NUMERICAL ANALYSIS OF ENHANCED HEAT TRANSFER IN DEVELOPING LAMINAR PIPE FLOW USING DECAYING SWIRL AT THE INLET

In the present work, laminar forced convection in the developing region of pipe flow with decaying swirl is numerically investigated. A two-dimensional swirl axisymmetric computation region has been modeled with uniform axial velocity and constant angular velocity at the pipe inlet. The effect of the inlet swirl velocity on heat transfer is described mainly through the friction coefficient and the wall Nusselt number. The results show that decaying swirl enhances local heat transfer but at the cost of increasing pumping pressure. The data shows that as swirl number increases from 0 to 2.5, the maximum local Nusselt number increases from 0% to 40%, while maximum local friction coefficient increases from 0% to 360%. Hence the insertion of a swirl generator in a tube heat exchanger reduces the size of the heat exchanger but it increases pumping system size and cost.