NEWS CENTER
Oasis Iceberg
11
2024
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07
What are the reasons that affect the cooling effect of the closed cooling tower?
The closed cooling tower reduces the waste of water resources and achieves the effect of energy saving and emission reduction. At the same time, the device also has many problems. For example, the cooling effect of closed cooling tower is not ideal, which is the problem we need to pay attention!
The closed cooling tower reduces the waste of water resources and achieves the effect of energy saving and emission reduction. At the same time, the device also has many problems. For example, the cooling effect of closed cooling tower is not ideal, which is the problem we need to pay attention!
Cooling principle of 1. cooling tower
The temperature difference between water and air is used to dissipate heat according to the contact between warm water and cold air and the evaporation of water itself.
2. cooling tower concepts.
In order to explain the cooling temperature of the cooling tower, the following related concepts need to be introduced first.
1. Air temperature: dry bulb temperature and wet bulb temperature.
1.1 dry bulb temperature: it is the real temperature of the air, which can be directly measured with an ordinary thermometer.
1.2 wet bulb temperature: the air temperature when the water vapor in the air reaches saturation under the air state with the same enthalpy value. On the air enthalpy-psychrometric chart, it is the dry bulb temperature of the corresponding point from the air state point along the isenthalpy line to the 100% relative humidity line. Generally speaking, it is the lowest temperature that the current environment can reach only by evaporating water. The wet bulb temperature is different in different regions, and the average wet bulb temperature standard in China is 28 ℃. It is usually represented by the letters "t_w2.
2. Cold amplitude: it is equal to the temperature difference between the cooling water entering and leaving the tower, indicating the cooling range of the cooling water after passing through the cooling tower, usually expressed by the letter "∆t. Standard ∆t = t_1-t_2 = 5 ℃, where t_1 and t_2 are the inlet and outlet temperatures of the cooling tower, respectively.
3. Approximation: It is equal to the temperature difference between the water temperature of the cooling tower and the wet bulb temperature of the air, indicating the degree to which the water temperature of the tower approaches the wet bulb temperature, which is represented by the letter "A. Standard approximation A = 4 ℃.
4. To sum up, assuming that the wet bulb temperature in a certain area is 28 ℃, the standard outlet water temperature of the cooling tower in this area t_2 = t_w2 A = 28 ℃ 4 ℃ = 32 ℃, and the standard inlet water temperature t_1 = t_2 ∆t = 32 ℃ 5 ℃ = 37 ℃
3. Cooling Temperature Description
For example, when the wet bulb temperature t_w2 = 28 ℃, t_1 = 37 ℃, can the outlet temperature t_2 of the cooling tower be lower than 32 ℃, say 31 ℃ or 25 ℃?
Answer: The approximation degree directly affects the cooling capacity of the cooling tower. The smaller the approximation degree, the smaller the cooling capacity; on the contrary, the greater the approximation degree, the greater the cooling capacity. The outlet temperature of the cooling water tower can only approach the wet bulb temperature of the air and cannot be equal to or lower than the wet bulb temperature.
(1)t_2=25 ℃
(2)t_2=31 ℃>t_w2, which may happen. However, for example, when cooling 100 tons of water, the approximation is A = 3 ℃, and a standard cooling tower of 150 tons needs to be selected. Only when the approximation is A = 4 ℃ (I. e. t_2 = 32 ℃) can the standard 100 ton cooling tower be selected.
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