Abstract
This research investigates a novel solar latent heat thermal energy storage (LHTES) system designed for building windows, featuring cylindrical enclosures filled with phase change material (PCM). The system addresses the drawbacks of traditional PCM-filled double-glazed windows, such as daylight hindrance and leakage. Utilizing the advantages of the Lattice Boltzmann Method (LBM), such as its simplified algorithm and its superior ability to simulate complex physical processes, including phase transitions, the study simulates the volumetric radiation-conduction melting of PCM within a single cylinder, as well as time- and location-dependent boundary conditions. Incorporating realistic conditions like convective boundary conditions, shadow effects, and variable solar radiation angles. The analysis assesses multiple parameters, including cylinder diameter, extinction coefficient, scattering albedo, solar angle, shadow effect, and natural convection heat transfer coefficient, focusing on their influence on the melting fraction and charging time. Additionally, the research evaluates the impact of a cylindrical chamber's wall thickness and refraction index on the PCM melting process. It considers the refraction effects and heat loss due to varying wall thickness under constant or variable solar radiation intensities. The results reveal significant effects of convection heat loss and shadow on the charging time. For convective boundary conditions with heat transfer coefficients of 4, 8 and 12 𝑊/𝑚2𝐾 , the charging time increased by 11%, 30% and 50%, respectively, compared to an insulated boundary condition without shadow, and by 38%, 91% and 175% with a 90-degree shadow. The study also highlights that the refractive index of the wall decreases the charging period by approximately 22% in insulated enclosures and 19% in those with convective boundaries. Keywords: Melting, solar radiation, LBM, PCM, shadow, refraction