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At least 1,387 records · Page 77

Centralized and Decentralized Control for Demand Response

Demand response has been recognized as an essential element of the smart grid. Frequency response, regulation and contingency reserve functions performed traditionally by generation resources are now starting to involve demand side resources. Additional benefits from demand response include peak reduction and load shifting, which will defer new infrastructure investment and improve generator operation efficiency. Technical approaches designed to realize these functionalities can be categorized into centralized control and decentralized control, depending on where the response decision is made. This paper discusses these two control philosophies and compares their relative advantages and disadvantages in terms of delay time, predictability, complexity, and reliability. A distribution system model with detailed household loads and controls is built to demonstrate the characteristics of the two approaches. The conclusion is that the promptness and reliability of decentralized control should be combined with the predictability and simplicity of centralized control to achieve the best performance of the smart grid.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Spark plasma sintering (SPS) densified U 3 Si 2 pellets: Microstructure control and enhanced mechanical and oxidation properties

Dense U 3 Si 2 pellets with controlled grain structure and enhanced thermal-mechanical and oxidation properties are synthesized with spark plasma sintering (SPS). Microstructure and phase composition of the SPS densified pellets are characterized systematically using SEM, EDS, and XRD. Thermal-mechanical properties and oxidation behavior of the sintered silicide fuel pellets are analyzed by laser flash, indentation, and dynamic thermogravimetric analysis. Dense U 3 Si 2 pellets are consolidated by combining high energy ball milling and rapid sintering by SPS, and the microstructure structures are controlled from micron-sized (~5.7 μm grain size) for conventional silicide to a nanocrystalline matrix with an average grain size of ~280 nm. A dominant phase of distorted U 3 Si 2 was identified with lattice expansion due to residual thermal stress upon SPS consolidation and rapid cooling processes. Both micron-sized and nano-sized pellets show exceptional thermal transport properties, consistent with monolithic silicides reported in literature. The SPS-densified pellets possess simultaneously high hardness and fracture toughness. The SPS-densified silicide pellets also demonstrate exceptional oxidation performance with extended onset oxidation temperature above 500 °C and reduced oxidation kinetics, particularly for nano-sized pellets. A strong strain effect was proposed in which compressive stress in nano-sized pellets enhances the oxidation resistance of silicide fuels, as evidenced by the degradation of oxidation performance upon strain relaxation by isothermal annealing. The correlation among the sintering process – microstructure control – physical properties and fuel behavior is established. A new concept of strain engineering is proposed further properties optimization, enabling the development of potential oxidation and corrosion-resistant silicides with extended performance, the key technological challenge of U 3 Si 2 as the leading concept of accident tolerant fuels.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Integrating field observations and process-based modeling to predict watershed water quality under environmental perturbations

Watersheds play a critical role in supplying water resources needed for human use and ecosystem health. Understanding and predicting how, when, and where changes in the quantity and quality of water resources occur under different environmental stresses including extreme events is crucial for sustainable management of water resources under a changing environment. However, few studies have attempted to quantify or identify the factors and process interactions controlling the impact of extreme events across water-shed systems. Only few large-scale studies include coordinated monitoring and modeling efforts, which limits our ability to assess the large-scale impact of extreme events on water supply and quality. Methods are lacking to propagate uncertainty in process understanding through an integrated hydro-biogeochemical model framework and evaluate its importance, thus failing to take full advantage of the information potentially available through transformative advances in characterization technologies from high-resolution mass spectrometry to airborne and satellite-based remote sensing. There are consequent risks to our nations water security and to human and ecosystem health that may become exacerbated with the increasing frequency of extreme events that is projected for the coming decades. This paper reviews the current status of watershed science for both water quantity and quality and identifies critical gaps in our current knowledge and modeling capability in addressing the emergent needs in predicting watershed hydrologic and biogeochemical responses (i.e., water quantity and quality) under natural and anthropogenic perturbations. We highlight the need to (1) understand how environmental perturbations including extreme events like floods and droughts propagate through watershed systems and assess their short- and long-term impacts on watershed biogeochemistry, water quality and their recovery pathways; (2) develop and improve a watershed water quality model that reflects the state of scientific understanding gained from observations; and (3) construct a data-model fusion system for watershed characterization, process identification, and mechanistic model parameterization. A large base of modeling, monitoring and data capabilities have been built by various federal government agencies given the relevance of water to their critical missions. An emerging need is to build an integrated national capability for watershed water availability and quality that can address water-related missions across multiple federal agencies.

13 HYDRO ENERGY↗

Power management across heterogeneous processing units

A method includes controlling active frequency states of a plurality of heterogeneous processing units based on frequency sensitivity metrics indicating performance coupling between different types of processing units in the plurality of heterogeneous processing units. A processor includes a plurality of heterogeneous processing units and a performance controller to control active frequency states of the plurality of heterogeneous processing units based on frequency sensitivity metrics indicating performance coupling between different types of processing units in the plurality of heterogeneous processing units. The active frequency state of a first type of processing unit in the plurality of heterogeneous processing units is controlled based on a first activity metric associated with a first type of processing unit and a second activity metric associated with a second type of processing unit.

Paul, Indrani↗

Electron-stimulated purification of platinum nanostructures grown via focused electron beam induced deposition

In this paper, platinum–carbon nanostructures deposited via electron beam induced deposition from MeCpPt(IV)Me 3 are purified during a post-deposition electron exposure treatment in a localized oxygen ambient at room temperature. Time-dependent studies demonstrate that the process occurs from the top–down. Electron beam energy and current studies demonstrate that the process is controlled by a confluence of the electron energy loss and oxygen concentration. Furthermore, the experimental results are modeled as a 2nd order reaction which is dependent on both the electron energy loss density and the oxygen concentration. Finally, in addition to purification, the post-deposition electron stimulated oxygen purification process enhances the resolution of the EBID process due to the isotropic carbon removal from the as-deposited materials which produces high-fidelity shape retention.

36 MATERIALS SCIENCE↗

Chronocoulometry for quantitative control of mass removal in micro-structures and sensors

In this work, tungsten wires have been etched in a KOH electrolyte solution. Based on the oxidation state of the electrolytic dissolution reaction's product and time integration of the Faradaic current produced during the reaction, this method is capable of providing a direct measurement of the change in mass of a structure from anodic dissolution. To assess the application of this process for controlled mass removal spanning sub-micrograms to milligrams, two experimental studies and accompanying uncertainty analyses have been undertaken. In the first of these, 5 tungsten wires of length 30 mm were used to remove mass values ranging from 50 to 350 {mu}g. Uncertainty estimates indicate relative combined standard uncertainties of less than 0.3% in the mass changes determined from the measurement of Faradaic current. Comparison of the mass change determined using the electrolytic method, and using a precision ultra-microbalance agreed within this uncertainty. The charge-based method was then applied to modify the dynamic characteristics of a quartz tuning fork oscillator. In these experiments, tungsten fiber attached to one tine of the oscillator was etched in 5 {mu}g increments up to 120 {mu}g of total removed mass. In general, frequency shifts of 2.8 Hz{center_dot}{mu}g{sup -1} were observed, indicating sub-microgram resolution for the characterization of probes based on frequency shift and charge-based mass measurement. Taken together, this study provides the basis for a precision method for determining changes in mass based on electrical measurements from an electrochemical system. The utility of this technique is demonstrated through controlled modification of the dynamic properties of a mechanical oscillator.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Hydrogen effect on the morphology and structure of 3D porous titanium in the HFCVD-diamond growth environment

Titanium hydride was obtained from hydrogenation process on pure titanium (Ti) using a hot filament chemical vapor deposition reactor. The Ti samples were produced from powder metallurgy technique and present three-dimensional porosity. The experimental parameters of the hydrogenation process were controlled in a similar way as those for diamond growth. The pressure inside the reactor was kept at 6.6 kPa for a H{sub 2} flow rate of 100 sccm and hydrogenation time of 1 hour. The distance from the filaments to the Ti surface was kept at 5 mm. Hydrogenation processes were carried out at different temperatures of 773, 873, 973 and 1073 K. The morphology of the titanium hydrides was studied by scanning electron microscopy. The images showed an increase in the roughness titanium surface as well as the formation of cracks due to the hydride titanium precipitation. The structure of these titanium hydrides was analyzed by X-ray diffraction, performed through {theta}-2{theta} scans from 1 to 15{sup o} grazing incident angle. The results revealed that the temperature enhanced the titanium hydride concentration in the samples with a predominant precipitation of TiH phase for the four temperatures studied. - Highlights: {yields} Hydrogen quickly spread out in the Ti matrix reacting and generating TiH phases. {yields} The higher the hydrogenation temperature the higher the amount of TiH formation. {yields} The volume increasing associated with the TiH formation caused tensions in the Ti metallic matrix. {yields} The TiH increases the Ti surface roughness influencing the grain size reduction.

36 MATERIALS SCIENCE↗

Microstructure evolution and mechanical properties of Cu/Sn/Ag TLP-bonded joint during thermal aging

Highlights: • The thermal reliability of the Cu/Sn/Ag TLP-bonded joint was investigated through high-temperature storage. • A diffusion reaction occurred at the interface between Cu{sub 3}Sn and Ag{sub 3}Sn during thermal aging. • The mechanism of the Cu{sub 3}Sn/Ag{sub 3}Sn interfacial reaction was investigated from thermodynamics and kinetics. - Abstract: Low-temperature transient liquid phase (TLP) bonding is a promising joining technology for high-temperature electronic devices packaging. However, the effect of thermal aging on the joint microstructure and performance has been rarely studied so far. In this paper, the relationship between microstructural evolution and mechanical property was developed for the Cu/Sn/Ag TLP-bonded joint during 350 °C aging. Experimental results show that an interfacial reaction occurs between the intermetallic compounds (IMCs) of Cu{sub 3}Sn and Ag{sub 3}Sn, which induces that a great amount of Cu{sub 3}Sn particles or wedges embed into the Ag-Sn phase layer. The reaction process is controlled by a volume diffusion of Cu elements from the Cu substrate, and capable of promoting the transformation from Ag{sub 3}Sn into Ag(Sn) solid solution. Cu{sub 41}Sn{sub 11} phase can be formed at the expense of Cu{sub 3}Sn and Cu, of which transformation process is completely achieved after aging for 480 h, and the Cu(Sn) solid solution intimately contacts with the opposite Ag(Sn) solid solution in many areas after aging for 960 h. The joint mechanical property initially declines due to the formation of Cu{sub 41}Sn{sub 11} phase and Cu-Sn IMCs grain coarsening, and then increases because of the complete depletion of Cu{sub 3}Sn and substantial precipitation of Cu(Sn) solid solution. After aging for nearly 1000 h, the joint still maintains a high shear strength of >40 MPa, indicating an excellent thermal reliability.

36 MATERIALS SCIENCE↗

Influence of crystalline phase and defects in the ZrO{sub 2} nanoparticles synthesized by thermal plasma route on its photocatalytic properties

Graphical abstract: Thermal plasma synthesized nanophase zirconia showing the blue shift in the band gap of monoclinic phase as found from the photoabsorption spectroscopy was found to be the dominant parameter for the enhancement in its photocatalytic activity. The existence of different defect states and their concentration in as synthesized samples also inferred from the photoabsorption measurements were also found to be responsible for the enhanced photocatalytic activity of the samples. Highlights: ► Phase controlled structural formation of nanophase ZrO{sub 2} by thermal plasma route. ► Enhanced photocatalytic degradation rate of methylene blue dye. ► The blue shift in the band gap of monoclinic phase of nanocrystalline ZrO{sub 2}. ► Existence of different defect states in the as synthesized nano phase ZrO{sub 2}. ► Several competing processes which controls the photocatalytic degradation rate. -- Abstract: The photocatalytic activity of pure ZrO{sub 2} samples, prepared by a thermal plasma route, and characterized by X-ray diffraction technique was tested for the degradation of methylene blue, which is known to be a hazardous dye. Although, all these samples synthesized at different operating pressures of the thermal plasma reactor showed the photocatalytic activity; the sample synthesized at 1.33 bar of operating pressure showed the highest photocatalytic activity. The blue shift in the band gap of monoclinic phase, as observed from the photo-absorption spectroscopy, may be attributed to the enhanced photocatalytic activity. The existence of different defect states and their concentration as, inferred from the photo-absorption measurements were also found to be responsible for the enhanced photocatalytic activity of the as synthesized samples.

36 MATERIALS SCIENCE↗

AN INTERNET RACK MONITOR-CONTROLLER FOR APS LINAC RF ELECTRONICS UPGRADE

To support the research and development in APS LINAC area, the existing LINAC rf control performance needs to be much improved, and thus an upgrade of the legacy LINAC rf electronics becomes necessary. The proposed upgrade plan centers on the concept of using a modern, network-attached, rackmount digital electronics platform –Internet Rack Monitor-Controller (or IRMC) to achieve the goal of modernizing the rf electronics at a lower cost. The system model of the envisioned IRMC is basically a 3-tier stack with a high-performance DSP in the mid-layer to perform the core tasks of real-time rf data processing and controls. The Digital Front-End (DFE) attachment layer at bottom bridges the applicationspecific rf front-ends to the DSP. A network communication gateway, together with an embedded event receiver (EVR) in the top layer merges the Internet Rack MonitorController node into the networks of the accelerator controls infrastructure. Although the concept is very much in trend with today’s Internet-of-Things (IoT), this implementation has actually been used in the accelerators for over two decades.

Ma, Hengjie↗

Long-term stewardship - surveillance and maintenance at Hanford - 15155

In FY 2015, Hanford's Long-Term Stewardship (LTS) Program is tasked to complete the required entries into five cocooned plutonium production reactors (105-C, 105-D, 105-F, 105-H and 105-N), which sit adjacent to the Columbia River. The first reactor entered in October 2014, the cocooned plutonium production reactor, 105-F, signaled the LTS Program's entry into the Surveillance and Maintenance (S and M) era. Reactor entries at Hanford are conducted at 5-year intervals to assess the condition of the structures and evaluate potential deterioration of the reactor core, shield walls and roof. The cocooned structures are designed to protect the reactor core for up to 75 years while radioactive decay continues, ultimately making the structures safe for demolition and removal. The 105-F entry demonstrates that the LTS program at Hanford is shifting from a program focused on transitioning cleaned up land and waste sites to a program focused primarily on S and M activities. The entry process is carefully planned, choreographed and monitored to ensure safety of the workers and minimize the time the reactor structure is opened. The process includes controlled opening of the reactor, air quality monitoring, structural safety inspections, and radiological clearance. Once the structure is cleared for entry, assessments of the structural integrity and radiologic conditions are completed. Evaluation of the interior temperature and flood monitoring equipment is conducted. Facility visits by regulators and DOE personnel close out the process prior to welding the door closed until the next assessment, five years later. This paper will document execution of the entry work package, identify challenges overcome, and provide video documentation as reference material for future workers and the public. The current LTS program has responsibility for approximately 100,000 acres, over 200 waste sites and six cocooned reactors. Just over 5,600 documents have been identified, indexed and tagged for storage in the LTS document library. The program has successfully completed seven consecutive transitions since July 2011, with six more transitions planned in the next 18 months to support the U.S. Department of Energy Richland Operations Office's (DOE-RL) near-term cleanup objectives to significantly reduce the footprint of active cleanup operations for the River Corridor. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Use of Separator with Regular Granular Filling in Extraction Processes - 12209

The separator with a regular granular filling has been developed to be used for the operations of the removal of carbon-black impurities from the aqueous flow; the intra-cycle regeneration of back-extractants; and the concentrating back-extraction of plutonium in the extraction SNF reprocessing technology. The process conditions for those operations have been experimentally tested using this separator. Thus, the separator for operations of concentrating reextraction of plutonium and regeneration recycling extractant allows to: - derive plutonium from the organic stream into an extremely concentrated form, reducing the amount of liquid radioactive waste (raffinate, decantate) plutonium branches to a minimum; - controlling the processes of concentration of uranium and plutonium, get uranium-plutonium product with required concentration and the amount of metal with required ratio; - eliminate contamination of the emulsion flows; - simplify the purification of uranium from the extract plutonium; - test results showed that when working on a solution 'hydrazine-DTPA' in the separator it is achieved the extraction of plutonium re-extract - 82% TC - at 56-65%. With the transition to the reextraction by solution 'U (IV)-hydrazine', of plutonium into re-extract increases to 95%, technetium - up to 83%; - regenerate the extractant recycling minimizing the amount of liquid radioactive waste generated as a technology used as well as alternative 'salt-free' systems; - it is found that the regeneration of the extractant solution of soda and EDA in the separator at a load of 3.2 m{sup 3} / (m{sup 2}.h) it can be achieved almost complete phase separation. Residual carryover of 0,005-0,006% emulsion is on the verge of analytical detection. - It is shown that in the depth of separation phase a separation of the extractant regeneration of quality superior is more than 5-7 times to the extraction. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Employing Eye Trackers to Reduce Nuisance Alarms

When process operators anticipate an alarm prior to its annunciation, that alarm loses information value and becomes a nuisance. This study investigated using eye trackers to measure and adjust the salience of alarms with three methods of gaze-based acknowledgement (GBA) of alarms that estimate operator anticipation. When these methods detected possible alarm anticipation, the alarm’s audio and visual salience was reduced. A total of 24 engineering students (male = 14, female = 10) aged between 18 and 45 were recruited to predict alarms and control a process parameter in three scenario types (parameter near threshold, trending, or fluctuating). The study evaluated whether behaviors of the monitored parameter affected how frequently the three GBA methods were utilized and whether reducing alarm salience improved control task performance. The results did not show significant task improvement with any GBA methods (F(3,69) = 1.357, p = 0.263, partial η 2 = 0.056). However, the scenario type affected which GBA method was more utilized (X 2 (2, N = 432) = 30.147, p < 0.001). Alarm prediction hits with gaze-based acknowledgements coincided more frequently than alarm prediction hits without gaze-based acknowledgements (X 2 (1, N = 432) = 23.802, p < 0.001, OR = 3.877, 95% CI 2.25–6.68, p < 0.05). Participant ratings indicated an overall preference for the three GBA methods over a standard alarm design (F(3,63) = 3.745, p = 0.015, partial η 2 = 0.151). This study provides empirical evidence for the potential of eye tracking in alarm management but highlights the need for additional research to increase validity for inferring alarm anticipation.

99 - GENERAL AND MISCELLANEOUS↗

Data analytics approach for melt-pool geometries in metal additive manufacturing

Modern data analytics was employed to understand and predict physics-based melt-pool formation by fabricating Ni alloy single tracks using powder bed fusion. An extensive database of melt-pool geometries was created, including processing parameters and material characteristics as input features. Correlation analysis provided insight for relationships between process parameters and melt-pools, and enabled the development of meaningful machine learning models via the use of highly correlated features. We successfully demonstrated that data analytics facilitates understanding of the inherent physics and reliable prediction of melt-pool geometries. This approach can serve as a basis for the melt-pool control and process optimization.

36 MATERIALS SCIENCE↗

Scaling Effects of Cr(VI) Reduction Kinetics. The Role of Geochemical Heterogeneity

The natural subsurface is highly heterogeneous with minerals distributed in different spatial patterns. Fundamental understanding of how mineral spatial distribution patterns regulate sorption process is important for predicting the transport and fate of chemicals. Existing studies about the sorption was carried out in well-mixed batch reactors or uniformly packed columns, with few data available on the effects of spatial heterogeneities. As a result, there is a lack of data and understanding on how spatial heterogeneities control sorption processes. In this project, we aim to understand and develop modeling capabilities to predict the sorption of Cr(VI), an omnipresent contaminant in natural systems due to its natural occurrence and industrial utilization. We systematically examine the role of spatial patterns of illite, a common clay, in determining the extent of transport limitation and scaling effects associated with Cr(VI) sorption capacity and kinetics using column experiments and reactive transport modeling. Our results showed that the sorbed mass and rates can differ by an order of magnitude due to of the illite spatial heterogeneities and transport limitation. With constraints from data, we also developed the capabilities of modeling Cr(VI) in heterogeneous media. The developed model is then utilized to understand the general principles that govern the relationship between sorption and connectivity, a key measure of the spatial pattern characteristics. This correlation can be used to estimate Cr(VI) sorption characteristics in heterogeneous porous media. Insights gained here bridge gaps between laboratory and field application in hydrogeology and geochemical field, and advance predictive understanding of reactive transport processes in the natural heterogeneous subsurface. We believe that these findings will be of interest to a large number of environmental geochemists and engineers, hydrogeologists, and those interested in contaminant fate and transport, water quality and water composition, and natural attenuation processes in natural systems.

58 GEOSCIENCES↗

Alternative High-Performance Ceramic Waste Forms

This final report (M5NU-12-NY-AU # 0202-0410) summarizes the results of the project titled “Alternative High-Performance Ceramic Waste Forms,” funded in FY12 by the Nuclear Energy University Program (NEUP Project # 12-3809) being led by Alfred University in collaboration with Savannah River National Laboratory (SRNL). The overall focus of the project is to advance fundamental understanding of crystalline ceramic waste forms and to demonstrate their viability as alternative waste forms to borosilicate glasses. We processed single- and multiphase hollandite waste forms based on simulated waste streams compositions provided by SRNL based on the advanced fuel cycle initiative (AFCI) aqueous separation process developed in the Fuel Cycle Research and Development (FCR&D). For multiphase simulated waste forms, oxide and carbonate precursors were mixed together via ball milling with deionized water using zirconia media in a polyethylene jar for 2 h. The slurry was dried overnight and then separated from the media. The blended powders were then subjected to melting or spark plasma sintering (SPS) processes. Microstructural evolution and phase assemblages of these samples were studied using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion analysis of x-rays (EDAX), wavelength dispersive spectrometry (WDS), transmission electron spectroscopy (TEM), selective area x-ray diffraction (SAXD), and electron backscatter diffraction (EBSD). These results showed that the processing methods have significant effect on the microstructure and thus the performance of these waste forms. The Ce substitution into zirconolite and pyrochlore materials was investigated using a combination of experimental (in situ XRD and x-ray absorption near edge structure (XANES)) and modeling techniques to study these single phases independently. In zirconolite materials, a transition from the 2M to the 4M polymorph was observed with increasing Ce content. The resulting powders were consolidated via SPS. Ce was reduced to the trivalent oxidation state and the zirconolite was converted into undesirable perovskite. The zirconolite polymorphs found in the synthesized powders were recovered after a post-SPS heat treatment in air. These results demonstrated the potential of processing in controlling the phase assemblage in these waste forms. Hollandites with Cr 3+ trivalent cations were identified as potential hosts for Cs immobilization and are being investigated for Cs retention properties. Series of compositions Ba 1.15-x Cs 2x Cr 2.3 Ti 5.7 O 16 , with increasing Cs loadings, were prepared by sol-gel process and characterized for structural parameters. Structural characterization was performed by a combination of powder XRD and neutron powder diffraction. Phase pure hollandite adapting monoclinic symmetry (I2/m) was observed for 0 ≤ x ≤ 0.55. These results were used to develop a new structural model to interpret Cs immobilization in these hollandites. Performance of these waste forms were evaluated for chemical durability and radiation resistance. Product consistency testing (PCT) and vapor hydration testing (VHT) were used for testing of chemical durability. Radiation resistance was tested using He + ions to simulate $\alpha$ particles and heavy ions such as Au 3+ to simulate a recoil. These results showed that these waste forms were chemically durable. The waste forms also amorphized to various degrees on exposure to simulated radiation.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Refractory-based thermal energy storage for industrial process heat: one-dimensional modeling, control, and optimization

The variable and weather-dependent output of wind and solar power plants present a substantial challenge for planning and operating electricity-systems, particularly in the absence of cost-effective and dispatchable energy storage technologies. This study investigates a high-temperature, electrically heated, refractory-based thermal energy storage (RTES) system that stores electrical energy as sensible heat in dense ceramic bricks over the 950–1800 °C range. The stored heat can be discharged as a controlled hot-gas stream for industrial heating, fuel substitution in high-temperature processes, or electricity generation. The main novelty is a comprehensive modelling, control, mapping, and optimization framework that integrates one-dimensional transient gas–solid heat transfer, fan-assisted discharge, bypass-flow regulation, reheating logic, fan-power evaluation, insulation-loss assessment, and genetic-algorithm-based design optimization. The model uses feedback from outlet temperature and delivered power to regulate discharge, while a two-stage genetic algorithm optimizes brick-channel geometry, gas-flow operation, and multilayer insulation thicknesses. Storage capacities below 50 MWh and discharge powers of 5–30 MW are analyzed to evaluate hold time, thermal delivery, fan-power penalty, heat loss, state-of-charge evolution, and indicative capital cost. Results demonstrate that optimized and well-insulated refractory-based thermal energy storage units can provide stable, efficient, and repeatable heat delivery over multiple discharge cycles. The generated performance and cost maps support modular refractory thermal energy storage as a practical option for large-scale integration of wind and solar generation and for high-temperature industrial process heat.

25 ENERGY STORAGE↗