Enhanced thermal and optical performance of sustainable beeswax-rice husk composite phase change material: An experimental and simulation analysis

• Utilizing waste as functional additives for enhanced PCM performance. • 48 % thermal conductivity rise with 0.6 wt% rice husk , reaching 0.37 W/m·K. • UV–Vis shows 53.9 % light transmittance reduction in rice husk composite. • Thermal aging after 500 cycles: excellent chemical resilience, stable latent heat. • COMSOL simulation offers insight into melting dynamics and phase transition. Low thermal conductivity and long-term stability are key challenges while using phase change materials (PCMs). Commonly available carbon and metallic additives to enhance thermal conductivity are often expensive and raise environmental concerns. The best alternative is to explore the potential of bio-based additives that not only enhance thermal performance but also mitigate the environmental consequences. This study deals with synthesizing one type of waste derived bio-based rice husk microparticles (RHMPs). The raw rice strands were pyrolyzed at 1000 ℃, and ball milled for 5 h at 800 rpm to obtain the RHMPs of 400 nm size. The RHMPs were then dispersed into the beeswax (BW) PCM following a two-step ultrasonication process. The potential of the prepared composite PCM was subsequently analyzed in terms of its chemical integrity, thermal conductivity , heat storage behavior and light absorption capability. The results revealed that the addition of 0.6 wt% of RH micro-particles to the PCM-BW resulted in 48 % enhancement in thermal conductivity. Furthermore, the prepared composite maintained its latent heat up to 120.22 J/g with a 53.9 % light transmittance. The thermal aging analysis after 500 cycles showed the composite maintains excellent resilience to its thermophysical properties. The COMSOL simulation of the thermal performance and phase transition behavior provided insights into the melting dynamics of the composites. Additionally, the heat sink application demonstrated that the BRH 3 composite outperformed to reduce the heat sink surface temperature than PCM-BW. This study highlights the dual benefit of waste utilization and thermal performance enhancement.