scholarly journals Design and development of a low-cost system to convert solar thermal energy into electricity for households in South Africa using solar concentrators

2021 ◽  
Vol 32 (4) ◽  
pp. 102-116
Author(s):  
Lukas W. Snyman ◽  
Glen Maeko
Keyword(s):  
South Africa ◽  
Energy Conversion ◽  
Thermal Energy ◽  
Low Cost ◽  
Solar Spectrum ◽  
Electrical Energy ◽  
Pulse Mode ◽  
Solar Irradiation ◽  
Solar Thermal Energy ◽  
Energy Conversion Systems

South Africa is, due its specific latitude location in the southern hemisphere, exposed to high solar irradiation levels. Black thermal absorbers have a high absorbance for solar incident radiation, while commercial photovoltaic technology only converts about 10% of energy available in the solar spectrum. In this article, low-cost Peltier conversion cells, that are normally used for cooling purposes, and that are freely available in supply stores in South Africa, were identified as suitable conversion cells for converting thermal energy into electricity. Two prototypes of thermal-to-electricity energy conversion systems were subsequently designed and developed. Particularly, advanced pulse mode DC- to- DC conversion technology, a special electronic control system, was developed, that could extract high amounts of electrical energy from the cells and could store the energy in standard storage batteries. A 3 W and a 30 W output continuous conversion capacity system were developed. A power conversion of up to 2 W capacity per individual cell was achieved. The systems used no movable parts, and the lifespan of the systems is projected to be at least twenty years. Cost and viability analyses of the systems were performed and the results were compared to existing solar photovoltaic energy conversion systems. Combining the 30 W capacity system with a black body and reflector plate absorber system revealed a cost structure of only ZAR 0.8 per kWh, as compared with a derived ZAR 3 per kWh for a combined photovoltaic and solar geyser combination, as calculated for a ten-year term. The technology as developed is suitable to be incorporated in South African households and rural Africa applications.

scholarly journals Ultra-Broadband Refractory All-Metal Metamaterial Selective Absorber for Solar Thermal Energy Conversion

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1872
Author(s):  
Buxiong Qi ◽  
Wenqiong Chen ◽  
Tiaoming Niu ◽  
Zhonglei Mei
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Solar Spectrum ◽  
Solar Thermal ◽  
Solar Irradiation ◽  
Selective Absorption ◽  
Solar Thermal Energy ◽  
Photothermal Conversion ◽  
Broadband Absorption ◽  
Thermal Energy Conversion

A full-spectrum near-unity solar absorber has attracted substantial attention in recent years, and exhibited broad application prospects in solar thermal energy conversion. In this paper, an all-metal titanium (Ti) pyramid structured metamaterial absorber (MMA) is proposed to achieve broadband absorption from the near-infrared to ultraviolet, exhibiting efficient solar-selective absorption. The simulation results show that the average absorption rate in the wavelength range of 200–2620 nm reached more than 98.68%, and the solar irradiation absorption efficiency in the entire solar spectrum reached 98.27%. The photothermal conversion efficiency (PTCE) reached 95.88% in the entire solar spectrum at a temperature of 700 °C. In addition, the strong and broadband absorption of the MMA are due to the strong absorption of local surface plasmon polariton (LSPP), coupled results of multiple plasmons and the strong loss of the refractory titanium material itself. Additionally, the analysis of the results show that the MMA has wide-angle incidence and polarization insensitivity, and has a great processing accuracy tolerance. This broadband MMA paves the way for selective high-temperature photothermal conversion devices for solar energy harvesting and seawater desalination applications.

Nanofluid-Based Absorbers for High Temperature Direct Solar Collectors

2010 ◽  
Author(s):  
Andrej Lenert ◽  
Yoshio S. Perez Zuniga ◽  
Evelyn N. Wang
Keyword(s):  
Solar Radiation ◽  
Energy Conversion ◽  
Thermal Energy ◽  
Design Guidelines ◽  
Transfer Model ◽  
Solar Collectors ◽  
Solar Thermal Energy ◽  
High Concentration ◽  
Fluid Medium ◽  
Energy Conversion Systems

Solar collectors with surface receivers have low overall energy conversion efficiencies due to large emissive losses at high temperatures. Alternatively, volumetric receivers promise increased performance because solar radiation can be transferred into a fluid medium, which subsequently reduces the concentrated heat at the surface. Nanofluid-based direct solar receivers, where nanoparticles in a liquid medium can scatter and absorb solar radiation, have recently received interest to efficiently distribute and store the thermal energy. We present a combined modeling and experimental study to investigate the efficiency of fluid-based solar receivers seeded with carbon-coated absorbing nanoparticles. A simple one-dimensional transient heat transfer model was developed to compare idealized surface receivers to idealized volumetric receivers. In the limit of idealized behavior, volumetric receivers were shown to be more efficient than selective-surfaces for high concentration levels (C > 100) and/or tall receiver designs (H > 10 cm). Furthermore, volumetric receivers allowed the working range of the fluid to be extended to higher temperatures while maintaining relatively high receiver efficiency. We also designed and custom built a cylindrical receiver to experimentally demonstrate the concept of nanofluid-based receivers and validate the modeling efforts. We explored the effect of particle characteristics such as size, distribution, and material properties, as well as collector parameters such as absorbing depth and level of solar concentration. The work offers design guidelines for the development of efficient volumetric receivers for future solar thermal energy conversion systems.

Ceramic Technology for Solar Thermal Receivers

1983 ◽  
Vol 105 (1) ◽  
pp. 73-79
Author(s):  
A. A. Kudirka ◽  
R. H. Smoak
Keyword(s):  
Thermal Energy ◽  
Low Cost ◽  
Ceramic Materials ◽  
Ceramic Technology ◽  
Solar Thermal ◽  
Receiver Design ◽  
Solar Thermal Energy ◽  
Energy Applications ◽  
Temperature Capability ◽  
Solar Applications

Development of ceramic receiver technology for advanced solar thermal energy applications is being pursued in order to achieve significant reductions in energy cost and increase the potential application of solar thermal energy. Basically, structural ceramics are being seriously considered for solar applications because of their high temperature capability, their nonstrategic nature, and their potential for low cost. In this paper, candidate ceramic materials for solar receivers and their characteristics are described, potentially applicable fabrication and processing methods are discussed, and their applicability and promise for solar receivers is assessed. Receiver design requirements as well as system requirements for solar applications are reviewed. Promising areas of application of ceramic receivers in the near future are also discussed. Current ceramic receiver development status and plans are described, including one receiver which has been successfully tested at gas exit temperatures of up to 1425°C.

Solar Thermal Energy Conversion

2007 ◽  
pp. 20-1-20-134
Author(s):  
Agami Reddy ◽  
Riccardo Battisti ◽  
Werner Weiss ◽  
Jeffrey Morehouse ◽  
Sanjay Vijayaraghavan ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Thermal Energy Conversion
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