AC-5 Airflow Problems in Forced Draft Air-Cooled Heat Exchangers

A. Ganguli

A literature review, description of a new HTRI research unit, and test results are reported on selected aspects of airflow problems in forced draft air-cooled heat exchangers. A one-third scale model of a three-fan commercial installation was designed, built, and operated at the HTRI Research Facilities. The research unit was 5-ft 10-in. (1.78-m) wide by 16-ft (4.88-m) long, with three 4-ft (1.22-m) diameter fans operating side by side. All tests were isothermal and the fans were built to scale, with characteristic curves similar to those of large size fans. The results are presented on the effects of fan height above ground, plenum depth, fan intake blockage, multiple fan interactions, tapered plenum, fan ring, and fan guard. The parameters investigated included total air flow rate, airflow distribution, fan power, and fan speed. Tests showed that significant reductions in airflow with adverse distributions will occur for a given fan power under certain system and geometry conditions. Methods and correlations are presented to quantify such effects. Good agreement was found between this study and other related studies.