Haiyan Lei

Local exergy loss rate in convective heat transfer

The equation of local exergy loss rate in forced convective heat transfer has been derived in present work. The obtained exergy loss equation involves exergy loss due to heat transfer and pressure drop as well as exergy generation on account of viscous heat dissipation. The dimensionless form of local exergy loss rate and entropy generation different from the previous can also be obtained. Moreover, the calculation results of two convective heat transfer problems about local exergy loss and local entropy generation proposed by Bejan are given. The effect of temperature difference, Prandtl number and Eckert number on exergy loss and entropy generation has been analysed and the comparison between exergy loss and entropy generation under various conditions has been made. Results shows that for Poiseuille flow the local exergy loss greatly differs from the entropy generation due to the presence of pressure drop. However, viscous dissipation takes an important role in exergy loss for Couette flow on account of no pressure drop.