EFFECT OF ECCENTRICITY AND THERMAL-BOUNDARY CONDITIONS ON LAMINAR FULLY-DEVELOPED FLOW IN ANNULAR DUCTS

Numerical solutions for laminar, fully developed, forced convective he at transfer in ecccentric annuli are presented. With an insulated oute r surface, two types of thermal boundary conditions have been consider ed: constant wall temperature (T), and uniform axial heat flux with co nstant peripheral temperature (H1) on the inner surface of the annulus ; these are representative of many practical applications. Isothermal friction factors and Nusselt numbers for concentric annulus are in exc ellent agreement with previously reported results. Velocity and temper ature profiles, and isothermal fRe, NUi,T, and Nu(i,H') values for dif ferent eccentric annuli (O less than or equal to epsilon less than or equal to 0.6) with varying aspect ratios (0.25 less than or equal to r less than or equal to 0.75) are presented. The eccentricity is foun d to have a strong influence on the flow and temperature fields. The f low tends to stagnate in the narrow section and has higher peak veloci ties in the wide section. This flow maldistribution is found to produc e greater nonuniformity in the temperature field and a degradation in the average heat transfer. Also results show that the H1 condition sus tains higher heat transfer coefficients relative to the T condition on the inner surface, except for very large eccentricity.