What are the advantages of using air coolers and water coolers together compared to using air coolers and water coolers separately?

I think the biggest advantage of this setup is that it ensures an effective cooling effect while reducing the pressure drop across the cooler. When air cooling is used alone, the number of air coolers must be increased to ensure an effective cooling effect, which in turn increases the pressure drop; the pressure drop in water coolers is even greater than that in air coolers.

In projects where water supply is unrestricted, temperatures are suitable, and water is easily accessible, it is still recommended to use a separate circulating water cooler to cool the process medium； The advantage of a combined air-cooling and water-cooling cooling system is, of course, more flexible temperature control and greater operability. However, this combined approach also has its own disadvantages: for example, it requires more space, is more difficult to install, needs more supporting utility systems, and results in higher fixed investment costs. I used air coolers in three projects, located in Daqing (northeast), Yanchang (northwest), and Sichuan (southwest). The environmental conditions in these areas vary significantly, which makes the design and selection of air coolers quite challenging. 1) Winter operating conditions: The most common problem is the freezing and blockage of the air coolers. Even with the louvers fully closed, the fans turned off, timely drainage of condensate, the tube bundles arranged at an angle, and steam coils installed, freezing and blockage still occur to varying degrees ； 2) Summer operating conditions: If the design air temperature is set based on the average daily maximum value for the hottest month as recommended in the manual, overheating will definitely occur during the hottest periods of summer ； If extremely high temperatures are adopted, the heat exchange area of the air cooler will increase, which in turn will lead to freezing and blockages during winter ； Because even when all the fans in the air cooler are variable-frequency with adjustable blade angles, the temperature control error remains at ±3°C; when half of the fans are operated in variable-frequency mode, the error increases to ±6°C, while fans operating at a fixed frequency have an error of ±16°C. This is not suitable for applications that require precise temperature control.

Personally, I think water cooling is better; air cooling requires regular cleaning of the tubes, and cleaning them can easily damage them. In winter, the amount is small and it freezes easily. It is inconvenient to adjust the temperature after cooling using water cooling; with air cooling, a variable-frequency motor can be installed directly for control via a central system. Generally, stable devices don’t need any adjustments either

As the guy upstairs said clearly, secondly, it’s necessary to determine which option to choose based on factors such as the air quality, water availability, and space size at the location in question. These are my personal opinions; please forgive any shortcomings.

Question: What is the difference in sequence between air cooling + water cooling and water cooling + air cooling?

Our equipment operates in a combined air-cooling and water-cooling mode. Currently, during winter, all 45 air-cooling units are operated at around 40% load; sometimes the load is a bit over 50% due to variable frequency control, while the water-cooling valves are used at less than 10% capacity. My suggestion is to adjust the load on those 4 air-cooling units – start using water cooling first, and then gradually shut down the air-cooling units. If water cooling can meet the requirements, I won’t turn on the air-cooling units at all. Is this approach the most energy-efficient and optimal? Our medium is free of water, so the issue of preventing freezing in the air-cooled tube bundles is not a concern.