Air coolers are a shortened term for air-cooled heat exchangers. Compared to water-cooled heat exchangers, air coolers have advantages such as corrosion resistance, compact structure, long lifespan, simple operation, low pollution, good working environment, and water saving (up to 80%). The reason why air coolers were widely used in the petrochemical industry early on was not primarily due to their water-saving advantages. However, the widespread application of air coolers in power plants in water-scarce areas is due to their excellent water-saving performance. Air cooling technology was applied in power plants in 1938. Air coolers can be divided into two main categories according to the shape of the heat transfer elements: plate type and tube type. Tube-type air coolers are basically used in air-cooled power plants, while plate-type air coolers are only used in a very small number of small power plants. Power plant air cooling systems are divided into two categories: indirect air cooling systems and direct air cooling systems.

Power plant indirect air cooling systems consist of a condenser that condenses the exhaust steam generated by the steam turbine and a radiator installed in the air cooling tower. They can be further divided into three types. The first is an indirect air cooling system with a jet condenser and an aluminum Forgo radiator, which was applied early on and is also known as the Heller (mixed) indirect air cooling system. Single-unit Heller indirect air-cooled units include the 4×325MW units of the Arak Power Plant in Iran (peak coolers and auxiliary cooling towers provided by Haikongtiao) and the 2×325MW units of the Sahand Power Plant in Iran (Forgo radiators provided by Haikongtiao). The second is an indirect air cooling system with a surface condenser and a steel radiator, developed based on the Heller indirect air cooling system. It is also known as the Hammond (surface) indirect air cooling system. It is more complex than the Heller system but does not consume electricity. The cooling water system and steam-water system are strictly separated. Single-unit Hammond indirect air-cooled units include the 6×690MW units of the Kendal Power Plant in South Africa. The third is an indirect air cooling system with a surface condenser and an aluminum Forgo radiator, which combines the advantages of the previous two indirect air cooling systems. It was developed by the North China Electric Power Design Institute of China Electric Power and the Datang Yangcheng Power Plant. It was first applied to the 2×600MW indirect air-cooled units of the second phase of the Datang Yangcheng Power Plant and is called the SCAL indirect air cooling system. The cooling water system and steam-water system are also strictly separated, and it has the advantages of small land occupation and low investment of the Heller indirect air cooling system. Given that the cooling water system and steam-water system of the Hammond and SCAL indirect air cooling systems are strictly separated, they are more suitable for promotion in air-cooled nuclear power plants than the Heller indirect air cooling system and direct air cooling system.

Air-cooled units equipped with indirect air cooling systems have higher initial investment, higher standard coal consumption for power generation, and require output restrictions for a short period of time in summer. While wet-cooled units equipped with wet cooling systems have fewer of the above problems, they require a large amount of circulating water. Therefore, some people have proposed that power plants adopt a combined dry-wet cooling system of air cooling (dry cooling) and water cooling (wet cooling).

Power plant direct air cooling systems, also known as air condenser systems, air cooling islands, and abbreviated as ACC, are characterized by large base tube diameters and high heat transfer coefficients of the heat exchangers. Direct air cooling systems are also divided into three types according to the number of fin rows of the radiator tube bundles: three-row tubes (the base tube cross-section was originally circular, now changed to elliptical, produced by Spick), two-row tubes (the base tube cross-section is elliptical, produced by Keye and Haikongtiao, Shuangliang will have a capacity of 1200MW), and single-row tubes (the base tube cross-section is flat, also known as large flat tubes). To date, the single-unit direct air-cooled unit is the 1×750MW air-cooled unit of Kogen Creek in Australia, which was put into operation at the end of 2007. The world's largest single-unit direct air-cooled unit under construction is the 1×850MW air-cooled unit of the Langage Power Plant in the UK and the 2×1000MW air-cooled units of the Lingwu Phase II in China.