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 hydrau lic diameters,low Reynolds numbers and fins. Emphasis is placed on win g-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 trans fer enhancement and pressure loss. Detailed data are presented for flo w structure, local and global heat transfer and pressure losses. The h igh potential of WVGs for compact heat exchangers is shown. Comparison of WVG-fins with offset-strip fins and louvered fins shows the advant ages of WVGs. Examples of fin-tube heat exchanger elements indicate th e large saving potential inherent in WVGs. Because of the many geometr ical parameters of WVGs, many possibilities for improvements and incor poration into heat exchangers exist. Examples of fin-tube and fin-plat e heat exchanger elements with and without WVGs are given.