International Research Journal of Education and Technology

In recent years, growing concerns about pollution from fossil fuels and the need for distributed power generation in regions without grid access, such as rural India, have driven interest in utilizing low-grade heat sources like solar energy. This paper presents a comprehensive analysis and modeling of small-scale Organic Rankine Cycle (ORC) systems integrated with scroll expanders for micro-solar applications (~10 kW). We evaluate thermodynamic cycles, working fluids, and expander designs suitable for moderate-temperature heat sources (350-450 K). A semi-empirical model is developed for scroll expander optimization, complemented by Computational Fluid Dynamics (CFD) simulations to provide spatial insights into thermal-fluid properties. Dimensional analysis using Ns-Ds diagrams positions scroll expanders in a unique domain, highlighting their suitability for small-scale operations. Results show that regenerative ORC configurations with fluids like R134a achieve efficiencies up to 80% in scroll expanders, with leakage losses being the dominant factor. The study concludes with recommendations for optimized designs, emphasizing the potential for cost-effective distributed solar power in India.

Keywords: Organic Rankine Cycle, Scroll Expander, Solar Thermal, Thermodynamic Analysis, CFD Simulation, Ns-Ds Diagram