DRA 3. Friction in corrugated heat exchanger tubes

摘要

The friction characteristics of three externally finned, internally corrugated heat exchanger copper tubes are determined. Results for the two tubes with 17.0 and 22.6 mm inner diameter respectively, are significantly lower than the manufacturer's data. The deviations are reasonable, as the data from the manufacturer account for the coiling of the tubes in a heat exchanger and provide a safety margin for design purposes. The fortuitous agreement between the data for the 13.3 mm tube is caused by unusually high corrugations, beyond tolerance in specifications. The results was correlated with empirical equations using the actual geometrical dimensions rather than the equivalent sand roughness. 19 refs, 9 figs, 3 tabs