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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 1,711 records · Page 95
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Method and system embodiments for converting ethanol to para-xylene and ortho-xylene

Disclosed herein are embodiments of a method and system for converting ethanol to para-xylene. The method also provides a pathway to produce terephthalic acid from biomass-based feedstocks. In some embodiments, the disclosed method produces p-xylene with high selectivity over other aromatics typically produced in the conversion of ethanol to xylenes, such as m-xylene, ethyl benzene, benzene, toluene, and the like. And, in some embodiments, the method facilitates the ability to use ortho/para mixtures of methylbenzyaldehyde for preparing ortho/para xylene product mixtures that are amendable to fractionation to separate the para- and ortho-xylene products thereby providing a pure feedstock of para-xylene that can be used to form terephthalic anhydride and a pure feedstock of ortho-xylene that can be used for other purposes, such as phthalic anhydride.

Ramasamy, Karthikeyan K.↗
DOE OSTI2022

Nonlinear hydrostatic control of a wave energy converter

Increased energy harvesting is realized using a nonlinear buoy geometry for reactive power generation. By exploiting the nonlinear dynamic coupling between the buoy geometry and the potential wideband frequency spectrum of incoming waves in the controller/buoy design, increased power can be captured in comparison to conventional wave energy converter designs. In particular, the reactive power and energy storage system requirements are inherently embedded in the nonlinear buoy geometry, therefore requiring only simple rate-feedback control.

Wilson, David G.↗
DOE OSTI2022

Process for converting alkanes to olefins

A process and apparatus for converting an alkane to an olefin. In one embodiment, the process involves oxidative coupling of an alkane, e.g., methane, with an oxidant, such as air, to produce an olefin having twice the number of carbon atoms as the alkane, e.g., ethylene. In another embodiment, the process involves oxidative dehydrogenation of an alkane, e.g., ethane, with an oxidant to form an olefin having the same number of carbon atoms as the alkane, e.g., ethylene. The process involves passing a flow of the oxidant from a first flow passage through a porous medium; diffusing a flow of the alkane from a second flow passage into the porous medium; and contacting the reactant alkane and the oxidant in the presence of a catalyst within the porous medium to produce the olefin.

Weissman, Jeffrey↗
DOE OSTI2022

Techno-Economic Implications of Electrical Machine Scaling for Wave Energy Converters: Preprint

The sizing of an electrical machine for a Wave Energy Converter (WEC) can have a substantial impact on the overall sizing, cost, and rating of the device. An electrical generator is typically part of the power take-off (PTO) system, which is the mechanism by which the energy absorbed by the prime mover is transformed into useable electrical. For practically all WECs, the rate of change of actuation is predominantly determined by the wave resource (i.e., the wave height and frequency) and devices will see a sinusoidally varying velocity according to the wave conditions. The same can then be said for both directly and indirectly coupled PTOs with electrical generators. This techno-economic study investigates electrical machine scaling and associated cost implications through core machine design theory, manufacturer data, supporting literature, and the DOE sponsored Reference Model Project (RMP). The RMP was a partnered effort to develop open-source marine energy (ME) point designs as reference models (RMs) to benchmark ME technology performance and costs, methods for design and analysis of ME technologies, estimations for capital costs, operational costs, and levelized costs of energy (LCOE). The results from this study show torque is directly related to (1) the physical size of the machine required to increase the airgap sheer stresses, (2) the amount of active material, (3) the support structure, (4) bearing size and rating, and (5) offshore cable rating, all of which have a significant effect on overall system costs in terms of both CAPEX and OPEX. This paper aims to be a critical benchmark in helping determine an “optimal” nameplate rating for wave energy devices and their associated PTO. With an optimized rating and sizing process, WEC costs can be reduced, and overall performance can be improved.

cables↗
DOE OSTI2022

Techno-Economic Implications of Electrical Machine Scaling for Wave Energy Converters

The sizing of an electrical machine for a Wave Energy Converter (WEC) can have a substantial impact on the overall sizing, cost, and rating of the device. An electrical generator is typically part of the power take-off (PTO) system, which is the mechanism by which the energy absorbed by the prime mover is transformed into useable electrical. For practically all WECs, the rate of change of actuation is predominantly determined by the wave resource (i.e., the wave height and frequency) and devices will see a sinusoidally varying velocity according to the wave conditions. The same can then be said for both directly and indirectly coupled PTOs with electrical generators. This techno-economic study investigates electrical machine scaling and associated cost implications through core machine design theory, manufacturer data, supporting literature, and the DOE sponsored Reference Model Project (RMP). The RMP was a partnered effort to develop open-source marine energy (ME) point designs as reference models (RMs) to benchmark ME technology performance and costs, methods for design and analysis of ME technologies, estimations for capital costs, operational costs, and levelized costs of energy (LCOE). The results from this study show torque is directly related to (1) the physical size of the machine required to increase the airgap sheer stresses, (2) the amount of active material, (3) the support structure, (4) bearing size and rating, and (5) offshore cable rating, all of which have a significant effect on overall system costs in terms of both CAPEX and OPEX. This paper aims to be a critical benchmark in helping determine an “optimal” nameplate rating for wave energy devices and their associated PTO. With an optimized rating and sizing process, WEC costs can be reduced, and overall performance can be improved.

cables↗
DOE OSTI2022

Progress on Machine Learning for the SNS High Voltage Converter Modulators

The High-Voltage Converter Modulators (HVCM) used to power the klystrons in the Spallation Neutron Source (SNS) linac were selected as one area to explore machine learning due to reliability issues in the past and the availability of large sets of archived waveforms. Progress in the past two years has resulted in generating a significant amount of simulated and measured data for training neural network models such as recurrent neural networks, convolutional neural networks, and variational autoencoders. Applications in anomaly detection, fault classification, and prognostics of capacitor degradation were pursued in collaboration with the Jefferson Laboratory, and early promising results were achieved. This paper will discuss the progress to date and present results from these efforts.

Pappas, Chris↗
DOE OSTI2022

Power supply circuit with multiple stages for converting high voltage to low voltage and power train having the same

A power supply circuit for converting a first voltage to a second voltage where the first voltage is greater than the second voltage, and a power train having the same, are provided. The power supply circuit may have multiple stages and each stage of the power supply circuit may include a first circuit block configured to provide a start-up power to a second circuit block; a second circuit block configured to generate a Pulse-Width-Modulation (PWM) signal that controls a pulse duration of a transistor; a third circuit block configured to activate or deactivate the transistor based on the PWM signal; a fourth circuit block configured to reset a magnetic flux in a transformer to a zero state when the transistor is deactivated; and a fifth circuit block configured to maintain an output of a stage below a predetermined value by adjusting a voltage across the transformer.

Singh, Brij N.↗
DOE OSTI2022

Three-phase differential mode converter

A system for charging a battery includes three sub-modules, each receiving a respective phase of a three-phase alternating current (AC) signal. The three sub-modules cooperate to transform the respective phases of the three-phase AC signal to a direct current (DC) signal by passing the respective phases of the three-phase AC signal through a respective semiconductor device configured to discontinuously modulate the respective phase of the three-phase AC signal to convert it to a DC signal provided to the battery to charge the battery.

Mazumder, Sudip K.↗
DOE OSTI2022

Wave energy converter buoy with variable geometry

A nonlinear control design technique capitalizes on a wave energy converter comprising a shaped buoy having a variable geometry wave energy. For example, the shaped buoy can have an hourglass (HG) geometry having a variable cone or steepness angle. The HG buoy is assumed to operate in the heave motion of the wave. The unique interaction between the HG buoy and the wave creates a nonlinear cubic storage effect that produces actual energy storage or reactive power during operation. A multi-frequency Bretschneider spectrum wave excitation input was simulated for the HG design both with constant and varying steepness angle profiles which demonstrated further increased power generation with changing sea states for the variable design.

Wilson, David G.↗
DOE OSTI2023

Low-cost connectors for inverters and converters and methods of manufacturing and using the same

In some embodiments, systems and methods for connector assembly for use with an AC or DC power interface of a power conversion device, such as a converter and an inverter, are provided. The connector assembly can include a circuit board, a power connector, and a pin. The power connector can have a base configured to be secured relative to the circuit board and define a first channel extending through the power connector along a first channel axis. The first pin can have a first pin body that extends along a first pin axis and a first connection element that extends along the first pin axis from the first pin body to a first terminal end that is skewed relative to the first pin axis.

Khaligh, Alireza↗
DOE OSTI2012

A high converter concept for fuel management with blanket fuel assemblies in boiling water reactors

Studies on the natural Uranium saving and waste reduction potential of a multiple-plant BWR system were performed. The BWR High Converter system should enable a multiple recycling of MOX fuel in current BWR plants by introducing blanket fuel assemblies and burning Uranium and MOX fuel separately. The feasibility of Uranium cores with blankets and full-MOX cores with Plutonium qualities as low as 40% were studied. The power concentration due to blanket insertion is manageable with modern fuel and acceptable values for the thermal limits and reactivity coefficients were obtained. While challenges remain, full-MOX cores also complied with the main design criteria. The combination of Uranium and Plutonium burners in appropriate proportions could enable obtaining as much as 40% more energy out of Uranium ore. Moreover, a proper adjustment of blanket average stay and Plutonium qualities could lead to a system with nearly no Plutonium left for final disposal. The achievement of such goals with current light water technology makes the BWR HC concept an attractive option to improve the fuel cycle until Gen-IV designs are mature. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Power packet networks for wave energy converter arrays

One of the biggest challenges for all renewable energy sources (RES) is that they are variable power generators which will require reactive power or energy storage systems (ESS) to provide reliable power quality (ideally power factor of one) at the power grid generation side. The present invention is directed to a power packet network (PPN) for integrating wave energy converter (WEC) arrays into microgrids. Specifically, an array of WECs can be physically positioned such that the incoming regular waves will produce an output emulating an N-phase AC system such that the PPN output power is constant. ESS requirements are thereby minimized whilst maintaining grid stability with high power quality. This will enable RES integration onto a future smart grid for large-scale adoption and cost reduction while preserving high efficiency, reliability, and resiliency.

Wilson, David G.↗
DOE OSTI2023

Control of matrix converters using machine learning

A method of controlling a matrix converter system is provided. The method includes receiving an operating condition and consulting a trained Q-data structure for reward values associated with respective switching states of the switching matrix for an operating state that corresponds to the operating condition. The Q-data structure is trained using Q-learning to map a reward value predicted for respective switching states to respective discrete operating states. The method further includes sorting the reward values predicted for the respective switching states mapped to the operating state that corresponds to the operating condition, selecting a subset of the set of the mappings as a function of a result of sorting the reward values associated with the switching states of the operating state, evaluating each switching state included in the subset, and selecting an optimal switching state for the operating condition based on a result of evaluating the switching states of the subset.

Chamie, Mahmoud El↗
DOE OSTI2023

Mooring structure for ocean wave energy converters

A mooring system for an Ocean Wave Energy Converters (OWEC) includes multiple structural members such as legs and braces that are linearly extendible and connected using mobile joints, each joint providing two degrees of freedom for rotations about the joint. Mobile joints also attach bottom ends of the legs to mooring points. A jacking system can change lengths of the extensible structural members to adjust depth of the OWEC for operation or for storm safety, to lift the OWEC out of the water for maintenance, or to align the OWEC to an incoming wave direction.

Siegel, Stefan G.↗
DOE OSTI2023

Method and system embodiments for converting ethanol to para-xylene and ortho-xylene

Disclosed herein are embodiments of a method and system for converting ethanol to para-xylene. The method also provides a pathway to produce terephthalic acid from biomass-based feedstocks. In some embodiments, the disclosed method produces p-xylene with high selectivity over other aromatics typically produced in the conversion of ethanol to xylenes, such as m-xylene, ethyl benzene, benzene, toluene, and the like. And, in some embodiments, the method facilitates the ability to use ortho/para mixtures of methylbenzyaldehyde for preparing ortho/para xylene product mixtures that are amendable to fractionation to separate the para- and ortho-xylene products thereby providing a pure feedstock of para-xylene that can be used to form terephthalic anhydride and a pure feedstock of ortho-xylene that can be used for other purposes, such as phthalic anhydride.

Ramasamy, Karthikeyan Kallupalayam↗
DOE OSTI2024

Parameter-Varying Hydrodynamic Model of a Single Vane in a Variable-Geometry Oscillating Surge Wave Energy Converter: Preprint

This paper presents a study on the time-varying hydrodynamic modeling of an individual flap of a variable geometry oscillating surge wave energy converter (VGOSWEC). The WEC design incorporates controlled surfaces that can modify their orientation relative to the wave motion, reducing hydrodynamic pressure and related loads. This research focuses on characterizing the behavior of the oscillating WEC using a simplified model and three methods for achieving a continuous time-variant model: discrete hydrodynamic parameters, interpolation of hydrodynamic parameters, and a fitting function. The results of this study contribute to the understanding of time-varying hydrodynamic effects in variable geometry oscillating WECs. The findings provide insights into the potential for reducing structural loads and improving the overall performance of such devices. Further research and development in this area could lead to advancements in WEC technologies, enabling their integration into the competitive energy market.

HYDRO ENERGY,TIDAL AND WAVE POWER↗
DOE OSTI2024

WEC-Sim Modeling of Laminar Scientific's Patented Seesaw Wave Energy Converter: Preprint

Laminar Scientific's patented seesaw wave energy converter was modeled in WEC-Sim to predict performance. The device operates by utilizing ocean surface waves to rotate a truss in pitch about a pivot. The pivot is located at the top of two pylons, which are embedded in the seafloor. The seesaw has a float on either end, and the buoyancy forces from each float cause the system to rise or fall with passing waves. Device performance relies upon seesaw length and ocean wavelength creating an antiphase effect. The seesaw truss has an adjustable length intended to achieve this effect. The operation method enforces a narrow band of wavelengths which induce the largest rotational motion from the device. The hydrodynamic analysis of the device was performed using Capytaine, and the results confirmed that the device operates best in a narrow frequency band. Four float-to-float spacing cases and three pylon radii were examined. The hydrodynamic results indicate a match between the model and the physical expectations for the device, and that varying the pylon radii by 0.1-m increments for three instances creates minimal changes in hydrodynamic properties. Power matrices for three float spacing cases of the device were simulated with Joint North Sea Wave Project spectra waves and optimal power take-off damping in WEC-Sim. The maximum average power production for the 15-m spacing case was 14.1 kW with a 5.0-s peak wave period and 4-m significant wave heights. Plots of capture-width ratios indicated that the device performance was linear and confirmed that the device is optimal in a narrow frequency band. The maximum percentage of the available wave power produced by the 15-m device was approximately 16%. Simulations of the device in regular waves were used to produce plots of average power compared to a ratio of float spacing to wavelength. These plots indicate that the power production is maximized at a ratio of 0.5, and further confirm that the device has a narrow frequency response. The device was simulated at an example field location, where the device produced an annual average power rating of 1.6 kW given an average omnidirectional wave climate of 10.3 kW m-1 and an optimal, linearized power take-off model. While the maximum predicted device performance is reliant upon a narrow band of wave frequencies, the conducted analysis provides an opportunity to improve device design prior to prototyping and testing. Modifying the design to respond to a broader frequency range would improve device performance.

numerical modeling↗