numerical investigation on heat transfer and performance number of nanofluid flow inside a double pipe heat exchanger filled with porous media

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 dai=dao=0.1 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 dai=dao from 0.0001 to 0.1, results in an increase of 138%. for pressure drop, by keeping dai=dao=0.1 and increasing reynolds number from 500 to 2000, it is 40 times. furthermore, maintaining reynolds number at re=500 and changing dai=dao 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%.