An experimental study of natural convection in horizontal rod-bundle enclosures

An experimental study was conducted to investigate natural convection heat transfer in horizontally oriented rod-bundles. Experiments were performed on 3 x 3, 5 x 5, and 7 x 7 arrays of square pitched electrically heated rods. The bundles were contained in an isothermal square enclosure, and each rod was supplied with a uniform power dissipation per unit length. Steady state temperature results illustrate that the individual rods of a particular array have distinct characteristics, and furthermore patterns are observed as the array sizes increase. Temperature, power, and pressure data were reduced to develop engineering correlations in the form of Nusselt number as a function of Rayleigh number for all rods in the three arrays. A generalized correlation that incorporates array size as a parameter is also given for estimating maximum rod temperatures.