Session: 11-44-01: Heat and Mass Transfer for Renewable Energy Conversion Processes

Paper Number: 94797

94797 - Entropy Generation Analysis on a Thermoelectric Generator in an Exhaust Automotive Line With Porous Media 

Nowadays, a great attention is payed on waste heat recovery technologies that can be used to save energy. Steam turbines and gas turbines can be used to generate electricity when there are high and intermediate temperature wastes, but there are still problem in the utilization of waste heat in low-temperature range. Furthermore, industries and governments try to increase the power efficiency because of the increment of fuel costs. A considerable amount of energy is discharged into the atmosphere in the form of the exhaust gas. A thermoelectric generator (TEG) can improve fuel economy by harvesting the waste heat energy. TEG technology has no moving parts, and it is compact, quiet, highly reliable and environmentally friendly respect to the conventional methods. There are several existing researches; however, the efficiency of TEG is still too low. The TEG coupled to the exhaust line has the problem of the low convective heat transfer between the gas and the duct surface. For this reason, where the TEG is placed, the thermal resistance should be reduced and, consequently, the temperature difference between the hot and cold surfaces of the TEG increases. One possible method is the utilization of the metal foams inside the exhaust line in the zone where is the TEG.

In the present paper, entropy generation analysis on a two-dimensional steady state convective heat transfer problem in a channel partially filled metal foam with an external TEG component is accomplished. The channel simulates an automotive exhaust line and it is characterized by a length equal to 272 mm and by a height of 60 mm; instead, the TEG on the external surface has the dimensions equal to 65 mm and 8.5 mm. The analysis is carried out assuming the local thermal equilibrium model and the gas is assumed to have the same properties of the air and for assigned temperature of the upper surface of the TEG. The thermophysical properties are temperature independent and the TEG is studied as a solid with an internal energy generation. The governing equations for gas, porous media and TEG are solved by finite volume method using the Ansys-Fluent code. Different thicknesses of metal foam and their values range from 1/8 of the half height of the channel to the total height of the channel. Different porosity and pore density are considered in the investigation. Results in terms of local and global entropy generations related to the thermal and viscous effects are given.

Presenting Author: Oronzio Manca Università degli Studi della Campania "Luigi Vanvitelli"

Presenting Author Biography: Oronzio Manca is full professor at Università degli Studi della Campania “Luigi Vanvitelli”. Member of Scientific Council of International Center for Heat and Mass Transfer, American Society of Mechanical Engineering, AIGE and UIT. He was Associate Editor for ASME Journal of Heat Transfer and he is AE for Journal of Porous Media and Alexandria Journal of Engineering. Member of the Editorial Advisory Boards for several journals. He is author or coauthor of 610 scientific papers, 170 on peer reviewed journals and 16 book chapters. Head of PhD School of Polythecnic and Basic Sciences at his University. His h-index on Scopus is 38. Recent research interests are related to heat transfer in porous media, metal foams, heat transfer in microchannels, enhancement heat transfer techniques, such as baffles in channels and nanofluids, sensible and latent thermal energy storage systems analysis and nano PCM.

Authors:

Bernardo Buonomo Università degli Studi della Campania “Luigi Vanvitelli”
Anna Di Pasqua Università degli Studi della Campania “Luigi Vanvitelli”
Oronzio Manca Università degli Studi della Campania "Luigi Vanvitelli"
Sergio Nappo Università degli Studi della Campania “Luigi Vanvitelli”