SEARCH · Engineering Papers

Results for “efficiency improvement”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45

All sources NASA NTRS DOE OSTI

NASA NTRSDate not supplied

Lunar South Pole Regenerative Fuel Cell System Efficiency Analysis

It is expected that future NASA mission energy storage needs can be adequately met by regenerative fuel cells (RFCs). Aerospace RFCs package proton exchange membrane (PEM) electrochemical conversion devices based on hydrogen, oxygen, and water. To optimize system designs and direct further development, the most useful system metric is round-trip efficiency (RTE). Improving RTE generally increases specific energy and reduces system mass. The following analysis models the impact of several factors on RTE for RFCs at the lunar south pole scaling from 0.1 kW to 50 kW. The analysis demonstrates that higher electrolyzer operational pressure most negatively impacts both RFC RTE and specific energy. Optimal electrolyzer membrane thickness is evaluated as a function of operational current density and pressure. Reactant storage heating and power management losses are significant for RFCs of any scale but are reduced in impact at the south pole compared to colder equator applications. Solenoid valve power remains a noticeable parasitic load for smaller RFCs. Larger electrolyzers enable higher peak theoretical efficiencies when recharging at higher rates, if the RFC can be coupled with a corresponding higher power source. RFC design is a compromise of many interrelated factors, but this analysis provides a starting point for difficult decisions that must be made when designing a lunar south pole RFC.

regenerative fuel cell↗

NASA NTRS2010

Transparent Large Strain Thermoplastic Polyurethane Magneto-Active Nanocomposites

Smart adaptive materials are an important class of materials which can be used in space deployable structures, morphing wings, and structural air vehicle components where remote actuation can improve fuel efficiency. Adaptive materials can undergo deformation when exposed to external stimuli such as electric fields, thermal gradients, radiation (IR, UV, etc.), chemical and electrochemical actuation, and magnetic field. Large strain, controlled and repetitive actuation are important characteristics of smart adaptive materials. Polymer nanocomposites can be tailored as shape memory polymers and actuators. Magnetic actuation of polymer nanocomposites using a range of iron, iron cobalt, and iron manganese nanoparticles is presented. The iron-based nanoparticles were synthesized using the soft template (1) and Sun's (2) methods. The nanoparticles shape and size were examined using TEM. The crystalline structure and domain size were evaluated using WAXS. Surface modifications of the nanoparticles were performed to improve dispersion, and were characterized with IR and TGA. TPU nanocomposites exhibited actuation for approximately 2wt% nanoparticle loading in an applied magnetic field. Large deformation and fast recovery were observed. These nanocomposites represent a promising potential for new generation of smart materials.

Yoonessi, Mitra↗

NASA NTRSDate not supplied

Deep Neural Network Based Convergence Classification for Computational Fluid Dynamics

A supervised deep learning approach is coupled with heuristic convergence criteria to construct a classification model for detecting the completion (convergence) of computational fluid dynamics (CFD) simulations. Heuristic convergence criteria alone are not always sufficient and more complex decisions are often left to a human analyst. The proposed approach leverages heuristic convergence criteria as well as two deep neural network (DNN) models, one binary and one multi-class, to improve the efficiency and consistency of convergence classification across a wide range of flight regimes. The DNN models presented are each trained on a subset of ascent aerodynamic CFD simulations for NASA’s Space Launch System and were produced using NASA’s unstructured Navier-Stokes solver FUN3D. Individual solutions are analyzed intermittently and are classified as sufficiently converged, further iterations required, or switch from steady Reynolds Averaged Navier-Stokes (RANS) to unsteady RANS CFD based on the iterative histories of four aerodynamic coefficients. The implemented classification model is shown to produce solutions that closely correlate to solutions produced by a human analyst. This work lays groundwork for expanding the capabilities of DNNs for automating and improving more of the CFD process.

SLS↗

NASA NTRSDate not supplied

Developing a Vision for Maturing the Heliophysics Infrastructure towards Open Science: The DIARieS Analysis Ecosystem

In the dawn of open science and the upcoming requirements, we speak about the existing state of Heliophysics infrastructure and detail the evolution required to address capability or interconnection shortcomings. Such a daunting barrier calls for an analysis ecosystem with multi-faceted capability. We propose such an ecosystem, called DIARieS, to be built upon five conceptual pillars: Discovery, Implementation, Analysis, Reproducibility, and Sharing of results. The combination of these concepts in a single platform will enable users to more intuitively combine recent advances in technology to create ‘DIARieS’ of their workflows, which can be easily made open to others in the community. The DIARieS ecosystem will also increase our efficiency by streamlining our various workflow processes, including automatic incorporation of the impending requirements of open science. The various components of the ecosystem will simplify software installation and data implementation, including automatically generated citation lists based on the components included. Automatic containerization and version control of the ecosystem will make the custom workflows easily reproducible. Employing widget technology will ease the difficulty of producing publication and commercial quality visualizations and applying common analyses techniques. Incorporating multiple technologies will streamline the various sharing methods common in our work environments today. Overall, the totality of capabilities to be offered by this analysis ecosystem will drastically simplify the application of open science principles to our work in addition to improving our efficiency and ease of collaboration. This talk summarizes a vision of the proposed ecosystem, which is described in more detail in Ringuette et al. (2022: https://doi.org/10.1016/j.asr.2022.05.012).

infrastructure↗

NASA NTRSDate not supplied

Developing a Vision for Maturing the Heliophysics Infrastructure towards Open Science

Infrastructure↗

NASA NTRS1991

Calculated performance of p(+)n InP solar cells with In(0.52)Al(0.48)As window layers

The performance of indium phosphide solar cells with lattice matched wide band-gap In(0.52)Al(0.48)As window layers was calculated using the PC-1D computer code. The conversion efficiency of p(+)n InP solar cells is improved significantly by the window layer. No improvement is seen for n(+)p structures. The improvement in InP cell efficiency was studied as a function of In(0.52)Al(0.48)As layer thickness. The use of the window layer improves both the open circuit voltage and short circuit current.For a typical In(0.52)Al(0.48)As window layer thickness of 20 nm, the cell efficiency improves in excess of 27 percent to a value of 18.74 percent.

Jain, R. K.↗

NASA NTRS1996

Thermoelectric refrigerator

A refrigerator is provided which combines the benefits of superinsulation materials with thermoelectric devices and phase change materials to provide an environmentally benign system that is energy efficient and can maintain relatively uniform temperatures for extended periods of time with relatively low electrical power requirements. The refrigerator includes a thermoelectric assembly having a thermoelectric device with a hot sink and a cold sink. The superinsulation materials include a plurality of vacuum panels. The refrigerator is formed from an enclosed structure having a door. The vacuum panels may be contained within the walls of the enclosed structure and the door. By mounting the thermoelectric assembly on the door, the manufacturer of the enclosed structure is simplified and the overall R rating of the refrigerator increased. Also an electrical motor and propellers may be mounted on the door to assist in the circulation of air to improve the efficiency of the cold sink and the hot sink. A propeller and/or impeller is preferably mounted within the refrigerator to assist in establishing the desired air circulation flow path.

Park, Brian V.↗

NASA NTRS2008

Study of Conical Pulsed Inductive Thruster with Multiple Modes of Operation

An electrodeless, pulsed, inductively coupled thruster has several advantages over current electric propulsion designs. The efficiency of a pulsed inductive thruster is dependent upon the pulse characteristics of the device. Therefore, these thrusters are throttleable over a wide range of thrust levels by varying the pulse rate without affecting the thruster efficiency. In addition, by controlling the pulse energy and the mass bit together, the ISP of the thruster can also be varied with minimal efficiency loss over a wide range of ISP levels. Pulsed inductive thrusters will work with a multitude of propellants, including ammonia. Thus, a single pulsed inductive thruster could be used to handle a multitude of mission needs from high thrust to high ISP with one propulsion solution that would be variable in flight. A conical pulsed inductive lab thruster has been built to study this form of electric propulsion in detail. This thruster incorporates many advantages that are meant to enable this technology as a viable space propulsion technology. These advantages include incorporation of solid state switch technology for all switching needs of the thruster and pre-ionization of the propellant gas prior to acceleration. Pre-ionizing will significantly improve coupling efficiency between drive and bias fields and the plasma. This enables lower pulse energy levels without efficiency reduction. Pre-ionization can be accomplished at a small fraction of the drive pulse energy.

Miller, Robert↗

NASA NTRS2017

Stochastic Modelling of Wireless Energy Transfer

This study investigates the efficiency of a new method of powering remote sensors by the means of wireless energy transfer. The increased use of sensors for data collection comes with the inherent cost of supplying power from sources such as power cables or batteries. Wireless energy transfer technology eliminates the need for power cables or periodic battery replacement. The time and cost of setting up or expanding a sensor network will be reduced while allowing sensors to be placed in areas where running power cables or battery replacement is not feasible. This paper models wireless channels for power and data separately. Smart scheduling for the data channel is proposed to avoid transmitting data on a noisy channel where the probability of data loss is high to improve power efficiency. Analytical models have been developed and verified using simulations.

Veilleux, Shaun↗

NASA NTRSDate not supplied

Failure Modes and Mitigation Strategies for a Turboelectric Aircraft Concept with Turbine Electrified Energy Management

The electrification of gas turbine engines represents a major step-change in aircraft propulsion systems commonly known as Electrified Aircraft Propulsion (EAP). EAP involves the integration of electric machines potentially functioning as generators for large scale power extraction, as motors providing electrical augmentation of the engine spools, and even as a means of driving propulsors beyond the immediate scope of the engine. It may also include the use of energy storage. These and other characteristics of hybrid electric propulsion systems are relatively new to aircraft propulsion. The expanded propulsion architecture can be leveraged to improve propulsive efficiency and achieve better vehicle aerodynamics and controllability. It can also allow for additional benefits such as those enabled through Turbine Electrified Energy Management (TEEM). As the propulsion system and its functions expand, new failure modes are introduced. Due to the highly coupled nature of the propulsion system, failures could propagate throughout the system in ways that are unique to the new EAP architectures. To build confidence in the safety and practicality of EAP concepts, these failure modes need to be identified, explored, and addressed through mitigation strategies. This paper seeks to evaluate failure modes and failure mitigation strategies for the EAP concept known as the Single aisle Turboelectric AiRCaft with Aft Boundary Layer propulsor (STARC-ABL). The TEEM control concept is applied to improve transient operability. Several failure modes are considered and control based failure mitigation strategies are proposed with the goal of retaining operability and overall thrust. The results demonstrate the ability to maintain operability and a substantial amount of thrust in the event of various types of failures. Some challenges are also identified and discussed.

Turbine Electrified Energy Management↗

NASA NTRS1992

Mechanical design of a rotary balance system for NASA. Langley Research Center's vertical spin tunnel

A new, lightweight Rotary Balance System is presently being fabricated and installed as part of a major upgrade to the existing 20-Foot Vertical Spin Tunnel (Figure 1) located at NASA's Langley Research Center. This upgrade, to improve model testing productivity of the only free-spinning vertical wind tunnel in the Western Hemisphere, includes a modern fan/drive and tunnel control system, an updated video recording system, and the new rotary balance system. The rotary balance is a mechanical apparatus which enables the measurement of aerodynamic force and moment data under spinning conditions (100 rpm). This data is used in spin analysis and is vital to the implementation of large amplitude maneuvering simulations required for all new high performance aircraft. The present system is over 40 years old and is worn beyond acceptable tolerances, as well as being susceptible to frequent breakdowns. It has serious limitations in model weight, position adjustment and spin-rate capabilities. The new rotary balance system described in this report will permit greater test efficiency and improved data accuracy. Rotary Balance testing with the model enclosed in a tare bag can also be performed to obtain resulting model forces from the spinning operation. The rotary balance system will be stored against the tunnel sidewall during free-flight model testing.

J. W. Allred↗

NASA NTRS2010

On-Orbit Propulsion and Methods of Momentum Management for the International Space Station

Since the first documented design of a space station in 1929, it has been a dream of many to sustain a permanent presence in space. Russia and the US spent several decades competing for a sustained human presence in low Earth orbit. In the 1980 s, Russia and the US began to openly collaborate to achieve this goal. This collaboration lead to the current design of the ISS. Continuous improvement of procedures for controlling the ISS have lead to more efficient propellant management over the years. Improved efficiency combined with the steady use of cargo vehicles has kept ISS propellant levels well above their defined thresholds in all categories. The continuing evolution of propellant and momentum management operational strategies demonstrates the capability and flexibility of the ISS propulsion system. The hard work and cooperation of the international partners and the evolving operational strategies have made the ISS safe and successful. The ISS s proven success is the foundation for the future of international cooperation for sustaining life in space.

Russell, Samuel P.↗

NASA NTRSDate not supplied

NASA Hybrid Thermally Efficient Core (HyTEC) Project Overview

The HyTEC Project goal is to mature compact core aircraft engine technologies as part of the NASA-led Sustainable Flight National Partnership (SFNP) that contributes to the United States Aviation Climate Action Plan goal for aviation net zero carbon emissions by 2050. Individual technologies were proposed and defined by industry partners, and then selected technology maturation activities are cost shared. Phase 1 contracts were awarded in 2021, and since then, the project has matured numerous technologies to TRL 4-5. Some of the Phase 1 efforts have been completed with successful results. An initial systems analysis study has been completed to estimate the impact of Phase 1 technologies against project performance metrics, with results indicating significant progress is being made toward meeting those metrics. HyTEC will culminate with an engine core demonstration that will integrate many of the Phase 1 technologies into a large-scale integrated ground demonstration that will achieve TRL 6 to enable industry to transition the technologies into the next single-aisle engine architecture. The goal of the demonstration is to fully meet the project performance metrics that define a compact engine core with substantial improvements in efficiency, durability, performance, hybridization, and sustainability over the baseline established in the year 2020. HyTEC will also incorporate hybrid electric technology into the engine core with the intention to bring the first electrified turbofan engines into production. The core demonstration has been awarded with a cost-share partnership and is planned to occur by the end of 2028.

Anthony L Nerone↗

NASA NTRS2018

Conductivity of a Copper-Carbon Covetic Composite

NASA is currently engaged in the development of highly electrically conductive wire for space and aviation power and propulsion applications. Higher levels of electrical conductivity and lower densities compared to copper and aluminum are needed to improve the efficiency of commercial aviation and space flight. Carbon, in various forms, is being considered as a component in composites to increase conductivity and decrease density in Cu and Al. One form of carbon that is currently receiving much interest is known as covectic. The technology currently known as covetics was first introduced by Shugart and Scherer whose patents claimed "Carbon can be incorporated into any of these metals by melting the metal, mixing the carbon into the molten metal and, while mixing, applying a current of sufficient amperage to the molten mixture such that the carbon becomes incorporated into the metal, thereby forming a single phase metal-carbon material." It is reported that in this process a conversion reaction occurs with the carbon forming covalent bonds with the host metal, and that covetic processing enables higher carbon solubility and improvements in properties. Although there is a growing body of work supporting covetic materials, it is still a very new and somewhat controversial field. Composition, density, and electrical conductivity measurements of a covetically processed alloy ingot of Cu and C, with a nominal composition of Cu-0.4wt.% C, were made. A pure Cu ingot was similarly processed for comparison. Sections of these ingots were worked into wire and tested. Only small amounts of C could be detected in the Cu-0.4wt.% C ingot, and trace amounts (0.006 wt.%) in the wire. All wires had densities very close to the full density of pure Cu, indicating a high level of Cu purity and low void fraction. Finally, the electrical conductivity of the Cu-0.4wt.% C wires were 9% lower than the samples similarly processed but without C additions. The wires made without C additions had conductivities approximately equal to pure Cu. The low conductivity of the Cu-0.4wt.% C material is believed to be due to: (1) a structure of interfaces in the wire created by collapsed voids lined with elemental C, (2) impurities, such as Fe in the Cu, which came from the added C, and (3) a small volume fraction of voids.

Degroh, Henry C.↗

NASA NTRS2022

Lunar Equator Regenerative Fuel Cell System Efficiency Analysis

It is expected that future NASA mission energy storage requirements can be adequately met by regenerative fuel cells (RFCs). Aerospace RFCs are likely to package proton exchange membrane electrochemical conversion devices based on hydrogen, oxygen, and water. To optimize system designs and direct further development, the most useful system metric is round-trip efficiency (RTE). Improving RTE generally increases specific energy and reduces system mass. The following analysis models the impact of several factors on RTE for RFCs scaling from 0.1 to 50 kW. The analysis demonstrates that higher electrolyzer (EZ) operational pressure most negatively impacts both RFC RTE and specific energy. Reactant storage heating and power management losses are significant for RFCs of any scale, but solenoid valve power becomes a noticeable parasitic load for smaller RFCs. Spherical gas storage vessels benefit RTE by only 2 to 4 percentage points but increase specific energy by ~50 percent. Cryogenic reactant storage is shown to depress RTE to below 15 percent in all cases. For a given RFC scale, there is an RTE benefit to specifying larger EZs and recharging at higher rates—if the RFC can be coupled with a corresponding power source. Although fuel cell (FC) operation is less impactful on RTE than EZ factors, efficiency is maximized by sizing the FCs relatively large and keeping current density low. RFC design is a balance of many interrelated factors, but this analysis provides a starting point for difficult decisions that must be made when designing a lunar equator RFC.

regenerative fuel cell↗

NASA NTRS2004

Analysis of Electrical Characteristics of Thin Film Photovoltaic Cells

Solar energy is the most abundant form of energy in many terrestrial and extraterrestrial environments. Often in extraterrestrial environments sunlight is the only readily available form of energy. Thus the ability to efficiently harness solar energy is one of the ultimate goals in the design of space power systems. The essential component that converts solar energy into electrical energy in a solar energy based power system is the photovoltaic cell. Traditionally, photovoltaic cells are based on a single crystal silicon absorber. While silicon is a well understood technology and yields high efficiency, there are inherent disadvantages to using single crystal materials. The requirements of weight, large planar surfaces, and high manufacturing costs make large silicon cells prohibitively expensive for use in certain applications. Because of silicon s disadvantages, there is considerable ongoing research into alternative photovoltaic technologies. In particular, thin film photovoltaic technologies exhibit a promising future in space power systems. While they are less mature than silicon, the better radiation hardness, reduced weight, ease of manufacturing, low material cost, and the ability to use virtually any exposed surface as a substrate makes thin film technologies very attractive for space applications. The research group lead by Dr. Hepp has spent several years researching copper indium disulfide as an absorber material for use in thin film photovoltaic cells. While the group has succeeded in developing a single source precursor for CuInS2 as well as a unique method of aerosol assisted chemical vapor deposition, the resulting cells have not achieved adequate efficiencies. While efficiencies of 11 % have been demonstrated with CuInS2 based cells, the cells produced by this group have shown efficiencies of approximately 1 %. Thus, current research efforts are turning towards the analysis of the individual layers of these cells, as well as the junctions between them, to determine the cause of the poor yields. As a student of electrical engineering with some material science background, my role in this research is to develop techniques for analyzing the electrical characteristics of the CuInS2 cells. My first task was to design a shadow mask to be used to place molybdenum contacts under a layer of CuInS;! in order to analyze the contact resistance between the materials. In addition, I have also analyzed evaporated aluminum top contacts and have tested various methods of increasing their thicknesses in order to decrease series resistance. More recently I have worked with other members of the research group in reviving a vertical cold-wall reactor for experimentation with CuInS2 quantum dots. As part of that project, I have improved the design for a variable frequency and pulse width square wave generator to be used in driving the precursor injection process. My task throughout the remainder of my tenure is to continue to analyze and develop tools for the analysis of electrical properties of the CuInS2 cells with the ultimate goal of discovering ways to improve the efficiency of our photovoltaic cells. Traditionally, photovoltaic cells are based on a single crystal silicon absorber. While The research group lead by Dr. Hepp has spent several years researching copper indium

Kasick, Michael P.↗

NASA NTRS1994

Direct numerical simulations of on-demand vortex generators: Mathematical formulation

The objective of the present research is the development and application of efficient adaptive numerical algorithms for the study, via direct numerical simulations, of active vortex generators. We are using innovative computational schemes to investigate flows past complex configurations undergoing arbitrary motions. Some of the questions we try to answer are: Can and how may we control the dynamics of the wake? What is the importance of body shape and motion in the active control of the flow? What is the effect of three-dimensionality in laboratory experiments? We are interested not only in coupling our results to ongoing, related experimental work, but furthermore to develop an extensive database relating the above mechanisms to the vortical wake structures with the long-range objective of developing feedback control mechanisms. This technology is very important to aircraft, ship, automotive, and other industries that require predictive capability for fluid mechanical problems. The results would have an impact in high angle of attack aerodynamics and help design ways to improve the efficiency of ships and submarines (maneuverability, vortex induced vibration, and noise).

Koumoutsakos, Petros↗

NASA NTRS1990

New directions in InP solar cell research

Recent research efforts representing new directions in InP solar cell research are reviewed. These include heteroepitaxial growth on silicon and gallium arsenide substrates, V-grooved cells, large area high efficiency cells, and surface passivation. Improvements in heteroepitaxial cell efficiency are described together with processing of 19.1 percent, 4 sq cm cells. Recommendations are made for improvements in processing leading to increased efficiencies.

Weinberg, I.↗