Mehdi Karami - School of Mechanical Engineering, Shiraz University, Shiraz, ۷۱۹۳۶-۱۶۵۴۸, Iran
Mahmood Yaghoubi - School of Mechanical Engineering, Shiraz University, Shiraz, ۷۱۹۳۶-۱۶۵۴۸, Iran- The Academy of Science of IR Iran, P.O. Box ۱۹۷۳۵/۱۶۷, Tehran, Iran

In the present study, natural convection heat transfer ofthree finned-tube exchangers with array of square fins isanalyzed experimentally. Total length of each exchanger is200 mm and the length of the covered zone with fins is100±1 mm. The fin spacing (s) is changed from 5 to 14 mm.For study of natural convection heat transfer, various finspacing and thermal input power (Q) are examined. Forexperiments, the exchangers are placed in a control room inwhich its temperature and humidity are automaticallycontrolled via heating, cooling, humidifying equipment. Thethermal input power for heating varied from 8.4 to 56.7Watt. Based on experimental results, an empiricalcorrelation is developed for Nusselt number when Rayleighnumber based on the fin spacing is changed from 6.5 to1335.

Natural convection - Finned tube - Nusselt number - Square fins