AC-7 Airflow Performance in Induced-Draft Air-Cooled Heat Exchangers

G. Breber

Test results are reported on selected aspects of the airflow performance in induced-draft air-cooler heat exchangers. The experiments were performed on a one-third scale model of a three-fan commercial installation built in 1985 and operated at the HTRI Research Facilities from 1985 to 1988. The research unit was 1.78-m (5-ft 10-in.) wide by 4.88-m (16-ft) long, with three 1.22-m (4-ft) diameter fans operating side by side. The unit was operated first in the forced-draft mode, and later, after modification, in the induced-draft mode. 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 bundle height aboveground, plenum depth, fan intake blockage, multiple fan interactions, fan ring, and fan guard. The parameters investigated include total airflow 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.