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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Low-cost crushed-rock heat storage with oil or salt heat transfer

The demand for variable electricity and heat is met by fossil-fuel power plants because the power plant capital costs and the cost of storing fossil fuels are low. A low-carbon economy requires replacement of the storage function of fossil fuels to provide variable heat and electricity as needed. The Crushed Rock Ultra-large Stored Heat (CRUSH) system is a new technology with the goal to provide heat storage at an incremental capital cost of $2–4/kWh at scales of 10 s to 100 s of GWhs that enables economic daily to multi-week storage. CRUSH can be coupled to nuclear power plants, concentrated solar power (CSP) plants and thermal energy batteries to provide variable electricity and heat on demand. Sensible heat is stored in crushed rock—the lowest-cost heat-storage material. Heat is transferred to and from the crushed rock using nitrate salt or heat-transfer oils but these fluids do not store heat. Heat from a nuclear reactor, CSP plant or conversion of low-price electricity into heat is used to heat the salt or oil. The hot fluid is poured over the crushed rock, trickles downward by gravity through the rock, heats the rock and is collected by the drain pans under the crushed rock. To recover heat cold salt or oil is poured over hot crushed rock, trickles down by gravity while being heated and is collected by the drain pans under the crushed rock. The system design and engineering trade-offs are described. The technology is in the early stages of development.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2016

Coupled modeling of a directly heated tubular solar receiver for supercritical carbon dioxide Brayton cycle: Optical and thermal-fluid evaluation

In single phase performance and appealing thermo-physical properties supercritical carbon dioxide (s-CO 2 ) make a good heat transfer fluid candidate for concentrating solar power (CSP) technologies. The development of a solar receiver capable of delivering s-CO 2 at outlet temperatures ~973 K is required in order to merge CSP and s-CO 2 Brayton cycle technologies. A coupled optical and thermal-fluid modeling effort for a tubular receiver is undertaken to evaluate the direct tubular s-CO 2 receiver’s thermal performance when exposed to a concentrated solar power input of ~0.3–0.5 MW. Ray tracing, using SolTrace, is performed to determine the heat flux profiles on the receiver and computational fluid dynamics (CFD) determines the thermal performance of the receiver under the specified heating conditions. Moreover, an in-house MATLAB code is developed to couple SolTrace and ANSYS Fluent. CFD modeling is performed using ANSYS Fluent to predict the thermal performance of the receiver by evaluating radiation and convection heat loss mechanisms. Understanding the effects of variation in heliostat aiming strategy and flow configurations on the thermal performance of the receiver was achieved through parametric analyses. Finally, a receiver thermal efficiency ~85% was predicted and the surface temperatures were observed to be within the allowable limit for the materials under consideration.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Analysis of thermal and mechanical properties with inventory level of the molten salt storage tank in central receiver concentrating solar power plants

Molten salt thermal energy storage (TES) tanks ensure steady power output of concentrating solar power (CSP) plants; however, recent tank failures have highlighted the need for further analysis. Current studies primarily focus on analyzing the molten salt flow, heat transfer, and thermal efficiency. Additionally, research on the latest tank structures is limited and lacks newest experimental validation. This study measures temperature and molten salt inventory levels in the high-temperature tank at a 50 MW central receiver CSP plant, connected to the power grid in 2019. A multi-physics model was developed to evaluate thermal and mechanical properties of TES tanks by combining computational fluid dynamics and finite element modeling using real plant data. Heat loss, temperature, displacement, and stress distribution of the tank at different inventory levels were investigated. Results show that ambient air velocity near the tank roof reaches 2.14 m/s, much higher than 0.2 m/s near the wall. The temperatures of inventory fluid and tank are close, varying slightly at different levels due to thermal conduction and radiation. Because the heat loss strongly depends on temperature, the total tank loss remains nearly constant across inventory levels. Larger temperature gradients and thermal stresses are primarily localized along the tank floor edge and the air-salt interface. Notably, the maximum thermal stress at the tank edge is three times higher than that at the interface. The magnitude of total stress changes by less than 5 MPa with and without thermal load, indicating that high temperatures exert only a minor impact on tank stress. In contrast, thermal load significantly affects tank deformation, particularly at the roof edge, where values exceed 150 mm. Despite the large variation in molten salt levels, tank wall temperatures and displacements present a minor change, suggesting a weak correlation with inventory levels. In conclusion, the findings obtained in this study provide important insights on the TES tank that could be used to optimize tank design and operation strategies.

14 SOLAR ENERGY↗
DOE OSTI2019

Cogeneration using multi-effect distillation and a solar-powered supercritical carbon dioxide Brayton cycle

Supercritical carbon dioxide (sCO 2 ) Brayton cycles are considered to be a potentially viable option for reducing the cost of electricity generation from solar power tower plants, owing to theoretically high efficiency, low compressor work, and compact turbomachinery. These cycles have relatively high heat rejection temperatures (>70 degrees C), which are ideal for integration with multi-effect distillation (MED) for distillate generation from seawater, without being a parasitic load to the power plant as compared to cogeneration with steam Rankine cycle. The intermittency of solar radiation reduces the annual capacity factor of concentrating solar power (CSP) plants to about 50-60% even with a molten salt storage tank of 10-h. This reduces the annual distillate generation and increases the cost of the distillate. A novel concept to reduce distillate cost is introduced, whereby the waste heat from the sCO 2 Brayton cycle is stored. A two-tank demineralized water storage tank is selected and is shown to allow for the integration of a smaller MED system operating at an increased capacity factor. The optimal storage tank design reduces the distillate cost by 19% and increase the MED capacity factor from 46.4% to 75%. Different coastal locations with good solar resource are studied for cogeneration with the CSP-sCO 2 Brayton cycle. Techno-economic analysis shows the cost of distillate produced by MED is 16% cheaper than the distillate produced from reverse osmosis system for Yanbu, Saudi Arabia.

14 SOLAR ENERGY↗
DOE OSTI2015

Creating a spatial multi-criteria decision support system for energy related integrated environmental impact assessment

By their spatially very distributed nature, profitability and impacts of renewable energy resources are highly correlated with the geographic locations of power plant deployments. A web-based Spatial Decision Support System (SDSS) based on a Multi-Criteria Decision Analysis (MCDA) approach has been implemented for identifying preferable locations for solar power plants based on user preferences. The designated areas found serve for the input scenario development for a subsequent integrated Environmental Impact Assessment. The capabilities of the SDSS service get showcased for Concentrated Solar Power (CSP) plants in the region of Andalusia, Spain. The resulting spatial patterns of possible power plant sites are an important input to the procedural chain of assessing impacts of renewable energies in an integrated effort. The applied methodology and the implemented SDSS are applicable for other renewable technologies as well. - Highlights: • The proposed tool facilitates well-founded CSP plant siting decisions. • Spatial MCDA methods are implemented in a WebGIS environment. • GIS-based SDSS can contribute to a modern integrated impact assessment workflow. • The conducted case study proves the suitability of the methodology.

14 SOLAR ENERGY↗
DOE OSTI2015

Web tools concerning performance analysis and planning support for solar energy plants starting from remotely sensed optical images

We present innovative web tools, developed also in the frame of the FP7 ENDORSE (ENergy DOwnstReam SErvices) project, for the performance analysis and the support in planning of solar energy plants (PV, CSP, CPV). These services are based on the combination between the detailed physical model of each part of the plants and the near real-time satellite remote sensing of incident solar irradiance. Starting from the solar Global Horizontal Irradiance (GHI) data provided by the Monitoring Atmospheric Composition and Climate (GMES-MACC) Core Service and based on the elaboration of Meteosat Second Generation (MSG) satellite optical imagery, the Global Tilted Irradiance (GTI) or the Beam Normal Irradiance (BNI) incident on plant's solar PV panels (or solar receivers for CSP or CPV) is calculated. Combining these parameters with the model of the solar power plant, using also air temperature values, we can assess in near-real-time the daily evolution of the alternate current (AC) power produced by the plant. We are therefore able to compare this satellite-based AC power yield with the actually measured one and, consequently, to readily detect any possible malfunctions and to evaluate the performances of the plant (so-called “Controller” service). Besides, the same method can be applied to satellite-based averaged environmental data (solar irradiance and air temperature) in order to provide a Return on Investment analysis in support to the planning of new solar energy plants (so-called “Planner” service). This method has been successfully applied to three test solar plants (in North, Centre and South Italy respectively) and it has been validated by comparing satellite-based and in-situ measured hourly AC power data for several months in 2013 and 2014. The results show a good accuracy: the overall Normalized Bias (NB) is − 0.41%, the overall Normalized Mean Absolute Error (NMAE) is 4.90%, the Normalized Root Mean Square Error (NRMSE) is 7.66% and the overall Correlation Coefficient (CC) is 0.9538. The maximum value of the Normalized Absolute Error (NAE) is about 30% and occurs for time periods with highly variable meteorological conditions. - Highlights: • We developed an online service (Controller) dedicated to solar energy plants real-time monitoring • We developed an online service (Planner) that supports the planning of new solar energy plants • The services are based on the elaboration of satellite optical imagery in near real-time • The validation with respect to in-situ measured hourly AC power data for three test solar plants shows good accuracy • The maximum value of the Normalized Absolute Error is about 30% and occurs for highly variable meteorological conditions.

14 SOLAR ENERGY↗
DOE OSTI2016

Effect of multi-tank thermal energy storage, recuperator effectiveness, and solar receiver conductance on the performance of a concentrated solar supercritical CO 2 -based power plant operating under different seasonal conditions

Renewable energy technologies based on solar energy concentration are important alternatives to supply the rising energy demand in the world and to mitigate the negative environmental impact caused by the extensive use of fossil-fuels. In this work, a thermodynamic model based on energy and exergy analyses is developed to study the transient behavior of a Concentrated Solar Power (CSP) supercritical CO2 plant operating under different seasonal conditions. The system analyzed is composed of a central receiver, hot and cold thermal energy storage units, a heat exchanger, a recuperator, and three-stage compression and expansion subsystems with intercoolers between compressors and reheaters between turbines, respectively. From the exergy analysis, the recuperator, the hot thermal energy storage, and the solar receiver were identified as the main sources for exergy destruction with more than 70% of the total lost work in the plant. These components offer an important potential to improve the system’s performance via design optimization. With reference parameters, the system reaches efficiencies of about 18.5%. These efficiencies are increased with a combination of improved design parameters, reaching values of between 24.1% and 26.2%, depending on the season, which are relatively good for CSP plants.

14 SOLAR ENERGY↗
DOE OSTI2025

Impact of molten salt inflow on the temperature distribution in thermal energy storage tanks at startup for central receiver concentrating solar power plants

Concentrating Solar Power (CSP) systems with molten salt thermal energy storage (TES) tanks are one of the most promising, renewable-based energy conversion technologies for larger-scale power generation. The TES tank is one of the most critical components in CSP plants due to its high-temperature operation (up to 565 °C), daily thermal cycling, and intermittent solar radiation conditions. The plant startup is one of the most challenging operation conditions that could lead to damaging thermal gradients due to low salt inventory levels. In this study an analytical model for the sparger ring was developed and integrated with a detailed computational fluid dynamics model of a commercial-scaled molten salt tank. The integrated model allows an accurate representation of the tank operation to evaluate the effect of molten salt inflow on the mixing process. The tank filling process during plant startup was analyzed considering sparger rings with variations in design features, including inlet orifice configurations, number of orifices, direction of the inlets, and orifice diameter. The results demonstrated that higher temperature gradients are obtained in the tank floor during the plant startup. A sparger ring configuration with a predetermined orifice inlet inclination (30°, 45° and 60°) leads to significant temperature differences in the floor, between 57 °C and 62 °C, but better homogeneity in the temperature of the salt inventory. Lower salt inflow velocities result in a more homogeneous floor temperature, with maximum temperature differences under 38 °C. The sparger ring configuration with 52 orifices of 1-in. diameter and vertical flow showed better homogeneity in the temperature differences as a function of the salt level and lower temperature gradients in the tank floor. Because large temperature gradients in the tank's floor have been identified as one of the main factors contributing to tank failures, assessing various sparger ring design features is fundamental to determining proper inflow conditions that lead to low-temperature gradients and reducing failure susceptibility.

14 SOLAR ENERGY↗
DOE OSTI2026

Evaluation of thermal energy storage for central receiver concentrating solar power plants under charging cycles through structural assessment

Electricity production by concentrated solar power (CSP) systems has stood out among energy transition alternatives due to their large generation capacity (between 30 MW and 400 MW) and high capacity factor (80%) when incorporating thermal storage systems (TES). Although TES tanks in operation worldwide are made of austenitic steels with remarkable mechanical and anticorrosive properties, operational failures have been reported due to low-cycle fatigue, creep, and the abrupt release of residual stresses generated during tank manufacturing. A critical operation for salt tanks is the initial daily charging operation, given the low fluid level and the thermal gradients between the inventory and the salt entering the tank. This study presents a structural simulation of a 39.6 m-diameter molten salt tank for central receiver CSP plants, accounting for temperature and pressure variations during charging and different sparger ring inlet configurations. The initial pre-stressed condition of the floor, resulting from the manufacture of welded plates, is used as a boundary condition. The fatigue and creep life analyses were performed in accordance with the ASME BPVC and API standards. It was found that the tank's floor is in a less favourable mechanical condition than the wall, due to its initial manufacturing condition and the maximum temperature differences during charging. A critical zone was identified in an area affected by residual stress on the floor and under the sparger ring. The baseline sparger ring configuration, with 52 2-inch-diameter orifices and a flow direction of 90 degrees , results in an average floor stress of approximately 25 MPa and creep damage after 1.2 years of tank operation.

14 SOLAR ENERGY↗
DOE OSTI2021

Measurement of High-temperature Thermophysical Properties of Bulk and Coatings Using Modulated Photothermal Radiometry

This paper presents the development of instrumentation for the measurement of high-temperature thermal conductivity of bulk and coatings using a modulated photothermal radiometry (MPR) method, where a sample is heated by an intensity-modulated laser to probe into different layers of the sample. While MPR has been previously established, most of the previous studies only focus on the measurement at room temperature. The MPR has not been well studied for measurements of bulk and coating materials at high temperatures, which are increasingly important for a multitude of applications, such as materials used in the concentrating solar power (CSP) plants and the nuclear reactors. MPR is a non-contact technique that utilizes the intrinsic thermal emission from the specimens for thermometry, which is favorable for measurements at high temperatures in harsh environment. The authors designed and utilized a sample holder suitable for high temperature measurement up to 973 K with good temperature uniformity within the sample. The high-temperature MPR setup was validated by measuring bulk materials with known thermal conductivity. The setup and technique were then extended to the measurement of black solar-absorbing coatings of 10 to 50 μm thick on various substrates by modulating the frequency of the laser heating beam and the thermal penetration depth. Here, the studies showed that thermal conductivities of typical solar-absorbing coatings are 0.4 ~ 0.8 W m -1 K -1 , indicating a possibly large temperature drop within the coating under high solar irradiation flux, such as over 1000-sun for central solar towers in CSP plants.

14 SOLAR ENERGY↗
DOE OSTI2017

High temperature thermal energy storage in the CaAl 2 system

Concentrated solar power (CSP) has been gaining significant attention as a method to produce electricity, but requires a suitable thermal energy storage (TES) system for continuous operation when the sun is unavailable. Thermochemical energy storage systems based on metal hydrides have advantages due to their high energy densities, potential for cost reductions, and higher operating conditions versus commonly utilized molten salts. Higher operational temperatures are desired for CSP power plants to achieve higher efficiencies and therefore lower costs. Herein, we demonstrate the feasibility of CaAl 2 as a high temperature thermal energy storage material for concentrated solar power applications. CaAl 2 is demonstrated to operate at 600 °C and have excellent reversibility, reasonable thermal conductivities, and equilibrium pressures practical for metal hydride based thermal energy storage systems. Furthermore, CaAl 2 was determined to hydrogenate in a two-step process mechanism to form CaH 2 and Al and dehydrogenate to reform CaAl 2 at 600 °C by adjusting hydrogen pressure. To our knowledge, this material represents the lowest cost metal hydride TES material capable of operating at or above 600 °C.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Computational singular perturbation analysis of stochastic chemical systems with stiffness

Computational singular perturbation (CSP) is a useful method for analysis, reduction, and time integration of stiff ordinary differential equation systems. It has found dominant utility, in particular, in chemical reaction systems with a large range of time scales at continuum and deterministic level. On the other hand, CSP is not directly applicable to chemical reaction systems at micro or meso-scale, where stochasticity plays an non-negligible role and thus has to be taken into account. In this work we develop a novel stochastic computational singular perturbation (SCSP) analysis and time integration framework, and associated algorithm, that can be used to not only construct accurately and efficiently the numerical solutions to stiff stochastic chemical reaction systems, but also analyze the dynamics of the reduced stochastic reaction systems. Furthermore, the algorithm is illustrated by an application to a benchmark stochastic differential equation model, and numerical experiments are carried out to demonstrate the effectiveness of the construction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Multielectrode Array Sensors to Enable Long-Duration Corrosion Monitoring and Control of Concentrating Solar Power Systems

Molten mixtures of MgCl2-KCl-NaCl are promising heat transfer fluid (HTF) candidates for the next generation of concentrating solar power systems (Gen3 CSP), because of their low cost, high decomposition temperature, and favorable heat transfer characteristics. However, if the chemistry of the salts is not properly controlled, molten chlorides can cause corrosion of high-temperature metal alloys, such as Inconel (R), in CSP systems. Here we demonstrate a corrosion monitoring system that can be used to monitor the health of the structural alloys over long durations. The monitoring system includes a multielectrode array voltammetry sensor that measures the redox potential of molten MgCl2-KCl-NaCl mixture as well as the presence of corrosion products and impurities. The sensors have been successfully operated in static molten salt environments for long durations, and are capable of detecting corrosion products, such as Cr2+ and Fe2+, quantitatively at low concentrations (i.e., approximately 100 ppm) with less than 4% error.

Concentrated solar power↗
DOE OSTI2019

Comparing hydrothermal sintering and cold sintering process: Mechanisms, microstructure, kinetics and chemistry

In this study, we report the sintering of zinc oxide (ZnO) through the comparison between the hydrothermal sintering (HS) and the cold sintering process (CSP) operating in closed and open conditions, respectively. Sintering was performed at 155 ± 5 °C applying a pressure of 320 MPa, and during different holding times (0 min, 20 min, 40 min and 80 min). Whatever the low sintering process used, ceramics characteristics are almost similar in terms of relative densities and ZnO structure. However, several differences such as the nature of stabilized phases, grain sizes and quantities of residual molecules in the densified pellets, were characterized and explained. The formation of zinc acetate “bridges” was observed ex situ in hydrothermally sintered samples. Lastly, a detailed ReaxFF molecular dynamics simulation was performed to help understand the formation mechanisms of zinc acetate “bridges” and compare the chemical activities between HS and CSP.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Structure and Interactions of the CS Domain of Human H/ACA RNP Assembly Protein Shq1

Shq1 is an essential protein involved in the early steps of biogenesis and assembly of H/ACA ribonucleoprotein particles (RNPs). Shq1 binds to dyskerin (Cbf5 in yeast) at an early step of H/ACA RNP assembly and is subsequently displaced by the H/ACA RNA. Shq1 contains an N-terminal CS and a C-terminal Shq1-specific domain (SSD). Dyskerin harbors many mutations associated with dyskeratosis congenita. Structures of yeast Shq1 SSD bound to Cbf5 revealed that only a subset of these mutations is in the SSD binding site, implicating another subset in the putative CS binding site. Here in this paper, we present the crystal structure of human Shq1 CS (hCS) and the nuclear magnetic resonance (NMR) and crystal structures of hCS containing a serine substitution for proline 22 that is associated with some prostate cancers. The structure of hCS is similar to yeast Shq1 CS domain (yCS) and consists of two β-sheets that form an immunoglobulin-like β-sandwich fold. The N-terminal affinity tag sequence AHHHHHH associates with a neighboring protein in the crystal lattice to form an extra β-strand. Deletion of this tag was required to get spectra suitable for NMR structure determination, while the tag was required for crystallization. NMR chemical shift perturbation (CSP) experiments with peptides derived from putative CS binding sites on dyskerin and Cbf5 revealed a conserved surface on CS important for Cbf5/dyskerin binding. A HADDOCK (high-ambiguity-driven protein-protein docking) model of a Shq1-Cbf5 complex that defines the position of CS domain in the pre-H/ACA RNP was calculated using the CSP data.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Diverse Antibody Responses to Conserved Structural Motifs in Plasmodium falciparum Circumsporozoite Protein

Malaria vaccine candidate RTS,S/AS01 is based on the central and C-terminal regions of the circumsporozoite protein (CSP) of P. falciparum. mAb397 was isolated from a volunteer in an RTS,S/AS01 clinical trial, and it protects mice from infection by malaria sporozoites. However, mAb397 originates from the less commonly used VH3-15 germline gene compared to the VH3-30/33 antibodies generally elicited by RTS,S to the central NANP repeat region of CSP. The crystal structure of mAb397 with an NPNA4 peptide shows that the central NPNA forms a type I β-turn and is the main recognition motif. In most anti-NANP antibodies studied to date, a germline-encoded Trp is used to engage the Pro in NPNA β-turns, but here the Trp interacts with the first Asn. This “conserved” Trp, however, can arise from different germline genes and be located in the heavy or the light chain. Variation in the terminal ψ angles of the NPNA β-turns results in different dispositions of the subsequent NPNA and, hence, different stoichiometries and modes of antibody binding to rsCSP. Diverse protective antibodies against NANP repeats are therefore not limited to a single germline gene response or mode of binding.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Development of graphite foam infiltrated with MgCl 2 for a latent heat based thermal energy storage (LHTES) system

Thermal energy storage (TES) systems that are compatible with high temperature power cycles for concentrating solar power (CSP) require high temperature media for transporting and storing thermal energy. To that end, TES systems have been proposed based on the latent heat of fusion of the phase change materials (PCMs). However, PCMs have relatively low thermal conductivities. In this paper, use of high-thermal-conductivity graphite foam infiltrated with a PCM (MgCl2) has been investigated as a potential TES system. Graphite foams with two porosities were infiltrated with MgCl2. The infiltrated composites were evaluated for density, heat of fusion, melting/freezing temperatures, and thermal diffusivities. Estimated thermal conductivities of MgCl2/graphite foam composites were significantly higher than those of MgCl2 alone over the measured temperature range. Furthermore, heat of fusion, melting/freezing temperatures, and densities showed comparable values to those of pure MgCl2. Results of this study indicate that MgCl2/graphite foam composites show promise as storage media for a latent heat thermal energy storage system for CSP applications.

25 ENERGY STORAGE↗
DOE OSTI2015

A general method to analyze the thermal performance of multi-cavity concentrating solar power receivers

Concentrating solar power (CSP) with thermal energy storage has potential to provide grid-scale, on-demand, dispatachable renewable energy. As higher solar receiver output temperatures are necessary for higher thermal cycle efficiency, current CSP research is focused on high outlet temperature and high efficiency receivers. Here, the objective of this study is to provide a simplified model to analyze the thermal efficiency of multi-cavity concentrating solar power receivers.

14 SOLAR ENERGY↗