ENTROPY GENERATION ANALYSIS ON A THERMOELECTRIC GENERATOR IN AN EXHAUST AUTOMOTIVE LINE WITH POROUS MEDIA

In the present paper, an entropy generation analysis on a 2-D steady state problem in convective regime of an aluminum foam partially and totally filled channel with an external TEG element is solved in numerical way. The channel has a length of 272 mm and a height equal to 60 mm; instead, the TEG is characterized by a length equal to 65 mm and by a thickness of 8.5 mm. The numerical analyses are accomplished with the assumption of the local thermal equilibrium (LTE) model in order to consider the metal foam presence. The working fluid is exhaust gas characterized by the same properties of the air in correspondence to the TEG upper surface temperature. The TEG is considered as a solid component characterized by an internal energy generation. The thermophysical properties are assumed temperature independent. Ansys-Fluent code is employed in order to resolve the governing equations for exhaust gas, metal foam and TEG. Different exhaust gas mass flow rates on the inlet section are assumed. Several thicknesses of aluminum foam values are employed. The porous media are characterized by a porosity from 0.90 to 0.978 and number of pores per inch (PPI) equal to 5, 10, 20, 40. Results are given in terms of global entropy generations related to the thermal and viscous effects.