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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

GEOPHIRES v2.0

GEOPHIRES v2.0 is a geothermal techno-economic simulation tool upgraded from GEOPHIRES v1.2. The name stands for "GEOthermal energy for Production of Heat and electricity (“IR”) Economically Simulated". GEOPHIRES combines reservoir, wellbore, and surface plant technical models with cost correlations and levelized cost models to estimate the capital and operation and maintenance costs, instantaneous and lifetime energy production, and overall levelized cost of energy of a geothermal plant. In addition to electricity generation, direct-use heat applications and combined heat and power or cogeneration can be modeled. Various upgrades have been implemented to develop GEOPHIRES v2.0, including: updating the built-in cost correlations, coupling to the external reservoir simulator TOUGH2, enhancing the built-in wellbore simulator, converting the programming language to Python, and making the code open-source. Users are encouraged to build upon the tool, e.g. by implementing their own correlations or coupling to other simulators.

Beckers, Koenraad↗
DOE OSTI2024

EGS Reservoir Modeling for Developing Geothermal District Heating at Cornell University: Preprint

Cornell University is pursuing development of an enhanced geothermal system (EGS) for providing heating to its main campus in Upstate New York. A ~10,000 ft (~3 km) deep vertical observation well ("CUBO") was drilled in 2022 to characterize the subsurface using wellbore logging, borehole imaging, fluid sampling, mini-frac tests, coring and drill cutting analysis. Down-hole temperatures measured at 3 km depth are about 80 degrees C, sufficiently high for direct-use heating. The well drilled through generally low porosity and low permeability Paleozoic sedimentary formations and into metamorphic basement rock, encountered at about 9,400 ft depth. Leveraging subsurface data obtained through CUBO, we investigated technical feasibility and design requirements of a doublet well system with horizontal laterals connected to a fracture network created through hydraulic fracturing. The EGS reservoir is sized to provide a nominal heat output in the range 5 to 10 MWth of continuous heating over a 15 year-lifetime with limited thermal drawdown. We applied the Gringarten Multiple parallel fracture model, the Cornell Discrete Fracture Simulator FOXFEM and the commercial simulator ResFrac to estimate required heat transfer area and design a potential hydraulic stimulation treatment. Reservoir simulations indicate that, depending on fluid flow rate and injection temperature, 2 to 3 km2 of effective fracture heat transfer area is required to supply the target heat output of 5 to 10 MWth over 15 years.

district heating↗
DOE OSTI2025

EGS Reservoir Modeling for Developing Geothermal District Heating at Cornell University

Cornell University is pursuing development of an enhanced geothermal system (EGS) for providing heating to its main campus in Upstate New York. A ~10,000 ft (~3 km) deep vertical observation well ('CUBO') was drilled in 2022 to characterize the subsurface using wellbore logging, borehole imaging, fluid sampling, mini-frac tests, coring and drill cutting analysis. Down-hole temperatures measured at 3 km depth are about 80 degrees C, sufficiently high for direct-use heating. The well drilled through generally low porosity and low permeability Paleozoic sedimentary formations and into metamorphic basement rock, encountered at about 9,400 ft depth. Leveraging subsurface data obtained through CUBO, we investigated technical feasibility and design requirements of a doublet well system with horizontal laterals connected to a fracture network created through hydraulic fracturing. The EGS reservoir is sized to provide a nominal heat output in the range 5 to 10 MWth of continuous heating over a 15 year-lifetime with limited thermal drawdown. We applied the Gringarten Multiple parallel fracture model, the Cornell Discrete Fracture Simulator FOXFEM and the commercial simulator ResFrac to estimate required heat transfer area and design a potential hydraulic stimulation treatment. Reservoir simulations indicate that, depending on fluid flow rate and injection temperature, 2 to 3 km2 of effective fracture heat transfer area is required to supply the target heat output of 5 to 10 MWth over 15 years.

district heating↗
DOE OSTI2020

Thermionic emission and energy conversion

This project worked on development of a transformative heat-to-electricity conversion device based on thermionic energy conversion. The research provided a unique opportunity to transform the thermionics technology of the 1950-1990s by applying modern materials and 21st century wafer-scale fabrication methods. Research was conducted to further development of a thermionic energy converter based on modern microfabrication and new low work function anode materials that can surpass all other forms of direct heat-to-electricity conversion. This project completed the following goals: (1) Developed components for use in thermionic energy converters and electron emission devices, including electrode materials for electron emission and electron absorption with ultimate work functions below 5 eV; (2) Designed and fabricated thermionic devices for energy conversion and electron emission based on the components developed in (1); (3) Engineered test systems to characterize electronic, thermal, and mechanical properties of thermionic devices and electron emitters and their components, and test devices and components designed and fabricated in (1) and (2); and (4) Developed theoretical modeling capabilities in support of these technical objectives.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Exploring the Feasibility of INCONEL® ALLOY 740H® for Power Plant Headers: Integrating Machine Learning with Computational Fluid Dynamics (CFD)

This keynote presentation explores the behavior of headers—essential components of pipeline systems—using ANSYS simulation software and machine learning techniques. The study aims to predict the thermal and mechanical performance of headers under diverse conditions through both steady-state and transient simulations. We investigate critical parameters such as heat transfer coefficient, fluid velocity, and temperature to optimize header design. Conducted as part of a DOE project led by NCAT in collaboration with UNC Charlotte, this research encompasses multiple key topics. The initial section focuses on the behavior of header systems under steady-state conditions using ANSYS simulation. It underscores the importance of headers in industrial infrastructure, especially in the energy sector, and examines the implications of material selection and flow direction on heat transfer dynamics. Methodologically, we employ Computational Fluid Dynamics (CFD) analysis through ANSYS, detailing the development of models, material properties, geometry specifications, boundary conditions, and meshing strategies. Our simulations explore various operational parameters, including temperature and mass flow rates, crucial for predicting heat transfer coefficients and enhancing header design. Results from the study include parametric investigations into mesh sensitivity, viscosity model evaluations, and the effects of heat transfer locations, all validated against theoretical calculations. We conclude with insights on mesh optimization, the suitability of viscosity models, and recommendations for future research aimed at improving header system efficiency and sustainability in industrial applications.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2022

Process-informed adsorbent design guidelines for direct air capture

Direct air capture using solid adsorbents is a proven technology critical to reducing our net greenhouse gas emissions to zero and beyond. Currently, academic research into the technology mainly focuses on the development of new adsorbents. However, there is a discord between the adsorbent design and process performance. Many materials scientists focus on maximising metrics such as the CO 2 capacity of their adsorbent. Here, we combine detailed process modelling, machine learning, and extensive global sensitivity analysis, which entails varying all of the model parameters together, on a direct air capture process to show that the dry CO 2 adsorption capacity does not influence process performance for an amine-functionalised adsorbent operating in a temperature vacuum swing adsorption (TVSA) process, while it is important in a steam-assisted TVSA (S-TVSA) process. In fact, adsorption kinetics, density, and thermal conductivity are all critical attributes to obtaining a low energy penalty and reduced costs. The analysis also highlights the importance of heat transfer, directing process engineers to (alternative) adsorber designs that maximise this. By an in-depth evaluation of how process performance indicators are affected by materials properties and process operating parameters, this work provides guidance to both material scientists and process engineers towards the design of a “unicorn adsorbent” and intensified DAC processes. This will improve the performance of solid adsorbent direct air capture and help drive down the costs of this vital technology to avert the worst impacts of climate change.

42 ENGINEERING↗
DOE OSTI2024

RF antenna helicity dependent particle heating in a helicon source

Experiments have demonstrated that ion phenomena, such as the lower hybrid resonance, play an important role in helicon source operation. Damping of the slow branch of the bounded whistler wave at the edge of a helicon source (i.e. the Trivelpiece-Gould mode) has been correlated with the creation of energetic electrons, heating of ions at the plasma edge, and anisotropic ion heating. Here we present ion velocity distribution function measurements, electron density and temperature measurements, and magnetic fluctuation measurements on both sides of an m = |1| helical antenna in a helicon source as a function of the driving frequency, magnetic field strength, and magnetic field orientation relative to the antenna helicity. Significant electron and ion heating (up to two times larger) occurs on the side of the antenna consistent with the launch of the m = +1 mode. The electron and ion heating occurs within one electron skin depth of the plasma edge, where slow wave damping is expected. The source parameters for enhanced particle heating are also consistent with lower hybrid resonance effects, which can only occur for Trivelpiece-Gould wave excitation.

wave modes↗
DOE OSTI2025

Large electron-phonon drag asymmetry and reverse heat flow in the topological semimetal θ-TaN

A broad range of unusual transport behaviors have been discovered in topological semimetals. However, to date, the effect on the thermopower from intrinsic momentum exchange between electrons and phonons has received little attention. Here we report that huge electron-phonon drag enhancements of the thermopower of the to- pological semimetal, θ-phase tantalum nitride (θ-TaN), can occur that persist even up to room temperature. Our first principles calculations also identify a surprising asymmetry in which the large drag-enhanced thermopowers found slightly above the material’s chemical potential disappear just below it. The large thermopower en- hancements result from anomalous drag contributions from high frequency acoustic phonons with unusually small decay rates. The apparent vanishing drag results from (i) the emergence of an exceptionally high electrical conductivity promoted by the steep linear electronic dispersions extending below one of the topological nodal points; (ii) a remarkable cancellation in which momentum transferred from a charge current creates oppositely directed phonon heat currents of nearly equal magnitude, thereby masking the drag contributions. This extraordinary transport behavior is a consequence of an unusual interplay between intrinsic electron and phonon material properties in θ-TaN. Overall, our work gives new insights into the fundamental physical properties of coupled electron-phonon systems and motivates further exploration of drag effects in semimetals.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Capturing carbon dioxide from air with charged-sorbents

Emissions reduction and greenhouse gas removal from the atmosphere are both necessary to achieve net-zero emissions and limit climate change. There is thus a need for improved sorbents for the capture of carbon dioxide from the atmosphere, a process known as direct air capture. In particular, low-cost materials that can be regenerated at low temperatures would overcome the limitations of current technologies. In this work, we introduce a new class of designer sorbent materials known as ‘charged-sorbents’. These materials are prepared through a battery-like charging process that accumulates ions in the pores of low-cost activated carbons, with the inserted ions then serving as sites for carbon dioxide adsorption. We use our charging process to accumulate reactive hydroxide ions in the pores of a carbon electrode, and find that the resulting sorbent material can rapidly capture carbon dioxide from ambient air by means of (bi)carbonate formation. Unlike traditional bulk carbonates, charged-sorbent regeneration can be achieved at low temperatures (90–100 °C) and the sorbent’s conductive nature permits direct Joule heating regeneration using renewable electricity. Given their highly tailorable pore environments and low cost, we anticipate that charged-sorbents will find numerous potential applications in chemical separations, catalysis and beyond.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Thermal conductivity tensor of β -1,3,5,7-tetranitro-1,3,5,7-tetrazoctane ( β -HMX) as a function of pressure and temperature

Here, we have used reverse non-equilibrium molecular dynamics (RNEMD) simulations to determine the full thermal conductivity tensor for the monoclinic high explosive crystal β-1,3,5,7-tetranitro-1,3,5,7-tetrazoctane (β-HMX). In order to do so for the monoclinic crystal, four directions for heat propagation are used. Effects of the temperature and pressure are investigated between 200 and 500 K and 0 and 5 GPa, respectively, which approximately covers the range where the β polymorph is stable. Simulations are carried out with the Smith–Bharadwaj non-reactive empirical potential [Smith and Bharadwaj, J. Phys. Chem. B 103, 3570 (1999)], which is known to reproduce well the thermo-elastic properties of HMX. Our results indicate that the thermal conductivity, κ, is highly anisotropic, with 36% difference between the two extreme values at 300 K and 0 GPa. A simple function is used to interpolate κ in the pressure-temperature regime considered in this study, which can be used in continuum models. The results from RNEMD simulations compare well with available experimental results from the literature and allow the determination of κ for any direction and temperature and pressure within or around the fitting interval.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Optimizing Control for Efficient Load Shifting with Thermal Energy Storage in Existing HVAC Systems

This project developed the integration of a direct-contact heat exchanger (DCHX) based thermal energy storage (TES) system with a chiller–air handling unit (AHU) plant to evaluate its potential for reducing building energy costs. Detailed physical models of the TES unit, building envelope, and HVAC components were developed alongside simplified control-oriented models to support both high-fidelity simulation and real-time optimization. Two control strategies were implemented and compared: a rule-based control (RBC) aligned with utility time-of-use (ToU) rates, and a model predictive control (MPC) framework leveraging forecasts of building load, weather, and internal gains. Simulation results show that the RBC strategy reduced daily electricity costs by around 30% by shifting cooling production from on-peak to off-peak hours. In contrast, the MPC strategy achieved significantly greater performance, reducing daily operating costs by up to 44% and peak-hour costs by more than 60%. Both strategies maintained indoor thermal comfort within acceptable limits, with MPC further improving load distribution and reducing equipment cycling. The outcomes confirm that TES integration, particularly when coordinated with advanced predictive control, can provide substantial cost savings and on-peak demand reduction. . These findings directly support the U.S. Department of Energy’s goals for grid-interactive efficient buildings and demonstrate the potential of TES-enabled HVAC systems for scalable deployment across the commercial building.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2022

Thermal conductivity tensor of γ and ε -hexanitrohexaazaisowurtzitane as a function of pressure and temperature

Using reverse non-equilibrium molecular dynamics simulations, we have determined the dependences on temperature and pressure of the thermal conductivity tensors for the monoclinic γ and ε polymorphs of hexanitrohexaazaisowurtzitane (HNIW or CL20). In this work, a recently developed non-reactive force field [X. Bidault and S. Chaudhuri, RSC Adv. 9, 39649–39661 (2019)], designed to study polymorphism and phase transitions in CL20, is employed. The effects of temperature and pressure are investigated between 200 and 500 K and up to 0.5 GPa for γ-CL20 and 2 GPa for ε-CL20. In order to obtain the full thermal conductivity tensor, $κ_{ij}$, for the monoclinic crystals, four distinct heat propagation directions are used. We find that $κ_{ij}$ for both polymorphs is more isotropic than for other energetic molecular crystals, including α- and γ-RDX, β-HMX, and PETN, with a maximum difference of 9.8% between orientations observed at 300 K and 0 GPa for γ-CL20 and a maximum difference of 4.8% for ε-CL20. The average thermal conductivity, $\bar{κ}$, of ε-CL20 is 6.4% larger than that of γ-CL20 at 300 K and 0 GPa. Analytic linear functions of the inverse temperature and the pressure are provided, which fit the data well and can be used to predict the thermal conductivity of both polymorphs for any orientation, pressure, and temperature in and around the fitting range. Our predictions agree reasonably well with the limited available experimental data, for which the polymorph type is unknown.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Elucidating the effect of preheating temperature on melt pool morphology variation in Inconel 718 laser powder bed fusion via simulation and experiment

In laser powder bed fusion (L-PBF) additive manufacturing, the mechanical performance, microstructure and defects of fabricated parts are closely associated with the melt pool morphology, e.g., its dimension and shape through the building process. Past studies have largely focused on how the process parameters such as laser power and scan speed affect melt pool characteristics. In this study, the melt pool morphology variation as a function of preheating temperature in the conduction, transition, and keyhole regimes and the underlying mechanisms in each regime are investigated through ex-situ sample characterization and computation thermal fluid dynamics (CtFD) simulation. Single tracks with different combinations of laser power and scan speed are deposited on an Inconel 718 bare plate preheated to a temperature range of 100–500 °C in the experiment. Significant changes are observed in melt pool morphology as a function of preheating temperature from optical measurements of melt track cross sections. The depth of melt pool in the three regimes increases monotonically with preheating temperature, e.g., at 500 °C, the experimental melt pool depth is increased by 49% in conduction regime, 34% in transition regime and 33% in keyhole regime, respectively, while the variation of melt pool width in each regime does not all follow an increasing trend but depends on the melt pool regimes. Melt pool width variation in the conduction and transition regimes is found to depend on the enhanced heat conduction directly related to temperature dependent thermal properties. Through validated CtFD simulations, it is found that in the keyhole regime the evaporation mass, recoil pressure, and laser drilling effect is enhanced with higher preheating temperature, which gives rise to a deeper melt pool. The simulations also reveal that preheating temperature significantly elongates the melt track length due to the increased flow rate and strong recoil pressure that accelerates the backward flow.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Sulfuric Acid Improves the Reactivity of Zeolites via Dealumination

The demand for supplementary cementitious materials (SCMs), like fly ash, slag, and silica fume, is projected to rise over the next few decades. However, global decarbonization efforts, such as decommissioning of coal-fired power plants, will limit the supply of SCMs. Therefore, alternative SCM sources are a critical need for the cement and concrete industry. However, the high crystallinity of zeolites limits their pozzolanic reactivity. The goal of this work was to improve the reactivity of two common zeolites, namely clinoptilolite and SSZ-13, by treating them with sulfuric acid. The treatment enhanced zeolite reactivity via dealumination and decreased particle sizes, which led to increased reactivity with calcium hydroxide, as indicated by a 42.0% increase in reaction heat measured by isothermal calorimetry. Here, we elucidate mechanistic understanding that smaller particle sizes induced by acid treatment accelerated peak heat evolution, while free aluminates from dealumination increased heat via direct reaction with aqueous Ca 2+ .

36 MATERIALS SCIENCE↗
DOE OSTI2025

A review of Geological Thermal Energy Storage for seasonal, grid-scale dispatching

Energy storage is essential for the decarbonization of the U.S. energy grid, especially with the increasing deployment of variable renewable energy sources like solar and wind. Geological thermal energy storage (GeoTES) has emerged as a promising long duration, grid scale solution, providing stability and security through flexible operations and valuable grid services. GeoTES utilizes subsurface reservoirs to store thermal energy for power generation and direct-use heating and cooling. This approach significantly enhances the use of low-temperature reservoirs, which would otherwise be unsuitable for geothermal power plants. It also aligns well with depleted oil and gas reservoirs, concentrating solar power, non-flexible renewables (photovoltaic and wind), and geothermal-related power cycles. Given the favorable marginal costs of GeoTES as storage duration increases, it becomes particularly competitive for seasonal, grid-scale dispatch, where few technologies are viable. This paper provides a comprehensive review of GeoTES systems and the research underpinning itsr development. This analysis begins by defining and categorizing the unique characteristics of thermal energy storage techniques, setting GeoTES apart from other technologies. The various components, configurations, subsurface characteristics, and modeling efforts that guide GeoTES development are then explored. Finally, challenges in GeoTES research, development, and deployment are discussed, along with mitigation strategies and lessons from related technologies. Beyond their economic benefits, GeoTES systems support grid resilience and decarbonize industrial processes. Their scalability, broad distribution, seasonal storage potential, and flexible dispatch capacity make GeoTES a valuable tool for expanding renewable energy deployment and addressing climate change.

15 - GEOTHERMAL ENERGY↗
DOE OSTI2022

Identifying the Gate-Opening Mechanism in the Flexible Metal–Organic Framework UTSA-300

Atomic-level understanding of the gate-opening phenomenon in flexible porous materials is an important step toward learning how to control, design, and engineer them for applications such as the separation of gases from complex mixtures. Here, we report such mechanistic insight through an in-depth study of the pressure-induced gate-opening phenomenon in our earlier reported metal–organic framework (MOF) Zn(dps) 2 (SiF 6 ) (dps = 4,4'-dipyridylsulfide), also called UTSA-300, using isotherm and calorimetry measurements, in situ infrared spectroscopy, and ab initio simulations. UTSA-300 is shown to selectively adsorb acetylene (C 2 H 2 ) over ethylene (C 2 H 4 ) and ethane (C 2 H 6 ) and undergoes an abrupt gate-opening phenomenon, making this framework a highly selective gas separator of this complex mixture. The selective adsorption is confirmed by pressure-dependent in situ infrared spectroscopy, which, for the first time, shows the presence of multiple C 2 H 2 species with varying strengths of bonding. A rare energetic feature at the gate-opening condition of the flexible MOF is observed in our differential heat energies, directly measured by calorimetry, showcasing the importance of this tool in adsorption property exploration of flexible frameworks and offering an energetic benchmark for further energy-based fundamental studies. Based on the agreement of this feature with ab initio-based adsorption energies of C 2 H 2 in the closed-pore structure UTSA-300a (“a” refers to the activated form), this feature is assigned to the weakening of the H-bond C–H···F formed between C 2 H 2 and fluorine of the MOF. Furthermore, our analysis identifies the weakening of this H-bond, the expansion of the closed-pore MOF upon successive C 2 H 2 coadsorption until its volume is close to that of the open-pore MOF, and the spontaneous gate opening to energetically favor C 2 H 2 adsorption in the open-pore structure as crucial steps in the gate-opening mechanism in this system.

36 MATERIALS SCIENCE↗
DOE OSTI2020

High-Performance Thermoelectric Generators for Field Deployments

Thermoelectric power generation is a reliable energy harvesting technique for directly converting heat into electricity. Recent studies have reported the thermal-to-electrical energy conversion efficiency of thermoelectric generators (TEGs) up to 11% under laboratory settings. However, the practical effectiveness of TEGs deployed under real environments is still not more than a few percent. In this study, we provide fundamental insight on the operation of TEGs in realistic environments by illustrating the combinatory effect of thermoelectric material properties, device boundary conditions, and environmental thermal resistivity on TEG performance in conjunction with the module parameters. Using numerical and experimental studies, we demonstrate the existence of a critical heat transfer coefficient that dramatically affects the design and performance of TEGs. Results provide a set of concrete design criteria for developing efficient TEGs that meet the metrics for field deployments. High-performance TEGs demonstrated in this study generated up to 28% higher power and 162% higher power per unit mass of thermoelectric materials as compared to the commercial module deployed for low-grade waste heat recovery. This advancement in understanding the TEG operation will have a transformative impact on the development of scalable thermal energy harvesters and in realizing their practical targets for efficiency, power density, and total output power.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗