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Results for “thermodynamic cycles”

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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Nacelle-airframe interference at low supersonic Mach numbers.

The aerodynamic interference between the propulsion system and airframe for a low supersonic transport with wing-mounted nacelles is examined. Both a flowfield analysis and the equivalent body approach were used to predict the interference lift, drag, and pitching moment as functions of nacelle size, shape, and position. The results indicate that the interference lift and pitching moment, as well as drag, must be included in the analysis to properly assess the interference effects. In addition, the performance of the basic wing was found to play an important role in determining the effectiveness of the interference lift in reducing the net installation drag. Based on a conservative prediction, the interference effects can reduce the installed propulsion system drag to 40% of the isolated drag of the nacelles. Furthermore, including the interference effects in the optimization of the engine cycle from a thermodynamic and weight standpoint can result in a considerable reduction in the net propulsion system weight fraction (fuel plus engines) while increasing the optimum engine bypass ratio of a typical transport vehicle.

Bencze, D. P.↗
NASA NTRS1976

A program for calculating turbofan-driven lift-fan propulsion system performance

The performance of a turbofan-powered lift fan propulsion system for vertical takeoff and landing (VTOL) aircraft is calculated. The program formulation consists of taking bleed air from a turbofan engine, heating the bleed air in an interburner, and passing it through a tip turbine to drive a lift fan. Two options are available: bleed air from the engine exhaust, or bleed air that has passed through the engine fan only. This computer program will benefit persons unfamiliar with the thermodynamics of engine cycle analysis.

Tauber, M. E.↗
NASA NTRS1989

On the dynamic response of pressure transmission lines in the research of helium-charged free piston Stirling engines

In free piston Stirling engine research the integrity of both amplitude and phase of the dynamic pressure measurements is critical to the characterization of cycle dynamics and thermodynamics. It is therefore necessary to appreciate all possible sources of signal distortion when designing pressure measurement systems for this type of research. The signal distortion inherent to pressure transmission lines is discussed. Based on results from classical analysis, guidelines are formulated to describe the dynamic response properties of a volume-terminated transmission tube for applications involving helium-charged free piston Stirling engines. The scope and limitations of the dynamic response analysis are considered.

Miller, Eric L.↗
DOE OSTI2021

Fracture fluid alteration to mitigate barite scale precipitation in unconventional oil/gas shale systems

An acid spearhead formulation for mineral scale reduction that includes a sulfuric acid solution having an acidity that is substantially equivalent to a hydrochloric acid solution in an acid spearhead formulation, a sodium citrate compound, where an acid spearhead formulation for mineral scale reduction is formed, the acid spearhead formulation is disposed in a well bore to stabilize mineral scales, the acid spearhead formulation is disposed in the well bore to chelate solubilized calcium in a rock bed of the well bore, and the well bore includes a temporal thermodynamic subsurface barite cycling having a subsurface barite dissolution temporal phase, a subsurface barite transport to fractures temporal phase, a subsurface barite precipitation to fracture temporal phase and a subsurface barite dissolution to fracture space temporal phase, where the acid spearhead formulation for mineral scale reduction reacts with the well bore within the subsurface barite dissolution temporal phase.

Jew, Adam↗
NASA NTRS1992

HFAST - A harmonic analysis program for Stirling cycles

HFAST is a general-purpose third-order harmonic analysis and design program for predicting the cyclic-steady state thermodynamic performance of Stirling cycles. It represents the state-of-the-art results of years of research efforts at Mechanical Technology Inc. (MTI) in the development of Stirling cycle machines. The code has been extensively used at MTI to support the development of both free-piston and kinematic Stirling cycle machines. Lately, HFAST has undergone many major improvements, both in the analysis method and in the user's interface. This paper presents a brief description of the current analysis method used in HFAST.

Huang, S. C.↗
NASA NTRS1983

Computer program for analysis of split-Stirling-cycle cryogenic coolers

A computer program for predicting the detailed thermodynamic performance of split-Stirling-cycle refrigerators has been developed. The mathematical model includes the refrigerator cold head, free-displacer/regenerator, gas transfer line, and provision for modeling a mechanical or thermal compressor. To allow for dynamic processes (such as aerodynamic friction and heat transfer) temperature, pressure, and mass flow rate are varied by sub-dividing the refrigerator into an appropriate number of fluid and structural control volumes. Of special importance to modeling of cryogenic coolers is the inclusion of real gas properties, and allowance for variation of thermo-physical properties such as thermal conductivities, specific heats and viscosities, with temperature and/or pressure. The resulting model, therefore, comprehensively simulates the split-cycle cooler both spatially and temporally by reflecting the effects of dynamic processes and real material properties.

Brown, M. T.↗
DOE OSTI2023

Analysis of Real-World Preignition Data Using Neural Networks

Increasing adoption of downsized, boosted, spark-ignition engines has improved vehicle fuel economy, and continued improvement is desirable to reduce carbon emissions in the near-term. However, this strategy is limited by damaging preignition events which can cause hardware failure. Research to date has shed light on various contributing factors related to fuel and lubricant properties as well as calibration strategies, but the causal factors behind an individual preignition cycle remain elusive. If actionable precursors could be identified, mitigation through active control strategies would be possible. This paper uses artificial neural networks to search for identifiable precursors in the cylinder pressure data from a large real-world data set containing many preignition cycles. It is found that while follow-up preignition cycles in clusters can be readily predicted, the initial preignition cycle is not predictable based on features of the cylinder pressure. Further, this indicates that the alternating pattern of preignition cycles within clusters is influenced by the thermodynamic state as reflected in the pressure, but that the trigger for the initial preignition cycle is not thermodynamic in nature, but more likely tied to a critical threshold in the chemistry of the fuel/lubricant mixture in the upper crevice or other factors related to the presence of an ignition source.

33 ADVANCED PROPULSION SYSTEMS↗
NASA NTRSDate not supplied

A Thermodynamic Paradigm for Studying Disease Vector’s Habitats & Life Cycles Using NASA’s NextGen Remote Sensing Instruments

Global public health is entering a new informational age through the use of spatial models of disease vector/host ecologies driven by the use of remotely sensed data to measure environmental and structural factors critical in determining disease vector habitats, distributions, life cycles, and host interactions. The vector habitat microclimates can be quantified in terms of the surface energy budget measured by satellites. The epidemiological equations (processes) can be adapted and modified to explicitly incorporate environmental factors and interfaces required by a specific disease and its vector/host cycle. Remote sensing can be used to measure or evaluate or estimate both environment (state functions) and interface (process functions). Remote sensing can be used to measure or evaluate or estimate both environment (state functions) and interface (process functions) defining vector habitats. The products of remote sensing can be integrated directly into the epidemiological equations to significantly enhance our understanding of disease vector’s life cycles and habitats. The next generation of NASA’s remote sensing instruments recently operational will provide a significant enhancement in our ability to study disease vector’s life cycles and habitats. Three new instruments have become operational on the International Space Station (ISS) In June 2018, ECOSTRESS (The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station), a five channel, thermal IR instrument with 70 m resolution and approximately 4-5 day repeat cycle of day/night pairs along with DESISa hyperspectral sensor system 235 channels (between 400 and 1000 nanometers), 30 m resolution, and data only being acquired on demand. In November 2018. GEDI (Global Ecosystem Dynamics Investigation). GEDI is a high-resolution laser ranging of Earth’s forests and topography. These instruments set the stage for NASA’s new global designated observables set of remote sensing measurements collecting hyperspectral and multispectral thermal data called SBG (Surface Biology Geology). The SBG is currently in the planning stage. The availability and use of level 1-4 data products generated from these ISS instruments will be discussed.

thermodynamics↗
NASA NTRS1976

Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 10: Liquid-metal MHD systems

Electric Power Plant costs and efficiencies are presented for two basic liquid-metal cycles corresponding to 922 and 1089 K (1200 and 1500 F) for a commercial applications using direct coal firing. Sixteen plant designs are considered for which major component equipment were sized and costed. The design basis for each major component is discussed. Also described is the overall systems computer model that was developed to analyze the thermodynamics of the various cycle configurations that were considered.

Holman, R. R.↗
DOE OSTI2020

A Cost-Performance Analysis of a Sodium Heat Engine for Distributed Concentrating Solar Power

We present that a sodium thermal electrochemical converter (Na-TEC) generates electricity directly from heat through isothermal expansion of sodium ions across a beta"-alumina solid-electrolyte. This heat engine has been considered for use with conventional concentrating solar power (CSP) systems before. However, unlike previous single-stage devices, the improved design uses two stages with an interstage reheat, allowing more economical and efficient conversion up to 29% at a hot side temperature of 850 °C. Herein, a cost-performance analysis for this improved design assesses opportunities for distributed-CSP in the context of micro-combined heat and power systems. A high-level techno-economic analysis (TEA) is presented that explores four scenarios where a Na-TEC is used as the heat engine for a distributed-CSP system. Overnight capital cost and levelized cost of electricity (LCOE) are estimated for a system lifetime of 30 years, revealing that overnight capital costs in a range from $3.57 to $17.71 per W e are feasible, which equate to LCOEs from 6.9 to 17.2 cents kWh e -1 . This analysis makes a significant contribution by concurrently quantifying the efficiency and unit costs for a range of multistage configurations, and demonstrating that a Na-TEC may be a promising alternative to Stirling engines for distributed-CSP systems at residential scale of 1–5 kW e .

14 SOLAR ENERGY↗
NASA NTRS1977

Design of closed-cycle MHD generator with nonequilibrium ionization and system

A method is developed to include the nonequilibrium ionization process in the MHD generator duct design equations, and these equations are coupled to the thermodynamic conditions of the closed cycle system. This is used to relate MHD generator size, configuration and gas conditions to the overall thermodynamic efficiency of the system. The system studied consists of an MHD loop (Ar + Cs or He + Cs) topping a steam bottoming plant.

Voshall, R. E.↗
DOE OSTI2023

Intensified Catalytic Conversion of CO2 into High Value Chemicals

The utilization of CO2 produced from power generation plants as a feedstock for creating new valuable products offers a strategy to reduce GHG emissions, offset carbon capture costs, and facilitate the rebalancing of the carbon cycle. After considering the thermodynamic requirement of potential products from CO2 utilization and their market size, formic acid is a desirable target that offers widespread utility in industrial chemical production and chemical energy storage as a liquid fuel. To effectively utilize CO2 from power generation plants, UK proposes an enhanced bimetallic oxide carbon utilization process (EBOCU) that enables electrochemical CO2 conversion to formic acid. The UK intensified electrocatalytic process combines three main components: 1) a novel bimetallic oxide electrocatalyst; 2) a stable electrochemical reactor using robust electrodes; and 3) a pressurized electrochemical reactor. The output from this project showed the economic viability of producing high-value formic acid from CO2 to both offset the cost associated with post-combustion CCS and reduce GHG emissions. This project developed and screened a series engineered catalysts to selectively reduce CO2 directly to formic acid. The best performing catalyst based on formic acid production, stability, and Faradaic efficiency, was immobilized on carbon electrodes, and tested inside a flow through reactor. After lab-scale testing was completed, the experimental data was used to perform a Life-Cycle Analysis (LCA) and conduct an Initial Technical and Economic Feasibility Study. The LCA showed a pathway to a net negative CO2 utilization process with the incorporation of renewable energy, while the TEA showed the potential to produce formic acid below the current commercial price. The UK EBOCU process was successfully demonstrated at the TRL3 level and has a clear pathway to further development and contribution to the nation’s ambitious decarbonization goals.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2021

Ab Initio Study of Atomic and Electronic Structure of Promising Ba4XMn3O12 (X = Nb, Ce, Pr) Oxides for Solar Thermochemical Hydrogen Production

The two-step metal oxide water-splitting cycle is one of the most viable approach for Solar Thermochemical Hydrogen (STCH) production. Challenges exist in finding suitable oxides that can satisfy thermodynamics of the STCH redox cycle under viable range of temperatures and partial pressures. Recently, BXM family members, i.e., Ba4NbMn3O12 (BNM), Ba4CeMn3O12 (BCM), Ba4PrMn3O12 (BPM) are discovered to exhibit promising STCH performance. However, the magnetic degrees of freedom of their experimental crystal structures is not characterized, and only hypothetical models exist for their electronic structure. We performed Monte-Carlo sampling for the magnetic spin arrangement of Mn atoms to provide explicit atomic structure models for their ground state 12R polytype and determined the most stable spin configuration for each member after structure relaxation using density functional theory (DFT) calculations. We also elucidate the most stable charge configuration (Mn3+/Mn4+ arrangement) for BNM among the existing hypothesis in literature. We investigate these strongly correlated oxides using different levels of theory (DFT+U, Hybrid-DFT) to develop better understanding of their electronic structure. These calculations allowed us to develop a model based on molecular orbital interactions that help explain the observed changes in their experimental x-ray spectroscopy measurements. Thereby, help link differences in electronic structure of BXM family members to their varying water-splitting behavior. These structure models will further facilitate future in-depth defect studies to model STCH redox cycle of these oxides.

atomic and magnetic structure↗
DOE OSTI2026

Unraveling Fundamental Activity–Stability Relationships in Rutile Oxides

The oxygen evolution reaction (OER) is a key anodic half-cell reaction that accompanies several critical electrochemical reduction reactions of interest to a variety of applications. Despite steady advances in understanding and qualitatively predicting OER activity and selectivity trends, a comprehensive description or prediction of material aqueous (in)stability and degradation mechanisms remains elusive, even though these processes critically influence device lifetime and economic feasibility. In this work, we investigate the interplay, or lack thereof, between OER activity and material aqueous stability across rutile oxides, with a particular focus on iridium oxide (IrO 2 ). By applying a Born–Haber cycle, we calculate the thermodynamic driving force for metal dissolution as a function of the applied bias and electrolyte conditions. We apply interpretable machine learning techniques, including principal component analysis and symbolic regression, to analyze trends across rutile oxides and find that key thermodynamic descriptors for OER activity and surface stability are only very weakly correlated. Instead, the local atomic environment─especially electronic structure signatures for interactions between the active site and its neighbors─plays a more important role in predicting material stability. Leveraging these insights, we investigate the impact of doping IrO 2 with a range of transition metals and show that the stability of Ir active sites can be tuned largely independently of its predicted OER activity. These insights lay the foundation for material design to improve stability with respect to corrosion, with the ultimate aim to enhance long-term stability without sacrificing catalytic performance in the OER.

evolution reactions↗
NASA NTRS1973

Gasdynamic lasers and photon machines.

The basic operational highlights of CO2-N2 gasdynamic lasers (GDL's) are described. Features common to powerful gas lasers are indicated. A simplified model of the vibrational kinetics of the system is presented, and the importance of rapid expansion nozzles is shown from analytic solutions of the equations. A high-power pulsed GDL is described, along with estimations of power extraction. A closed-cycle laser is suggested, leading to a description of a photon generator/engine. Thermodynamic analysis of the closed-cycle laser illustrates in principle the possibility of direct conversion of laser energy to work.

Christiansen, W. H.↗
NASA NTRS1989

Total ozone time variations during the spring reversals in the high latitudinal stratosphere of the Northern Hemisphere during the 20th and 21st solar cycles

The principal features of the thermodynamic regime of the stratosphere are governed by the development of the winter stratospheric low and the Aleutian and Atlantic heights. These are fed by the influx of the eddy energy transported into the stratosphere by the planetary waves. The intensity and variability of planetary waves and vortices associated with the waves determine the conditions of low-to-high latitudes ozone transport in the winter hemisphere. The ozone distributions are zonally inhomogeneous. The planetary wave dynamics are affected by solar activity variations during solar cycles. The 20th solar cycle maximum was accompanied by decreases of stratospheric planetary wave amplitudes, the 21st cycle was accompanied by increases of amplitudes.

Kidiyarova, V. G.↗