YUHONG GROUP - Air cooler classification and characteristics

An air cooler is a heat exchanger that uses air to cool a hot fluid. The hot fluid inside the tube exchanges heat with the air outside the tube through the tube wall and fins, and the air used is usually supplied by a ventilator.
Air cooler can be divided into power plant air cooler and petrochemical air cooler according to the different occasions of use.
According to the cooling method, can be divided into dry, wet, and dry - wet combined air cooler.
Ventilation of air coolers can be carried out in two ways: by blowing air and by inducing air.

1. Wet air cooler
Wet air cooler according to the water spray method, can be divided into surface evaporation type, humidification type and spray type 3 kinds, in the petrochemical industry after the two main. Surface evaporation type air cooler is a use of water film evaporation outside the tube to strengthen the heat transfer, composed of light tube air-cooling device. Humidification type wet air cooler is only suitable for relative humidity less than 50% of the dry, hot areas, because the relative humidity of the dry air is smaller, the more humidification after cooling, the more significant cooling effect. Spray-type wet air cooler is directly on the finned tube bundle spray water, the use of water evaporation of latent heat exchange and air is humidified cooling to enhance heat transfer, at the same time, the presence of water spray can make the air cooler inlet air temperature close to the ambient wet bulb temperature, improve the average temperature difference in heat transfer, in 3% of the spray volume of heat transfer coefficient can be compared to the dry air cooler to improve the heat transfer factor of 2 ~ 4 times.
 

2. Dry air cooler

Dry air cooler relies only on the air temperature rise of sensible heat to exchange heat, relying on the finned tube and fan forced circulation to strengthen heat transfer. Simple operation, easy to use, but because of its cooling temperature depends on the dry bulb temperature of the air, so generally can only be cooled to the hot fluid inside the tube to higher than the ambient temperature of 15 ~ 20 ℃.

3. Dry-wet combined air cooler

Dry - wet combined air cooler, that is, dry air cooler and wet air cooler combination integration. Combination of the general principle is that the process fluid in the high-temperature zone with dry air cooler, the role of gas condensation; in the low-temperature zone using wet air cooler, the role of condensate cooling. In short, the choice of which form of air cooler, according to the local atmospheric temperature, wind speed and relative humidity and other environmental and climatic conditions, combined with the final cooling temperature of the medium and other heat transfer process requirements, and taking into account the economy, for a comprehensive consideration to determine.

Air cooler ventilation method

1. Blowing type: air flows through the ventilator first and then flows into the tube bundle.
2. induced air type: the air first flow through the tube bundle after flowing into the ventilator. The former operating costs are more economical, the turbulence generated by the heat transfer is favourable, more often used.

The latter air distribution is uniform, in favour of precise temperature control, noise, is the direction of development. Thermal fluid outlet temperature is mainly controlled by adjusting the airflow through the tube bundle, i.e., adjusting the inclination angle of the blades, the speed of the ventilator and the degree of opening of the louvre, etc.. For the winter easy to condense, easy to freeze the fluid, can use hot air circulation or steam heating methods to regulate the fluid outlet temperature.