Cooling tower works - Huaqiang Electronic Network

A cooling tower is a device that utilizes the contact of water and air to dissipate waste heat generated in an industrial or refrigeration air conditioner by evaporation. The basic principles of its work are:

The dry (low enthalpy) air enters the cooling tower from the air inlet net after being twitched by the fan; the high temperature water molecules with large partial pressure of saturated steam flow to the low pressure air, and the wet heat (high enthalpy) water self-broadcast The water system is spilled into the tower. When the water droplets come into contact with the air, on the one hand, due to the direct heat transfer between the air and the water, on the other hand, due to the pressure difference between the surface of the water vapor and the air, evaporation occurs under the action of the pressure, and the latent heat of evaporation is brought to the present. The heat in the water is taken away to evaporate and heat transfer, thereby achieving the purpose of cooling.

The working process of the cooling tower takes the working process of a circular counterflow cooling tower as an example:

The hot water is pumped from the main room through the water pump to the watering system of the cooling tower through the pipeline, the throat, the throat and the central throat. The water is evenly spread on the packing through the small holes in the water pipe. The dry low-value air enters the tower from the bottom into the wind net under the action of the fan, and the hot water flows through the surface of the packing to form a water film and air for heat exchange. The high-humidity and high-value hot air is extracted from the top and cooled. The water drops into the bottom basin and flows into the main unit through the outlet pipe. Under normal circumstances, the air entering the tower is the air that dries the low-humidity temperature. There is obviously a difference in concentration of water molecules and a difference in kinetic energy between the water and the air. When the fan is running, under the action of static pressure in the tower, Water molecules continuously evaporate into the air, becoming water vapor molecules, and the average kinetic energy of the remaining water molecules is reduced, thereby lowering the temperature of the circulating water. It can be seen from the above analysis that the evaporative cooling and the temperature of the air (generally the dry bulb temperature) are not related to or higher than the water temperature, and as long as the water molecules can continuously evaporate into the air, the water temperature is lowered. However, the evaporation of water into the air does not continue indefinitely. When the air in contact with water is not saturated, the water molecules continuously evaporate into the air, but when the air on the contact surface of the water vapor reaches saturation, the water molecules cannot evaporate, but are in a state of dynamic equilibrium. The amount of water molecules that evaporate is equal to the amount of water molecules that return from the air to the water, and the water temperature remains the same. It can be seen that the drier the air in contact with water, the easier it is to evaporate and the lower the water temperature.

Cooling tower classification

First, according to ventilation, there are natural ventilation cooling towers, mechanical ventilation cooling towers, and mixed ventilation cooling towers.

Second, according to the contact mode of hot water and air, there are divided into a wet cooling tower, a dry cooling tower, and a dry and wet cooling tower.

Third, according to the flow direction of hot water and air, there are a counterflow cooling tower, a cross flow (AC) cooling tower, and a mixed flow cooling tower.

Fourth, according to the purpose of the general air conditioning cooling tower, industrial cooling tower, high temperature cooling tower.

5. According to the noise level, it is divided into ordinary cooling tower, low noise cooling tower, ultra low noise cooling tower and ultra quiet cooling tower.

6. Others such as jet cooling towers, fanless cooling towers, hyperbolic cooling towers, etc.

Cooling tower application range

The waste heat generated during industrial production or refrigeration processes is generally guided by cooling water. The function of the cooling tower is to exchange heat between the cooling water with waste heat and the air in the tower to transfer the waste heat to the air and to the atmosphere.

For example, in a thermal power plant, the boiler heats the water into high-temperature and high-pressure steam, and pushes the steam turbine to work to make the generator generate electricity. The steam exhausted by the steam turbine is discharged into the condenser, and is exchanged with the cooling water to form water, and then pumped with water. Return to the boiler for recycling. In this process, the waste heat of the spent steam is transferred to the cooling water to raise the temperature of the water, and the cooling water with waste heat is transferred to the air in the cooling tower and discharged into the atmosphere from the air duct.

Cooling tower application range: mainly used in air conditioning cooling system, refrigeration series, injection molding, tanning, foaming, power generation, steam turbine, aluminum profile processing, air compressor, industrial water cooling, etc. The most widely used air conditioning cooling, freezing, Plastic chemical industry.