Influence of metal foam and nanoparticles on convective melting in a rectangular cavity under heating of bottom wall

Abstract

Highly thermally conductive elements such as metal foams and nanoparticles are often used as heat transfer enhancers for phase change materials. The influence of each factor separately has been well studied, but very few works have been devoted to the combined interaction of porous media and nanoparticles in PCM. Present study is devoted to the topic of phase transition intensification using the metal foam and nanoparticles. The melting process in a closed two-dimensional cavity with a porous copper insert filled with lauric acid has been numerically studied. The mathematical model has been formulated in terms of dimensionless stream function, vorticity and temperature. Using the finite difference technique in combination with enthalpy approach the local temperature and hydrodynamic characteristics of the process have been obtained, also the melting front has been traced. As a result of numerical simulation, the effects of the physical properties of the metal foam and the concentration of nanoparticles on the features of heat transfer and melting phenomenon have been analyzed. It has been shown that metal foam with low porosity can significantly reduce the temperature due to an increase in the thermal conductivity of the medium, however, depending on the structural properties of the metal foam at a high heat flux q = 4000 W/m2, the differentiation of local temperatures can reach 30 °C with a change in porosity and exceed 50 °C when changing the pore density. In this case, the addition of nanoparticles has an insignificant effect on the enhancement of heat transfer and, in some cases, increases the temperature of the heated surface.

Keywords

• Phase change material
• Metal foam
• Nanoparticles
• Natural convection
• Numerical analysis