The inlet air temperature of air-cooled heat exchanger has a great influence on its thermal performance. If the air-cooled heat exchanger is improperly arranged, the air temperature at the inlet of the air cooler will sometimes be higher than the local average temperature. Especially in summer, when this happens, the cooling effect of air-cooled heat exchanger will be greatly affected. One reason is that part of the hot air discharged from the air-cooled heat exchanger is pumped back by the fan, which is called hot air circulation; Second, the air cooler is too close to some equipment with high temperature. Of the two reasons, the former is particularly important.

Hot air recirculation seriously affects the heat transfer performance of some air coolers. In some cases, due to the influence of hot air recirculation, the air temperature at the inlet of air-cooled heat exchanger may increase by 5 ℃, so that the heat transfer of air-cooled heat exchanger with logarithmic average temperature difference of 15 ℃ can be reduced by 30%. In order to reduce or avoid hot air circulation, the air-cooled heat exchanger should be reasonably arranged according to the main wind direction in summer. It is better not to arrange the air-cooled heat exchanger in the downwind of large equipment or high buildings, otherwise it will affect the air circulation. The fan shall not be too close to the ground, and shall be placed on the upper part of the platform or pipe rack all the time. If the inclined roof air cooler is arranged improperly, it is easier to cause hot air circulation. It must be noted that the tube bundle of the inclined top air cooler should not face the dominant wind direction, especially the main wind direction in summer. In addition, in order to prevent corrosion, scaling and ignition of the air-cooled heat exchanger, pay attention not to discharge corrosive gas, dust and oil gas at its upwind.