Internal Longitudinal Fins Research Articles

Conjugate heat transfer in channels with internal longitudinal fins

A computational study examines the fully developed laminar flow and heat transfer characteristics of a parallel-plate channel with internal, longitudinal, rectangular fins. The fins are integrally attached to the channel top wall, whose outer surface is heated uniformly. The bottom wall is adiabatic. The study determines the effects of varying the fin height, the fin thickness, the fin pitch, and the wall-to-fluid thermal conductivity ratio on the pressure drop in the channel and the heat transfer from the exposed channel wall and fin surfaces. The results of the conjugate heat transfer study, which are applicable to the design of heat exchangers, include the overall heat transfer, the channel pressure drop, the heat transfer per unit pumping power, and the distributions of the local temperature and velocity.

Experimental Investigation of Laminar Mixed Convection in Tubes With Longitudinal Internal Fins

Experiments were performed to study the pressure drop and heat transfer characteristics for laminar flow in a smooth tube and four tubes with internal longitudinal fins, with emphasis on showing how the experimental results relate to previous analytical predictions. Measured quantities include the fully developed friction factor, local and fully developed Nusselt numbers. Good agreements were obtained between the friction factor results and previous analytical predictions, and between Nusselt number results for the smooth tube and previous experiments. Free convection is shown to have a strong influence on heat transfer in finned tubes and the results approach the forced-convection predictions as Rayleigh number decreases. Internal fins appear to retard the onset of significant free convective currents; however, once initiated, a faster rate of heat transfer enhancement occurs compared to the smooth tube. An empirical correlation of fully developed Nusselt number is presented taking into account the influences of tube geometry.

Analysis of Laminar Heat Transfer in Internally Finned Tubes with Uniform Outside Wall Temperature

An analysis is presented for fully developed laminar convective heat transfer in tubes with internal longitudinal fins and uniform outside wall temperature. The governing momentum and energy equations were solved numerically, with the influence of fin conductance accounted for by a single parameter. The distributions of fin temperature, fluid temperature and local heat flux (both at the fin and unfinned surfaces) are presented. These are shown to be strongly dependent on finned tube geometry and, in some cases, on the fin conductance parameter as well. Based on average heat transfer per unit area, the various fins proved more effective than the unfinned surfaces. Values for overall Nusselt number indicated significant heat transfer enhancement over smooth tube conditions.

Solution of some boundary problems of heat conduction for cylindrical bodies provided with longitudinal fins

The paper deals with a solution of the temperature field in cylindrical bodies consisting of several annuli provided with external or internal longitudinal fins in the shape of annular sectors or prisms. The problem is analysed for boundary conditions varying along the periphery, and for an arbitrary distribution of sources over the cross section. Problems of this type are encountered in thermal-engineering computations of longitudinally finned nuclear reactor fuel elements or of longitudinally finned tubes of heat exchangers. The method evolved in the paper can also be applied to problems concerning laminar flow in non-circular channels.