Cooling tower is a kind of equipment that uses the contact between water and air to dissipate the waste heat generated in industry or refrigeration and air conditioning through evaporation.
The basic principle is that dry (low enthalpy) air enters the cooling tower from the air inlet network after being twitched by the fan; High temperature water molecules with high partial pressure of saturated steam flow to the air with low pressure, and hot and humid (high enthalpy) water is sprinkled into the tower from the water seeding system. When water drops contact with air, on the one hand, due to the direct heat transfer between air and air, on the other hand, due to the pressure difference between the surface of water vapor and air, evaporation occurs under the action of pressure, taking away the latent heat of evaporation at present and the heat in water, that is, evaporation heat transfer, so as to achieve the purpose of cooling down. Working process of cooling tower: Take the working process of circulating countercurrent cooling tower as an example: the hot water main room pumps the circulating water into the water sowing system of the cooling tower through pipes, horizontal throats, curved throats and central throats at a certain pressure, and evenly sprinkles the water on the filler through small holes in the water sowing pipe; Dry air with low Han value enters the tower from the bottom through the air net under the action of the fan, hot water flows through the surface of the packing to form a water film to exchange heat with the air, hot air with high humidity and high Han value is pumped out from the top, and cooling water drips into the bottom basin and flows into the main engine through the water outlet pipe. Under normal circumstances, the air entering the tower is dry air with low wet bulb temperature, and there is obvious concentration and kinetic energy pressure difference between water and air. When the fan is running, under the action of static pressure in the tower, water molecules continuously evaporate into the air and become water vapor molecules, and the average kinetic energy of the remaining water molecules will decrease, thus reducing the temperature of circulating water. From the above analysis, it can be seen that evaporative cooling has nothing to do with whether the air temperature (usually called dry bulb temperature) is lower than or higher than the water temperature. As long as water molecules can continuously evaporate into the air, the water temperature will drop. However, the evaporation of water into the air will not go on endlessly. When the air in contact with water is not saturated, water molecules evaporate into the air continuously, but when the air in contact with water and gas is saturated, water molecules cannot evaporate, but are in a dynamic equilibrium state. The number of water molecules evaporated is equal to the number of water molecules returned from the air to the water, and the water temperature remains unchanged. It can be seen that the drier the air in contact with water, the easier it is to evaporate and the easier it is to lower the water temperature.
Classification of cooling towers
First, according to the ventilation mode, there are natural ventilation cooling towers, mechanical ventilation cooling towers and mixed ventilation cooling towers.
Second, according to the contact mode between hot water and air, there are wet cooling towers, dry cooling towers and dry-wet cooling towers.
Three, according to the flow direction of hot water and air, there are evaporative cooling towers, countercurrent cooling towers, cross-flow (AC) cooling towers and mixed-flow cooling towers. HVAC- air conditioning-online
Four, according to the use of general air conditioning cooling tower, industrial cooling tower, high temperature cooling tower.
Five, according to the noise level is divided into ordinary cooling tower, low noise cooling tower, ultra-low noise cooling tower, ultra-quiet cooling tower. Six, others such as jet cooling tower, fan-less cooling tower, hyperbolic cooling tower, etc.