Second law performance of a novel four-layer microchannel heat exchanger operating with nanofluid through a two-phase simulation

A 3D two-phase analysis is conducted to evaluate the second law features of a counter-flow four-layer microchannel heat exchanger (MCHE) operating with an Al2O3-water nanofluid. The coolant is considered water, while the hot fluid is the nanofluid. Three MCHEs with varied number of channels are examined. This investigation highlights the minimization of the exergy destruction to figure out the conditions in which the amount of degraded energy is lowest. Suspending more nanoparticles diminishes the thermal irreversibility of the nanofluid up to 61.6%, whereas the cold water experiences around 11.7% higher thermal irreversibility. At the small flow rates, increasing the volume fraction causes smaller exergy destruction, while at great flow rates, the trend becomes slightly ascending. The greater flow rate results in the greater thermal and frictional entropy generations. The second law efficiency firstly escalates via increasing the volume fraction but then remains almost constant or even descends somewhat. (C)& nbsp;2021 Elsevier B.V. All rights reserved.

Automated summary

This study conducts a 3D two-phase analysis to evaluate the second law features of a counter-flow microchannel heat exchanger operating with a nanofluid. The results show that suspending more nanoparticles can reduce the thermal irreversibility of the nanofluid, but it increases the thermal irreversibility of the cold water. The volume fraction of the nanofluid has different effects on the exergy destruction and entropy generation at different flow rates.