Design dry-bulb temperature:
- The typically selected temperature => 2.5 percent of the warmest consecutive 4 months.
- add 1 to 3°C (2 to 6°F) to the tabulated value.
- Considering prevailing winds
- Considering locations and elevations of buildings, equipment, fired heaters, etc.,
- Use same bank type, i.e., all forced-draft or all induced-draft.
- Place banks far enough apart to minimize air recirculation.
Winter time operations:
- Provision weather conditions such as heavy rain, strong winds, freezing of moisture upon the fins, etc.
- Noise level at the plant site is affected by the exchanger position
- Consider reflective surfaces near the fan, the hardness of these surfaces, and noise from adjacent equipment.
Ground area and space requirements:
- Air-cooled units can be installed above other equipment such as pipe racks, shell-and-tube exchangers, etc.
- Some operators avoid such installations because of safety requirements.
- Leaks in air-cooled units are directly to the atmosphere and can cause fire hazards or toxic-fume hazards.
- However, the large air flow through an air-cooled exchanger greatly reduces any concentration of toxic fluids.
- Locate away from corrosive vapors and fumes from vent stacks.
- Air-side fouling is generally negligible if kept away from corrosive sources.
- Tube chemical or mechanical cleaning.
Process-side design pressure:
- Keep high-pressure process fluid in the tubes
- Bond resistance gets affected by vibration and thermal cycling.
- The approach temperature, which is the difference between the process-fluid outlet temperature and the design dry-bulb air temperature.
- For lower process-fluid outlet temperature, an air-humidification chamber can be provided to reduce the inlet air temperature toward the wet-bulb temperature.
- Typically 5.6°C (10°F) approach is feasible.