Natural convection heat transfer from helicoidal pipes
Conference
Xin, RC, Ebadian, MA. (1995). Natural convection heat transfer from helicoidal pipes
. American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 310(8),
Xin, RC, Ebadian, MA. (1995). Natural convection heat transfer from helicoidal pipes
. American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 310(8),
An experimental investigation is reported on natural convection heat transfer in air from outer surface of uniformly heated helicoidal pipes with vertical and horizontal orientations. The temperatures along the flow direction and peripheral direction of the tube wall were measured. The test Rayleigh numbers range from 4000 to 100,000. The local and average Nusselt numbers are evaluated and correlated. For the vertical case, the results are compared with those of single horizontal cylinder and column of horizontal cylinders. It is found that the heat transfer from the first turn is almost the same as that of single horizontal cylinder. The heat transfer coefficient on the outer coil wall (ψ = π/2) is higher than that on the inner coil wall (ψ = 3π/2) in the middle turns of the coil, due to the tube curvature. For the horizontal orientation, the results are well correlated with the tube diameter as characteristic length. The local heat transfer characteristics is discussed as well. The overall average Nusselt number of the horizontal coil is higher than that of the vertical coil in the laminar region.
