Laminar Convective Heat Transfer in Rotating Curved Pipes

Abstract

When a coiled pipe rotates about the coil axis, the fluid flowing in it is subjected to both Coriolis and centrifugal forces. These combined effects complicate the flow characteristics beyond those seen in stationary curved pipes. Following a previous paper on the flow characteristics, a combined theoretical and numerical study on forced convective heat transfer is made for a fully developed laminar flow in rotating curved pipes. The similarity analysis reveals that convective heat transfer in loosely-coiled rotating pipes is characterized by four parameters : the Dean number K_LC, the body force ratio F, the Rossby number Ro and the Prandtl number Pr. The Prandtl number determines the sensitivity of heat transfer to the secondary flow ; limiting behaviours of the temperature field are discussed for various Pr based on the dimensionless energy equation. The variations of temperature structure with K_LC, F and Pr are shown, and the effect of Ro on heat transfer is described. Semi-empirical formulae for average heat transfer rate are given for a wide range of these parameters by using a new dimensionless variable.