Controlling energy loss from roof structures equipped by round-corner double semi-hexagonal ferro- phase change material layer using magnetic field

Abstract

Improving the thermal characteristics of building enclosures is a must in the context of rising global energy consumption. Heat losses through roof enclosures are one of the main causes of excessive energy consumption in the Heating, ventilation, and air conditioning systems in buildings. Designing novel roof structures to reduce heat losses is essential. The Phase Change Materials through their thermal properties can provide an effective passive solution in this regard. The present paper is dedicated to the analysis of a roof structure incorporating a Ferro-Phase Change Material enhanced with nanoparticles and subjected to an external magnetic field. The Ferro- Phase Change Material is placed in a round-corner semi-hexagonal block that can be oriented horizontally or vertically in the roof structure. The equations governing the heat and flow are developed and presented in the non-dimensional form. The set of equations were discretized and solve using control volume based finite element method. The effect of Hartmann number, the inclination of the magnetic field and the orientation of the Phase Change Material block on the flow and thermal behaviors of the Phase Change Material and on the thermal resistance of the roof structure are assessed. It is found that when the Ferro- Phase Change Material block is oriented vertically, it offers 30% less thermal resistance than the horizontal configuration in the absence of magnetic field. Increasing Hartmann number from 0 to 200 raises the thermal resistance by 80% for the vertical case and 45% for the horizontal case. Changing the inclination angle of the magnetic field has more effect on the Phase Change Material when its block is oriented vertically, with 30% faster melting and 45% decrease in the thermal resistance are found when the magnetic field is applied vertically instead of horizontally.