Abstract
Abstract:
Experiments were performed to investigate the performance
enhancement of single-phase flow and boiling heat transfer in
the 3D inner finned helical tubes. The tests for single-phase flow
and heat transfer were carried out in the helical tubes with a
curvature of 0.0663 and a length of 1.15m, the range of the
Reynolds number examined varies from 1000 to 8500. In
comparison to the smooth helical tube, the experimental results
of two finned helical tubes with different inner fin geometry
showed that the heat transfer and flow resistance in the 3D inner
finned helical tube gains greater augmentation. Within the
measured range of Reynolds number, the average augmentation
ratio of heat transfer of the two finned tubes are 71% and 103%,
compared with the smooth helical tube, and 90% and 140% for
flow resistance, respectively. The tests for flow boiling heat
transfer was carried out in the 3D inner finned helical tube with
a curvature of 0.0605 and a length of 0.668m.Compared with
that in the smooth helical tube, the boiling heat transfer
coefficient in the 3D inner finned helical tube is increased by
40%~120% under varied mass flow rate and wall heat flux
conditions, meanwhile, the flow resistance coefficient increased
by 18%~119%.