Investigation of a novel hybrid photovoltaic-thermoelectric generator system

Shittu, Samson

Abstract

Effective thermal management of photovoltaic is essential for improving its conversion efficiency and increasing its life span. Photovoltaics can convert the ultraviolet and visible regions of the solar spectrum into electrical energy directly while thermoelectric generators utilize the infrared region to generate electrical energy. Consequently, the combination of photovoltaic (PV) and thermoelectric generators would enable the utilization of a wider solar spectrum. Therefore, this research aims to present an innovative thermal management technique for photovoltaic by the incorporation of thermoelectric generator (TEG) and heat pipe to form a hybrid photovoltaic system with improved overall efficiency, increased electricity generation and greater energy harvesting from the solar spectrum.
The strength and innovation of the hybrid system studied in this thesis are as follows: (1) a low cost and high efficiency microchannel heat pipe (MCHP) is used to reduce thermal resistance of heat flow across interfaces and increase heat transfer capacity; (2) the flat plate structure of the MCHP eliminates geometry mismatch and reduces thermal losses; (3) water cooling is used for the TEG cold side thus, the hybrid system feasibility for co-generation of electricity and hot water is demonstrated; and (4) the use of flat plate MCHP results in significant reduction in TEG quantity needed thereby reducing the system cost. These structural innovations are intended to overcome some of the drawbacks and provide experimental data for the development of hybrid photovoltaic-thermoelectric (PV-TE) systems.
A basic methodology of combined theoretical and experimental analysis is followed in this thesis and it involves, detailed literature review, conceptual design, mathematical analysis, computer simulation model development, experimental testing, model validation, and optimization case studies. Computer simulation models are developed to predict and optimize the performance of the systems using three- dimensional finite element models and COMSOL Multiphysics software.
Experimental results show that the electrical conversion efficiencies of the PV- TE-MCHP with and without insulation and that of the photovoltaic only after 1 h are 11.98%, 12.19% and 11.94% respectively. Therefore, the hybrid system provides an enhanced performance. In addition, the highest and lowest thermal efficiencies obtained are 69.53% and 56.57% respectively under certain conditions. Steady state computer simulation results show that that at a high ambient temperature of 50 °C, the PV-TE-MCHP overall efficiency is greater than that of the PV only and PV-TE systems by 9.76% and 14.46% respectively. Therefore, the hybrid PV-TE-MCHP is recommended for sunny regions with high ambient temperature. Results also show that the asymmetrical leg geometry provides enhanced TEG only performance compared to the symmetrical leg geometry although the reverse is the case for the hybrid concentrated PV-TE system.
This research shows that the hybrid PV-TE-MCHP design is feasible and provides enhanced performance compared to the PV only and PV-TE systems. In addition, the effectiveness of thermoelectric geometry optimization for performance enhancement is demonstrated in this research. Therefore, the experimental and simulation results from this research provide fundamental data for developing highly efficient hybrid photovoltaic-thermoelectric systems and thermoelectric generators.

Citation

Shittu, S. Investigation of a novel hybrid photovoltaic-thermoelectric generator system. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4222856

• Thesis Type: Thesis
• Deposit Date: Feb 25, 2021
• Publicly Available Date: Feb 23, 2023
• Keywords: Mechanical engineering
• Public URL: https://hull-repository.worktribe.com/output/4222856
• Additional Information: Department of Mechanical Engineering, The University of Hull
• Award Date: Aug 1, 2020