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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Comparison of Conventional and Constrained Variational Methods for Computing Large-Scale Budgets and Forcing Fields

Analyses of atmospheric heat and moisture budgets serve as an effective tool to study convective characteristics over a region and to provide large-scale forcing fields for various modeling applications. This paper examines two popular methods for computing large-scale atmospheric budgets: the conventional budget method (CBM) using objectively gridded analyses based primarily on radiosonde data and the constrained variational analysis (CVA) approach which supplements vertical profiles of atmospheric fields with measurements at the top of the atmosphere and at the surface to conserve mass, water, energy, and momentum. Successful budget computations are dependent on accurate sampling and analyses of the thermodynamic state of the atmosphere and the divergence field associated with convection and the large-scale circulation that influences it. Utilizing analyses generated from data taken during Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign conducted over the central Indian Ocean from October to December 2011, we evaluate the merits of these budget approaches and examine their limitations. While many of the shortcomings of the CBM, in particular effects of sampling errors in sounding data, are effectively minimized with CVA, accurate large-scale diagnostics in CVA are dependent on reliable background fields and rainfall constraints. Finally, for the DYNAMO analyses examined, the operational model fields used as the CVA background state provided wind fields that accurately resolved the vertical structure of convection in the vicinity of Gan Island. However, biases in the model thermodynamic fields were somewhat amplified in CVA resulting in a convective environment much weaker than observed.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Is stochastic thermodynamics the key to understanding the energy costs of computation?

The relationship between the thermodynamic and computational properties of physical systems has been a major theoretical interest since at least the 19th century. It has also become of increasing practical importance over the last half-century as the energetic cost of digital devices has exploded. Importantly, real-world computers obey multiple physical constraints on how they work, which affects their thermodynamic properties. Moreover, many of these constraints apply to both naturally occurring computers, like brains or Eukaryotic cells, and digital systems. Most obviously, all such systems must finish their computation quickly, using as few degrees of freedom as possible. This means that they operate far from thermal equilibrium. Furthermore, many computers, both digital and biological, are modular, hierarchical systems with strong constraints on the connectivity among their subsystems. Yet another example is that to simplify their design, digital computers are required to be periodic processes governed by a global clock. None of these constraints were considered in 20th-century analyses of the thermodynamics of computation. The new field of stochastic thermodynamics provides formal tools for analyzing systems subject to all of these constraints. We argue here that these tools may help us understand at a far deeper level just how the fundamental thermodynamic properties of physical systems are related to the computation they perform.

computation↗
DOE OSTI2021

Thermoeconomic analysis of a multigeneration system using waste heat from a triple power cycle

Multigeneration systems represent an appealing concept, due to their multiple benefits compared to standalone systems, which has motivated researchers to develop different types of multigeneration systems for several applications. Considering their significance, in this study, a novel multigeneration is proposed that uses the waste heat of a thermodynamically efficient triple power cycle with a 100 MWe capacity. The proposed system, which can generate power, freshwater, cooling, and domestic hot water concurrently, is evaluated using detailed thermodynamic and economic analyses. The triple cycle includes a simple Brayton cycle coupled with a supercritical carbon dioxide recompression cycle and a high-temperature organic Rankine cycle. The waste energy of the recompression and organic Rankine cycles is recovered by a half effect absorption chiller, a multi-effect distillation unit, and two heat exchangers. The results show that for an optimized triple cycle, up to 1,804 kW cooling and 8,472 m 3 /day of hot water can be generated from the hot supercritical carbon dioxide stream with a levelized cost of cooling and hot water of 0.0362/ton-hr and $0.6823/MWth, respectively. The integration of a multi-effect distillation unit with 7 effects can generate 4,167 m 3 /day freshwater with a levelized cost of water of $1.142/m 3 . Finally, the proposed multigeneration system offers a very promising application and a number of benefits such as a generating multiple useful products with no adverse effect on the thermodynamic efficiency of the triple power cycle.

Thermoeconomic analysis↗
DOE OSTI2022

Thermodynamically Driven Formation of Intercalated Cu Carpets from Supported Cu Pyramids on MoS 2

Thermodynamic and kinetic analyses based on our first-principles density functional theory calculations are used to interpret the experimentally observed formation of Cu carpets intercalated under the top layer of a 2H-MoS 2 substrate. Spontaneous Cu transport from Cu pyramids on top of the MoS 2 substrate through surface point defects to the growing Cu carpet is shown to be driven by a slightly lower chemical potential for the Cu carpet. We demonstrate that the competition between a preference for a thicker Cu carpet and the cost of elastic stretching of the top MoS 2 layer results in a selected Cu carpet thickness. Furthermore, we also propose that Cu transport occurs primarily via vacancy-mediated diffusion through constricting point defect portals.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Review of low salinity waterflooding in carbonate rocks: mechanisms, investigation techniques, and future directions

This review analyses the fundamental thermodynamic theory of the crude oil-brine-rock (COBR) interface and the underlying rock-brine and oil-brine interactions. Next, the available data are reviewed to outline potential mechanisms responsible for increased oil recovery from low salinity waterflooding (LSWF). We propose an approach to studying LSWF and identify the key missing links that are needed to explain observations at multiple length scales. The synergistic effect of LSWFon other chemical enhanced oil recovery methods such as surfactant, alkaline, nanoparticle and polymer flooding are also outlined. We specifically highlight key uncertainties that must be overcome to fully implement the technique in the field.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Corrosion property of Alloy 625 in Molten FLiNaK salt according to the Tellurium Concentrations

For this work, the corrosion properties of Alloy 625 have been studied in molten FLiNaK salt for 48 h at 700 °C as a function of tellurium (Te) concentrations using immersion tests and electrochemical methods. Under specific Te concentrations, we found that Te-induced corrosion can be suppressed and help protect the alloy against corrosion. The sample after the immersion test containing 0.1 wt.% Te (0.1 wt.% Te sample) had the lowest corrosion depth and mass loss, coupled with the highest charge transfer resistance, obtained using electrochemical impedance spectroscopy (EIS). On the other hand, the alloy with Te content above 0.1 wt.% exhibited severe corrosion penetration and lower charge transfer resistance in FLiNaK. Based on thermodynamical and electrochemical analyses, a corrosion mechanism of Alloy 625 in the molten salt containing Te was theorized involving the formation of stable corrosion products such as Ni/Fe rich layer depleted in Cr, nickel telluride, and chromium oxide.

Hong, Minsung↗
DOE OSTI2025

In-situ formation of stable interface towards Li-in anode for halide solid-state electrolyte

Halide-based solid-state electrolytes (SSEs) are promising candidates for next-generation all-solid-state lithium batteries (ASSLBs) due to their high ionic conductivity and chemical stability. However, their poor interfacial compatibility with lithium metal anode and Li-In alloy significantly hinder practical application due to the requirement for a protective interlayer. In this study, a novel approach to overcome this limitation is presented by introducing iron (Fe) doping into Li 3 InCl 6 (LIC), which enables direct and stable contact with lithium-indium (Li-In) metal without a protective interlayer. Thermodynamic and computational analyses identified Fe 3+ as a suitable dopant based on its similar reduction potential to In 3+ and structural compatibility within the halide lattice. The synthesized 10 at. % Fe-doped LIC exhibits high phase purity, retained ionic conductivity, and notably improved interfacial stability. Full-cell tests using Fe-LIC achieve over 300 cycles with 80 % capacity retention. At the same time, symmetric Li-In/ Fe-LIC/ Li-In cells sustain over 500 h of operation, representing the first reported long-term cycling of LIC-based ASSLB without a protective interlayer. In conclusion, this work establishes Fe doping as an effective strategy to stabilize halide SSEs of In system against Li-In alloy, thereby simplifying cell architecture and advancing the development of safer, high-performance halide-based solid-state electrolytes.

Halide-based solid-state electrolytes↗
DOE OSTI2025

ATR-SEIRAS Reveals Potential Inversion and Associated Electron Transfer Kinetics in the Reduction of Surface-Confined Anthraquinone

The detection of stable semiquinone radicals on an anthraquinone (AQ) layer chemically grafted to an electrode surface in aqueous electrolytes has been elucidated by using attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). In very alkaline conditions (pH 13), the reduction of the AQ involves no proton transfer, but surface sensitive infrared spectroscopy reveals that the anthraquinone dianion forms a strong hydrogen bonding network with coadsorbed water, leading to irreversible features in the voltammetry. The potential dependence of the IR band assigned to the AQ radical is consistent with the enhanced hydrogen bonding network causing increased stabilization of the quinone radical and supports the predicted response of a system under mild potential inversion, whereby the formal potential for the reduction of the anthraquinone radical is positive of the reduction potential of the neutral AQ molecule. Time-resolved ATR-SEIRAS is used to measure the transient formation of the AQ •– radical, from which rate constant information can be extracted using the Butler–Volmer model involving two one-electron transfers without a direct disproportionation reaction. The potential dependence of the rate constants is consistent with the potential inversion and can be used to qualitatively simulate the measured cyclic voltammograms. In conclusion, the thermodynamic and kinetic analyses re-emphasize long established deficiencies associated with using one-electron reaction formalisms to characterize multi-electron systems.

37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗
DOE OSTI2021

An orthogonal metabolic framework for one-carbon utilization

Metabolic engineering often entails concurrent engineering of substrate utilization, central metabolism, and product synthesis pathways to maximize the conversion of a carbon substrate into desired product(s). Here, we report an alternative approach using synthetic pathways for C1 bioconversion that are orthogonal to the host metabolic network, thus minimizing interdependency on native metabolism and enabling more efficient biocatalysts. Here, the engineered pathways are based on formyl-CoA elongation (FORCE) reactions catalyzed by the enzyme 2-hydroxyacyl-CoA lyase (HACL) and generate multi-carbon products directly from C1 elongation units in the form of formyl-CoA. Herein, we use thermodynamic and stoichiometric analyses to evaluate different FORCE pathway variants, including aldose elongation, α-reduction, and aldehyde elongation. Promising variants were further prototyped using cell-free systems (purified enzymes and cell extracts) as well as resting and growing cultures of non-methylotrophic bacterium Escherichia coli. We demonstrate that C1 substrates formate, formaldehyde, and methanol can be used as inputs for FORCE pathways and that FORCE reactions can serve as a platform for varied product synthesis including glycolate, ethylene glycol, ethanol, and glycerate. Furthermore, the orthogonal FORCE pathways have the potential to be integrated with host metabolism for synthetic methylotrophy by the production of native growth substrates as demonstrated in a two-strain culture system.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Acetyl-CoA Synthesis Through a Bicyclic Carbon-Fixing Pathway in Gas-Fermenting Bacteria

Gas-fermenting acetogens can upgrade one-carbon (C1) compounds (such as CO2 and CO) to the two-carbon (C2) metabolite acetyl coenzyme A (CoA) and convert sugar feedstocks to acetyl-CoA with minimal CO2 emissions. Fulfilling the biosynthetic potential of these microbes requires overcoming challenges in pathway engineering. Here we design a synthetic acetyl-CoA bi-cycle-in addition to the natural carbon-fixing pathways-for C2 metabolite synthesis. This pathway produces an acetyl-CoA by fixation of two CO2 equivalents via three functional modules acting in sequence: carbon fixation, gluconeogenesis and non-oxidative glycolysis. The pathway was examined by in silico thermodynamic and kinetic analyses. The prototypic pathway was implemented in a syngas-fermenting organism, Clostridium ljungdahlii DSM 13528, by expressing a heterologous phosphoketolase that can work with other native enzymes in the host acetogen. The carbon conversion pathway is possible under various growth conditions and is independent of the Wood-Ljungdahl pathway for the valorization of H2 and CO2. This study reports the improvement of carbon conversion using a reductive acetyl-CoA bi-cycle and the potential impact of redox homoeostasis in the acetogenic host for industrial applications of gas fermentation.

Acetyl-CoA↗
DOE OSTI2025

Nonenzymatic RNA copying with a potentially primordial genetic alphabet

Nonenzymatic RNA copying is thought to have been responsible for the replication of genetic information during the origin of life. However, chemical copying with the canonical nucleotides (A, U, G, and C) strongly favors the incorporation of G and C and disfavors the incorporation of A and especially U because of the stronger G:C vs. A:U base pair and the weaker stacking interactions of U. Recent advances in prebiotic chemistry suggest that the 2-thiopyrimidines were precursors to the canonical pyrimidines, raising the possibility that they may have played an important early role in RNA copying chemistry. Furthermore, 2-thiouridine (s 2 U) and inosine (I) form by deamination of 2-thiocytidine (s 2 C) and A, respectively. We used thermodynamic and crystallographic analyses to compare the I:s 2 C and A:s 2 U base pairs. We find that the I:s 2 C base pair is isomorphic and isoenergetic with the A:s 2 U base pair. The I:s 2 C base pair is weaker than a canonical G:C base pair, while the A:s 2 U base pair is stronger than the canonical A:U base pair, so that a genetic alphabet consisting of s 2 U, s 2 C, I, and A generates RNA duplexes with uniform base pairing energies. Consistent with these results, kinetic analysis of nonenzymatic template-directed primer extension reactions reveals that s 2 C and s 2 U substrates bind similarly to I and A in the template, and vice versa. Our work supports the plausibility of a potentially primordial genetic alphabet consisting of s 2 U, s 2 C, I, and A and offers a potential solution to the long-standing problem of biased nucleotide incorporation during nonenzymatic template copying.

Science & Technology - Other Topics↗
DOE OSTI2020

Catabolism and interactions of uncultured organisms shaped by eco-thermodynamics in methanogenic bioprocesses

We currently understand the carbon cycle in methanogenic environments as trophic interactions revolving around interspecies H 2 transfer between organotrophs and methanogens. However, many H 2 -generating processes are thermodynamically sensitive to H 2 accumulation and can be inhibited by high H 2 concentrations produced by other metabolisms. To uncover how anaerobes combat this H 2 conflict in situ, we employ metagenomics and metatranscriptomics to revisit a model ecosystem that has inspired many foundational discoveries in anaerobic ecology – methanogenic bioreactors. Through analysis of 15 anaerobic digesters, we recover 1343 high-quality metagenome-assembled genomes (MAGs) and corresponding gene expression profiles for diverse uncultured lineages spanning 66 phyla and reconstruct their individual metabolic capacities. We discover that diverse uncultured organotrophic populations can drive H 2 -sensitive degradation through (i) metabolic coupling with concurrent H 2 -tolerant catabolism, (ii) unprecedented shifts from H 2 generation to CO 2 -reducing formate transfer and cytochrome/pili-mediated direct interspecies electron transfer for avoiding thermodynamic conflict, and (iii) integration of low-concentration O 2 as an ancillary thermodynamics-enhancing electron sink. Archaeal populations in situ support the above processes through novel metabolisms distinct from conventional methanogenesis – high-affinity H 2 oxidation driven by methyl-reducing methanogenesis and concomitant uptake of formate, electrons, and acetate from HS metabolism by Methanothrix. In total, synthesis of omics analyses and eco-thermodynamics reveals overlooked metabolic behavior and interactions of uncultured organisms that address a central issue in methanogenic carbon cycling, thermodynamic conflict among diverse concurrent metabolic processes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Utilization of waste heat from a commercial GT for freshwater production, cooling and additional power: Exergoeconomic analysis and optimization

In this work, a multigeneration system is proposed for power, cooling and freshwater production. The waste heat from a SIEMENS SGT6-2000E GT is utilized to drive a supercritical CO 2 recompression Brayton cycle (SCRBC) and multi-effect desalination (MED) with thermal vapor compressor (TVC), while the waste heat from the pre-cooler of the SCRBC is utilized to drive an absorption cooling cycle. Detailed thermodynamic, exergy and exergoeconomic analyses are performed for the proposed multigeneration system using Engineering Equation Solver (EES). A sensitivity study is also performed to study the effects of the main operational parameters on the proposed system performance. Finally, multi-objective optimization using a genetic algorithm approach in EES is carried out to reach the optimal design. The proposed system can consume 34.2% less energy input and reduce CO 2 emission by 39.3% compared to the stand-alone systems for power, cooling and freshwater production. The results show that the energy utilization factor and exergy efficiency of the proposed system are improved by 33.6% and 14.3%, respectively, while the total unit product cost is reduced by 11.3% compared to the stand-alone GT cycle. Further, from exergoeconomic optimization, the proposed system can produce 132.4 MW of power, 7.09 MW of cooling and 650 kg/s of freshwater at energy utilization factor of 57.5%, exergy efficiency of 39.7% and total unit product cost of 16.3 $/GJ.

42 ENGINEERING↗
DOE OSTI2023

Effect of Cr and Ni concentrations on resilience of cast Nb- alloyed heat resistant austenitic steels at extreme high temperatures

Austenitic Cr–Ni alloyed heat resistant steels with Nb additions are used for intensively thermo-mechanically loaded cast components working in extreme high temperature oxidizing environment. Their performance during static oxidation and transient thermo-mechanical loading was investigated to recommend an optimal cost-effective Cr/Ni composition of Nb-alloyed austenitic class steels. Here, the static oxidation and transient thermo-mechanical behavior of three austenitic steels with different Cr/Ni alloying levels were investigated and compared for variety of working conditions. Static oxidation was performed between 900 °C and 1000 °C in air for 400 h. The critical temperature which increases spallation during static oxidation was determined for each of the steel alloying levels. In addition, thermal cycling of a constrained specimen was done with varying upper cycling temperatures between 850 °C and 1000 °C. SEM and TEM analyses were supported by thermodynamic simulation of the phases precipitated in the metal matrix and the structure of formed oxide layers. These studies were used to determine the mechanisms of degradation of thermo-mechanically loaded Cr/Ni austenitic steels at extreme high temperatures. A recommendation for a cost-effective Cr/Ni alloying level for different working conditions was determined.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Continental-Scale Controls on Hyporheic Respiration Revealed by Knowledge-Guided Machine Learning

Hyporheic zone sediments regulate organic matter turnover and in-stream respiration, yet controls on sediment respiration remain poorly constrained across heterogeneous river networks, limiting prediction of stream metabolism and carbon processing at continental scales. Here, we integrate observations from ~90 river corridors across the United States in the WHONDRS consortium with a knowledge-guided machine learning (KGML) framework that couples thermodynamic rate theory with machine learning to identify dominant controls on hyporheic respiration. Diagnostic analyses show that organic matter concentration and thermodynamic favorability define an upper bound on respiration potential, whereas biological catalytic capacity and physical accessibility jointly govern realized respiration rates through interaction effects. To represent unmeasurable accessibility constraints, we use the mechanistic model as a scaffold for KGML, allowing machine learning to target residual structure not explained by process theory. This hybrid framework improves predictive skill relative to both the mechanistic model alone and fully data-driven models while preserving interpretability. These results indicate that variability in hyporheic respiration is largely mechanistically structured and demonstrate how integrating process theory with explainable AI enhances predictive performance while enabling scalable synthesis of river corridor observations.

Zheng, Jianqiu↗
DOE OSTI2024

Flame kinetics at scramjet-engine-relevant conditions: Role of prompt dissociation of weakly-bound radicals

Combustion in high-speed ram-based propulsion engines occurs under distinct thermodynamic conditions of high reactant temperatures (greater than 1000 K) and relatively low pressures (<5 atm). There is a lack of fundamental flame measurements at such conditions that result in adiabatic flame temperatures (T ad ) exceeding 2500 K. In this work, we have measured laminar flame speeds of oxygen-enriched CH 4 /oxidizer mixtures at sub-atmospheric conditions to probe kinetics at high T ad using the isobaric spherically expanding flame approach. Simulations with recent kinetic models revealed increasing differences between data and model predictions with increasing T ad , reaching up to 25 %. Kinetic analyses reveal that at the thermodynamic conditions in these O 2 -enriched flames, i.e., lower pressures and higher T ad , the effects of HCO prompt dissociation are accentuated. In addition to HCO, the prompt dissociations of CH 2 OH and C 2 H 5 are also considered. Here, the prompt dissociations of all three radicals were evaluated and their effects considered in flame speed simulations. Reaction path analysis for the present flames revealed that approximately half of the reaction flux for HCO formation undergoes prompt dissociation to H + CO. Furthermore, these analyses also revealed that the pathways and sensitive reactions are similar between oxygen-enriched fuel/oxidizer mixtures and preheated fuel/air mixtures, if both have similar T ad . Thus, flames of oxygen-enriched mixtures could be a surrogate to probe the flame chemistry of highly preheated mixtures at relatively low pressures that are often encountered in ram-based propulsion engine combustors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Structure-function studies of Vibrio cholerae quorum-sensing receptor CqsR signal recognition

Ethanolamine signaling through the transmembrane quorum-sensing receptor CqsR influencesVibrio choleraeniche recognition and host colonization. In this study, we present a comprehensive structure-function analysis of CqsR. Specifically, we have determined X-ray crystal structures of the CqsR periplasmic domain bound to the signaling agonist ethanolamine and its analogs, serinol and L-alaninol, as well as the ligand-free (apo) form of CqsR. The periplasmic ligand-binding domain of CqsR is a Cache domain, the most prevalent extracellular sensory module in prokaryotes. Our findings provide a rare structural comparison of ligand-bound and unbound states of a Cache domain receptor. Coupled with thermodynamic binding assays and genetic analyses, these structures elucidate the molecular basis of CqsR ligand specificity. This study not only advances the understanding of Cache domain function but also informs the identification of ligands for orphan Cache receptors and the rational design of signaling agonists and antagonists. Lastly, we discuss ligand-induced conformational changes in the CqsR Cache domains and explore the potential for the existence of additional regulatory ligands.

Microbiology↗
DOE OSTI2020

Experimental evaluation of the role of redox during glauconite-CO 2 -brine interactions

Greensands formations are globally abundant sedimentary rocks rich in Fe clays (typically glauconite) that commonly contain natural hydrocarbon accumulations and may be important reservoirs for geologic storage of anthropogenic CO 2 . Diagenesis in greensands is commonly accompanied by the conversion of primary glauconite to siderite (FeCO 3 ), a process that could be exploited for the permanent trapping of CO 2 . Importantly, siderite formation after glauconite requires that the mostly oxidized Fe in the primary Fe clay minerals is reduced during diagenetic interactions. Here, we explore the effect of solution redox state on the stability of glauconite in sandstones with implications for the diagenetic and/or engineered formation of siderite. We performed two flow-through experiments on intact, glauconite-rich sandstone cores at 150 °C and 150 bar. Both experiments employed a 1 mol NaCl/kg, 0.1 mol NaHCO 3 /kg solution charged with ~0.58 mol CO 2 /kg solution, but the redox state of the injected fluid was manipulated between experiments in order to compare glauconite reactivity and siderite saturation state at oxidizing and reducing end-member conditions. After reaction with the oxidizing (O 2 (aq) ≈ 6 μmol/kg) fluid, chemical and Mӧssbauer spectroscopic analyses indicate the production of Fe(III)-oxy/hydroxide minerals from glauconite, whereas, in the reducing (H 2 (aq) ≈ 5–40 mmol/kg) experiment, thermodynamic calculations and coupled chemical, mineralogical, and Mӧssbauer analyses suggest glauconite dissolution and precipitation of an Fe(II) mineral, likely siderite, and minor magnetite formation. These experimental results, along with thermodynamic calculations, confirm that solution redox state is the master variable dictating siderite formation in greensands.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗