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ISSN Online: 2379-1748
ISBN Flash Drive: 978-1-56700-517-2
5-6th Thermal and Fluids Engineering Conference (TFEC)
NUMERICAL INVESTIGATION ON THERMAL BEHAVIORS OF A COMPACT HEAT EXCHANGER WITH FLAT − TUBE IN ALUMINUM FOAM
要約
A numerical analysis on a heat exchanger in aluminum foam with flat − tubes is conducted. The local volume averaging process is considered for the microscopic flow equations in two-dimensional steady state regime. The Darcy-Brinkman −Forchheimer model and local thermal non-equilibrium (LTNE) condition between fluid phase and solid matrix are assumed. The foam is characterized by porosity and (number) pores per inch respectively equal to 0.9353 and 20. Different air flow rates are imposed to the entrance of the heat exchanger with an assigned surface flat - tube temperature. The distance between the axis of two consecutive tubes and the
hydraulic diameter are assumed constant whereas the distance between the external surfaces of two consecutive tubes, 2I, changes as the ratio between the flat - tube length and the radius changes. The numerical solutions are carried out by means of the Ansys-FLUENT code. The results in terms of pressure drop between the inlet and the exit of the system and in terms of average heat transfer coefficient evaluated on the external surface of the flat - tube are given. Moreover, a comparison with a configuration characterized by a cylinder tube is conducted. The results point out that the heat transfer rate for the flat tube is greater than the one for the circular tube. In terms of thermal performance, the circular tube configuration is more convenient for Reynolds number, Re,
lower than 400 whereas for Re>400 the flat-tube configuration is better.