The biggest difference between the closed cooling tower and the open cooling tower we used before is that the closed cooling tower exchanges heat between the cooled medium (circulating water) and the spray water and air outside the tube through the coil. The closed circulation system ensures that the quality of the circulating water is not polluted, protects the efficient operation of the main equipment, and improves the service life. When the outside temperature is low, the sprinkler system can be stopped, which saves water. The principle of an open cooling tower is relatively simple. It sprays circulating water onto the PVC filler, through the contact of water and air, to achieve heat exchange, and then a fan drives the airflow in the tower to circulate, and it will exchange heat with water. The hot air flow is brought out, so as to achieve the purpose of cooling. Compared with open cooling towers, closed cooling towers ensure the clean water quality of circulating water, higher heat exchange efficiency, water saving and environmental protection, so they have been more widely used in industries such as steel, metallurgy, electronics, machinery, and air conditioning systems.
1 Structure and working principle of counterflow closed cooling tower Closed cooling tower is an application form of tubular indirect evaporative cooler. The structure is shown in Figure 1 below. Its working principle is: when the closed cooling tower is working, it is divided into three Part of the loop:
(1) Primary side heat exchange cycle: When the circulating hot water on the primary side (external circulation) flows through the coil of the closed cooling tower, it is divided into four stages for heat transfer:
1) First, the heat of the heat-carrying solution is transferred to the inner surface of the coil through convection heat transfer;
2) Heat conduction through the tube wall to the outer surface of the coil;
3) Convection heat transfer from the outer surface of the coil to the water film flowing outside the tube; 4) Finally, heat transfer from the water film to the air by evaporation and convection heat transfer.
(2) Secondary side pre-cooling cycle: the secondary side (self-circulation) spray water is pumped from the lower water pan of the cooling tower to the water distribution system by the spray water pump, and sprayed onto the heat sink through a special equalizing water head , Perform latent heat and sensible heat exchange with air, pre-cooled and flow to the coil group, forming a stable water film on the outer wall of the tube, absorbing the heat transferred from the medium in the tube, and finally returning to the water tray, and the cycle is endless.
(3) Air circulation: The fan draws the unsaturated air outside the cooling tower into the tower, and the air flows through the coil, the heat sink and the spray water on the secondary side to exchange latent heat and sensible heat to absorb heat, and then pass through a special water baffle. Enter.
Guangdong Trlon Energy-saving Air Conditioning Equipment Co., Ltd.
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