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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Preliminary Pilot-scale Study and Techno-economic Analysis of Chemical Heat Pump with Conventional Nuclear Reactors

The energy economy is continually evolving, particularly in terms of primary energy sources, their conversions to useful forms such as electricity and heat, and their utilization in different sectors, in response to socio-political factors. Because nuclear source is clean and non-carbon-emitting energy source, it is crucial to consider its role in the evolution of the energy economy. A pilot-scale study was conducted for Chemical Heat Pump (ChHP) system at three different scales (25-, 100-, and 1000-kW thermal outputs) using steady state thermal model. To establish the viability of selling heat rather than electricity alone, techno-economic analysis was undertaken for advanced Small Modular Reactor (SMR), and SMR paired with varied thermal output ChHP systems was referred to as the nuclear hybrid energy system (NHES) in this study. Using the U.S. Energy Information Administration statistics, pricing for electricity and natural gas were anticipated for U.S. regions (California, Northwest, Midwest, Southwest, New England, and PJM). Based on thermal output from ChHP, advanced SMR with 100 MWth and four alternative NHES scenarios were explored, namely 50-, 10-, 5-, and 1-MWth. Net present value, payback period, discounted cash flow return, and levelized cost of energy were evaluated for all scenarios. Based on the economic analysis, selling heat to high-temperature industrial processes is more profitable compared to selling electricity only. Higher carbon taxes showed significant improvement in economic parameters for NHESs. Providing heat to high-temperature industries could be beneficial, helping to reduce the greenhouse gas emissions by slashing the fossil fuel consumption.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1989

Steady-state thermal-solutal diffusion in a float zone

A model for a float zone in a thin vertical sheet is used to study the formation of the zone configuration for both pure and binary systems of Si and GeGa. Equations describing the steady two-dimensional diffusion of solute in the melt and diffusion of heat in the feed material and the product crystal are presented. The material properties, asymptotic solutions for the temperature and concentration profiles, and melting, solidifying, and melt/gas interfacial shapes are determined in the small aspect ratio limit.

Young, G. W.↗
NASA NTRS2004

Numerical Modeling of the South Pole-Aitkin Impact

The South Pole-Aitkin (SPA) basin, on the far side of the Moon, is the largest and oldest impact structure still preserved in the solar system. The crater is about 2500 km in diameter and formed in the Pre-Nectarian era of lunar history, over 4 Gyr ago. At this time, the thermal state of the Moon was much hotter than it is today. Accretional energy from the rapidly forming Moon melted the outermost few hundred kilometers of the Moon. As this magma ocean differentiated and cooled a 60 100-km thick low-density crust formed at the surface; below this the residual melt, with a higher density, cooled to form the lunar mantle. The giant SPA impact event punctured the Moon some time during the cooling of the magma ocean and thus provides a unique window for studying the lunar interior and the early formative processes of the Moon. The impact excavated otherwise inaccessible samples of the deep crust and (possibly) upper mantle, which has inspired proposed sample return missions. Furthermore, the thermal and rheologic state of the early Moon played a role in shaping the final structure of the basin. To aid in site selection for future sample return missions to the SPA basin, and to investigate the effect of thermal state on final crater structure, we performed some numerical simulations of the SPA impact event.

Collins, G. S.↗
NASA NTRS1979

Finite element methodology for transient conduction/forced-convection thermal analysis

Finite element methodology for steady state thermal analysis of convectively cooled structures has been extended for transient analysis. The finite elements are based on representing the fluid passages by fluid bulk-temperature nodes and fluid-solid interface nodes. The formulation of the finite element equations for a typical flow passage is based on the weighted residual method with upwind weighting functions. Computer implementation of the convective finite element methodology using explicit and implicit time integration algorithms is described. Accuracy and efficiency of the methodology is evaluated by comparisons with analytical solutions and finite-difference lumped-parameter analyses. The comparative analyses demonstrate that finite element conduction/conduction methodology may be used to predict transient temperatures with an accuracy equal or superior to the lumped-parameter finite-difference method.

Thornton, E. A.↗
NASA NTRS1990

Thermal-structural finite element analysis using linear flux formulation

A linear flux approach is developed for a finite element thermal-structural analysis of steady state thermal and structural problems. The element fluxes are assumed to vary linearly in the same form as the element unknown variables, and the finite element matrices are evaluated in closed form. Since numerical integration is avoided, significant computational time saving is achieved. Solution accuracy and computational speed improvements are demonstrated by solving several two and three dimensional thermal-structural examples.

Pandey, Ajay K.↗
NASA NTRS1991

Composite material systems for hydrogen management

The task of managing hydrogen entry into elevated temperature structural materials employed in turbomachinery is a critical engineering area for propulsion systems employing hydrogen or decomposable hydrocarbons as fuel. Extant structural materials, such as the Inconel series, are embrittled by the ingress of hydrogen in service, leading to a loss of endurance and general deterioration of load-bearing dependability. Although the development of hydrogen-insensitive material systems is an obvious engineering option, to date insensitive systems cannot meet the time-temperature-loading service extremes encountered. A short-term approach that is both feasible and technologically sound is the development and employment of hydrogen barrier coatings. The present project is concerned with developing, analyzing, and physically testing laminate composite hydrogen barrier systems, employing Inconel 718 as the structural material to be protected. Barrier systems will include all metallic, metallic-to-ceramic, and, eventually, metallic/ceramic composites as the lamellae. Since space propulsion implies repetitive engine firings without earth-based inspection and repair, coating durability will be closely examined, and testing regimes will include repetitive thermal cycling to simulate damage accumulation. The target accomplishments include: generation of actual hydrogen permeation data for metallic, ceramic-metallic, and hybrid metallic/ceramic composition barrier systems, practically none of which is currently extant; definition of physical damage modes imported to barrier systems due to thermal cycling, both transient temperature profiles and steady-state thermal mismatch stress states being examined as sources of damage; and computational models that incorporate general laminate schemes as described above, including manufacturing realities such as porosity, and whatever defects are introduced through service and characterized during the experimental programs.

Pangborn, R. N.↗
DOE OSTI2023

Coherences of Photoinduced Electron Spin Qubit Pair States in Photosystem I

Here, this publication presents the first comprehensive experimental study of electron spin coherences in photosynthetic reaction center proteins, specifically focusing on photosystem I (PSI). The ultrafast electron transfer in PSI generates spin-correlated radical pairs (SCRPs), which are entangled spin pairs formed in well-defined spin states (Bell states). Since their discovery in our group in the 1980s, SCRPs have been extensively used to enhance our understanding of structure–function relationships in photosynthetic proteins. More recently, SCRPs have been utilized as tools for quantum sensing. Electron spin decoherence poses a significant challenge in realizing practical applications of electron spin qubits, particularly the creation of quantum entanglement between multiple electron spins. This work is focused on the systematic characterization of decoherence in SCRPs of PSI. These decoherence times were measured as electron spin echo decay times, termed phase memory times (T M ), at various temperatures. Decoherence was recorded on both transient SCRP states P 700 + A 1 – and thermalized states. Our study reveals that T M exhibits minimal dependence on the biological species, biochemical treatment, and paramagnetic species. The analysis indicates that nuclear spin diffusion and instantaneous diffusion mechanisms alone cannot explain the observed decoherence. As a plausible explanation we discuss the assumption that the low-temperature dynamics of methyl groups in the protein surrounding the unpaired electron spin centers is the main factor governing the loss of the spin coherence in PSI.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Phase Transitions and Thermal Equation of State of Fe‐9wt.%Si Applied to the Moon and Mercury

Abstract Accurate knowledge of the phase transitions and thermoelastic properties of candidate iron alloys, such as Fe‐Si alloys, is essential for understanding the nature and dynamics of planetary cores. The phase diagrams of some Fe‐Si alloys between 1 atm and 16 GPa have been back‐extrapolated from higher pressures, but the resulting phase diagram of Fe 83.6 Si 16.4 (9 wt.% Si) is inconsistent with temperature‐induced changes in its electrical resistivity between 6 and 8 GPa. This study reports in situ synchrotron X‐ray diffraction (XRD) measurements on pre‐melted and powder Fe 83.6 Si 16.4 samples from ambient conditions to 60 GPa and 900 K using an externally heated diamond‐anvil cell. Upon compression at 300 K, the bcc phase persisted up to ∼38 GPa. The hcp phase appeared near 8 GPa in the pre‐melted sample, and near 17 GPa in the powder sample. The appearance of the hcp phase in the pre‐melted sample reconciles the reported changes in electrical resistivity of a similar sample, thus resolving the low‐pressure region of the phase diagram. The resulting high‐temperature Birch‐Murnaghan equation of state (EoS) and thermal EoS based on the Mie‐Gruneisen‐Debye model of the bcc and hcp structures are consistent with, and complement the literature data at higher pressures. The calculated densities based on the thermal EoS of Fe‐9wt.%Si indicate that both bcc and hcp phases agree with the reported core density estimates for the Moon and Mercury.

Berrada, Meryem↗
DOE OSTI2025

Generalized geometric speed limits for quantum observables

Leveraging quantum information geometry, we derive generalized quantum speed limits on the rate of change of the expectation values of observables. These bounds subsume and, for Hilbert space dimension ≥3, tighten existing bounds—in some cases by an arbitrarily large multiplicative constant. Our theoretical results are supported by illustrative examples and an experimental demonstration using a superconducting qutrit. We also derive two upper bounds on the generalized quantum Fisher information in terms of the condition number of the density matrix. One of these bounds applies only to coherent dynamics and depends also on the variance of the Hamiltonian. The other bound depends also on the so-called Wigner-Yanase skew information. These bounds generalize well-known bounds on the symmetric logarithmic derivative quantum Fisher information and are tighter than the existing bounds for sufficiently mixed states (e.g., for sufficiently high temperature thermal states).

open quantum systems & decoherence↗
NASA NTRS1989

Thermal-structural finite element analysis using linear flux formulation

A linear flux approach is developed for a finite element thermal-structural analysis of steady-state thermal and structural problems. The element fluxes are assumed to vary linearly in the same form as the element unknown variables, and the finite element matrices are evaluated in closed form. Since numerical integration is avoided, significant computational time saving is achieved. Solution accuracy and computational speed improvements are demonstrated by solving several two-and three-dimensional thermal-structural examples.

Pandey, Ajay K.↗
NASA NTRS2014

LADEE Multi-Domain Simulation

The Lunar Atmosphere Dust Environment Explorer (LADEE) was a small explorer class spacecraft that was launched on Sept 7, 2013 and that was de-orbited and successfully impacted the Moons surface on April 17, 2014 after completing all of the mission objectives. The low-cost rapidly prototyped hardware design used for the spacecraft was extend to the development of the software base. To achieve this goal, a Model Based Design approach was utilized to develop the onboard flight software, and out of this development a model based multipurpose simulator was created of the LADEE spacecraft and its mission environment. This simulator extended the traditional function of propagating the vehicle's kinematic and rotational states and included the electrical and thermal states propagation. Traditionally, these domains are handled by domain specific high fidelity simulations that use the states histories from other domains as input. By reducing the fidelity and abstracting the relevant features being monitored and controlled by the flight software, it was possible to model the coupling across these domains resulting in more accurate overall system behavior. A faster than real-time workstation (WSIM) version of the LADEE simulator was used to develop and test the software control algorithms in the Simulink environment. To maximize the performance of the simulation, modeling knobs were introduced to reduce the resolution of the some of the domains models when the effects of that domain were not significant for the scope of that simulation. The automatic code generation feature in Simulink was used to port the simulation to several real-time environments to support Processor-in-the-Loop (PIL) and Hardware-in-the-Loop (HIL) testing, verification and validation. The real-time environment required that the design of each of the domain models be deterministic as possible in the time required to perform all of the calculations to update its states. The simulation interface was designed to be compatible with the command interface employed by the LADEE mission operation team. The WSIM, PIL, and HIL simulators thus used a common interface and thus were used for flight software testing, for mission operations personnel training (nominal and off-nominal operations) prior to the mission and to perform command sequence verification during the mission. This presentation will look at the modeling strategies used to create a common interface to the simulator and to model and couple multiple domains within the simulation, the results of those strategies, and the lessons learned.

Multi-Domain↗
DOE OSTI2021

Temperature and solvent-dependent photoluminescence quenching in [Ru(bpy) 2 (bpy-cc-AQ)] 2+

I have herein investigated the solvent-dependent photoluminescence quenching mechanism of [Ru(bpy) 2 (bpy-cc-AQ)] 2+ using variable temperature emission spectroscopies. In this wok, the photophysics of this complex are dominated by an excited-state thermal equilibrium between a photoluminescent 3 MLCT state and a charge-separated state that lies higher in energy relative to the 3 MLCT state in low polarity solvents and approximately isoenergetic in high polarity solvents. Furthermore, an unusual photoluminescence temperature-dependence in high polarity solvents is shown to arise from competition between enthalpic factors favouring the charge-separated state and entropic factors favouring the photoluminescent 3 MLCT state, analogous to the molecular light-switch effect of [Ru(bpy) 2 (dppz)] 2+ . The solvent-dependent photoluminescence quenching of [Ru(bpy)2(bpy-cc-AQ)] 2+ is attributed to two key solvent-dependent factors: (1) the excited-state equilibrium position and (2) the rate of charge-recombination from the charge-separated state.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2018

Creating a Voyager Thermal Model 39 Years Into the Flight Mission, Along with Model Correlation and Application

After 39 years of continuous operation in space, the output of the Voyager 1 & 2 spacecraft RTG power systems has decreased to the point where managing the power margin and maintaining thermal control has become increasingly difficult. As the total power dissipation in the bus has decreased, propellant line temperatures and margin above minimum AFTs have decreased, creating risk of the hydrazine freezing (at 1.6°C). This is further complicated by the lack of existing thermal models that can be used to assess propellant tank and line temperatures. In 2014, an effort was begun to create a Voyager spacecraft thermal model for that purpose.A steady-state Thermal Desktop model has been created from scratch over the past two years. The initial thermal model development was started by Applied Sciences Laboratory (ASL) under contract to JPL. The effort relied primarily on archived manufacturing drawings, limited documentation, interviews of senior engineers who worked on the Voyager design and implementation, and the experience of the Voyager Flight Operations team.Data from the Voyager System Thermal Vacuum tests is no longer available, making it necessary to correlate the model to more recent flight data and small in-flight tests. Correlation was achieved to within ±5°C for a hot case and a cold case (both data sets from 2014). However, the flight system has very few temperature sensors directly on propellant lines. So the task remains to determine how best to use the model, in conjunction with flight data, to make sure the Voyagers can continue to fly successfully. How does one go about creating a thermal model for a spacecraft that is already launched, has limited existing mechanical description files, no thermal model in order to do a maneuver that was never planned when the spacecraft was designed?

Ledeboer, William C.↗