Why Finned Tubes Are Used for Waste Heat Recovery

Waste heat is often available in air or exhaust gas, while the useful load may require hot water, combustion air or process heat. Air and gas generally offer less effective heat transfer than liquids. A smooth tube may therefore need a large surface to transfer the required duty.

Fins solve part of that problem by extending the outside area of the tube. Heat travels from the hot gas through the fin and tube wall into the water, glycol, thermal oil or air circuit. More external area can help the designer package the exchanger into a practical casing and reduce the amount of bare tube required for the same general duty.

Fins are useful when:

• The gas-side heat-transfer resistance is high.

• The recovery source is air or flue gas.

• The site has limited space.

• The plant needs gas-to-water or gas-to-air recovery.

• The fan or draft system can accept the coil pressure drop.

• The fin surface can be cleaned and maintained.

CSTHEATEXCHANGER’s Finned Tube Heat Exchanger category includes steam heaters, flue-gas air heaters, flue-gas waste-heat recovery, air preheaters and boiler economizers. These applications share an air- or gas-side heat-transfer requirement, although the final coil design varies from project to project.

The fin pattern, pitch, material, tube spacing, gas velocity and cleaning method must be selected together. More fins can add area, but they can also increase pressure drop and collect deposits.

How CSTHEATEXCHANGER Supports Finned-Tube Waste-Heat Recovery

When we review a finned-tube waste-heat-recovery request, we ask for the source gas data, heat-demand data, required medium, pressure limits, corrosion basis, fouling condition, footprint, cleaning method, bypass requirements and project documentation.

CSTHEATEXCHANGER’s Finned Tube Heat Exchanger category includes flue-gas waste-heat recovery, flue-gas air heaters, air preheaters, boiler economizers and air-cooler tube bundles. Its Flue Gas Waste Heat Recovery page describes gas-to-water and gas-to-gas recovery routes. The Industrial Heat Recovery category and About Us page provide related industrial and replacement heat-exchanger information.

We support new and replacement finned-tube projects, including tube, fin, material, airflow, pressure-drop, bypass and cleaning reviews. Contact CSTHEATEXCHANGER to discuss a finned-tube heat exchanger for waste heat recovery.

A finned-tube heat exchanger can recover useful energy from hot exhaust gas or process air by adding external surface where the gas-side heat-transfer resistance is high. The best design balances extended area with pressure drop, fan power, fouling, condensation, corrosion, cleaning access and the actual heat demand. Final capacity, efficiency and energy savings must come from measured source conditions and an approved project calculation.