GC Series Heat Exchangers

GC Series Gas Coolers

Cooling Gas at Temperatures Liquid Units Never See

Gas has a poor heat transfer coefficient and, in the streams the GC is built for, arrives extremely hot. The 1000°F rating is what separates this range from everything else in the Bell & Gossett shell and tube line, and it drives the material and construction choices.

Surface area is the consequence of a low coefficient. Gas-side film coefficients sit far below liquid, so the gas side controls the design almost regardless of what is on the other side. That is why the GC range runs to 168 inch shell lengths: the duty needs length because it cannot get help from the coefficient.

Pressure drop is usually the binding constraint. Raising gas velocity improves the coefficient, and pressure drop rises with roughly the square of it. On a compressed or ducted gas stream that drop is either compression work already paid for or draft the system does not have. Send the allowable drop with the enquiry.

Copper or steel tubes. The catalogued range offers both. Copper transfers heat better; steel tolerates higher temperature and resists some gas chemistries that attack copper. At the top of the temperature range steel is generally the answer, and the part number records which a given unit carries.

Design for the condensate, not the gas. As gas cools past its dew point, the first liquid to form concentrates whatever acid the gas carries into a very small volume against the tube wall. That film is what corrodes, and it can be far more aggressive than the dry gas analysis suggests.