Abstract
Solar thermoelectric generators (STEGs), which are used for various applications, (particularly small size electronic devices), have optical concentration systems for high energy conversion efficiency. In this study, a refraction-assisted STEG (R-STEG) is designed based on phase-change materials. As the phase-change material (PCM) changes phase from solid to liquid, its refractive index and transmittance also change, resulting in changes in the refraction of the sunlight transmitted through it, and concentration of solar energy in the phase-change lens. This innovative design facilitates double focusing the solar energy through the optical lens and a phase-change lens. This mechanism resulted in the peak energy conversion efficiencies of the R-STEG being 60% and 86% higher than those of the typical STEG at solar intensities of 1 kW m−2 and 1.5 kW m−2, respectively. In addition, the energy stored in PCM can help to generate steady electrical energy when the solar energy was removed. This work presents significant progress regarding the optical characteristic of PCM and optical concentration systems of STEGs.
Highlights
Solar energy is a clean and sustainable source of renewable energy; harvesting solar energy is one of the most attractive methods for overcoming energy shortage
According to Equation (1), an energy conversion efficiency of approximately 1% can be reached by applying a temperature difference of 20 °C across telluride alloys used in solar thermoelectric generators (STEGs) with ZT = 1 and Tc = 25 °C9
We investigated solar energy harvesting by coupling a thermoelectric generators (TEGs) and a phase-change lens that was produced by the solar power melting the phase-change material (PCM)
Summary
Solar energy is a clean and sustainable source of renewable energy; harvesting solar energy is one of the most attractive methods for overcoming energy shortage. Commercial materials with ZT = 1 are not yet available; these material limitations are the primary concern for practical applications[12] Another method that can improve the energy conversion efficiency is the creation of a significant temperature difference across the TEGs with the solar radiation flux. Li et al designed a prototype optical-concentrated STEG and evaluated its performance using a numerical method Their results showed that 14.1% is the highest possible efficiency of a TEG that employs LAST (AgPbmSbTe2+m) alloys as the www.nature.com/scientificreports/. A TEG can generate 4.9 W, corresponding to 2.9% efficiency[14] Another approach for creating the temperature difference across the STEG is the use of a selective absorber configuration that exploits thermal concentration.
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