Nanofluid pool boiling and deposition on a cylinder

Abstract

There are still some unknown aspects of nanofluids regarding simulations. Pool boiling flows are complicated in terms of numerical modelling and presence of particles can noticeably expand this complexity. Two-dimensional pool boiling flow with nanoparticles is numerically solved around a horizontal cylinder for validation purposes. For further study, a tube bundle with four tubes is considered with nanofluid pool boiling. Unsteady Eulerian two-fluid model in ANSYS-Fluent is used to simulate the liquid and vapour flows in the computational domain. On the other hand, the particles are injected and tracked in the domain in the Lagrangian frame via the discrete model. Coupling between two frames is carried out through some user defined functions and the effects of final outcomes appear as thermos-physical properties. It means that nanofluid mixture properties are a function of local volume fraction. Superheat temperature and heat transfer coefficient from modelling are compared with experimental measurements. The good agreement is found and further discussion regarding particles migration and deposition are presented. Since the real fluctuation of the surface roughness cannot be introduced, an estimation of deposition predicted by the discrete model is presented. It is found that the percentage of deposition depend on heat flux and a weak function of particle concentration.