DEVELOPING TURBULENT MIXED CONVECTION IN A HORIZONTAL CIRCULAR TUBE WITH STRIP-TYPE INSERTS

An experimental study was undertaken for developing turbulent mixed co nvection in a horizontal circular tube with strip-type inserts (longit udinal strip LS and crossed-strip CS inserts) for 6500 less than or eq ual to Re less than or equal to 19,500 and 5.82 x 10(4) less than or e qual to Gr less than or equal to 9.78 x 10(7). Temperature data were measured and heat transfer rates at different heat flux levels were ca lculated and correlated in the form of relevant parameters. The buoyan cy effect was detailedly examined for 1.53 x 10(-4) less than or equal to Gr/Re-2 less than or equal to 2.31. It is found that the buoyancy effect has less influence for tubes with inserts compared to the bare tubes. Moreover, the heat transfer enhancement was found 2-3 times th an those of bare tubes. (C) 1997 Elsevier Science Ltd.