Heat transfer of fully developed flow in curved tubes
Abstract
Fully developed laminar flow for a horizontal heated curved tube is studied numerically. The tube is heated so as to maintain a constant axial temperature gradient. A physical model is introduced which accounts for the combined effects of both buoyancy and centrifugal force. Results for a Prandtl number of one are presented for a moderate range of Dean numbers and the product of the Reynolds and Rayleigh numbers. Detailed predictions of the flow resistance, the average heat transfer rate and the secondary flow streamlines are given. Also presented are results on the position of the local maximums of shear stress and heat transfer rate. The numerical results reveal that the mass flow rate is drastically reduced due to the secondary flow for a given axial pressure gradient. Consequently, the total heat transfer rate decreases for a more curved tube as well as for a larger axial temperature gradient. A flow regime map is provided to indicate the three basic regimes where (1) centrifugal force dominates, (2) both buoyancy and centrifugal forces are important, or (3) buoyancy force dominates.
 Publication:

ASME and American Institute of Chemical Engineers, 20th National Heat Transfer Conference
 Pub Date:
 August 1981
 Bibcode:
 1981ceht.conf.....P
 Keywords:

 Curvature;
 Heat Transfer;
 Laminar Flow;
 Pipe Flow;
 Buoyancy;
 Flow Equations;
 Heat Transfer Coefficients;
 Secondary Flow;
 Temperature Gradients;
 Fluid Mechanics and Heat Transfer