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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Effects on the Sustainable Development Goals of Wood Pellet Production in the Southeastern United States

Wood-based pellets produced in the southeastern United States (SE US) and shipped overseas for the generation of heat and power support achievement of several of the United Nation’s Sustainable Development Goals and their targets. If improperly implemented, pellet supply chains, like most energy technologies, can have negative impacts on water and air quality, biodiversity, and other ecosystem services. Cooperation between regional and local industry partners and local communities as well as readily accessible information on environmental and societal effects of the industry are important for addressing sustainability goals. Strengths of this supply chain include replacement of fossil coal with bioenergy; support for renewable energy goals; conservation of forests through sustainable, green economy jobs; and more efficient use of waste materials.

09 BIOMASS FUELS↗
DOE OSTI2022

U.S. High Temperature Materials Highlights

U.S. GIF VHTR work is continuing on graphite qualification, Alloy 617 regulatory issues beyond the Code space, Alloy 800H weldments, and ASME Codes and Standards R&D is still considering both pebble bed and prismatic and steam generator and heat exchanger U.S. DOE Advanced Reactor Demonstration Program (ARDP) Two U.S.-based teams were selected to demonstrate advanced nuclear reactors in the United States that can be operational by 2027 One of the teams is X-energy (Rockville, MD) which will demonstrate a modular gas-cooled reactor design (Xe-100) with four 80 MWe, TRISO fuel, pebble bed reactors A number of U.S.-based teams were selected to design and develop safe and affordable reactor technologies that can be licensed and deployed over the next 10 to 14 years (Risk Reduction) One of the teams is BWXT Advanced Technologies, LLC which will develop a commercially viable transportable microreactor with the design focused on using TRISO fuel particles and silicon carbide (SiC) matrix A number of U.S.-based teams were selected to assist the progression of advanced reactor designs in their earliest phases (Advanced Reactor Concepts-20) One of the teams is Massachusetts Institute of Technology which will mature the Modular Integrated Gas-Cooled High Temperature Reactor (MIGHTR) concept with a horizontal compact design from a pre-conceptual stage to a conceptual stage to support commercialization

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Hydrogen generation using a fuel cell system with an REP

A fuel cell system includes a fuel cell having an anode and a cathode configured to output cathode exhaust. The fuel cell is configured to generate waste heat. The fuel cell system further includes a reformer configured to partially reform a feed gas using the waste heat and output a hydrogen-containing stream. The fuel cell system further includes a reformer-electrolyzer-purifier (“REP”) having an REP anode configured to receive a first portion of the hydrogen-containing stream and an REP cathode.

Jahnke, Fred C.↗
DOE OSTI2022

Need for research and training reactors for advanced reactor designs

Full text of publication follows. Research and training reactors have served a valuable role in helping train workforce for currently operating fleet of light water reactors. These research and training reactors have been used in reactor laboratory classes to familiarize the students with such vital concepts as approach to criticality, reactor period, neutron moderation, reactivity, flux distribution and leakage, etc. As the industry moves toward advanced non-light-water reactor designs, it is critical that research and training reactors be developed and deployed at university campuses to help train the new generation of nuclear and non-nuclear engineers who are likely to design, build, and operate these advanced reactors. Among the designs currently being pursued for nuclear power generation include molten salt, sodium cooled, and gas cooled designs, with options for various fuel forms. Thus, industry and DOE in collaboration with academic institutions should devise plans on how to familiarize the next generation of nuclear workforce with hands-on experience necessary for such designs. These research and training reactors will play a vital role in familiarizing the future workforce with hands-on experience with concepts associated with fast spectrum reactors, gas cooled reactors, and other features not associated with light water reactors. In addition to classical nuclear engineering concepts, these advanced research and training reactors can also be used for hands-on training as well as for research on features being considered in the design of GEN-IV reactors: cyber security for digital control room operations, hybrid energy system, hydrogen generation, district heating, autonomous control... (author)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2023

The Accident Tolerant Fuels’ Neutronics Scoping Study (ATF-2Pert)

This summary discusses an ongoing scoping study to better understand the neutronic characteristics surrounding the center flux trap of the advanced test reactor. This summary details the need for the study, the means by which it was carried out, the study's results, and how the results benefit the accident tolerant fuels program.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2026

Oxidation of Materials and Coatings at 1000°C and 250 bar for use in Oxy-Combustion Turbine

Combinations of materials and coatings were tested in supercritical CO2 (sCO2) to evaluate their reliability in an oxy-fuel turbine being designed to operate in the 150-300 MWe size range at inlet temperatures of 1,150 °C at 300 bar and exhaust temperatures in the 725-775 °C range. Nickel alloys and stainless steels were exposed to supercritical CO2 at 1,000 °C and 250 bar for a total of over 1,500 hours. The materials were tested bare, with a nanocrystalline MCrAlY bond coat only, or with one of two types of bond coat and a thermal barrier coating. A novel test facility using a localized heat zone generated by an induction heater inside an externally cooled autoclave was developed to perform those tests. The specimens were weighed before and after exposure to determine the oxidation rate. All specimens were inspected visually, and a smaller group of coated specimens were studied using secondary electron microscopy (SEM). The integrity of the coating, and the morphology and composition of the thermally grown oxide were especially of interest for the SEM investigation. This paper presents the up-to-date results of the testing coated and uncoated superalloys in sCO2 at up to 1150 °C and up to 300 bar performed at Southwest Research Institute.

Bocher, Florent [Southwest Research Institute, San↗
DOE OSTI2024

The next-generation magnetic recoil spectrometer (MRSnext) on OMEGA and NIF for diagnosing ion temperature, yield, areal density, and alpha heating

The next-generation magnetic recoil spectrometer (MRSnext) is being designed to replace the current MRS at the National Ignition Facility and OMEGA for measurements of the neutron spectrum from an inertial confinement fusion implosion. The MRSnext will provide a far-superior performance and faster data turnaround than the current MRS systems, i.e., a 2× and 6× improvement in energy resolution at the NIF and OMEGA, respectively, and 20× improvement in data turnaround time. The substantially improved performance of the MRSnext is enabled by using electromagnets that provide a short focal plane (12–16 cm) and unprecedented flexibility for a wide range of applications. In addition to being able to measure neutron yield, apparent ion temperature, areal density, and plasma-flow velocity over a wide range of yields, the NIF MRSnext will be able to directly, uniquely assess the alpha heating of the fuel ions through measurements of the alpha knock-on tail in the neutron spectrum. The goal is to implement a radiation-hard electronic detection system capable of providing rapid data acquisition and analysis. The development of the MRSnext will also set the foundation for the more advanced, time-resolving MRSt and serve as a testbed for its implementation on the NIF.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Combined thermal energy storage and heat exchanger unit

The invention provides a method for storing heat and continuously generating electricity, the method comprising a phase change material; first fluid conduit in thermal communication with the phase change material wherein the first conduit is adapted to receive a first fluid; a second fluid conduit in thermal communication with the phase change material, wherein the second conduit is adapted to receive a second fluid; and a turbine in thermal communication with the second fluid. Also provided is a method for continuously charging the energy power block portion of a combined thermal energy storage and heat exchanger unit with heated fluid generated by concentrated solar power, the method comprising intermittently storing heat in a phase change material; and continually directing the heat from the phase change material to a turbine such that the phase change material buffers the turbine against inconsistent solar heat inputs.

France, David M.↗
DOE OSTI2020

Steam generator with inclined tube sheet

A steam generation system may include a plurality of heat transfer tubes configured to circulate a secondary coolant of the steam generation system. The steam generation system may be thermally coupled to a reactor vessel, and the reactor vessel may be configured to house a primary coolant. Heat generated from within the reactor vessel may be transferred from the primary coolant to the secondary coolant. The steam generation system may further include an inclined tube sheet fluidly coupled to the plurality of heat transfer tubes. The inclined tube sheet may be attached to a wall of the reactor vessel in a non-horizontal orientation.

42 ENGINEERING↗
DOE OSTI2025

Pool boiling heat transfer evaluation of next-generation dielectric fluid: Opteon™ 2P50

The growing use of artificial intelligence has led to heavy thermal loads and high heat dissipation rates in data centers. Conventional air-cooled technologies are not able to fulfill these requirements. To overcome these challenges, two-phase immersion cooling (2PIC) has emerged as one of the leading technologies for high power-density chips. 2PIC increases the heat dissipation rate and efficiency of the system while reducing the footprint of the cooling equipment. A fluid with adequate dielectric properties, a suitable normal boiling temperature to maintain chip temperatures, and good material compatibility, is desired for 2PIC system. In this study, the pool boiling heat transfer of a new developmental dielectric fluid, Opteon™ 2P50, was experimentally investigated. The heat transfer coefficients at various heat fluxes (20–150 kW/m 2 ) and the critical heat flux were measured using a smooth aluminum surface. Compared with HFE-7100, Opteon™ 2P50 shows higher heat transfer coefficient (up to 59% higher) and a slightly lower value of critical heat flux (around 5.9% lower). The modified Cooper correlation with the optimized leading constant resulted in reliable prediction accuracy with a 5.3% mean absolute error percentage. Overall, these results indicate that the new dielectric fluid provides similar thermal performance to some legacy fluids.

2P50↗
DOE OSTI2021

Impact on Cycle Efficiency of Small CHP Plants from Increasing Firing Temperature Enabled by AM of Turbine Blades

Combined Heat and Power (CHP) systems are gaining popularity because of their potential for high overall thermodynamic efficiency and increased need for distributed power generation. Most CHP systems include a gas turbine for electricity generation and a heat recovery steam generator (HRSG) for steam generation. The steam can be used to power a steam turbine for additional electricity generation or to drive rotating equipment, for space heating, for absorption chillers, etc. A CHP cycle configuration is often driven by the ‘principal’ utility for the facility that it services; steam or electricity. In either case, performance improvements in the gas turbine have the potential to increase the steam and power output from the cycle, which is a direct result of improvements in the gas turbine efficiency and power output. One possible opportunity to improve an existing gas turbine’s performance is to increase the firing temperature with improved turbine cooling and increased compression ratio.<br>In this study, the impact on CHP cycle performance from increasing the turbine firing temperature by 100 °C and improving the turbine blade cooling for a 6-MW scale gas turbine is estimated using an analytical cooled gas turbine model and a steam cycle model. A sensitivity analysis was performed to understand the impact of increasing the internal cooling effectiveness, thermal barrier coating performance and blade material upgrades on gas turbine and CHP cycle efficiency. The impacts of turbine blade cooling improvements were studied for three common CHP cycle configurations identified from the literature. Various definitions for CHP cycle efficiency from the literature are used in the comparisons. The results showed that a 100 °C increase in firing temperature can increase the gas turbine efficiency by 1 percentage point without improving cooling effectiveness and add 2 additional percentage points in efficiency by using advanced turbine blades with higher internal cooling efficiency. Studied engine upgrades showed potential for increasing the CHP cycle efficiency by 3 percentage points while increasing the steam generation rate by 8%.<br>

Uysal, Selcuk Can↗
DOE OSTI2020

High operating temperature heat transfer fluids for solar thermal power generation. Final report

This is the final technical report for the DOE MURI project on developing high-operating temperature heat transfer fluids for solar thermal power generation. This project aimed to evaluate liquid metals as a heat-transport fluid and potential energy storage medium for concentrated solar powered (CSP) systems. The project consisted of five phases, starting with fluid selection and screen and ending with potential CSP integration. The initial fluid selection arrived at heavy liquid metals as candidate fluids such as lead bismuth eutectic (LBE) as the prime liquid-alloy candidate to be studied, given the conditions above. Fifty-seven liquid compositions were initially identified with liquidus temperatures lower than 200°C, composed of elements that provide no driving force to the reduction of Cr 2 O 3 or Al 2 O 3 passivation layers in pipe material which is required for corrosion prevention. LBE was identified as the primary candidate fluid after these compositions were compared against computational thermodynamic modeling to screen all of the selected systems that would be compatible with our design objectives. Twenty-eight of these compositions were also investigated with the rapid characterization methods; the accuracies of the liquidus temperature and the specific heats predicted by the computations were better than 3 percent and 9 percent, respectively. We conducted numerus corrosion tests of various Fe-Cr-Al based steels in LBE and its variants at temperate as high as 800°C. It was found that minor additions to the liquid did not provide sufficient corrosion protection to warrant their use in real applications. Furthermore, we investigated the detailed mechanism of corrosion between heavy liquid metal and the pipe material at these very high temperatures. A liquid metal loop was constructed to operate at these high temperatures. The loop construction and operation lead to valuable lessons learned that will be needed for industrial scale loops. Furthermore, we learned that electromagnetic pumps at these extreme temperatures will have to be reengineered and redesigned to be used for CSP applications.

14 SOLAR ENERGY↗
DOE OSTI2023

Automotive Silicon Carbide Power Module Cooling With A Novel Modular Manifold And Embedded Heat Sink

The next generation of integrated power electronics packages will implement wide-bandgap devices with ultrahigh device heat fluxes. Although jet impingement has received attention for power electronics thermal management, it is not used in commercial electric vehicles (EVs) because of the associated pressure drop and reliability concerns. Here, in this paper, we present a modular thermal management system designed for automotive power electronics. The system achieves superior thermal performance to benchmarked EVs, while adhering to reliability standards and with low pumping power. The system utilizes a low-cost and lightweight plastic manifold to generate jets over an optimized heat sink, which is embedded in the direct-bonded-copper (DBC) substrate. The embedded heat sink concept leverages additive manufacturing to add elliptical pin fins to the DBC substrate. The heat sink geometry is optimized for submerged jet impingement using a unit-cell model and an exhaustive search algorithm. The model predictions are validated using unit-cell experiments. A full-scale power module model is then used to compare the DBC-embedded heat sink against direct DBC cooling and baseplate-integrated heat sinks for single-sided (SS) and double-sided (DS) cooling concepts. Using the SS and DS DBC-embedded cooling concepts, the models predict a thermal resistance that represents a reduction of 75% and 85% compared to the 2015 BMW i3, respectively, for the same water-ethylene glycol inverter flow rate. We have shown that an inverter with a 100-kilo-Watt-per-liter power density is achievable with the proposed design.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2023

Large Eddy Simulation of Convective Heat Transfer in a Random Pebble Bed Using the Spectral Element Method

The development of fluoride-cooled high-temperature reactors has drastically increased the demand for an in-depth understanding of the heat transfer (HT) in packed beds cooled by liquid salts. The complex flow fields and space-dependent porosity found in a pebble bed require a detailed understanding to ensure the proper cooling of the reactor core during normal and accident conditions. As detailed experimental data are complicated to obtain for these configurations, high-fidelity simulation such as large eddy simulation and direct numerical simulation (DNS) can be employed to create a high-resolution heat transfer numerical database that can assist in addressing industrial-driven issues associated with the heat transfer behavior of fluoride-cooled high-temperature reactors. In this paper, we performed a series of large eddy simulation using computational fluid dynamics (CFD) code NekRS to investigate the heat transfer for a bed of 1741 pebbles. Further, the characteristics of the flow, such as average, rms, and time series of velocity and temperature, have been analyzed. Porous media averages have also been performed. The simulation results show a good agreement between non-conjugate heat transfer and conjugate heat transfer. The generated data will be used to benchmark heat transfer modeling methods and local maxima/minima of heat transfer parameters. It will also be used for supporting convective heat transfer quantification for Kairos Power and benchmarking lower fidelity models.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2025

Synergistic heat pumped thermal storage and flexible carbon capture system

A power plant system is disclosed. The power plant system includes a combustor configured, a turbine configured to generate electricity, a heat exchanger and a steam turbine, a carbon capture system configured to remove at least a portion of carbon-based gasses from the flue gas downstream from the heat recovery steam generator, and a thermal storage system including a hot storage unit configured to store thermal energy at a hot temperature, the hot temperature greater than ambient temperature. The power plant is configured to operate in at least a first mode for storing thermal energy in the thermal storage system and a second mode for releasing the stored thermal energy from the thermal storage system and during the second mode, heat stored in the hot storage unit is transferred to the carbon capture system.

Bandhauer, Todd M.↗
DOE OSTI2025

Compact Counter Flow Fluidized Bed Heat Exchanger (Final Report)

Generation 3 concentrating solar power systems which utilize solid granular media as the heat transfer and storage media hold promise in reducing the levelized cost of electricity relative to generation 2 systems which utilize molten salt. The particles can be heated to temperatures exceeding 800 °C which enables the use of high efficiency supercritical CO 2 Brayton power cycles. A key challenge associate with the use of solid media is its low bulk thermal conductivity which limits the ability to transfer heat from the particles to a working fluid, such as supercritical CO 2 . Tradition shell and tube and shell and plate heat exchangers feature gravity driven particle flow which limits the maximum particle side heat transfer coefficient in these systems to approximately 400 W/m 2 K. A fluidized bed heat exchanger does not rely solely on gravity for particle flow. Instead, enhanced mixing and horizontal conveyance is achieved through fluidization induced through air injection at the bottom of a bed of particles. A tube bundle within the bed conveys the supercritical CO 2 which is heated via the turbulent particle motion at the tube wall.

14 SOLAR ENERGY↗
DOE OSTI2026

Computationally inexpensive part-scale thermal history of additive friction-stir deposition

This study presents an analytical model for steady-state power generation and tool heat loss in additive friction-stir deposition (AFSD), developed to enable part-scale thermal simulation while remaining computationally inexpensive. The model predicts total generated power, yielding 3.7–4.7 kW across deposition temperature setpoints of 400–460 °C for the deposition of AA6061 with a Be-Cu tool. This corresponds to 90–95% of the reported spindle power. Tool heat loss is experimentally determined by calibrating a steady-state energy balance between the generated power, the substrate-deposition thermal gradient, and a temperature dependent tool heat loss term: q tool (T) = a + b (T - 400°C) with a = 2.7 x 10 6 Wm -2 and b = 9.5 x 10 3 Wm -2 K -1 . The calibration indicates that about 69% of the generated heat is conducted into the tool for this configuration, which is much higher than previously reported. The calibrated heat-source is implemented in finite element software (Adamantine) to simulate the transient thermal history of a 100 cm 3 representative build in 8 min on a standard desktop (at 0.635 mm build-height resolution). For the first three layers, the substrate temperatures between simulation and experiment are within 10% mean absolute percentage error. Sensitivity analysis indicates that uncertainties in average deposition temperature and deformation localization (stir-zone geometry, depth, and spatial dependance of strain-rate and flow stress) dominate model variance, motivating additional experimental verification.

Additive Friction-Stir Deposition↗
DOE OSTI2022

An additively-manufactured molten salt-to-supercritical carbon di-oxide primary heat exchanger for solar thermal power generation – Design and techno-economic performance

The design and techno-economic performance of a compact additively manufactured (AM) molten salt (MS)-to-supercritical carbon di-oxide (sCO2) primary heat exchanger (PHE) for solar thermal application is described. The PHE design consists of sCO2 flow through an array of microscale pin fins while the MS flows through mm-scale rectangular channels. Constraints imposed by AM using laser powder bed fusion method are considered in the design. Structural and fluid flow simulations are performed to arrive at a viable design of the core and headers. A simplified one-dimensional steady state model for the PHE is developed including the impact of surface roughness from the AM process. A process-based cost model is used to determine the tradeoff between thermofluidic design and manufacturing cost. A parametric study is performed using the thermo-fluidic and cost models to determine the set of geometrical and flow variables that result in high power density and low cost, while restricting the pressure drop on the sCO2 side to less than 2% of line pressure. Flow rates of MS and sCO2 were varied over heat capacity rate ratios ranging from 0.2 to 1. Results indicate that it is possible to design a low-pressure drop AM PHE with an effectiveness of 90% and a power density in excess of 10 MW/m3 (including headers). Fabrication of representative nickel superalloy specimens are shown to demonstrate that low-porosity parts with the requisite dimensional tolerance of PHE core can be generated.

14 SOLAR ENERGY↗