| Abstract: |
There is no doubt that the study of the heat transfer characteristics of longitudinal rectangular-fin arrays has a great deal of research efforts for developing compact heat exchanger devices such as aerospace and automobile vehicles, gas-cooled nuclear reactors, cooling of electronic component for digital computers, the instrumentation of modern aircraft investigations have been performed to study the heat transfer, the fluid flow and the pressure DROP characteristics of longitudinal rectangular-fin arrays. Three different orientations of the test model in the flow field; (i) Parallel flow, (ii) Impinging flow and (iii) Reverse impinging flow were done to determine the optimal position for the fin array in the flow field. Then determine the response of the heat transfer from a longitudinal fin arrays (the optimal position in the flow field) to the presence of clearance between the fin tips and an adjacent shroud. During the experiments, the clearance was varied parametrically; starting with the no-clearance case. Two shroud types were used: the first one is plain and the other is equipped with wire coil (modified shroud). The heat transfer coefficient corresponding to the presence and absence of clearance were compared under the condition of equal air flow rate. The study also investigate the effect of the fin arrays geometries (fin thickness, fin height and inter-fin space) and Reynolds number on the flow and heat transfer characteristics. Different geometrical parameters were varied during the study such as the fin height H = 23,46 and 92 mm, the fin thickness t = 3, 6 and 10 mm, the inter-fin space W = 10, 14.6, 18, 22.8, 30 and 42 mm and the fins number N = 12, 10, 8, 7, 6, 5 and 4 fins with the fin length L = 150 mm, was kept fixed during all experiments. Air is the working fluid in all experiments, the flow regime is turbulent, with assuming constant properties, and Prandtl number 0.7 with Reynolds number ranging from 7x104 to 5x105 based on the test section hydraulic diameter. The flow entered the tested section with uniform velocity and temperature profiles.
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