Numerical Investigation on Heat Transfer and Performance Number of Nanofluid Flow inside a Double Pipe Heat Exchanger Filled with Porous Media

Abstract

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 500 to 2000, an increase of 56.09% was observed in the performance number. Furthermore, maintaining Reynolds number at Re=500 and changing from 0.0001 to 0.1, results in an increase of 138%. For pressure drop, by keeping and increasing Reynolds number from 500 to 2000, it is 40 times. Furthermore, maintaining Reynolds number at Re=500 and changing from 0. 1 to 0.0001, the pressure drop is 250 times. Besides, adding 3% nano particles to the base fluid enhances the performance number by about 50% and increase pressure drop by about 20%.