Concentrated Solar Power Systems Research Articles

Fabrication, Modeling, and Testing of a Prototype Thermal Energy Storage Containment

Abstract Increasing penetration of variable renewable energy resources requires the deployment of energy storage at a range of durations. Long-duration energy storage (LDES) technologies will fulfill the need to firm variable renewable energy resource output year round; lithium-ion batteries are uneconomical at these durations. Thermal energy storage (TES) is one promising technology for LDES applications because of its siting flexibility and ease of scaling. Particle-based TES systems use low-cost solid particles that have higher temperature limits than the molten salts used in traditional concentrated solar power systems. A key component in particle-based TES systems is the containment silo for the high-temperature (>1100 ∘C) particles. This study combined experimental testing and computational modeling methods to design and characterize the performance of a particle containment silo for LDES applications. A laboratory-scale silo prototype was built and validated the congruent transient finite element analysis (FEA) model. The performance of a commercial-scale silo was then characterized using the validated model. The commercial-scale model predicted a storage efficiency above 95% after 5 days of storage with a design storage temperature of 1200 ∘C. Insulation material and concrete temperature limits were considered as well. The validation of the methodology means the FEA model can simulate a range of scenarios for future applications. This work supports the development of a promising LDES technology with implications for grid-scale electrical energy storage, but also for thermal energy storage for industrial process heating applications.

A Dual-Mode Hybrid System Combining Solar Thermal With Pumped Thermal Energy Storage

A hybrid system that delivers renewable electricity generation and electricity storage capabilities is introduced. This dual-mode hybrid system is based on Pumped Thermal Energy Storage (PTES) which uses a heat pump to convert electricity into thermal energy that is transferred to silica particles which are stored in concrete silos. The stored heat is later converted back to electricity in a heat engine. The heat pump and heat engine use a closed Joule-Brayton cycle and fluidized bed heat exchangers. If the PTES system is co-located with an array of concentrating solar mirrors and a particle receiver, then the silica particles may also be heated up by the concentrating solar power (CSP) system. The PTES heat engine may also be used to convert the stored solar heat into electricity, thereby sharing this system between the PTES and CSP systems and reducing costs. However, this requires careful management of the heat engine off-design parameters. A thermodynamic model is used to evaluate the performance of the dual mode PTES-CSP hybrid system. The model accounts for turbomachinery efficiency, and approach temperature and pressure loss in heat exchangers, as well as other sources of inefficiency, such as motor-generator losses, and air fan power. The hybrid system also requires the evaluation of the turbomachinery efficiency and pressure ratio at off-design conditions since the CSP system operates over different temperature ratios than the Carnot Battery. Several design variables and design modifications are investigated, such as pressure ratios and maximum temperatures.

Soiling, Adhesion, and Surface Characterization of Concentrated Solar Power Reflectors: Insights and Challenges in the MENA Region

Desert environments are prime locations for concentrated solar power (CSP) applications due to abundant direct normal irradiance. Despite this advantage, the accumulation and adhesion of dust on CSP mirror surfaces present significant challenges to plant efficiency. This paper comprehensively explores soiling phenomena and dust adhesion mechanisms, complemented by advanced measurement techniques tailored for CSP reflector mirrors. By elucidating the factors influencing dust accumulation and delving into the thermodynamics of self-cleaning coatings, alongside an analysis of various mirror materials, this study aims to enrich our understanding of soiling in CSP systems. This study aims to provide valuable insights that will help develop strategies to reduce dust-related efficiency losses in CSP plants, ultimately supporting the development of more reliable and sustainable solar energy solutions for the MENA region.

Corrosion behavior of alloys 600, 617, and hastelloy N in molten KCl salt

Molten chloride salts are promising fluids for use in molten salt reactors (MSRs) and concentrated solar power (CSP) systems. Hence, understanding the corrosion phenomenon caused by individual chloride salts is essential to determine their effect on the corrosion of structural alloys. This study aimed to explore the corrosion behavior of nickel-based alloys, namely alloys 600, 617, and Hastelloy N, in individual KCl salt. The findings demonstrated that the corrosion of all alloys in molten KCl salt primarily results from the preferential dissolution of the Cr element along grain boundaries, leading to the formation of pits. Furthermore, the corrosion rate was estimated to be 53.2 μm/year for alloy 600, 104.5 μm/year for alloy 617 with the fastest, and 34.8 μm/year for Hastelloy N with the slowest. These results indicate that Hastelloy N with the lowest pristine Cr content exhibits excellent corrosion resistance compared to alloys 600 and 617 in molten KCl salt.

Molecular dynamics study on thermophysical properties of K2CO3 molten salt-based SiO2 nanofluids using Buckingham potential framework

In concentrated solar power (CSP) systems, molten salt plays a vital role as a medium for both storing and transferring heat. This research conducts molecular dynamics (MD) simulations to investigate the thermophysical properties of K2CO3 molten salt-based SiO2 nanofluids within the Buckingham potentialframework. MD results show that the Buckingham potential along with the derived parameters can well reproduce the thermophysical properties of K2CO3 molten salt. At 1.0 wt% of nano-SiO2, the nanofluids achieve a 11.80 % enhancement in specific heat capacity compared with the pure molten salt. The thermal conductivity of molten salt nanofluids is increased as the doping ratio of nano SiO2 is increased. Specifically, when the doping ratio reaches 3.0 wt%, the thermal conductivity is increased by 14.31 % compared with the undoped base salt. It has been found that the enhanced specific heat capacity of nanofluids is primarily resulted from the change in the Coulomb energy due to the addition of the nano-SiO2 and a compression layer surrounding the nanoparticles. Heat flow decomposition of the nanofluid has also shown that its enhanced thermal conductivity is mainly caused by the strengthened nonbonded interactions by adding the nanoparticles.

Design and Simulations of Solar-Based Hydrogen Production System via Methane Decomposition

A solar-based hydrogen production system is analyzed and studied with the intention of optimizing the parameters involved in oil refining industry and the environment of the United Arab Emirates. Methane decomposition in molten salt media using a concentrated solar power system was adopted, since the temperature range required in the system design is achievable with this method. The System Advisor Model software was used in this study with three cases to optimize the system using the levelized cost of heat concept. In Case 1, a levelized cost of heat of 9.32 ¢/kWh was achieved using an optimized system with a CSP-RTUVR-2014 receiver and a Luz LS-3 collector. The design of Cases 1 and 2 exhibited pressure drops along the system of just 10 bar, significantly lower than the 50 bar of Case 3. Similarly, designs of Cases 1 and 2 resulted in maximum receiver thermal losses of around 7 MW, whereas Case 3 yielded 14 MW loss. Analysis of the best-suited molten salt option showed that HITEC solar salt was better than HITEC XL and standard HITEC. A regression analysis was carried out to examine the pressure drop responses since it is a key variable affecting the integrity of the solar system. It was observed that the receiver mass flow rate is the main contributing cause of pressure drop. Through careful operator control of receiver mass flow rate, premature failures of the solar system caused by the pressure drop can be avoided.

Microstructure Evolution and Molten Salt Corrosion Resistance Dependent on Pre-Oxidation Treatment of NiAl Coatings

The chloride-infused molten salt shows the most potential as the medium for the upcoming generation of concentrated solar power system. However, the molten salt put for ward higher corrosion resistance demand on the critical components of concentrated solar power system. The application of NiAl coating proves to be a highly efficient method for preventing corrosion. In this paper, the microstructure, adhesion, and corrosion resistance of NiAl coatings on 310S stainless steel with/without pre-oxidation treatment were studied. The coating predominantly consisted of β-NiAl phase nanocrystals with an Al content of 41.0 at.%. Continuous α-Al2O3 oxide film was formed and no obvious cracks were observed after pre-oxidation. The adhesion strength of NiAl coating was increased by about 70% to 40.0 N through pre-oxidation. Importantly, the corrosion results of NiAl coatings by pre-oxidation treatment in the mixed salt of NaCl/MgCl2/KCl at 1073.15 K for 10 h showed no obvious diffusion of molten salt elements into the coatings. Compared to 310S stainless steel, the pre-oxidized coating sample exhibited a significant reduction of 50.2% in corrosion mass loss. The pre-oxidation of the NiAl coating creates an Al2O3 oxidation layer that effectively blocks corrosion, offering a new method for protecting stainless steels in concentrated solar power system plants.

Enhanced heat transfer and thermal storage performance of molten K2CO3 by ZnO nanoparticles: A molecular dynamics study

Molten salt serves as a popular medium for thermal storage and transfer in concentrated solar power (CSP) systems. The existing experimental studies have found the capacity of enhancing the heat storage property of the molten carbonate by doping ZnO nanoparticles. However, it has been rarely reported to conduct simulations of ZnO/molten carbonate nanofluids, and the underlying mechanism of how ZnO nanoparticles enhance the heat transfer and storage capacity has less been explored. In this study, molecular dynamics (MD) simulation has been used to investigate the heat transfer and storage properties of a molten K2CO3 nanofluid containing ZnO nanoparticles. It was found that as the nanoparticle mass ratio in molten salt based nanofluids rises, their specific heat capacity initially increases but subsequently diminishes. The specific heat capacity peaks when the ZnO mass ratio is at 1 wt%, resulting in an increase of 17.83 % compared with the base salt. The thermal conductivity in nanofluids based on molten salt increases with the increasing of ZnO mass ratio. Multi-perspective analysis of the mechanism how ZnO nanoparticles enhance the thermal energy storage performance of molten salt, including the microstructural analysis, number density, vibrational density of state, and heat flow decomposition, is conducted. In addition, results of the number density illustrates that a compressed layer of K+ is formed surrounding the ZnO nanoparticles, and the change in the potential energy leads to an increasing heat capacity. Analysis of the heat flow decomposition suggests that the enhanced nonbonded interaction is the main reason for the improvement of thermal conductive performance in the nanofluids based on molten salt. The findings in the present study provide a new perspective of how ZnO nanoparticles enhance the thermophysical properties of molten salts.

Development of Macro-Encapsulated Phase-Change Material Using Composite of NaCl-Al2O3 with Characteristics of Self-Standing

Developing thermal storage materials is crucial for the efficient recovery of thermal energy. Salt-based phase-change materials have been widely studied. Despite their high thermal storage density and low cost, they still face issues such as low thermal conductivity and easy leaks. Therefore, a new type of NaCl-Al2O3@SiC@Al2O3 macrocapsule was developed to address these drawbacks, and it exhibited excellent rapid heat storage and release capabilities and was extremely stable, significantly reducing the risk of leakage at high temperatures for industrial waste heat recovery and in concentrated solar power systems above 800 °C. Thermal storage macrocapsules consisted of a double-layer encapsulation of silicon carbide and alumina and a self-standing core of NaCl-Al2O3. After enduring over 1000 h at a high temperature of 850 °C, the encapsulated phase-change material exhibited an extremely low weight loss rate of less than 5% compared with NaCl@Al2O3 and NaCl-Al2O3@Al2O3 macrocapsules, for which the weight loss rate was reduced by 25% and 10%, respectively, proving their excellent leakage prevention. The SiC powder layer, serving as an intermediate coating, further prevented leakage, while the use of Al2O3 ceramics for encapsulation enhanced the overall mechanical strength. It was innovatively discovered that the Al2O3 particles formed a network structure around the molten NaCl, playing an important role in maintaining the shape and preventing leakage of the composite thermal storage phase-change material. Furthermore, the addition of Al2O3 significantly enhanced the rapid heat storage and release rate of NaCl-Al2O3 compared to pure NaCl. This encapsulated phase-change material demonstrated outstanding durability and rapid heat storage and release performance, offering an innovative approach to the application of salt phase-change materials in the field of high temperature rapid heat storage and release and encapsulating NaCl as a high-temperature thermal storage material in a packed bed system. Compared with conventional salt-based phase-change materials, the developed product is expected to significantly improve the reliability and thermal efficiency of thermal storage systems.

Thermal Cycling Test of Solar Salt in Contact with Sustainable Solid Particles for Concentrating Solar Power (CSP) Plants

Thermal energy storage (TES) is crucial in bridging the gap between energy demand and supply globally. Concentrated Solar Power (CSP) plants, employing molten salts for thermal storage, stand as an advanced TES technology. However, molten salts have drawbacks like corrosion, solidification at lower temperatures, and high costs. To overcome these limitations, research is focusing on alternative TES materials such as ceramic particles. These solids match molten salts in energy density and can withstand higher temperatures, making them well-suited for CSP systems. This study revolves around subjecting Solar Salt alone and Solar Salt alongside Volcanic Ash (VA) and Electric Arc Furnace Slag (EAFS) to a comprehensive thermal cycling test. This test is designed to assess the compatibility over the thermal cycles of the Solar Salt and the Solar Salt in contact with these solids in a CSP plant with a thermocline configuration. With a final thermal and chemical evaluation, our observations indicate that EAFS and VA demonstrate promising compatibility but an increase in the reduction rate of the Solar Salt due to a catalyst effect from EAFS in contact with the salt. No discernible alterations were detected in the properties of either the solid materials or solar salt when combined.

Selection of phase change material for latent heat thermal energy storage using a hair-pin heat exchanger: Numerical Study

Abstract Phase change materials (PCMs) are promising for storing thermal energy as latent heat, addressing power shortages. Growing demand for concentrated solar power systems has spurred the development of latent thermal energy storage, offering steady temperature release and compact heat exchanger designs. This study explores melting and solidification in a hairpin-type heat exchanger (HEX) using three PCMs (RT 50, RT 27, and RT 35). A 3D model of the hairpin type heat exchanger (HEX) is drawn using Ansys-workbench. High-temperature fluid/Low-temperature fluid (HTF/LTF) with Stefan numbers (0.44, 0.35, and 0.23) flows through the inner pipe to charge the outer pipe's PCM. The Enthalpy-porosity model is used to study the melting and solidification of various PCMs, and the results were compared. Also, individual thermophysical properties that affect the heat transfer during the melting and solidification process have been discussed. It is observed that low thermal conductivity material with high latent heat is preferred for cold climates. In this study, RT 27 excels in cold climates due to extended solidification time, while RT 50 is effective in tropical regions due to its high melting points and lower latent heat.

Thermal analysis and dynamic attributes of a sustainable CSP-fossil hybrid power plant utilizing organic Rankine cycles for enhanced plant performance

The increasing global demand for energy, driven by population growth, highlights the need for sustainable solutions to ensure a sustainable future. This article outlines the design and optimization process of a 1 MW CSP-Fossil hybrid power plant that examines the utilization of toluene and cyclohexane as working fluids within three distinct Organic Rankine cycle (ORC) configurations (simple, recuperated, and with Open Feed Organic Heater). This study aims to propose a sustainable and effective solution for satisfying energy needs while addressing the intermittent nature of solar resources by enhancing system architecture and incorporating fossil fuel technologies. The solar field design has been based on a Concentrated Solar Power (CSP) system, which generated 44% of the total energy output from renewable solar sources. The analysis takes into consideration a selection of criteria, notably thermal efficiency, overall efficiency, power generation capacity, and cost-effectiveness. The selection of relevant performance indicators, evaluation of alternative ORC configurations and working fluids, and optimization of the solar multiple and thermal storage capacity are included among the criteria for conducting the parametric investigation. Based on the investigation, it has been determined that the ORC configuration, which includes a recuperator and utilizes cyclohexane as the working fluid, demonstrates the most favorable design. This configuration offers enhanced efficiency and improved performance. Additionally, it is determined that a solar multiple value of 1.7 and the integration of a 12-hour thermal energy storage system are optimal. This led to a 4-5 hour increase in the availability of daily power generation, thereby improving the reliability and flexibility of the CSP plant. The incorporation of fossil fuels into the hybrid CSP-Fossil plant results in a notable enhancement of the Capacity Utilization Factor (CUF). This improvement guarantees uninterrupted energy generation even when solar resources are limited. The implications of the findings are significant for the future development of CSP systems. These findings provide valuable insights into enhancing energy efficiency and tackling sustainability challenges.

Optimal energy collection with rotational movement constraints in concentrated solar power plants

In concentrated solar power (CSP) plants based on parabolic trough collectors (PTC), the sun is tracked at discrete time intervals, with each interval representing a movement of the collector system. The act of moving heavy mechanical structures can lead to the development of cracks, bending, and/or displacement of components from their optimal optical positions. This, in turn, diminishes the overall energy capture performance of the entire system. In this context, we introduce two combinatorial optimization problems of great interest to PTC plants. The minimum tracking motion (MTM) problem is aimed at detecting the minimum number of movements needed while maintaining production within a given range. The maximal energy collection (MEC) problem seeks to achieve optimal energy production within a predetermined number of movements. Both problems are solved assuming scenarios where the energy collection function contains any number of local maximums/minimums due to optical errors of the elements in the PTC system. The MTM and MEC problems are solved in O(n) time and O(n2mω∗) time respectively, where n is the number of steps in the energy collection function, m the maximum number of movements of the solar structure, and ω∗ the maximal amplitude angle that the structure can cover. The advantages of the solutions are shown in realistic experiments. While these problems can be solved in polynomial time, we establish the NP-hardness of a slightly modified version of the MEC problem. The proposed algorithms are generic and can be adapted to schedule solar tracking in other CSP systems.

Encapsulation effectiveness and thermal energy storage performance of aluminum-graphite composite phase change materials subjected to oxide coating

The utilization of metals as phase change materials (PCMs) in high-temperature latent heat storage technology holds promising prospects, especially when integrated with concentrated solar power (CSP) systems, as it enables higher working temperatures for CSP and enhances power generation cycle efficiency. However, the practical application of metal-based phase change processes faces challenges such as liquid leakage and high-temperature corrosion, which impede their widespread implementation. In this study, aluminum (Al) is employed as the PCM, while expanded graphite (EG) is used as the matrix material. Composite PCMs with embedded structures were synthesized using powder metallurgy techniques. Notably, an oxidation pre-treatment process was employed to create an oxide layer on the surface of Al particles, thereby improving the encapsulation performance and thermal properties of the composite PCM. By increasing the oxidation pre-treatment temperature to 1100°C, the maximum encapsulation ratio was enhanced from 50 wt% to 80 wt%, and the latent heat energy storage density increased from 101.0 J/g to 188.2 J/g. Moreover, the composite PCM subjected to oxidation pre-treatment at temperatures of 670°C and above maintained a stable structure, chemical composition, and energy storage density after 50 thermal cycles. Within the temperature range of 600–700°C, the total energy storage density of the composite PCM reached 284.5 J/g. These results indicate that the oxidation pre-treatment is a promising technology in high-temperature energy storage technology.

Assessing parabolic trough collectors and linear Fresnel reflectors direct steam generation solar power plants in Northwest México

Concentrating solar power (CSP) systems offer promising solutions for harnessing solar energy. Parabolic trough collectors (PTC) are prevalent in CSP, but direct steam generation (DSG) in solar fields is an innovative alternative that eliminates the need for thermal oils. This study compares EuroTrough PTC and optimized linear Fresnel reflector (LFR) geometries for DSG for Mexican operating conditions. Two 10 MW Rankine cycles with two and three steam extractions are considered. The study evaluates 16 solar field configurations capable of delivering 400 °C superheated steam at 100 bar. Assessment parameters include effective concentration area, nominal loop inlet pressure, energy and exergy efficiency, and hypothetical thermal storage size. The findings strongly favor PTC solar fields with 14 loops, exhibiting superior performance. However, three-loop LFR configurations are suggested where pressure reduction prevails. Three-loop LFR arrays minimize land utilization for spatially constrained installations, while larger five-loop configurations optimize efficiency. Employing 14 PTC loops prioritizes thermal energy storage. In contrast, 8 PTC loops maximize storage capacity. The study underscores the advantages of Fresnel reflectors over parabolic troughs in specific scenarios, presenting avenues for future exploration. This analysis lays the groundwork for assessing these technologies in the distinctive context of Mexican operations, offering valuable insights into sustainable energy applications.

Thermal properties analysis and thermal cycling of HITEC molten salt with h-BN nanoparticles for CSP thermal energy storage applications.

Molten salts are the operational fluid for most concentrated solar power (CSP) systems, which has attracted more attention among the scientific community due to the augmentation of their properties with the doping of nanoparticles. Hexagonal boron nitride (h-BN) nanoparticles were dispersed in HITEC molten salt to create a novel nanofluid and evaluate the h-BN nanoparticles' influence on HITEC thermophysical properties. The influence of nanoparticle concentration (0.1, 0.5, and 1wt.%) of h-BN and HITEC was studied in this research. HITEC and nano-enhanced HITEC molten salt (NEHMS) were characterized using energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy (FT-IR). Specific heat capacity, latent heat, and melting temperature were assessed using differential scanning calorimetry (DSC). The maximum working temperature was evaluated with thermogravimetric analysis (TGA). The ideal nanoparticle concentration is 0.1 wt.% h-BN, which results in a 27% increase in heat capacity, a 72% increase in latent heat, and a 7% enhancement in thermal stability. The thermal cycling stability test proved the stability of the enhanced thermophysical properties. The material characterization revealed that the samples with improved thermophysical properties have a homogeneous dispersion of nanoparticles with minor nanoparticle agglomeration. The system advisor model (SAM) simulation comparison of the optimum sample with solar salt and HITEC salt revealed that using the optimum sample increases CSP plant efficiency by 0.4% and reduces power costs by 0.13¢/kWh.

A novel zero emission combined power and cooling system for concentrating solar power: Thermodynamic and economic assessments and optimization

This study aims to develop a zero-emission multi-generation system based on concentrated solar power to reduce solar thermal power cost and improve the efficiency of power generation. The multi-generation system mainly includes concentrated solar power system, supercritical carbon dioxide recompression Brayton cycle, organic flash cycle and absorption refrigeration cycle. A comprehensive energy, exergy, environment and economic analysis is carried out. Five key parameters are considered to assess the effect of decision parameters on system performance. An optimization method combining genetic algorithm and machine learning is used to accelerate the optimization process. Results display that compared with the stand-alone supercritical carbon dioxide recompression Brayton cycle, the energy utilization factor and exergy efficiency of the multi-generation system can improve 18.7 % and 6.4 %, respectively, and the decrement of levelized cost of electricity is reduced by 4 %. A higher turbine-Ⅰ inlet temperature can improve the exergy efficiency and reduce the levelized cost of electricity. Using the proposed optimization method, the long optimization time of complex multi-generation system is overcome. Comparing the exergy efficiency optimization case with the basic case and the cost optimization case, the exergy efficiency optimization case has the highest net power output and exergy efficiency. This work exhibits great potential in utilizing solar energy for power and cooling.

Summary Paper: An Initial Heliostat Supply Chain Analysis

This paper summarizes the prior analysis, key findings, and recommendations from the published report titled “Initial Heliostat Supply Chain Analysis” [1]. Globally, the growing demand for concentrating solar power (CSP) technologies, primarily for electricity generation plants has been met with supply chains primarily composed of plentiful commodity materials such as steel, aluminum, and glass. Often the commodity materials can be sourced in the domestic market where power plant will be constructed. Although specialty components are required for CSP solar fields —including mirror panels used for heliostat applications—these specialty components constitute about 30-50% of total system installed costs [2]. Only a few companies and countries, including the United States, have developed the capacity to supply such specialty components. The U.S. heliostat supply chain at present is comprised of few companies (e.g., CSP developers), component suppliers, and is its infancy.
 By 2035, with current and aggressive solar photovoltaic (PV) capacity expansions, there is the potential for 500,000–1,500,000 direct and indirect jobs in the areas of manufacturing, installation and development, and operations and maintenance (O&M) [3]. Utilizing the CSP capacity estimations the recent NREL report [4], the construction of 39 gigawatts (GW) of CSP (assuming mainly power tower) in the U.S. could lead to approximately 195,000 manufacturing, construction, and O&M jobs. This does not include the longer-term jobs and economic impact (e.g., taxes from plant operations staff) from operating the plants once constructed. It is recommended that further CSP component and system supply chain analysis and modelling be undertaken.

A high-temperature solar selective absorber based on one-dimensional multilayer nanostructures

Selective absorbers play a crucial role in harvesting solar energy and realizing effective solar-thermal energy conversion in concentrated solar power systems and thermophotovoltaic systems. This study focuses on obtaining a high-temperature solar selective absorber which can well balance its thermal performance as well as structural complexity. Based on this, a selective absorber with simple one-dimensional multilayer nanostructures is designed to adapt to the high-temperature operation environments. The obtained absorber exhibits a total solar absorptance of 0.9504 to the AM1.5 solar radiation. Taking into account the infrared radiation loss, the solar-thermal efficiency of the absorber is found to be 91.2% under 1000 suns at 1273 K, and the total emittance is 0.1504 at the corresponding temperature. The absorber shows high insensitivity to both incident polarization angles and wide-angle incidence. Analysis of impedance and electromagnetic field distribution indicates that the selective absorption performance of the absorber is attributed to its impedance matching properties, resulting from the coupling effect of surface plasmon polaritons and magnetic polaritons.

Numerical Analysis of Non-Sphericity of Particles of Powder Material and their Effect on Packing Structure for Concentrated Solar Power Applications

Concentrated solar power technology represents a novel approach to generating solar power, characterized by high solar radiation density and uninterrupted operation. To store thermal energy and extend system operating hours, concentrated solar power systems rely on thermal energy storage. Selecting the appropriate heat storage media is crucial for designing a cost-efficient and straightforward system capable of withstanding high processing conditions. Among many powder materials, bauxite powder stands out as alternatives to conventional molten salt for thermal storage media due to its widespread availability and suitability for operating conditions. Particle shape, particularly its sphericity, plays a vital role in efficiently packing particles which directly affects to heat transfer properties. To investigate this effect, three samples of particles with different shape were formed: spheres, ellipses, and cylinders using Discrete Element Method with equal volume and material properties, and only variation of their sphericity factors. The study focused on the analysis of the porosity of the packed bed of particles with different shapes and its influence on the packing structure properties. The analysis of local packing fraction revealed that elliptical and cylindrical particles samples exhibited reduced heap formation and a more uniform distribution along z direction during vertical packing. The coordination number and radial distribution function analyses for these non-spherical particles showed a greater number of contacts between particles and disordered distribution of particles due to mechanical interlocking of non-spherical particles. The results indicated that the deviation of sphericity has a positive impact on the denser packing of particles generated more contacts and higher local packing fraction.