Unsteady convective heat transfer in nanofluids at instantaneous transition to film boiling

The paper analyses a novel model of unsteady convective heat transfer in a nanofluid layer on a flat vertical surface subject to instantaneous (abrupt ) onset of film boiling. It occurs i f heat flu x suddenly switched on exceeds the critical heat flux necessary to bring a nanofluid to fi l m boilin g regime. The usual system of equations of fluid flow and convective heat transfer is supplemented by an equation for the concentration of nanoparticles. To complement the problem statement, two sets of the bounda r y and initial conditions were used. The first con-dition corresponds to problem of film boiling derived by Bromley, whereas the second was suggested by Ellion for a stationary liquid at the vapor-liquid interface. The solution of the problem enabled predicting variation of temperature distributions, Nusselt numbers, velocity profiles and friction coefficients in time. Computations were performed numerically based on the self-similar equations derived using the Lie group transformations. Results of unsteady simulations of convective heat transfer during instantaneous onset of fi l m boiling of a nanofluid with different concentrations of nanoparticles demonstrated qualitative agreement with experiments.

Automated summary

This paper analyzes the unsteady convective heat transfer during instantaneous film boiling of a nanofluid on a flat surface, using numerical computations based on self-similar equations to demonstrate qualitative agreement between simulated and experimental results.