Internal forced convective heat transfer in coiled pipes

When a fluid flows through a coiled pipe the effect of the centrifugal forces is to superimpose a secondary flow onto the primary (axial) flow, acting in a plane perpendicular to the pipe axis. As a result of the secondary flow there is an increase in the rates of forced convective heat, mass and momentum transfer (and hence pressure drop) over the values obtained in a similar straight pipe. Heat transfer data for the flow of singlephase Newtonian fluids in coils is presented and is complementary to another item which can be used to calculate the corresponding pressure drop data. The data for helical coils is presented but some guidance is given for non-helical coils.