لخّصلي

This study numerically investigates integrating phase-change materials (PCMs) into passive solar buildings. A two-dimensional CFD model, using the enthalpy-porosity formulation, simulates PCM melting in a rectangular enclosure heated from one side (Th = 38.3 °C) while the opposite side is kept cold (Tc = 28.3 °C), with insulated horizontal walls. The impact of rectangular and triangular fins on heat transfer and melting is analyzed for a Rayleigh number around 10⁶. Results, showing melt fraction contours and temperature distributions, demonstrate that higher PCM specific heat capacity (Cp) and thermal conductivity (λ) accelerate melting. Rectangular fins sped up melting (from 35 to 32 minutes) due to increased surface area, while triangular fins promoted more uniform melting. The study details the effects of thermophysical properties and fin integration on flow structure and heat transfer.

The overall aim of this work is to integrate PCM elements into passive solar buildings. To achieve this goal numerical studies were carried out to describe the complex behavior of PCM melting filling a rectangular
enclosure initially set at a cold temperature Tc. The cavity is vertically heated from the right side wall with a
temperature Th = 38.3 °C while and the left cold wall was maintained at the cold temperature Tc = 28.3 °C. The
horizontal walls were insulated. A transient numerical model based on the enthalpy-porosity formulation is used
to study the heat transfer and the melting behaviors through two-dimensional CFD simulations. To enhance the
heat transfer and the melting process of the PCM, fins with a rectangular and triangular shape are proposed.
Moreover, the effects of both thermophysical properties and fins integration on the flow structure and heat
transfer characteristics are investigated in detail. The melt fraction contours with the natural convection driven
flow are described and compared, as well as the temperature distributions for a Rayleigh number of around
Ra = 106. It is found that the rate of the melting increases with the increase in the values of specific heat capacity
Cp as well as the thermal conductivity λ of the PCM Gallium. The results showed that the rectangular fin configuration
accelerated the PCM melting faster than the triangular fin's shape (the melting time has improved
from 35 min to 32 min) thanks to the increased exchange area, while the triangular fin uniformized the melting
process inside the enclosure.