Ehsan Aminian - Department of Mechanical Engineering, Iran University of Science and Technology, Iran
Babak Ahmadi - Department of Mechanical Engineering, Iran University of Science and Technology, Iran

Two common methods to augment heat transfer are the application of nanofluids and porous inserts. In the present work, heat transfer inside a double tube heat exchanger filled with porous media is analyzed numerically using two phase mixture model for the nanofluid flow and the Darcy-Brinkman-Forchheimer model for the flow inside porous media. Basically, porous media improve heat transfer at the expense of increasing pressure drop. A new PN (Performance number) -defined as the ratio of heat transfer to pressure drop on the base state (without porous media and nanoparticles)- is introduced to better judge the first law’s performance of configurations. Results indicated that by keeping  and increasing Reynolds number from ۵۰۰ to ۲۰۰۰, an increase of ۵۶.۰۹% was observed in the performance number. Furthermore, maintaining Reynolds number at Re=۵۰۰ and changing  from ۰.۰۰۰۱ to ۰.۱, results in an increase of ۱۳۸%. For pressure drop, by keeping  and increasing Reynolds number from ۵۰۰ to ۲۰۰۰, it is ۴۰ times. Furthermore, maintaining Reynolds number at Re=۵۰۰ and changing  from ۰. ۱ to ۰.۰۰۰۱, the pressure drop is ۲۵۰ times. Besides, adding ۳% nano particles to the base fluid enhances the performance number by about ۵۰%  and increase pressure drop by about ۲۰%.

CFD, Heat Exchanger, Performance Number, Porous Media