Y.B. Tao

Numerical study on performance and fin efficiency of wavy fin-and-tube heat exchangers

Three-dimensional numerical studies were performed for the performance of wavy fin-and-tube heat exchangers in Body-Fitted Coordinates (BFC) system. Effects of geometric parameters on air-side heat transfer and fluid flow characteristics and fin efficiency were examined. The results showed that with the increase in Reynolds number, wavy angle, fin thickness and the decrease in fin pitch and transverse tube pitch, the heat transfer performance are enhanced; however, pressure drops are also increased. So, in practical applications, the wavy angle had better be located between 10° and 20° and the fin pitch should be located between 1.2 mm and 2.0 mm. The fin efficiency and average fin surface temperature decrease with the increase of Reynolds number, wavy angle, fin pitch and transverse tube pitch. With the increase of fin thickness, the fin efficiency and average temperature on fin surface also increase.

Numerical study on the performance of wavy fin heat exchangers with different elliptic tube patterns

3D numerical studies on air side heat transfer and fluid flow characteristics of wavy fin-and-tube heat exchanger are performed for circular tube and four elliptic tube patterns. The elliptic tubes have the same tube perimeter, tube section area, tube hydraulic diameter and minimum airside free-flow area as circular tube respectively. Compared with circular tube, average Nu of the four elliptic tube patterns are enhanced 12.3, 14.6, 17.0 and 16.9% respectively; the f of the previous three elliptic tube patterns are decreased 23.9, 20.7 and 17.0%, but the friction factor for the fourth elliptic tube pattern increases 7.1%.