AC-9 Predicting Fans-Off Operation of Air-Cooled Heat Exchangers

R. S. Kistler

Based on HTRI Report AC-1, a computer-implemented procedure was developed for predicting the performance of air-cooled heat exchangers with the fans turned off. The technique was validated by HTRI natural draft heat exchanger research data and HTFS research data, previously obtained in a data exchange.

The calculational technique in Report AC-1 was adapted for use in an incremental program. The original method had to be modified because it was an overall row-by-row procedure and could not be applied to exchangers with side-by-side tubepasses. The procedure also did not consider incrementation down the tube length.

After modification, the method predicted 95 percent of HTRI’s research data to within ± 19 percent. The HTFS research data are also well predicted, although with more scatter than HTRI’s data.