Thermal behaviour of the flow boiling of a complex nanofluid in a rectangular channel: An experimental and numerical study

Abstract

The evaluation of the nanofluid flow boiling heat performance for VARs was stated experimentally and numerically in a rectangular tube. The nanofluid is composed of a salt solution (acetone‑zinc bromide) with graphene nanoparticles in suspension operating sub-level waste heat. Computational fluid dynamic (CFD) simulations were achieved to evaluate a numerical demonstration under the effects of different nanoparticle loadings and boiler temperature, which represent the experimental cases under the same boundary conditions. The experimental data showed that the base-fluid density affects the stability of the solution. The thermal conductivity enhanced by 4.5% with rising the loading of graphene by 0.5 vol%. The viscosity increases for a higher nanoparticle's concentration. The experimental work confirms details from the CFD models. Increasing the nanoparticles loading enhances the heat transfer coefficient at the heated surface as well as a higher boiling point increases both the vapour pressure and saturation temperature. The boiling point of the acetone increases with increasing the loading of the nanoparticles or the salt. Heat flux and heat transfer coefficient are linearly proportional to the boiler surface temperature. The improved heat transfer characteristics demonstrate that the fluid combination is a good candidate for the application considered. The experimental results prove the capability of the four phases CFD approach for concentrated salt solution nanofluid boiling.