TURBULENT-FLOW IN INTEGRALLY ENHANCED TUBES .2. ANALYSIS AND PERFORMANCE COMPARISON

This article analyzes heat transfer and friction fractor data for sing le-phase turbulent flow inside enhanced tubes for different enhanced t ube types and from different data soul ces. Data are given for several enhanced tube types such as extruded tubes (ribs ol disruptions with transverse and intermediate helix angles), spirally indented tubes, an d tubes with coil inserts. In general, there is good agreement between the heat transfer data for tubes of the same type-manufactured with t he same method-from different investigations with essentially the same disruption height, pitch, and helix angle. The variations increase (2 0-30%) when comparisons are mane with similar core geometries but diff erent types such as indented and extruded, or indented and coil insert s. The performance of tubes with coil inserts is very similar to that of tubes with discrete extruded disruptions. There is substantially mo re deviation of the friction factor data from different sources, even for the same tube type. Also, the analysts shows that more care is req uired to obtain repeatable and high-quality friction factor data than heat transfer data.