HEAT TRANSFER TO LAMINAR NON-NEWTONIAN FLOW IN A CIRCULAR TUBE WITH VARIABLE CIRCUMFERENTIAL WALL TEMPERATURE OR HEAT FLUX

摘要

An analysis is presented for fully developed heat transfer for laminar flow of a power-law non-Newtonian fluid in a circular tube with arbitrary circumferential wall temperature or heat flux. The results allow calculation of temperature or wall heat flux variations for various velocity profiles when the tube has a uniform axial heat input and an arbitrary peripheral wall-temperature or heat-flux variation. The circumferential variation of Nusselt modulus with respect to these temperature or heat-flux variations and velocity profiles is shown. It is found that heat-transfer analyses based on the assumption of a parabolic velocity distribution will introduce serious errors when the fluid exhibits a nonlinear shearing-stress - shearing-rate relation, so that the actual behavior of the velocity profile must be considered.