Heat transfer coefficient in laminar flow of non-Newtonian fluid in tubes

Heating of non-Newtonian fluids is of particular importance to food process ing systems. However, excessive pumping demand generally precludes developm ent of turbulence in tubular arrangements. So, laminar flow is all that can be developed in heat transfer equipment handling non-Newtonian materials. The paper presents a theoretical model of heat transfer, which is dependent only on the flow behaviour index of the fluid. Increase in flow behaviour index produces a lower convective heat transfer coefficient and for real no n-Newtonian fluids Nusselt's number approaches a fixed value corresponding to a flow behaviour index of 4. (C) 1999 Elsevier Science Ltd. All rights r eserved.