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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 937 records · Page 52

All sources NASA NTRS DOE OSTI

DOE OSTI2020

Component and efficient plate and frame absorber

An absorber for an absorption refrigeration system for a vertically mounted plate absorber has fins positioned over the plate to promote distribution of a fluid under flow as a nearly continuous thin film. The absorber has rows of fins that are evenly spaced with the fins occupying a portion of the active width of the plate with adjacent rows offset by the width of the plate. A combined evaporator-absorber module is constructed with the absorbing face of the absorber parallel with an evaporating surface of an evaporator where absorber solution and refrigerant fall as parallel falling sheets of liquid. The absorber is covered with a porous hydrophobic membrane to isolate the falling absorber solution from the falling liquid refrigerant.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2020

Electrostatic generator/motor electrodes located on the inner surface of an electromechanical battery rotor

A geometric design of E-S generator motor electrodes mounted on the inner surface of a fiber-composite rotor is provided. The electrode configuration is able to sustain very high g levels. The rotor may be funned of carbon-fiber wound on top of an inner E car S-glass fiber composite core. The electrode design provides the needed area to satisfy the power requirements of the storage system and utilizes a stacked wedge-like electrode array that both solves the high-g problem and results in a doubling or tripling of the electrode area, relative to that of electrodes that conform to the inner cylindrical surface of the rotor.

25 ENERGY STORAGE↗

DOE OSTI2020

Solar panel field array support system and apparatus and method for construction use

A combined PV panel assembly jig and forklift transport pallet is used to assemble PV panels for transport to a field array from a protected manufacturing environment. The panels are assembled to have adhesively applied rails for transport by a robotic drone on a ground-support rack and are pre-wired. The PV panel assembly jig holds, protects, and aligns the PV panels in an upside down position, opposite to their operational position, for ease of wiring in order to decrease the manual labor required in the field. Once the pallet is transported to the load station at the end of a row of solar panel racks in the field array, a robotic loader lifts the upside down PV panels from the combined PV panel assembly jig and forklift transport pallet in an arcing overhead motion that lifts, tilts, and deposits the PV panels in an upright position at the loading station of a railed rack support as ground-mounted in a solar panel field array.

14 SOLAR ENERGY↗

DOE OSTI2020

Analysis and Validation of Spectral Irradiance Simulations for 75 kW Bifacial Solar Test Field

This work investigates how the spectrum of irradiance incident on the rear of bifacial modules impacts their performance. Light incident on the rear of bifacial modules can be reflected from the ground, mounting structures, and other nearby objects, causing both the intensity and spectrum to be modified. As a result, PV cells and sensors with different spectral responses report different values for the rear irradiance, leading to increased uncertainty when modeling performance. Here, we calculate the spectral irradiance incident on the rear of modules through raytrace simulations and validate with measured field data collected from a 75kW single-axis-tracked bifacial test site. Spectral responses for different sensors and PV cells are applied and compared with field measurements for four days. Based on these results, a method for improving non-spectral simulations is proposed. In addition, a linear regression is applied to the modeled spectral results as a method to gain insight into the contributions of ground reflected light to total rear irradiance.

bifacial photovoltaics↗

DOE OSTI2020

Validation of a Generalized Formulation for Load-Sharing Behavior in Epicyclic Gears for Wind Turbines: Preprint

In an ideal epicyclic gear set every parallel gear path transmits the same amount of torque. However, it is well known that certain manufacturing variations result in unequal load sharing between the parallel gear paths. Previous works have developed and validated a general closed-form analytical model of this phenomenon that describes the load sharing characteristics of epicyclic gear sets from three to six planets at any torque level. More recently, this analytical model has been reformulated to include the effects of gravity, carrier bearing clearance, and external applied moments, all of which are relevant to most gearboxes and their mounting configuration in horizontal-axis wind turbines. In this paper, the reformulated model is compared to load measurements collected from two similar wind turbine gearboxes with three-planet epicyclic gear sets. The resulting load sharing values are also compared to the mesh load factor requirements in the AGMA 6006 and IEC 61400-4 wind turbine gearbox design standards. Load sharing factors as high as 1.16 at extreme rotor moments and 1.08 with no moment were measured for the gearbox with cylindrical roller bearings, but the load sharing factor remained below 1.10 for the gearbox with tapered roller bearings The results show that in the wind turbine application, load sharing is not equal - even for three-planet systems with a floating central member because of the effects of gravity, rotor moments, and the resulting relative motions among the epicyclic gear components within the carrier bearing clearance.

closed-form analytical model↗

DOE OSTI2020

Collaborative Exploration of Scientific Datasets Using Immersive and Statistical Visualization: Preprint

We discuss the value of collaborative, immersive visualization for the exploration of scientific datasets and review techniques and tools that have been developed and deployed at the National Renewable Energy Laboratory (NREL). We believe that collaborative visualizations linking statistical interfaces and graphics on laptops and high-performance computing (HPC) with 3D visualizations on immersive displays (head-mounted displays and large-scale immersive environments) enable scientific workflows that further rapid exploration of large, high-dimensional datasets by teams of analysts. We present a framework, PlottyVR, that blends statistical tools, general-purpose programming environments, and simulation with 3D visualizations. To contextualize this framework, we propose a categorization and loose taxonomy of collaborative visualization and analysis techniques. Finally, we describe how scientists and engineers have adopted this framework to investigate large, complex datasets.

collaborative visualization↗

DOE OSTI2020

Validation of a Generalized Formulation for Load Sharing Behavior in Epicyclic Gears for Wind Turbines

closed-form analytical model↗

DOE OSTI2020

The Future of Renewable Energy Generation: Photovoltaic Materials

There are myriad ways to harness solar energy, including, but not limited to: solar thermal, solar fuels, and photovoltaics (PV). Across the portfolio of solar energy technologies, PV is unique in that collected photons are directly converted to electricity. Traditionally, the dominant materials in PV are also the dominant semiconductor and optoelectronic materials. The cost of solar energy from PV is a product of a complex combination of non-material related factors, known as soft costs, e.g., permitting, zoning, and of balance-of-systems (BOS) costs, like inverters or other components needed to utilize cells and modules. While the soft costs are due to administrative/regulatory concerns, BOS costs are driven by details of cell/module fabrication, mounting, power electronics, and other concerns, which touch on a range of basic material science issues. There is some overlap of BOS and soft cost, as a lighter weight solar panel can reduce installations costs, as an example. At the PV-system level, the materials considerations span both electronic and structural components. The focus of this paper is the solar cell, which is the minimum operational unit device that converts light into electricity.

30 DIRECT ENERGY CONVERSION↗

DOE OSTI2020

Impact to Cooling Airflow from Truck Platooning: Preprint

We investigate tradeoffs between the airflow strategies related to engine cooling and the aerodynamic-enabled fuel savings created by platooning. By analyzing air temperatures, engine temperatures and cooling air flow at different platoon distances, we show the thermal impact to the engine from truck platooning. Previously, we collected wind and thermal data for numerous heavy-duty truck platoon configurations (gaps ranging from 4 to 87 meters) and reported the significant fuel savings enabled by these configurations. The fuel consumption for all trucks in the platoon were measured using the SAE J1321 gravimetric procedure as well as calibrated J1939 instantaneous fuel rate while travelling at 65 mph and loaded to a gross weight of 65,000 lb. Using thermocouples mounted 1 m ahead of each truck, anemometers at the grill and a grid of under-hood thermocouples as well as J1939 reported engine temperatures, we analyze the impact to critical operating temperatures from different platoon configurations. Results show significant changes in the engine and under-hood air temperatures that correlate with vehicle gap distance and platoon position.

47 OTHER INSTRUMENTATION↗

DOE OSTI2020

PWR decay heat removal system in which steam from the pressurizer drives a turbine which drives a pump to inject water into the reactor pressure vessel

In conjunction with a pressurized water reactor (PWR) and a pressurizer configured to control pressure in the reactor pressure vessel, a decay heat removal system comprises a pressurized passive condenser, a turbine-driven pump connected to suction water from at least one water source into the reactor pressure vessel; and steam piping configured to deliver steam from the pressurizer to the turbine to operate the pump and to discharge the delivered steam into the pressurized passive condenser. The pump and turbine may be mounted on a common shaft via which the turbine drives the pump. The at least one water source may include a refueling water storage tank (RWST) and/or the pressurized passive condenser. A pressurizer power operated relief valve may control discharge of a portion of the delivered steam bypassing the turbine into the pressurized passive condenser to control pressure in the pressurizer.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2020

Radiant boiler for pressurized oxy-combustion and method of radiant trapping to control heat flux in high temperature particle-laden flows at elevated pressure

A boiler has a shell surrounding a vertical centerline. The shell defines an inner surface having an inner diameter and an inner length extending between an upper upstream end and a lower downstream end. The inner surface defines a hollow interior, the boiler having a pre-combustion zone, a combustion zone downstream from the pre-combustion zone, and a post-combustion zone downstream from the combustion zone. The shell is tapered outward along its length in at least a portion of the combustion zone. An oxidizer inlet is in fluid communication with the pre-combustion zone, and a fuel nozzle introduces fuel into the combustion zone. A tube assembly is mounted in the hollow interior of the shell for transferring heat to fluid flowing through the tube assembly. A flue duct is in fluid communication with the post-combustion zone for transporting flue gases from the hollow interior.

20 FOSSIL-FUELED POWER PLANTS↗

DOE OSTI2020

Large-Scale Solar Development: A Playbook for Southwest Virginia

his playbook is an introductory guide for local governments to facilitate large-scale solar projects in Southwest Virginia. In a region that has a long history of energy production, solar technologies offer enormous potential for economic development and job growth. Large-scale solar can take many forms, including rooftop or ground-mounted installations at local corporate offices, nonprofit organizations, or schools. It can also encompass utility-scale projects over many acres on former agricultural or timberlands, mined lands, or industrial sites. Regardless of the type of project, solar is a widely popular, cost-competitive energy choice that helps create sustainable and prosperous communities. This playbook is directed to municipal and county governments that have an essential role to play in encouraging large-scale solar projects. The first section provides an overview of state and national trends, including recent state legislation that will impact local oversight of solar development. This is followed by an overview of the solar project approval process from a developer’s perspective. The next section is an overview of the state and local permitting process for solar projects, followed by other development considerations such as local tax revenue options, financing incentives, and considerations for solar on brownfields and previously mined lands. The playbook concludes with a step-by-step guide for local governments to facilitate large-scale solar development.This playbook is part of the Solar Workgroup of Southwest Virginia’s effort to bring solar energy and associated jobs to the region. Over the past few years, the workgroup has met with stakeholder groups and crafted a strategy for local solar energy development. The workgroup has collaborated with cities and counties to bring SolSmart designation to eight counties and cities, implemented group purchase campaigns for commercial solar, and led research efforts.

14 SOLAR ENERGY↗

DOE OSTI2021

Advanced Zonal Infiltration Measurement Method for Multifamily Buildings: A Novel Test Procedure to Determine Air Leakage Through External and Internal Surfaces

Measuring air infiltration through the external building envelope as well as between adjacent zones within a building is important since air leakage is related to increased energy use and poor indoor air quality (IAQ). State of the art methods can determine both leakages, however it can be both time consuming and labor intensive as it requires running both guarded and compartmentalization tests. This paper presents our work on developing a simplified testing procedure to determine power law flow equation leakage parameters of both external and internal boundaries of tested zones. The proposed Zonal Multipoint Pressure Test (ZMPT) method modulates airflow in the zone using a variable airflow measurement panel (mounted in either a window or the door), and solving the mass balance equations for the leakage parameters. ZMPT results were compared to conventional test results and found to correlate to within +/-7%.

Jayarathne, Tharanga↗

DOE OSTI2021

An analysis of gamma-ray data collected at traffic intersections in Northern Virginia

Gamma-ray spectral data were collected from sensors mounted to traffic signals around Northern Virginia. The data were collected over a span of approximately fifteen months. A subset of the data were analyzed manually and subsequently used to train machine-learning models to facilitate the evaluation of the remaining 50k anomalous events identified in the dataset. We describe the analysis approach used here and discuss the results in terms of radioisotope classes and frequency patterns over day-of-week and time-of-day spans. Data from this work has been archived and is available for future and ongoing research applications.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2020

Targets and processes for fabricating same

In one embodiment, the present disclosure provides a target or mold having one or more support arms coupled to a substrate. The support arm can be used in handling or positioning a target. In another embodiment, the present disclosure provides target molds, targets produced using such molds, and a method for producing the targets and molds. In various implementations, the targets are formed in a number of disclosed shapes, including a funnel cone, a funnel cone having an extended neck, those having Gaussian-profile, a cup, a target having embedded metal slugs, metal dotted foils, wedges, metal stacks, a Winston collector having a hemispherical apex, and a Winston collector having an apex aperture. In yet another embodiment, the present disclosure provides a target mounting and alignment system.

Malekos, Steven↗

DOE OSTI2020

Lighting fixture

A lighting fixture can comprise a substantially flat sheet of metal supporting a circuit that comprises one or more light emitting diodes with one or more associated optics for manipulating emitted light. The circuit can be attached to, mounted next to, or integrated with the sheet of metal. In some examples, a layer of dielectric material adheres to the sheet of metal, and circuit elements adhere to the layer of dielectric material. Such circuit elements may comprise electrical traces, light emitting diodes, and/or a light emitting diode driver. The sheet of metal can provide a substrate for the circuit or a support for a freestanding circuit board that may be rigid or flexible.

Nimma, Sridhar Reddy↗

DOE OSTI2020

Dual linear delta assemblies, linear delta systems, and related methods

A dual linear delta assembly includes a frame, a first linear delta system, and a second linear delta system concentric with the first linear delta system. Each of the first linear delta system and the second linear delta system may include rails mounted to the frame, linear actuators, each linear actuator coupled to a respective rail of the rails and configured to translate along a longitudinal length of the respective rail, pairs of parallel rods each operably coupled to a respective linear actuator of the linear actuators, and a platform coupled to a longitudinal end of each of the pairs of parallel rods opposite the respective linear actuator of the linear actuators.

Crawford, Anthony L.↗

DOE OSTI2020

Evaluation of radiation hardness of semiconductor materials against alpha particles for an API detector

An Associated Particle Imaging (API) system consists of a high vacuum chamber where deuterium ions are accelerated on a tritium-loaded target, resulting in alpha particles and neutrons emitted back-to-back, the latter escaping the chamber and used, for example, for tomography of a high-Z sample. An accurate determination of the alpha position is crucial to determine the trajectory of the neutron. Existing API systems have several limitations which a semiconductor-based API detector placed inside the vacuum chamber should not present. The semiconductor material can be either silicon or diamond. In particular, large and fast signals are generated by the alpha interactions in these materials. A pixelated API detector will measure the time and hit position of the alphas produced in the reaction. However, during the lifetime of the generator, the semiconductor detector will be exposed to an intense flux of alpha particles that will degrade its performance over time. To assess the radiation hardness of silicon and diamond against the alpha particles, we exposed single diodes made of either of the two materials to a 5 MeV alpha flux generated by an 241Am radioactive source. During irradiation, the diodes were biased and mounted on current-sensitive preamplifier boards. We have therefore been able to measure insitu the evolution of the waveforms as the damage was accumulating in their substrates.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗