Fresnel Lens-Based Concentrated Solar Thermal System for Compact High-Temperature Processing

High-temperature thermal storage and material processing applications demand efficient solar energy conversion with minimal thermal losses. Traditional concentrated solar power (CSP) receiver designs suffer from relatively large surface areas with significant convective and radiative losses, limiting practical operating temperatures and system scalability. This work presents a novel concentrated solar thermal (CST) architecture integrating a one-meter diameter PMMA Fresnel lens with an optical light pipe-based receiver, designed to achieve high concentration ratios while minimizing receiver surface area and associated thermal losses.

The system design is for high concentration ratios, in the order of 1000×, enabling large focal flux densities in the order of MW/m² and receiver temperatures exceeding 1000°C. The Fresnel lens, with a 1000 mm diameter aperture and over 80% optical efficiency, focuses incident solar radiation onto a compact coupling area (20 mm diameter), substantially reducing surface area-dependent thermal losses compared to lower-concentration systems, such as traditional parabolic troughs, and providing advantages over receiver designs susceptible to high convective and radiation losses.

The light pipe functions as an integrated thermal transport and energy storage medium, enabling enhanced energy conversion and control for both instantaneous thermal processes (material heating, melting, sintering) and sensible/latent heat storage for thermal buffering. The compact receiver geometry facilitates integration with high-temperature thermal storage materials, creating a unified thermal processing and storage system.

Performance analysis includes optical characterization of the Fresnel lens and light pipe coupling, as well as thermocouple-based temperature measurements to verify receiver heat transfer. Preliminary experimental results demonstrate the feasibility of achieving high temperature processing or storage under optimal operating conditions, with potential for further improvement through receiver optimization and system refinement.

This architecture offers significant scalability advantages through modular lens arrays and cost reduction potential via polymer Fresnel lens mass production, positioning it as a viable pathway for small-to-medium scale CSP applications where compact, high-temperature performance is commercially critical.