Air cooled heat exchanger perform their cooling function by flowing large quantity of cooled air around a bank of finned tubes by the help of large fans. The combination of finned tube and the air circulating fan has made fin-fan cooler a common term used for air coolers. There are two main types of air cooled heat exchanger: forced draft air cooled heat exchanger and induced draft air cooled heat exchanger.
(1) Forced draft- in this arrangement fan is located below the tube bundle and air is forced through the fin tubes;
(2) Induced Draft- in this arrangement fan is located above the tube bundle and air is induced or pulled through the fin tubes.
|
No |
Parameter |
Induced Draft Air Cooler |
Forced Draft Air Cooler |
|
1 |
Air Distribution |
Better distribution of air across the bundle. |
Less uniform distribution of air over the bundle. |
|
2 |
Air Re-circulation |
Less possibility of hot effluent air recirculating into the intake |
Increased possibility of hot air recirculation |
|
3 |
Process Control and Stability |
Better process control and stability. The plenum covers 60% of the bundle face area which reduces the effects of sun, rain, and hail. |
Less Process Control
|
|
4 |
Fan Efficiency |
Increased capacity in the fan |
Low natural draft capability of fan |
|
5 |
Horsepower Requirement |
Possibly higher horsepower requirements if the effluent air is very hot. |
Possibly lower horsepower requirements if the effluent air is very hot |
|
6 |
Temperature Limitation |
Effluent air temperature should be limited to 220°F to prevent damage to fan blades, bearings, or other mechanical equipment in the hot air stream |
Accommodates higher process inlet temperatures |
|
7 |
Fan Maintenance Access |
Fans are less accessible for maintenance |
Better accessibility of fans and upper bearings for maintenance. |
|
8 |
Bundle Maintenance Access |
Plenums must be removed to replace bundles |
Better accessibility of bundles for replacement |