Analysis of the Performance of a Solar Thermoelectric Generator for Variable Leg Geometry with Nanofluid Cooling

In this study, the impact of nanofluid use in solar-thermoelectric generators (Solar-TEG) on thermal performance is investigated through analysis and simulation methodology. For conventional cooling analysis, we use air as a coolant and graphene nanoplatelet aqueous nanofluids (GNAN) for nanofluid cooling. We make a comparison between traditional and nanofluid cooling to find the best performance. GNAN at a dispersion of 0.025, 0.05, 0.075, and 0.1-wt% are added to the cooling system. GNAN has been used in the technological development of energy conversion. It has been proposed as a material to achieve better efficiency in Solar-TEG. Five different geometries are developed to analyze the efficiency in a Solar-TEG to find the optimal design. The impact of the thermal concentration relationship, substrate area, and convective transfer coefficient on Solar-TEG performance is investigated. To simplify and speed up simulations, we use equivalent models based on FEM. We are considering the properties of temperature-dependent semiconductors. For thermoelement materials, we use lead-tellurium. Lead-tellurium is an excellent material for thermoelectric study and supports large temperature ranges (up to 750 K). The thermal concentration relationship depends on the substrate area, which affects the efficiency of Solar-TEG. The maximum efficiency between the five geometry types is 5.53%, with a substrate of 110 × 100 mm2. The efficiency and output power using 0.1% wt GNAN as the refrigerant is enhanced by 14.74% and 26.39%. GNAN cooling improves compared to conventional fluid cooling in a Solar-TEG. Different convection coefficients are used to verify this fact.

The combined impacts of leg geometry configuration and multi-staging on the exergetic performance of thermoelectric modules in a solar thermoelectric generator

The performance of thermoelectric generators (TEGs) can be improved either by the adoption of multi-stage or tapered leg configuration. So far, a hybrid device that simultaneously uses both multi-staging and tapered leg geometry to improve its performance has not been conceived. Thus, we present a thermodynamic modelling and optimization of a two-stage TEG with tapered leg geometries using ANSYS 2020 R2 software. The optimized parameters include the leg height, area, concentrated solar radiation and external load resistance. Firstly, the X-leg TEG only improves the performance of the trapezoidal leg TEG below a leg height of 3 mm. Beyond 3 mm, the performance of both TEGs become very similar. Long thermoelectric legs provide higher efficiencies, while short legs generate maximum power densities. To obtain maximum efficiencies, the initial leg height of the thermoelectric legs, 1.62 mm, is increased by 517.28%, while the initial leg area, 1.96 mm2, is decreased by 64.29%. Also, the proposed two-stage TEG with tapered legs (trapezoidal and X-legs) improves the exergetic efficiency of the base case, single-stage rectangular leg TEG, by 16.7%. Furthermore, the use of tapered leg TEGs; in single and multi-stage arrangements, reduces the exergy conversion index of conventional rectangular leg TEGs by 1.89% and 0.98%, respectively. Finally, the use of tapered legs and multi-stage configurations increases the thermodynamic irreversibilities of conventional rectangular leg TEGs, thus, reducing their thermodynamic stability.