Fin Pattern Effects on Air-Side Heat Transfer and Friction Characteristics of Fin-and-Tube Heat Exchangers with Large Number of Large-Diameter Tube Rows

Air-side heat transfer and friction characteristics of nine kinds of fin-and-tube heat exchangers, with a large number of tube rows (6, 9, and 12, respectively) and large diameter of tubes (18 mm), are experimentally investigated. The test samples consist of three types of fin configurations: plain fin, slit fin, and fin with delta-wing longitudinal vortex generators. The working fluid in the tube is steam. Results show that when the number of tube is larger than 6, the heat transfer and friction performance for three kinds of fins is independent of the number of tube rows, and slit fin provides higher heat transfer and pressure drop than the other two fins. The heat transfer and friction factor correlations for all the heat exchangers were acquired with Reynolds numbers ranging from 4000 to 10000. The air-side performance of heat exchangers with plain fin, slit fin, and longitudinal vortex-generator fin were evaluated under three sets of criteria, and the results showed that the heat exchanger with slit fin has better performance than that with vortex-generator fin, especially at high Reynolds numbers.