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The role of magnetic field and natural convection on the solid-liquid interface motion, flow, and heat transfer during melting of gallium on a vertical wall is reported in this paper. The classical geometry consisting of a rectangular cavity with uniform but different temperatures imposed at two opposite side walls, insulated top, and bottom walls is considered. The magnetic field is imposed in the horizontal direction. A numerical code is developed to solve for natural convection coupled to solidliquid phase transition and magnetic effects. The corresponding streamlines and isotherms predicted by the numerical model serve to visualize the complicated flow and temperature field. The interplay between the conduction and convection modes of heat transfer stimulated by the combination of the buoyancy-driven flow and the Lorentz force on the fluid due to the magnetic field are studied. The results show that the increase of Rayleigh number promotes heat transfer by convection, while the increase of Hartmann number dampens the strength of circulating convective currents and the heat transfer is then mainly due to heat conduction. These results are applicable in general to electrically conducting fluids and we show that magnetic field is a vital external control parameter in solid-liquid interface motion.

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A decrease in the utilization of fossil energies, mainly by replacing them with renewable energy sources (RESs), is regarded as a potential energy source in today’s applications. RESs are broadly utilized for heating purposes and particularly with applications in solar water heater (SWH). Despite the accessibility of SWH technologies and their affordable prices in Iran, there is no comprehensive study to explain the potential of Iranian regions to supply hot water for household applications. This one-year work, hence, attempts the first dynamical simulation of a solar heating system to provide sanitary hot water (SHW) as well as hot water demanded to heat 47 stations in Iran. Weather data were extracted from METEONORM and environmental-technical analyses performed by thermal solar (TSOL) software. Stations were ranked based on CCR and BCC models in data envelopment analysis (DEA) method using GAMS V 24.1. As with results, a total of 223.1 MWh solar heat is generated annually from all stations that prevent the emission of 64.5 t CO2 every year. According to CCR and BCC models, Bandar Abbas, Chabahar, Fasa, Iranshahr, Kermanshah, Khoramabad, Sarab, Shahr-e-kord, Yasuj, Zanjan, and Zahedan are the best in this regard. Also according to the economic analysis, the average price of home solar heating in Iran is 0.160 $/kWh.

Fluid-solid interaction phenomenon study is necessary for the analysis of several engineering systems such as structures and vessels that interact with wind and blood flow, respectively. In this study, the interactions between buoyancy-driven airflow and elastic baffle(s) inside a square enclosure were modeled numerically. While the two sidewalls of the enclosure were insulated, the lower and upper walls were kept at hot and cold temperatures, respectively. The heat transfer rate through the hot wall by calculating the Nusselt number and von Mises stress at the baffles’ root for various configurations of baffle(s) was considered. The domain was modeled in ANSYS Workbench, and the k-ε model was employed to solve the turbulent convective flow (Ra > 107). A two-way algorithm along with the finite element method was employed to simultaneously solve the equations governing the fluid flow and the solid phase. The dynamic mesh method was employed to account for the change in the location of the fluid domain at a new time step. The results show the elastic baffle, in comparison to solid baffle, intensifies the heat transfer rate by 15%. The results also indicate that the Nusselt number in the single-baffle case is higher than in double-baffle cases. The fact that the amount of von Mises is a function of the baffles’ configuration is another point obtained from the results. It was found that the von Mises stress at the baffles’ root represents more unsteady fluctuations in the asymmetric case, while it approaches a constant value in the symmetric case.