Jingchun
Min Tao
Tao Xiao-Feng
Peng ABSTRACT The fin efficiency of a finned oval tube heat exchanger is usually calculated by first converting the oval tube to an equivalent round tube and then using the Schmidt fin efficiency technique. There are two ways of selecting the equivalent round tube: one is to make the perimeter of the equivalent round tube equal to that of the oval tube; and the other is to make the area of the equivalent round tube equal to that of the oval tube. The present research uses the sector method to calculate the fin efficiency of finned oval tube exchangers. The fin efficiencies obtained from the equal-perimeter and equal-area methods were compared with those calculated from the sector method. The equal-perimeter method yields a higher fin efficiency, whereas the equal-area method gives a lower fin efficiency compared to the sector method. To make the Schmidt equation applicable to the oval tube case, correlations for determining the radius of the equivalent round tube were developed based on the results generated by the sector method. Correlations are provided for both staggered and in-line arrays of oval tubes. By combining the radius correlation with the Schmidt equation, one can readily determine the fin efficiency of a finned oval tube exchanger with accuracy comparable to that of the sector method.
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