How the speed impact the performance of air cooler?
Air cooler is a heat exchanger that uses air to cool hot fluids
The hot fluid in the tube exchanges heat with the outside air through the tube wall and fins. The air used is usually supplied by the fan.
Air cooler can be used for cooling or condensing
Widely used in: condensation of vapors at the top of oil refining and petrochemical industries; cooling of reflux oil and bottom oil;Cooling of various reaction products; cooling of the circulating gas and condensation of the exhaust gas of the power station turbine.
The windward surface of the air cooler refers to the windward side of the tube bundle. The area of the windward surface is the area within the inner wall of the tube bundle outer frame, which is approximately equal to the length and width of the tube bundle. The speed of the air passing through the windward surface is simply referred to as the wind speed.
When the airflow velocity of the air cooler on the windward side is too low, it affects the heat transfer rate, especially the wet air cooler.
If the wind speed is too low, water cannot be sucked into the surface of the tubes inside. Most of the tubes become dry air coolers, which greatly reduce the cooling effect. The wind speed is too large, which affects the air pressure drop and affects the power consumption.
Therefore, a certain range must be specified for the speed on the windward side, with a maximum of 3.4 m/s and a minimum of not less than 1.4 m/s.
The type and material of the tube bundle also have a great influence on the performance of the air cooler.
Since the heat transfer coefficient on the air side is very small, fins are often added outside the tube to increase the heat transfer area and fluid turbulence to reduce the thermal resistance. Most air coolers use radial fins
In the air cooler, a steel tube with an outer diameter of 25 mm is usually used, a low fin tube with a fin height of 12.5 mm, and a high fin tube with a fin height of 16 mm.
The fins are generally made of a material with high thermal conductivity (most commonly aluminum), wound or embedded in the light tube.
In order to enhance the heat transfer effect of the air cooler, water can be sprayed and humidified in the inlet air. This not only reduces the air temperature, but also increases the heat transfer coefficient
The use of air coolers can save a lot of industrial water, reduce environmental pollution, and reduce infrastructure costs. Especially in water-scarce regions, replacing air cooling with air-cooling can ease the contradiction of insufficient water resources.