Entropy generation analysis of nanofluids flow in various shapes of cross section ducts

Abstract

The selection of flow passage's cross section shape is important in thermal system design such as compact heat exchanger. A variety of duct's shapes can be used to enhance the thermal performance. However, it must be noted that different thermal and friction characteristics can be initiated due to this approach. Therefore this paper investigates the entropy generation characteristics of three types of duct's cross section subjected to constant heat flux. The considered shapes are circular, square and triangle (equilateral). Al2O3 and MWCNT based nanofluids are used as working fluids in the analysis. The study found that the total entropy generation of Al2O3 based nanofluids decreases with the increase of particle volume fractions. However, this parameter increases when working fluid's mass flow rate and heat flux applied to the duct increase. On the aspect of cross section's shape, circular duct exhibits lowest total entropy generation compared to other considered shapes. Moreover, it was also found that MWCNT based water nanofluids exhibit lower total entropy generation compared to Al2O3 based nanofluids due to its high thermal conductivity value.