Design and Performance of a Solar Water Heater Based on Nanocomposites of Polypropylene and Plasma-Modified Carbon Nanofibers

Fossil fuels, including coal and natural gas, remain the dominant sources of energy worldwide. However, their excessive use has led to severe environmental consequences, including climate change and global warming. This study contributes to mitigating environmental challenges by presenting the design, fabrication, and performance evaluation of a novel nanocomposite-based solar water heater (N-SWH). The tubular finned profile was optimized using finite element analysis and fabricated via the extrusion of polypropylene (PP) reinforced with plasma-modified carbon nanofibers (CNFs [M]). The assembled system was then connected to an insulated storage tank and subjected to field testing, following standardized theoretical validation protocols. Results demonstrate that the incorporation of CNFs [M] significantly enhances the dispersion and interfacial compatibility within the polymer matrix, leading to a 535% increase in thermal conductivity (from 0.14 to 0.89 W/m·°C), while maintaining the mechanical properties (elastic modulus, yield stress, and rupture stress) and thermal stability of pipe-grade PP. Field testing recorded a maximum outlet water temperature of 42 °C under a solar irradiance of approximately 808 W/m², corresponding to a collector efficiency of 0.6. This temperature is suitable for preheating water in conventional gas heaters, enabling daily gas savings of up to 76.6%. With a surface area of only 0.8 m² and a weight of 1.2 kg, the developed solar collector exhibits excellent functional performance and material properties, positioning it as a lightweight, durable, cost-effective, and environmentally friendly alternative to conventional metallic systems.