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The electrochemical CO2 reduction (ECR) to produce value-added fuels and chemicals using clean energy sources (like solar and wind) is a promising technology to neutralize the carbon cycle and reproduce the fuels. Presently, the ECR has been the most attractive route to produce carbon-building blocks that have growing global production and high market demand. The electrochemical CO2 reduction could be extensively implemented if it produces valuable products at those costs which are financially competitive with the present market prices. Herein, the electrochemical conversion of CO2 obtained from flue gases of a power plant to produce diesel and formic acid using a consistent techno-economic approach is presented. The first scenario analyzed the production of diesel fuel which was formed through Fischer-Tropsch processing of CO (obtained through electroreduction of CO2) and hydrogen, while in the second scenario, direct electrochemical CO2 reduction to formic acid was considered. As per the base case assumptions extracted from the previous outstanding research studies, both processes weren’t competitive with the existing fuel prices, indicating that high electrochemical (EC) cell capital cost was the main limiting component. The diesel fuel production was predicted as the best route for the cost-effective production of fuels under conceivable optimistic case assumptions, and the formic acid was found to be costly in terms of stored energy contents and has a facile production mechanism at those costs which are financially competitive with its bulk market price. In both processes, the liquid product cost was greatly affected by the parameters affecting the EC cell capital expenses, such as cost concerning the electrode area, faradaic efficiency, and current density.

Converting solar energy efficiently into hydrogen is a promising way for renewable fuels technology. However, high-temperature heat transfer enhancement of solar thermochemical process is still a pertinent challenge for solar energy conversion into fuels. In this paper, high-temperature heat transfer enhancement accounting for radiation, conduction, and convection heat transfer in porous-medium reactor filled with application in hydrogen generation has been investigated. NiFe-Aluminate porous media is synthesized and used as solar radiant absorber and redox material. Experiments combined with numerical models are performed for analyzing thermal characteristics and chemical changes in solar receiver. The reacting medium is most heated by radiation heat transfer and higher temperature distribution is observed in the region exposed to high radiation heat flux. Heat distribution, O2 and H2 yield in the reacting medium are facilitated by convective reactive gas moving through the medium's pores. The temperature gradient caused by thermal transition at fluid-solid interface could be more decreased as much as the reaction chamber can store the transferred high-temperature heat flux. However, thermal losses due to radiation flux lost at the quartz glass are obviously inevitable.

The electrochemical CO2 reduction (ECR) to produce valuable chemicals and fuels using clean energy resources is a promising and effective route to support energy storage and reduce the large CO2 concentration to avoid climate change. Among the presently adopted CO2 conversion technologies, electrochemical CO2 reduction (ECR) to valuable feedstock is presently a concern of critical research effort as a technology that can concurrently enable CO2 reduction and the storage of renewable energy. The ECR performance and economic viability are greatly influenced by the intrinsic characteristics of the catalyst employed. Many techniques have been practiced to improve the catalytic performance of heterogeneous catalysts by administering their morphology, size, crystal facets, grain boundaries, and surface defects and their integration with other synergistic constituents to fabricate nanomaterials. Presently, the fabrication of nanomaterials at the atomic level is an effective and strong technique to address the particular issues of catalytic performance and durability in ECR, by comprehending the structure–performance relationship of the nanomaterials. Herein, we present the recent technological advances with metal-derived nanomaterials, discussing the factors affecting their catalytic performance, their mechanism, and applications for the selective production of formic acid, carbon monoxide, alcohols, and hydrocarbons. Moreover, different commonly-adopted fabrication techniques for the synthesis of nanostructures have been incorporated to outline their working principles and their specialty to produce different kinds of nanostructures (nano-polyhedrons, nanowires, dendrites, and nano-frames).

Energy conservation has always been a prominent design goal for hierarchical routing protocols supporting sink mobility. Advertising the current position of mobile sink introduces control packet overhead which ultimately results in an increase in energy consumption and shorter network lifetime. Energy harvesting through ambient sources have enabled the utilization of rechargeable devices for Wireless Sensor Networks to perpetually remain operational. The modifications in the hierarchical structure of wireless sensor networks along with energy scavenging approaches could possibly minimize the control packet overhead and also provide a significant improvement in energy conservation. In this paper, we propose a novel Harvested Energy Scavenging and Transfer capabilities in Opportunistic Ring Routing protocol which uses a distinguishing approach of hybrid (ring + cluster) topology in which the network architecture is initially supported by the formation of a virtual ring structure and then a two-tier routing topology is used in the virtual ring as an overlay by grouping nodes into clusters. The rate of energy gain from solar harvesting and radio frequency transfer is the criterion for selecting cluster heads. The role of cluster heads is exploited to advertise the mobile sink current position as well as forward the aggregated data towards mobile sink using energy transfer based opportunistic routing. The simulation results reveal that our scheme considerably outperforms the existing benchmarks in terms of control packet overhead, energy conservation, network lifetime, packet delivery ratio and average end-end delay.

The continuous consumption of fossil fuels causes two important impediments including emission of large concentrations of CO2 resulting in global warming and alarming utilization of energy assets. The conversion of greenhouse gas CO2 into solar fuels can be an expedient accomplishment for the solution of both problems, all together. CO2 reutilization into valuable fuels and chemicals is a great challenge of the current century. Owing to limitations in traditional approaches, there have been developed many novel technologies such as photochemical, biochemical, electrochemical, plasma-chemical and solar thermochemical. They are currently being used for CO2 capture, sequestration, and utilization to transform CO2 into valuable products such as syngas, methane, methanol, formic acid, as well as fossil fuel consumption reduction. This review summarizes different traditional and novel thermal technologies used in CO2 conversion with detailed information about their working principle, types, currently adopted methods, developments, conversion rates, products formed, catalysts and operating conditions. Moreover, a comparison of these novel technologies in terms of distinctive key features such as conversion rate, yield, use of earth metals, renewable energy, investment, and operating cost has been provided in order to have a useful review for future research direction.

In this paper, the heat flow diagram of steam turbine model K-6-35 has been analyzed for innovative approaches towards improving the techno-economic and ecological indices of the small-scale power generation system. The numerical analysis is performed using IPSEpro process simulation software based on heat balance method under four different cases. It was found that the study of Solar Assisted Power Generation (SAPG) system has important practical significance in power generation with minimum pollutants and maximum efficiency. Both fuel-saving (FS) and power-boosting (PB) operation modes of the SAPG system are considered. Various types of stand-alone solar thermal power plants exhibited very low overall efficiency with many ecological advantages compared to the conventional thermal power plant based on fossil fuels. Besides, SAPG system with FS mode presented higher techno-economic indices and operation performance. An important reduction in fuel consumption and pollutant emissions could be obtained with SAPG system. Considering the hourly, daily, monthly, and yearly amount of saved fuel and reduced pollutants in the whole power plant, the SAPG system with FS mode can largely contribute to high ecological indices power generation. A thermal efficiency increased by 1.31% with specific equivalent fuel consumption decreased by 22.54 g/kWh was obtained with SAPG system. The coal consumption was reduced by 4.75% when SAPG system operates in FS mode.

Nowadays, using a solar-driven thermochemical reaction system to convert greenhouse gases into high-quality liquid fuels has been proven to be an effective way to address the growing depletion of traditional fossil fuels. However, the utilization of highly-concentrated solar irradiation runs the high risk of reactor damage issues resulting from thermal stress concentration, which seriously threatens the security and reliability of the total reactor system. In this study, the thermal radiation distribution and thermo-mechanical process in a volumetric reactor were numerically investigated by combining Monte Carlo ray-tracing method with computational fluid dynamics method. Based on the experimental results and thermal characteristic analysis, the formation mechanism of thermal stress concentration and the strategies of improving thermal stress distribution were discussed in detail. The simulation results indicate a great possibility of reactor damage at about 1000°C operating temperature and 9.0 kW lamp power, which is well-matched with related experimental results. The ceramic damage typically occurs at the inner edges of the through-holes, including the aperture, the gas inlet, and the thermocouple hole, then extends along the lines connecting these holes and finally causes brittle fracture. By reasonable control of the opening direction and the distance between the through-holes, the maximum compressive stress can be reduced by 21.78%.

The harmonious condition between nature and humans experiences severe challenges due to the continuous consumption of fossil fuels and the consequent rapid release of large CO2 levels into the atmosphere. It is urgent to explore sustainable resources of green energy and develop efficient techniques for CO2 conversion into value-added products. Being an indispensable component for CO2 re-utilization, the conversion of CO2 into valuable chemicals and fuels can provide a win–win situation to accomplish the effective exploitation of carbon resources and reduce the large volumes of CO2. Among the presently adopted CO2 conversion techniques, the electrochemical approach is a promising route to produce low carbon chemicals required for heavy-duty applications. Although significant progress has been accomplished in the electrochemical reduction of CO2 (ERC), there is a lack of basic research to understand the different factors that strongly influence the performance of ERC. In particular, very few studies have incorporated the effect of an electrolytic cell on ERC. This review summarizes the role of metal electrodes in the production of different products, the effect of the electrolyte, pressure and temperature, membrane, and CO2 mass transfer coefficient on the performance of ERC. Moreover, we have also comprehensively discussed the different types of an electrolytic cell in terms of their structure, working principle and capabilities of producing selective products to understand the impact of different cell configurations on the reduction process, and have presented a useful review of the future research prospects.

Plasmonic nanoparticles of noble metals, mostly gold (Au), show surface plasmon resonance features within the vicinities of visible and near-infrared spectrum, and its plasmonic techniques emerge from the cooperative oscillations of free electrons controlled by the electromagnetic field influence of the incident light within the region. This work aims at producing reduced cost surface-enhanced Raman spectroscopy (SERS) enhancement factor of gold nanoparticle (AuNP) using the finite-difference time-domain method. The result shows that for the selected three types of substrates of SiO2, Ge, and Al2O3, the SERS effects of Ag on SiO2 > Ge > Al2O3 agree with the enhancement order (i.e., SiO2 > Ge > Al2O3) from the previous experiment of Yang et al. (Appl Surf Sci 436:367–372, 2018). Due to the limitation of the semiconductor’s substrates, in subsequence simulations, Al substrate was used instead. Further simulations reveal that the intensity of Ag on Al substrate is greater than that of SiO2, Ge, and Al2O3 semiconductor substrates. In like manner, the simulation also gave a greater enhancement with AuNP/Al substrate. (The localized electric field enhancement effect of AuNP/Al substrate has more signal than the previous.) The results obtained from the consideration of different diameters of the Au sphere and the interparticle spacing for some specified range of numbers under consideration have enlarged the comprehension of SERS substrates. The operation (mechanism) of the wavelength’s arousal is a function of the particle’s structure, miniaturization, and substrate type for the SERS effect.

Due to the utilization of concentrated solar energy, a more complex high-temperature thermal environment will be formed inside the solar thermochemical reactor, thereby resulting in complicated behaviors of chemical reactions. This paper numerically investigates the carbon deposition behaviors inside a Ni/Al2O3-based catalyst porous-filled solar thermochemical reactor for the dry reforming of methane (DRM) process under various operational conditions. The reaction kinetics for DRM including four side reactions are programmed via UDFs. The simulation results indicate that the optimal structural parameters of porous media for high-value syngas products with less carbon deposition are ϕ = 0.8 and dp = 2 mm, while the optimal feed ratio is CH4/CO2 = 1. Besides, the operating condition at vin = 100 mL/min and Plamp = 0.7 kW has the advantage of obtaining higher conversion rate while reducing the carbon deposition rate to some extent.

Artificial Intelligence consist attribute of science and computer that creates the system or program or any machines perform the Intelligent and Imaginative functions of a human, independently and solution of problems which are able to make some actions. Basic areas of application are smart grids, electricity trading, the sector coupling of electricity, heating and transport etc. Prerequisites for a wide using of AI in the energy system are correspondingly large set of data that is evaluable and the digitalization of the energy sector. AI makes the energy industry more efficient and secure by analyzing and evaluating the data volumes. The main aim of AI and producing energy is creating system, which will be able to make predictions of solar energy resources in definite place. Data massive will be collected and separated on few types. The results shows “future” time: what amount of energy “we” can get in certain period of time in certain place. I use 2 points, which situated in different places (active solar power station); 1 square meter (kW-hr/m^2/day) by solar panel.

The design elements considered during the construction of a thermochemical reactor determine its thermal performance. This current study investigated the effect of design elements, such as boundary layer thickness, insulating materials for the outlet tube design and fluid inlet locations of the frustum, on the thermal performance of a proposed syngas production reactor with incident radiation heat transfer through quartz glass. The P1 radiation approximation model and fluid flow in the shallow path were integrated into a proposed radiation model. The result indicated that inlet mass flow rates from 5 &times, 10-4 to 14 &times, 10-4 kg/s increased the temperature in the cavity and the outlet. The fluid inlet located at the top of the quartz glass edges was found to have better thermal performance and maximum average outlet temperature. Insulation for fluid inlets tube above the quartz glass edges of the frustum was very important for the prevention of radiation loss through quartz glass and sedimentation of fluid particles around the quartz glass edge, and the facilitation of fast heat transfer towards the internal part of the reactor. The outlet that was a tube designed using an aluminum oxide-type insulator with a 50 mm boundary layer thickness was found to increase the average outlet temperature of the reactor. This study revealed that fluid entry and exit locations on the frustum and proper fluid outlet design were critical for the thermal performance analysis of the solar thermochemical reactor for heat transfer with quartz glass. Findings from this study will be of relevance to chemical and power engineering sectors, as well as academia.

Solar energy is a sustainable and low-cost renewable energy of enormous importance, especially at this time where non-renewable energy sources are unsustainable and costly. However, improving the thermal performance of a solar energy storage reactor poses some challenges. In this study, the location of fluid inlets and outlets in the given reactor design and its impact on the thermal performance were investigated. A P1 approximation radiation model coupled with shallow channel approximation of fluid flow was developed. By taking the frustum base as a reference, four fluid inlets along the edges of the frustum and two outlet locations at the base and side of the reactor were computed. Inlets located 4.81 cm from the base of the frustum and an outlet located at the side of the reactor were found to have a better thermal performance with a short conveyer energy flow system. It was also deduced that radiation applied at the edges of the frustum had better thermal performance than that applied at a quartz edge. Furthermore, increasing the laminar inflow rate from 0.36 (L/h) to 3.6 (L/h) increased the temperature distribution in the reactor. This study provides noteworthy insights of relevance to the power engineering industry and academia.

Limited energy resources of sensor nodes in Wireless Sensor Networks (WSNs) make energy consumption the most significant problem in practice. This paper proposes a novel, dynamic, self-organizing Hesitant Fuzzy Entropy-based Opportunistic Clustering and data fusion Scheme (HFECS) in order to overcome the energy consumption and network lifetime bottlenecks. The asynchronous working-sleeping cycle of sensor nodes could be exploited to make an opportunistic connection between sensor nodes in heterogeneous clustering. HFECS incorporates two levels of hierarchy in the network and energy heterogeneity is characterized using three levels of energy in sensor nodes. HFECS gathers local sensory data from sensor nodes and utilizes multi-attribute decision modeling and the entropy weight coefficient method for cluster formation and the cluster head election procedure. After cluster formation, HFECS uses the same techniques for performing data fusion at the first hierarchical level to reduce the redundant information flow from the first-second hierarchical levels, which can lead to an improvement in energy consumption, better utilization of bandwidth and extension of network lifetime. Our simulation results reveal that HFECS outperforms the existing benchmark schemes of heterogeneous clustering for larger network sizes in terms of half-life period, stability period, average residual energy, network lifetime, and packet delivery ratio.

Inspired by light harvesting of hierarchical structure, a biomimetic leaf-type hierarchical nanostructure was introduced for designing ultra-thin perovskite solar cell.

In terms of economy, electricity is a commodity capable of being bought, sold and traded. Electricity is difficult to store, and it has to be available on demand. Consequently, unlike other products, it’s impossible, under normal operating conditions, to keep it in stock, to ration it, or to have customers queue for it. The solar energy generating system, whether gridconnected or stand-alone, is most commonly used in places when possible to install solar equipment (roofs, pollutes areas, closed rubbish dumps, rural and suburban areas). It is based on converting solar radiation (i.e., photons that are sent from the sun) to produce electricity. The PV system has a lot of ways of applications. For example, in developing countries, PV is used for basic life needs, such as heating and cooking, while in developed countries, the system is used to supply electricity for homes and grids. Due to its importance in the solar energy field, global solar radiation data (GSR) forecasting has become more popular to facilitate solar system installation. This paper investigates the method of prediction of global solar radiation in Harbin by the artificial neural network (ANN) approach. Solar radiation prediction and forecasting carry out considering global weather solar radiation data.

The hybridization of solar energy with a coal-fired power plant is a promising way to reduce the numerous environmental issues related to a coal-based power generation sector. This paper examines a novel integration mechanism of solar energy into a 300 MW coal-fired power plant to improve the performance and techno-economic feasibility of the proposed system while decreasing pollutant emissions by coal consumption reduction. The concept of a novel integration mechanism includes replacing a part of the steam being used in the steam turbine of the proposed system with steam produced using the solar field installed near the power plant. The performance and techno-economic analysis of a 300 MW solar coal hybrid power generation (SCHPG) system were investigated under four different reference days (i.e. 22nd of March, 22nd of June, 22nd of September, and 22nd of December). Although the results revealed that the SCHPG system can operate well over the year, it exhibited the highest performance and techno-economic feasibility for the 22nd of June due to the higher direct normal irradiance and small incidence angle. In contrast, the lowest performance and techno-economic feasibility occurred on the 22nd of December. Besides, the performance and techno-economic feasibility for the 22nd of March and 22nd of September are almost similar.

In this paper, heat transfer and fluid flow of porous media solar thermochemical receiver with quartz glass cover were investigated. The Surface-to-surface radiation model and Rosseland approximation for radiation heat transfer were adopted for the transport of diffused solar irradiance and radiative transfer in the fluid phase and porous medium. An experimental test was conducted on a laboratory-scale solar thermochemical reactor. The effects of structural parameters in term of diffused irradiance intensity, the mass flow rate, heat transfer coefficient, quartz glass and inner cavity wall surface emissivity, the porosity and extinction coefficient that could affect heat transfer and fluid flow performance of the proposed solar cavity receiver were sufficiently investigated. It was found that the substantial drops in temperature were mainly attributed to the thermal losses by radiative, convective and conductive heat transfer. The numerical results are compared with the experimental data for the model validation. The thermal loss at the solar flux inlet of the receiver was obviously inevitable due to the stronger effect of heat transfer coefficient that altered the over increasing temperature and heat flux at the surface of diffuse irradiance. However, the use of optimum pore size and higher porosity material could significantly enhance the thermal performance of porous media solar thermochemical reactor.

This paper investigated radiative heat transfer and thermal characteristics of Fe-based oxides coated SiC and Alumina reticulated porous ceramic structures as integrated solar thermochemical reactor. High-flux solar radiation absorption and axial temperature distribution in the ceramic foams reactor were analyzed by adopting surface-to-surface radiation model coupled to the P1 approximation for radiation heat transfer. The radiative heat transfer and thermal characteristics of different foam-type RPC structures, including SiC, CeO2, FeAl2O4, NiFeAlO4, Fe3O4/SiC, and NiFe2O4/SiC were evaluated. The mass flow rate and foam structural parameters, including the permeability, pore mean cell size, and extinction coefficients have significantly affected the axial temperature distribution, pressure drop, heat transfer, and fluid flow. Integrated porous structure to the solar receiver could maximize the incorporation of redox powder in the reacting medium, lower the pressure drop, and enhance the thermal performance of the thermochemical reacting system. SiC structure was the candidate materials in the case where more heat flux and high axial temperature distribution is needed. However, Fe-based oxide coated Al2O3 structure could be considered regarding the heat transfer enhancement along with the catalyst activity of oxygen carriers for solar thermochemical reacting system performance.

As a key technical indicator of porous media solar thermochemical reactor, thermal transport and fluid flow characteristics have significant impacts on hydrogen production efficiency. These issues could be achieved more efficiently and at a lower cost by applying computational fluid dynamics (CFD). However, the choice of different thermal transport models might cause the variation of results. In this study, the thermal transport and fluid flow characteristics in high-temperature porous media solar thermochemical reactor were investigated with different thermophysical models using FLUENT software user-defined functions (UDFs). The results indicate that the local thermal non-equilibrium model (LTNE) and radiative transfer model are proved to be indispensable for the thermal performance analysis of high working temperature thermochemical reacting system. Besides, Wu model of momentum source is more suitable for pressure simulation, while Wu model and Vafai model of heat transfer show little difference in temperature distribution.

Thermal reduction of the partial oxidation of CH4 NiFe2O4 followed by oxidation with H2O and CO2 was numerically investigated for H2 and CO production. P1 radiation model was used to account for radiative heat transfer. The synergistic effect of the reactivity of Fe/Ni exhibited a very promising strategy for producing 45% of syngas with 2.54 ratios of H2:CO at the first step and 55% of syngas with 2.34 ratios of H2:CO at the second step. The increase in incident radiation heat flux to 437.69 kW/m2 resulted in higher reduction kinetics of species conversion until the formation of oxygen carriers consisting of 65% of FeO, 35% of Ni Fe and 2.6% of carbon deposition. However, during the reduction process, the decrease in total pressure to 0.05 MPa enhanced the species reactivity and the production of H2 and CO while minimizing carbon deposition. Moreover, the oxidation temperature, operating pressure and the concentration of oxidizing species have strong impacts on the oxidation kinetics. Unlike high thermal reduction process, increasing the total pressure to 1 MPa has favorable effects on syngas production at oxidation step.

Electrochemical CO2 conversion into useful products using renewable electricity is a promising route to mitigate the potential challenges regarding large CO2 emissions into the environment. However, there are limitations in accomplishing its practical utilization. Recently, many efforts have been made into increasing electrochemical CO2 reduction (ERC) performance using Pd-based catalysts. The Pd-based materials have exhibited unique electrocatalytic characteristics for ECR since they can convert CO2 to HCOOH and CO with high selectivity at equilibrium potential and certain negative potential range, respectively. This review provides useful insights into the recent progress made on Pd-based electrocatalysts. Different factors of Pd-based catalysts influencing ERC performance, such as the effect of size, alloy, morphology, load, and core–shell have been discussed in detail. In the end, future prospects of Pd-based catalysts have been included to briefly highlight the important future considerations of this rapidly growing technology.

A vector based freeform approach is proposed for the geometrical reverse design of reflecting solar concentrators. The effect of solar cone angle of incident vectors is taken into consideration in the method based on three-dimensional freeform optics. The method developed is a closed-loop program and did not need any other commercial software. According to the transmission pattern of solar concentrators, the source-target mapping should be initially established prior to constructing an initial geometry formed by discrete points using the Geometric Construction Method. The freeform surface is generated by connecting several triangular flat elements defined by these points and then the Monte-Carlo ray tracing was conducted. The freeform surface can then be further optimized through feedback modifications. Finally, the optimal shape is obtained when the design examples are the off-axis freeform reflectors with target circular/rectangular receivers for the use of Concentrated Photovoltaic. This method provides a practical approach for improving the optical performance of solar concentrators.

In this paper, the production mechanism analysis of H 2 and CO based on iron oxide was investigated. To deeply understand the reaction mechanism of the inner working of chemistry models, detailed chemical reaction mechanisms describing H 2 and CO formation were conceptually structured in a hierarchical manner with the assistance of reaction paths diagram. However, the main reaction pathways leading to syngas (H 2 and CO) formation derived from the conversion of H 2 O, CO 2 and Fe(A). The study revealed that the reactivity of H, O, HO and HO 2 in the reaction medium was crucial to determine syngas yield. The species reactivity in gas-Fe(A) reaction was limited by the rates of lattice oxygen extraction and diffusion from gas species to the iron bulk surface to replenish the extracted oxygen. However, the reaction paths diagram showed the main Fe(A) bulk phase of iron was not completely transformed to the fully oxidized Fe 3 O 4 phase because of the restricted oxygen transfer to Fe(A) possibly. The model has indicated a better control of surface temperature and operating pressure could result in high reactivity of species in the reaction medium. Moreover, the combination analysis of Fe 3 O 4 phase transformations and produced gas led to describe syngas production over several cycles of iron oxide redox reaction.

Regarding the trend of hydrogen-powered fuel cell engine development, hydrogen fuel is undisputedly the next generation renewable and sustainable energy carrier. The steam reforming of methane (SRM) is a field-proven technology for efficient hydrogen production. However, producing low-carbon hydrogen is the most technical challenge related to available hydrogen production technologies. This paper investigated the process analysis of SRM for low-carbon hydrogen production using concentrated solar energy as a heat source. Analysis of the solar SRM is carried out considering the reformate gas and their influencing factors. The operating temperature of 200–1000 °C and the pressure of 1.02–30 bar were considered when the mass ratio of steam-to-methane in feed gas was varied from 1.0 to 4.0. It was found that the composition of reformate gas, hydrogen yield, methane and steam conversion rate, the thermal efficiency of reforming reactor, and volume flow of reformate gas are significantly affected by the operating parameters including temperature, pressure, and the mass ratio of feed gas. Carbon content in the yield of hydrogen produced can be limited by considering the water–gas shift reaction in the SRM process. Besides, the centralized tower type solar concentrating system is selected as the heat source of the SRM process. The effect of solar radiation on the operation performance of the solar SRM process was analyzed. Direct normal irradiation is a key factor affecting the operating performance of the solar SRM process.

In this study, solar thermal power coupled with a direct irradiated solar thermochemical reactor using porous-medium NiFe2O4@ZrO2 oxygen exchange material was investigated by combining experiments to the numerical models. The ability of ZrO2, NiFe2O4, and NiFe2O4@ZrO2 to release/uptake O2 and their CO2-splitting characteristics are analyzed by the thermogravimetric analyzer (TGA) and the microstructural changes and chemical composition of NiFe2O4@ZrO2 are examined by scanning electron microscopy (SEM) and x-ray energy dispersive spectrometer (EDS). The experiment performed with a redox thermochemical reactor under a high-flux solar spectrum resulted in a total of 337.89 mL of CO collected during 46 min of CO2-splitting over NiFe2O4@ZrO2 redox material. Higher CO2-splitting activity of NiFe2O4 resulting in 186.545 μmol/g and 130.707 μmol/g of CO yield at 1293-795 °C and 100 sccm of CO2 flow rate were obtained by TGA at the first and second cycle, respectively. The results of both experiments showed significant CO yield at the early stages of oxygen carriers’ re-oxidation with CO2. This study provided important results that could have significant contributions to the solar thermochemical energy storage and CO2 chemical transformation processes.

Metal oxide materials are known for their ability to store thermochemical energy through reversible redox reactions. Metal oxides provide a new category of materials with exceptional performance in terms of thermochemical energy storage, reaction stability and oxygen-exchange and uptake capabilities. However, these characteristics are predicated on the right combination of the metal oxide candidates. In this study, metal oxide materials consisting of pure oxides, like cobalt(II) oxide, manganese(II) oxide, and iron(II, III) oxide (Fe3O4), and mixed oxides, such as (100 wt.% CoO, 100 wt.% Fe3O4, 100 wt.% CoO, 25 wt.% MnO + 75 wt.% CoO, 75 wt.% MnO + 25 wt.% CoO) and 50 wt.% MnO + 50.wt.% CoO), which was subjected to a two-cycle redox reaction, was proposed. The various mixtures of metal oxide catalysts proposed were investigated through the thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), energy dispersive X-ray (EDS), and scanning electron microscopy (SEM) analyses. The effect of argon (Ar) and oxygen (O2) at different gas flow rates (20, 30, and 50 mL/min) and temperature at thermal charging step and thermal discharging step (30–1400 °C) during the redox reaction were investigated. It was revealed that on the overall, 50 wt.% MnO + 50 wt.% CoO oxide had the most stable thermal stability and oxygen exchange to uptake ratio (0.83 and 0.99 at first and second redox reaction cycles, respectively). In addition, 30 mL/min Ar–20 mL/min O2 gas flow rate further increased the proposed (Fe,Co,Mn)Ox mixed oxide catalyst’s cyclic stability and oxygen uptake ratio. SEM revealed that the proposed (Fe,Co,Mn)Ox material had a smooth surface and consisted of polygonal-shaped structures. Thus, the proposed metallic oxide material can effectively be utilized for high-density thermochemical energy storage purposes. This study is of relevance to the power engineering industry and academia.

Obtaining the detailed transient heat transfer process between particles is one of the most important key factors to comprehensively understand the thermal conversion performance of the solar particle receiver. To present a clear understanding of heat transfer, a detailed two-dimensional transient numerical simulation of the solar particle receiver integrated with the Monte Carlo Ray Tracing method and the Finite Element Method is presented in this paper. The solar radiation flux distribution throughout the free-falling solar particle receiver is simulated by considering Monte Carlo Ray Tracing and the transient heat transfer in the circular particle process in the receiver is calculated using the Finite Element Method. Moreover, based on the coupling model, considering the transient heat transfer process inside the particles, the effects of different particle sizes, radiation fluxes, void ratio, and particle residence time on the temperature distribution and thermal performance of the solar particle receiver are also studied. The results show that the transient heat transfer process inside the single particles slightly affected the average outlet temperature of the receiver and the solar thermal energy conversion efficiency. A better outlet temperature and thermal conversion efficiency can be obtained when solid particles with a diameter of 0.2 ~ 0.4 mm in the experiment are used. This study provides basic theoretical insights and support for further research on the thermal performance, structural design, and optimization of the solar particle receiver.