1. What is a cooling tower?
See the picture, the chubby green tank in the picture is the cooling tower.
2. What types of cooling towers are there?
Cooling towers can be divided into open cooling towers and closed cooling towers;
1. The picture above is an open cooling tower. By spraying the circulating water onto the glass fiber filler, the contact between the water and the air can achieve heat exchange, and then the fan drives the air circulation in the tower to combine with the water The hot air flow after heat exchange is taken out to achieve cooling.
Features: Simple structure and low price, but the water quality of circulating water is not easy to control, and the water quality is poor.
2. The picture above is a closed cooling tower, the air intake passes through the air intake grille, there is no filler, and the main core part is a copper tube surface cooler. And the tower body is designed with internal circulation and external circulation in two ways. The outer circulation is the control spray system, and the inner circulation is the cooling medium pipeline. Multiple fans are designed on the top. The closed cooling tower consumes less water and has a long service life, but the price is 2~3 times more expensive than the open cooling tower and the maximum water volume of a single cooling tower is 300CMH.
The advantage is that the circulating water quality is easy to control and the water quality is good.
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The following types are introduced:
Cross-flow cooling towers and counter-flow cooling towers (belonging to open cooling towers)
1. Cross flow tower refers to a cooling tower in which hot water passes through the packing from top to bottom, while air flows through the packing from the horizontal direction, and the flow direction of hot water and air is nearly 90 degrees.
2. The countercurrent tower refers to a cooling tower in which hot water passes through the packing from top to bottom, while air flows through the packing from bottom to top. The flow direction of hot water and air is nearly 180 degrees.
The cross-flow cooling tower is more stable than the counter-flow cooling tower, with lower failure rate and low noise, so the cross-flow cooling tower is mostly used in civil buildings.
FRP cooling tower and stainless steel cooling tower
1. The FRP cooling tower has high cost performance, good corrosion resistance and light weight. Open cooling towers often use FRP materials.
2. The stainless steel cooling tower is relatively heavy, but it has good fire resistance, long service life and slightly expensive price. Closed cooling towers are often made of stainless steel.
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3. The characteristics of the cooling tower in the project
1. Noise
Sources: splashing water noise, fan noise, motor water pump and pipeline vibration noise
Treatment: basic measures for cooling tower noise control,
1), physical treatment: muffler, sound insulation screen, energy dissipation and noise reduction device for barrier falling into water, shock absorber and rubber soft connection
2) Due to the huge sound source of the cooling tower, the noise level decays very slowly within 10-25 m from the air inlet, so the cooling tower should be far away from the user if conditions permit.
3) Change the air inlet direction of the cooling tower to reduce the noise value.
2. Large size
Take a super high-rise office building as an example
The construction area is 165,000 square meters, the main engine is 4900RT, equipped with 8 cooling towers, 6 sets of 600CMH (each size is 6.3mX4.5mX7m), 1 set of 700CMH (7.4mX4.9mX8m), and 1 set of 400CMH ( 5.9 meters X4.0 meters X6.5 meters), covers an area of about 230 square meters, nearly 8 meters high.
If you want to lower the cooling tower, you need to splice and place two cooling towers to increase the floor area. The actual design should be in accordance with the building and structure to determine the location.
3. Whether noise elimination and aesthetics can avoid cooling towers
The function of the cooling tower is that the cooling water carries the waste heat in the air conditioning system to exchange heat with the air, and dissipates the waste heat into the atmosphere. If the surrounding wall is covered to affect its normal heat dissipation, the evaporator of the main engine in the refrigeration room will overheat, and the efficiency of the main engine will be greatly reduced or even crashed, which will affect the normal operation of the air conditioning system. Not only directly affect the functional use of the building, but also reduce the life of the air conditioner host.
4. Application of cross flow cooling tower
1. Air intake from one side or both sides, wind out from the top
2. Side air cooling tower
5. Several special ventilation methods for cooling towers
1. In the form of single-sided air inlet and top air outlet, it is necessary to increase the capacity of the cooling tower.
2. To be placed in a pit, there needs to be a pit large enough to ensure the wind, and the drainage problem needs to be solved.
6. The relationship between the location of the cooling tower and the building
1. Set up on the first floor: Due to the size and noise of the cooling tower, this case is rarely used in civil buildings, and it is used in industrial projects or projects with more green areas.
2. Located on the roof of the tower
The cooling tower is located in the tower (148.75 meters)
a. Advantages: It has little impact on the facade of the building, but it needs to coordinate with the track of the window cleaning machine on the roof of the tower. Improve the commercial value of podium roof use;
b. Disadvantages: The cooling water supply and return waterway is long, about 320 meters; the power of the water pump is relatively large, and the operating cost is high.
The condenser end of the chiller and the cooling water pipe system are all greater than 1.0 Mpa; it is necessary to use 2.0 MPa equipment to increase the initial investment and increase the probability of valve leakage damage.
3. Located on the roof of the podium
The cooling tower is located on the roof (elevation 20.9 meters)
a. Advantages: less cooling water supply and return pipelines, about 100 meters;
The power of the water pump is small and the operating cost is low.
The condenser end of the chiller and the cooling water pipe system are all less than 1.0 Mpa; valves and equipment operate at low pressure to reduce the probability of water leakage damage
b. Disadvantages: It has an impact on the podium roof swimming pool, roof landscape and building facade; it has an impact on heat dissipation, floating water and noise on the podium roof pool, roof activity area, and low-level users of the office tower; it has adverse effects on the 5th floor conference room noise impact.
4. Located on the top floor of a high-rise over 180 meters
When there is no podium or the location of the podium cannot meet the requirements of the cooling tower, the cooling tower should be placed on the top of the super high-rise building
a. Since the maximum pressure of the main engine is 2.0MPa, considering the safety, when the building exceeds 180 meters, the cooling tower needs to be installed on the roof to use a plate heat exchanger to reduce the pressure of the air conditioner main engine.
b. The impact on areas with high commercial value such as podium buildings is reduced, but the impact of equipment such as intermediate cooling water pumps on the upper and lower floors needs to be considered. At the same time, due to the addition of transmission equipment in the system, the operating cost of the system will be greatly increased, and the efficiency of the air-conditioning system will be reduced at the same time. The increased equipment and valves will not only increase the equipment room, but also increase the workload of later maintenance. The water pipe (DN700) , also affects the storey height near the equipment room. The power of the 34-layer cooling water pump (not including the standby) is 132X3+55X2=506kw, which costs about 5,000 yuan per day (10 hours of operation) on the hottest day.
7. Problems to be paid attention to when setting up cooling towers
Principle: The heat dissipation power of the cooling tower must be at the maximum design outdoor wet bulb temperature, which can meet the heat dissipation requirements of the refrigeration system at full load. When selecting a cooling tower, attention must be paid to the relevant noise requirements. The cooling tower must not exceed the allowable noise level when it operates alone or simultaneously with other equipment.
1. Due to the noise problem of the cooling tower, the location of the cooling needs to be confirmed by the EIA and passed the acceptance.
2. The cooling tower needs to be far away from the user if possible, and requires noise reduction and vibration isolation treatment.
3. Avoid the cooling tower being surrounded by walls, improve the ventilation and heat dissipation effect of the cooling tower, and improve the efficiency of the cooling tower.
4. The noise-generating rooms such as water pumps on the middle floor need to be treated with sound-absorbing and shock-absorbing treatment, including floating platforms.
5. The cooling water pipe well needs to be close to the air-conditioning machine room and cooling tower, far away from the office space. If it cannot be avoided, it needs to be silenced and shock-absorbed.
6. When it is located in the podium, the side air cooling tower can be used to match the building facade.
