What are the design points of air coolers?

1. Air coolers can be installed horizontally, vertically or tilted, but the condensed water of the cooler must flow down along the fins to prevent water accumulation on the fins and reduce heat transfer performance and increase air resistance.

2. A drip tray and a drain pipe should be installed at the bottom of the air cooler; when the coolers are stacked, we should install an intermediate drip tray and a drain pipe between the two coolers, and the drain pipe should be equipped with a water seal to prevent air from being sucked in.

3. According to the direction of air flow, air coolers can be installed in parallel or in series. Usually, when the amount of air passing through is large, parallel connection is appropriate; when a large air temperature drop is required, series connection should be used. For parallel air coolers, the water supply pipes should also be connected in parallel; for series air coolers, the water supply pipes should also be connected in series. Cold water and air should flow in reverse directions.

4. In the air cooler, the air and the refrigerant should flow in the opposite direction. The mass flow rate of the windward side is generally 2.5~3.5kg/(m2·s). When the mass flow rate is greater than 3kg/(m2·s), a water baffle should be added after the cooler. For coolers with water spray devices, water baffles should generally be installed.

5. The cold water inlet temperature of the air cooler should be at least 3.5℃ lower than the outlet dry bulb temperature of the air. The cold water temperature rise should be 5~10℃, and the flow rate should be 0.6~1.5m/s. The evaporation temperature of the refrigerant direct expansion air cooler should be at least 3.5℃ lower than the outlet temperature of the air; when the normal temperature air conditioning system is fully loaded, the evaporation temperature should not be lower than 0℃; when the load is low, the surface should be prevented from frosting.

6. When the air conditioning system uses a refrigerant direct expansion air cooler, it shall not be used as a refrigerant.

7. The number of cooler rows along the air flow direction is generally 4 to 6 rows, and should not exceed 8 rows.

8. When selecting an air cooler, factors such as surface dust accumulation and inner wall scaling should be considered and a certain safety factor should be added to increase the heat transfer area. During operation, the decrease in heat transfer coefficient can also be compensated by lowering the initial water temperature, which is relatively simple.

9. Select air coolers based on product samples and thermal calculations of each manufacturer.