VORTEX GENERATORS FOR COMPACT HEAT-EXCHANGERS

Compact heat exchangers are characterized by high heat duties per unit volume and high heat transfer coefficients. This implies small hydraulic diameters,low Reynolds numbers and fins. Emphasis is placed on wing-type vortex generators (WVG). They can be used as fins or to modify fins and are easily incorporated into heat exchangers. Different WVGs are evaluated experimentally and numerically with regard to heat transfer enhancement and pressure loss. Detailed data are presented for flow structure, local and global heat transfer and pressure losses. The high potential of WVGs for compact heat exchangers is shown. Comparison of WVG-fins with offset-strip fins and louvered fins shows the advantages of WVGs. Examples of fin-tube heat exchanger elements indicate the large saving potential inherent in WVGs. Because of the many geometrical parameters of WVGs, many possibilities for improvements and incorporation into heat exchangers exist. Examples of fin-tube and fin-plate heat exchanger elements with and without WVGs are given.