture and oil in compressed air. Utilization of Input Energy: The energy used in cooling processes like heat exchangers and blowers significantly enhances the overall utility of the compressed gas.