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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Stirling Convertor Controller Development at NASA Glenn Research Center

For nearly two decades, NASA Glenn Research Center has been supporting the development of radioisotope power systems (RPS). NASA desires higher conversion efficiency RPS options that are reliable and robust with long-life design. Dynamic conversion, such as Stirling and Brayton, offer the potential for higher conversion efficiencies than current RPS but have yet to be demonstrated in a flight application. The RPS program sent out a solicitation to investigate options for dynamic conversion technologies. As a result of this solicitation, four dynamic power convertor (DPC) technologies were selected for design and three are proceeding to the fabrication phase of prototype dynamic convertors. One lesson learned from the Advanced Stirling Radioisotope Generator (ASRG) project is that controller development should be coordinated with the development of a dynamic convertor. As a result of this, Glenn has been utilizing hardware from past Stirling convertor projects, including that of the ASRG, to support controller development for the DPCs. Glenn has developed a strong knowledge base on both analog and digital Stirling DPC controllers and will continue to expand and apply that knowledge to the DPCs. Over the past 15 years, controllers were developed at Glenn, at Lockheed Martin (LM), and by the Johns Hopkins University Applied Physics Laboratory (APL). Various generations of the controllers have been developed as lessons were learned through various component- and system-level tests. Some of the tests performed were fault tolerance, flight acceptance vibration, electromagnetic interference (EMI), spacecraft integration, and extended operation. The fault tolerance test characterized the controller’s ability to handle various fault conditions, including high or low bus power consumption, total open load or short circuit, and replacing a failed controller card while the backup maintains control of the Stirling convertor. The vibration test confirms the controller’s ability to control an Advanced Stirling Convertor (ASC) during launch. The EMI test characterized the alternating-current (AC) and direct-current (DC) magnetic and electric fields emitted by the single ASC and if the controller has an impact on the radiated EMI. Spacecraft integration testing in the Radioisotope Power Systems (RPS), System Integration Laboratory (RSIL) provided insight into the electrical interactions between the representative RPS, its associated control schemes, and realistic electric system loads. The extended operation test allows data to be collected over a period of thousands of hours to obtain long-term performance data of the system. This paper describes the history of controller development at Glenn, tests performed on these controllers, and lessons learned.

Dugala, Gina M.↗
NASA NTRS2016

Development of Filled-Skutterudite Based Thermopile for High Temperature Sensors for Space and Terrestrial Applications

The Thermal Energy Conversion Technologies Group at the Jet Propulsion Laboratory has been pursuing the development of thermopiles capable of higher temperature operation in support of terrestrial and space sensing applications in extreme environments. The next-generation sensor technology would rely on filled skutterudite (SKD) compounds, the same materials currently being considered for use in the enhanced Multi-Mission Radioisotope Thermoelectric Generator (eMMRTG). We report on the design, development and fabrication of SKD-based prototype thermopile devices. The beginning-of-life (BOL) experimental and predicted performance of the SKD-based prototype thermopile in terms of electrical resistance, output voltage, current, power output and efficiency in the 423 to 723 K operating temperature range is reported and discussed.

Smith, Kevin L.↗
NASA NTRS2017

Risk Management for Dynamic Radioisotope Power Systems

The implementation of dynamic power conversion technology in Radioisotope Power Systems (RPS) for spaceflight has potential for improved specific power and efficiency, compared with existing Radioisotope Thermoelectric Generators (RTGs). This proposed expansion of current RPS technology necessitates a full exploration of the requirements, goals, and concerns related to risks in developing and deploying such systems. The nature of dynamic systems also presents a new set of challenges related to the presence of moving machinery not intrinsic to traditional RTG units. A general RPS risk management methodology is outlined, which is used to identify and assess the variables and operational scenarios introducing risk throughout the design, fabrication, and system integration processes. This paper will demonstrate how mission requirements for Dynamic RPS concepts (DRPS) drive decisions throughout the development process. This work will define the standard practices for decision making within the scope of the risks associated with DRPS hardware development and deployment in sensitive spacecraft near sensitive payloads. Examples of potential risk areas are analyzed for the proposed dynamic systems, and compared to those associated with traditional RTG technologies. This analysis shows the promise for DRPS systems to elevate and extend the capabilities for power systems used in future NASA missions.

Matthes, Christopher S. R.↗
NASA NTRSDate not supplied

Dynamic Radioisotope Power Systems Development Status and Path to Flight

Dynamic power conversion offers the potential to produce Radioisotope Power Systems (RPS) that generate higher power outputs and utilize the Pu-238 radioisotope more efficiently. Additionally, dynamic power conversion offers the potential of producing generators with minimal degradation resulting in more power at the end of the mission, when the power is needed. Dynamic power conversion technologies being developed for space applications include the Stirling and Brayton thermodynamic cycle machines. Machines can be built based on these cycles while eliminating wear mechanisms of the moving components, enabling long design life necessary for space missions. The Dynamic Radioisotope Power Systems (DRPS) project at NASA Glenn Research Center (Glenn Research Center) is pursuing the realization of this type of power source on a flight mission. The project currently has three convertor development contracts that will deliver prototype hardware in 2020. This hardware will undergo a gamut of experimental performance verification efforts at NASA GRC. In parallel, the project has also initiated generator design efforts based on these underlying convertor options, and is also on track to build an in-house version of a generator for laboratory system-level testing. The project is also funding control electronics technology, which are necessary to convert alternating current from the dynamic devices to direct current for use by a spacecraft. A lunar mission is being targeted as the first use of this new technology, as DRPS enables a wide range of high-return scientific missions on the moon, while the mission being short in duration (2 years rather than 10 years for an outer planets mission).

Salvatore M Oriti↗
NASA NTRS2020

Thermodynamic Cycle Analysis of Superadiabatic Matrix-Stabilized Combustion for Gas Turbine Engines

In aircraft propulsion as well as stationary power generation, gas turbine engines remain a key energy conversion technology due to their high thermal efficiencies and low emissions. However, as emission requirements become increasingly stringent, engine manufacturers have sought to design combustion systems that operate near the fuel-lean limit of flammability. In this study, superadiabatic matrix-stabilized combustion, also known as porous media combustion, is evaluated as an advanced combustion concept for extending the lean flammability limit to achieve improved efficiency and emissions. To this end, a Brayton cycle analysis is developed and key parameters of the porous matrix are identified for maximizing the extension of the lean flammability limit. It is shown that stabilization of combustion below the nominal lean flammability limit allows for the design of engines with significantly higher pressure ratios and lower dilution ratios without increasing turbine inlet temperatures, thus improving cycle thermal efficiency. Combustor flammability limits were shown to be extendable by up to 32% when employing matrix-stabilized combustion, resulting in thermal efficiency gains of up to 11% compared to a nominal design.

Superadiabatic combustion↗
NASA NTRSDate not supplied

Dynamic Radioisotope Power Systems Status and Path to Flight

Dynamic power conversion offers the potential to produce Radioisotope Power Systems (RPS) that generate higher power outputs and utilize the Pu-238 radioisotope more efficiently. Additionally, dynamic power conversion offers the potential of producing generators with minimal degradation resulting in more power at the end of the mission, when the power is needed. Dynamic power conversion technologies being developed for space applications include the Stirling and Brayton thermodynamic cycle machines. Machines can be built based on these cycles while eliminating wear mechanisms of the moving components, enabling long design life necessary for space missions. The Dynamic Radioisotope Power Systems (DRPS) project at NASA Glenn Research Center (Glenn Research Center) is pursuing the realization of this type of power source on a flight mission. The project currently has three convertor development contracts that will deliver prototype hardware in 2020. This hardware will undergo a gamut of experimental performance verification efforts at NASA GRC. In parallel, the project has also initiated generator design efforts based on these underlying convertor options, and is also on track to build an in-house version of a generator for laboratory system-level testing. The project is also funding control electronics technology, which are necessary to convert alternating current from the dynamic devices to direct current for use by a spacecraft. A lunar mission is being targeted as the first use of this new technology, as DRPS enables a wide range of high-return scientific missions on the moon, while the mission being short in duration (2 years rather than 10 years for an outer planets mission).

Salvatore Oriti↗
NASA NTRSDate not supplied

Development of Stirling Convertors for Radioisotope and Fission Power Systems

NASA has been developing free-piston Stirling-cycle power convertors over the past 22 years for use in nuclear power systems that would provide electricity for space science missions to dark, dusty, or distant destinations where solar power is not practical. These nuclear power systems would generate heat from either the radioactive decay of isotopes or fission nuclear reactors. That heat would be converted to usable electricity using highly efficient Stirling convertors for a wide range of power needs needing 10s of watts to 50 kWe. NASA’s Radioisotope Power Systems (RPS) Program is maturing advanced thermoelectric and dynamic conversion technologies that would increase the system efficiency beyond what is currently possible using heritage systems to enable a larger number of robotic missions or higher power missions to solar system bodies of interest. The Dynamic Radioisotope Power Systems (DRPS) Project has matured prototype Stirling convertors to sufficiently increase the technology readiness level for infusion into flight development. Flexure and gas-bearing free-piston Stirling convertors were developed under contract by commercial partners and delivered to enable government evaluation. Gas-bearing designs have met performance and robustness requirements and were selected for flight development. This paper provides the status of SRSC test campaign and maturity level.

Dynamic↗
NASA NTRS2023

Development of Stirling Convertors for Radioisotope and Fission Power Systems

NASA has been developing free-piston Stirling-cycle power convertors over the past 22 years for use in nuclear power systems that would provide electricity for space science missions to dark, dusty, or distant destinations where solar power is not practical. These nuclear power systems would generate heat from either the radioactive decay of isotopes or fission nuclear reactors. That heat would be converted to usable electricity using highly efficient Stirling convertors for a wide range of power needs needing 10s of watts to 50 kWe. NASA’s Radioisotope Power Systems (RPS) Program is maturing advanced thermoelectric and dynamic conversion technologies that would increase the system efficiency beyond what is currently possible using heritage systems to enable a larger number of robotic missions or higher power missions to solar system bodies of interest. The Dynamic Radioisotope Power Systems (DRPS) Project has matured prototype Stirling convertors to sufficiently increase the technology readiness level for infusion into flight development. Flexure and gas-bearing free-piston Stirling convertors were developed under contract by commercial partners and delivered to enable government evaluation. Gas-bearing designs have met performance and robustness requirements and were selected for flight development. This paper provides the status of SRSC test campaign and maturity level.

Dynamic↗
DOE OSTI2020

NREL's Capabilities in Biorefinery Analysis

NREL remains at the forefront of expertise in conducting process, techno-economic, and life cycle analyses to connect research with future commercial process integration, a critical step in the scale-up of biomass conversion technologies. Technology areas covered include lignocellulosic biorefineries, algae, CO2 utilization, waste-to-energy, aviation and marine fuels, refinery modeling and analysis, and the circular economy.

BIOMASS FUELS,INORGANIC, ORGANIC, PHYSICAL, AND AN↗
DOE OSTI2022

Techno-Economic Analysis for Co-Processing Fast Pyrolysis Liquid in Fossil Refineries

Recent work at the National Renewable Energy Laboratory (NREL) and throughout the bioenergy community has highlighted incentives associated with co-processing bio-intermediates in existing refineries to reduce capital costs associated with renewable fuels and chemicals production and reduce overall risk for emerging biomass conversion technologies. This presentation summarizes the techno-economic analysis results from the NREL-Petrobras collaboration that focused on refinery integration of fast pyrolysis oil through co-processing in the fluid catalytic cracking (FCC) process. The NREL-Petrobras work highlights the economic opportunity for refiners to engage in co-processing for low-carbon products and introduces the risks for refiners based on variability in crude and fossil-product markets. The NREL-Petrobras results also serve as a basis to inform policy design that reduces economic risk for refinery co-processing and repurposing opportunities. The final topics in the presentation highlight experimental capabilities and emerging analysis approaches at NREL and partner laboratories that support the development and commercial deployment of refinery utilization strategies.

bio-fuels↗
DOE OSTI2022

Bioenergy: A Pathway to Decarbonization

An overview of BETO’s efforts to help engineer carbon reduction and decarbonize the atmosphere with improved carbon conversion technologies, along with bio-based alternatives to fossil fuels and petrochemical-related products.

biofuels, bioproducts, greenhouse gas, carbon foot↗
DOE OSTI2023

Using Co-Optimized Machine Learned Manifolds for Modeling Chemically Reacting Flows

Chemically reacting flows play a key role in a wide range of engineered systems, from chemical and polymer processing to combustion-based energy conversion technologies. Simulations of these flows involve solving a coupled set of partial differential equations for mass, momentum, energy, and all relevant chemical species in the system. Chemical reaction pathways may be extremely complex and involve hundreds or more intermediate species, with reactions that occur over timescales varying by several orders of magnitude - presenting a significant numerical stiffness challenge. The combination of these factors makes simulation of chemically reacting flows vastly more expensive than nonreactive simulations, and often makes direct solution of the governing equations intractable. It is necessary to apply lower-fidelity models in place of the detailed governing equations in order to reduce computational cost to enable reacting flow simulation tools to be used in the engineering design process. Many of the models employed for this purpose are based on reducing the dimension of the thermochemical state, motivated by the observation that the observed thermochemical states in a system lie on a low-dimensional manifold in thermochemical state space. This behavior occurs due to the fast equilibration of certain reactive and transport processes, and physics-based manifold models rely on idealized assumptions about the balance of timescales and the way in which chemistry and transport are coupled. In this work, we apply a novel method for data-driven manifold-based modeling that can leverage data from high-fidelity reacting flow simulations to improve model accuracy in cases where the physics-based modeling assumptions break down. The approach is designed to be broadly applicable across chemically reacting flow systems but is applied here to turbulent combustion modeling.

machine learning↗
DOE OSTI2023

Utilizing Conjugated Imine Polymers to Stabilize Nanoparticle Silicon Anodes

Silicon anodes provide a compelling route towards delivering high-capacity lithium-ion batteries, however they are notoriously difficult to stabilize in conventional liquid electrolytes that are compatible with high performance cathodes. Furthermore, the drastic changes in volume that occur as silicon is lithiated and delithiated can lead to rapid cell failure and novel polymeric binders are known to help mitigate mechanical issues. We have recently developed a novel method to synthesize the conjugated polymer phenylmethylimine (polyPMI) using an imine metathesis reaction. We have demonstrated that this polymer can be used to stabilize silicon nanoparticles to produce a composite lithium-ion battery anode that is electrochemically stable for hundreds of lithiation and delithiation cycles with a Coulombic efficiency that is greater than 99.95% in a traditional carbonate liquid electrolyte. This work covers the structure and properties of polyPMI within the context of the unique mechanical and electrochemical requirements of nanoparticle silicon anodes. The electrochemical behavior of this polymer also offers new opportunities as an organic lithium-coordinating material that can be used to stabilize a variety of other battery electrodes. More broadly, we posit that this solution-processed, ionically conductive, and electronically conductive polymer is applicable for a variety of energy storage and conversion technologies. Finally, this work demonstrates how this novel polymer chemistry provides additional opportunities for tuning electrode architecture to target high energy full cells.

conjugated polymers↗
DOE OSTI2024

Optimal operations of a nuclear-based integrated energy system: A mixed integer program approach

A nuclear-based integrated energy system (IES), consisting of multiple carbon-free energy generation and conversion technologies to meet heterogeneous end-use demands, offers a promising approach to decarbonizing the U.S. economy. Operating such an IES is challenging due to its complexity and the diverse end-use demands, such as heating and electricity. This paper aims to address the optimal operation of an IES composed of a small modular reactor (SMR), a steam manifold, a balance of plant (BOP), a high-temperature steam electrolysis (HTSE) system, a district heating (DH) network, and electrical grids. We formulate the system’s operation as a mixed integer linear programming (MILP) problem to maximize net revenues from sales of electricity and hydrogen. To evaluate the efficacy of the proposed model, we conduct a 24-hour simulation considering day-ahead (DA) electricity prices from CAISO and a varying DH demand profile with hourly resolution. The simulation results show that our model effectively optimizes the operation by selling electricity during on-peak periods and purchasing electricity for hydrogen production during off-peak periods, while satisfying operating constraints within the IES.

08 HYDROGEN↗
DOE OSTI2026

Integrating Phase Change Materials within Catalysts for Effective Heat Management

Here, most fuel conversion technologies, including Fischer-Tropsch synthesis, C-C coupling, methanol synthesis, and aldol condensation reactions, are highly exothermic, making precise temperature control essential to avoid thermodynamic limitations while maintaining selectivity and catalyst stability. Current industrial practice mitigates these effects primarily through reactor-level, ex situ temperature control strategies — such as heat exchangers, multi-tubular reactors, or quench cooling — but these approaches fall short in regulating the heat generated, transported, and dissipated at the catalyst particle scale.

Karakaya, Canan [Oak Ridge National Laboratory (OR↗
NASA NTRS1988

ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis Project

Fiscal year 1987 research activities and accomplishments for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division are presented. The project's technical activities were organized into three work elements. The Molecular Modeling and Applied Genetics work element includes modeling and simulation studies to verify a dynamic model of the enzyme carboxypeptidase; plasmid stabilization by chromosomal integration; growth and stability characteristics of plasmid-containing cells; and determination of optional production parameters for hyper-production of polyphenol oxidase. The Bioprocess Engineering work element supports efforts in novel bioreactor concepts that are likely to lead to substantially higher levels of reactor productivity, product yields, and lower separation energetics. The Bioprocess Design and Assessment work element attempts to develop procedures (via user-friendly computer software) for assessing the economics and energetics of a given biocatalyst process.

Source record↗