The principle and decisive factors of cooling tower cooling effect

The principle and decisive factors of cooling tower cooling effect

The role of the cooling tower is to exchange the cooling water carrying waste heat with the air inside the tower body, so that the waste heat is transferred to the air and dispersed into the atmosphere. The general term "cooling tower" is used to describe direct (open circuit) and indirect (closed circuit) heat dissipation equipment. Although most come up with a "cooling tower as an open direct contact heat sink", an indirect cooling tower, sometimes referred to as a "closed circuit cooling tower" is but also a cooling tower.

　　A direct, or open-circuit cooling tower is a means of sealing the inside of the structure by spraying circulating water onto the glass fiber filler. The filler provides a larger contact surface, and the heat exchange effect is achieved through the contact of water and air. The fan drives the air flow in the tower to circulate, and the hot air flow after heat exchange with water is taken out to achieve cooling.

"Indirect or closed-circuit cooling towers do not involve direct contact with air and liquids, usually water or glycol mixtures to be cooled. The difference is an open cooling tower, which has two independent fluid circuits indirectly. One is that the water in the external circuit is in the second track, which is the hot fluid process connected to the external loop of the tube bundle (the closed coil) is cooled and returned in a closed circuit. The air is drawn through the circulation of water cascaded outside the entire heat pipe, providing similar evaporative cooling to the opening of the cooling tower. The heat flow in operation from the internal fluid circuit, through the coil tube wall, the external circuit, and then heated by some evaporation of air and water, to the atmosphere. The actions of indirect cooling towers are therefore very similar, with one exception for opening the cooling tower. In this process, the coolant is in a "closed" circuit, not directly exposed to the atmosphere or external circulating water.

　　 travel upward through the filling or tube bundle in the countercurrent cooling tower, and the opposite water moves downward. In a cross-flow cooling tower, the air moves horizontally through the filling water and moves downward.

　　 There is another feature of cooling towers, in which the mechanical ventilation cooling towers of aviation movement rely on electric-driven fans to attract or force tower air. The natural draft cooling tower uses the high growth of the exhaust chimney to provide draft air buoyancy. Fan-assisted natural draft cooling tower adopts mechanical draft to increase the influence of buoyancy. Many early cooling towers relied on draft air generated by the wind direction.

　　 If the cooling water is returned to reuse from the cooling tower, some water must be added to the replacement or composition, and the flowing part evaporates. Since evaporation includes purified water, the concentration of dissolved minerals and other solids in circulating water tends to increase unless some dissolution, such as combat solids, is provided under control means. Some of the water is also lost and the droplets of the exhaust gas (drift) are being carried out, but this is usually reduced to a very small amount by installing a baffle-like device, called drift removal, to collect the droplets. The amount of compensation must be equal to evaporation, blowing down, total drift, such as wind blowout and other water leakage losses, to maintain a stable water level.

　　The cooling tower is used to achieve a certain cooling effect, and the cooling effect depends on the heat sink and the air volume of the fan. The cooling tower's water consumption, ventilation conditions, and installation location will also have a certain impact on its effect. Next, let's take a look at the influence of the cooling tower's heat sink and fan air volume on the cooling system:

1. Heat sink: It is the key component of the cooling tower. Small towers generally use PVC sheet hot pressing or thermal suction type, and large towers will use wood. The main purpose is to make the contact surface of air and water without affecting the wind resistance, the bigger the better At the same time, the heat exchange rate also reaches z*. The two parameters that affect the heat transfer effect of the heat sink are mainly the shape and height of the heat sink. When installing the water tower, try not to damage the heat sink to avoid poor water flow on the heat sink.

　　 2. Fan air volume: It mainly accelerates the air flow in the tower, accelerates the heat exchange between air and water, and takes away heat. The main factors affecting the air volume of the fan are the shape of the blades, that is, the width and length of the blades and their own deflection angle, the speed of the blades, the installation angle, the speed and the motor and transmission ratio. In addition, when the air volume is constant, the cooling effect of the same type of tower with a small amount of cooling water is better than a large amount of cooling water.