ESTUDIO EXPERIMENTAL DE LA TRANSFERENCIA DE CALOR EN BANCOS DE TUBOS CON ARREGLO TRIANGULAR

Abstract

In this thesis itself investigated experimentally, the Convective Heat Transfer in Staggered Bundles of smooth Tubes with dependence of the geometric in the relations of step S1/S2 = 1.0, 2.0, 3.0, 4.0 and 4.5, and different rate of flow 1000, 5000, 6300, 7900, 9900, 12500 and 15800 Reynolds, in order to obtain an empirical correlation for the calculation of the convective heat transfer in bundles of smooth tubes with crossed flow, where the dependence this one at the expense of the geometry of the bundles of tubes, in the longitudinal step S2 and the transverse step S1, and in the regime of flow ó number of Reynolds. For the accomplishment of this experiment to design a wind tunnel of acrylic, which is shaped by three sections, the first one is where there are registered the conditions of entry of the zone of tests, the second one, where the zone of tests is located and it her finalizes of capture of measurements to the exit of the zone of tests, all the these ones with a length of 1000 mm, a height of 230 mm and a width of 285 mm. The second section of the tunnel has a rectangular section opened of 285 mm as 540 mm where the zone of tests is located. The zone of tests is shaped by 43 calorimeters tubes and two calorimeters tubes thermocouple distributed in ten rows; five rows of five tubes (odd) and five rows of four tubes (pair), which have an optima length of 242 mm and a diameter of 12.7 mm. The calorimeters tubes thermocouple is located by it to the beginning and at the end of the zone of tests, these has with 10 thermocouples T (Cobre-Constantán) it distributed 4 in the central part of the tubes with a out of phase 90 º between them and three thermocouples in the top and low part of the tubes. Of equal form the system of heating was made; shaped by three modules, dissipation, administration and control, guaranteeing a equal dissipation of electrical potential in all the rows of the zone of tests. There was obtained the coefficient of average convection ( ) and the number of Nusselt (Nu) in total surface of heat transfer in the zone of tests, with a dependence in the geometry of the bundles of tubes S1/S2 principally and of the regime of flow. Of the experimental study there will be obtained five different correlations of the calculation which have an important dependence in the geometric of the bundles of tubes and where his structure consists of the exponent "n" (Ren) and of the constant "C" of the form Nu = C Ren, values that will be determined in the range of number of Reynolds from 1 000 up to 15 800 Re in the relations of steps S1/S2 =1.0, 2.0, 3.0, 4.0 and 4.5. The results obtained of number of Nusselt calculated with our correlations meet in differences of 24% in the top part of the comparison, up to 11% in the low part of the same one, with correlations of other investigators Zhukauskas, Grimison, Colburn, Tahat, etc …