A. Introduction

Air-cooled heal exchangers represent a growing segment of equipment being applied in the heat transfer field. It is quite common, these days, for air-cooled heat exchangers to handle more than half the heat dissipation load in a refinery or petrochemical plant. This rapid growth has occurred because of certain advantages inherent in air-cooled heat exchangers as compared to shell-and-tube or other types of heat exchangers. Some of the advantages are the following:

1. The heat exchangers can be located at any point within a refinery, thus eliminating long pipe runs for either the process fluid or the cooling water.
2. Scale buildup on the cooling water side of a shell-and-tube heat exchanger is eliminated, as well as the related shutdowns for cleaning.
3. Cooling tower water treatment and disposal of resulting waste water is eliminated.
4. The overall cost of dissipating heat by this means is generally less than by other methods for fluid streams above 66 °C (150 °F).

B. Types of air-cooled heat exchangers

The primary distinction in classifying this type of equipment is based on whether the fan is upstream from the finned-tube bundle (forced draft) or downstream (induced draft).