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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Pressure Regulator With Internal Ejector Circulation Pump, Flow and Pressure Measurement Porting, and Fuel Cell System Integration Options

An advanced reactant pressure regulator with an internal ejector reactant circulation pump has been developed to support NASA's future fuel cell power systems needs. These needs include reliable and safe operation in variable-gravity environments, and for exploration activities with both manned and un manned vehicles. This product was developed for use in Proton Exchange Membrane Fuel Cell (PEMFC) power plant reactant circulation systems, but the design could also be applied to other fuel cell system types, (e.g., solid-oxide or alkaline) or for other gas pressure regulation and circulation needs. The regulator design includes porting for measurement of flow and pressure at key points in the system, and also includes several fuel cell system integration options. NASA has recognized ejectors as a viable alternative to mechanical pumps for use in spacecraft fuel cell power systems. The ejector motive force is provided by a variable, high-pressure supply gas that travels through the ejector s jet nozzle, whereby the pressure energy of the fluid stream is converted to kinetic energy in the gas jet. The ejector can produce circulation-to-consumption-flow ratios that are relatively high (2-3 times), and this phenomenon can potentially (with proper consideration of the remainder of the fuel cell system s design) be used to provide completely for reactant pre-humidification and product water removal in a fuel cell system. Specifically, a custom pressure regulator has been developed that includes: (1) an ejector reactant circulation pump (with interchangeable jet nozzles and mixer sections, gas-tight sliding and static seals in required locations, and internal fluid porting for pressure-sensing at the regulator's control elements) and (2) internal fluid porting to allow for flow rate and system pressure measurements. The fluid porting also allows for inclusion of purge, relief, and vacuum-breaker check valves on the regulator assembly. In addition, this regulator could also be used with NASA's advanced nonflow-through fuel cell power systems by simply incorporating a jet nozzle with an appropriate nozzle diameter.

Vasquez, Arturo↗
DOE OSTI2022

EstG is a novel esterase required for cell envelope integrity in Caulobacter

Proper regulation of the bacterial cell envelope is critical for cell survival. Identification and characterization of enzymes that maintain cell envelope homeostasis is crucial, as they can be targets for effective antibiotics. In this study, we have identified a novel enzyme, called EstG, whose activity protects cells from a variety of lethal assaults in the α-proteobacterium Caulobacter crescentus. Despite homology to transpeptidase family cell wall enzymes and an ability to protect against cell-wall-targeting antibiotics, EstG does not demonstrate biochemical activity toward cell wall substrates. Instead, EstG is genetically connected to the periplasmic enzymes OpgH and BglX, responsible for synthesis and hydrolysis of osmoregulated periplasmic glucans (OPGs), respectively. The crystal structure of EstG revealed similarities to esterases and transesterases, and we demonstrated esterase activity of EstG in vitro. Using biochemical fractionation, we identified a cyclic hexamer of glucose as a likely substrate of EstG. Further, this molecule is the first OPG described in Caulobacter and establishes a novel class of OPGs, the regulation and modification of which are important for stress survival and adaptation to fluctuating environments. Our data indicate that EstG, BglX, and OpgH comprise a previously unknown OPG pathway in Caulobacter. Ultimately, we propose that EstG is a novel enzyme that instead of acting on the cell wall, acts on cyclic OPGs to provide resistance to a variety of cellular stresses.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2005

Integrated circuit cell library

According to the invention, an ASIC cell library for use in creation of custom integrated circuits is disclosed. The ASIC cell library includes some first cells and some second cells. Each of the second cells includes two or more kernel cells. The ASIC cell library is at least 5% comprised of second cells. In various embodiments, the ASIC cell library could be 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more comprised of second cells.

Whitaker, Sterling R.↗
NASA NTRS1988

Regenerative fuel cell energy storage system for a low earth orbit space station

A study was conducted to define characteristics of a Regenerative Fuel Cell System (RFCS) for low earth orbit Space Station missions. The RFCS's were defined and characterized based on both an alkaline electrolyte fuel cell integrated with an alkaline electrolyte water electrolyzer and an alkaline electrolyte fuel cell integrated with an acid solid polymer electrolyte (SPE) water electrolyzer. The study defined the operating characteristics of the systems including system weight, volume, and efficiency. A maintenance philosophy was defined and the implications of system reliability requirements and modularization were determined. Finally, an Engineering Model System was defined and a program to develop and demonstrate the EMS and pacing technology items that should be developed in parallel with the EMS were identified. The specific weight of an optimized RFCS operating at 140 F was defined as a function of system efficiency for a range of module sizes. An EMS operating at a nominal temperature of 180 F and capable of delivery of 10 kW at an overall efficiency of 55.4 percent is described. A program to develop the EMS is described including a technology development effort for pacing technology items.

Martin, R. E.↗
DOE OSTI2020

Emergent Degradation Phenomena Demonstrated on Resilient, Flexible, and Scalable Integrated Photoelectrochemical Cells

Photoelectrochemical (PEC) water splitting provides a pathway to generate sustainable clean fuels using the two most abundant resources on Earth: sunlight and water. Currently, most of the successful models of PEC cells are still fabricated on small scales near 1 cm 2 , which largely limits the mass deployment of solar-fuel production. Here, the scale-up to 8 cm 2 of an integrated PEC (IPEC) device is demonstrated and its performance compared to a 1 cm 2 IPEC cell, using state-of-the-art iridium and platinum catalysts with III–V photoabsorbers. The initial photocurrents at 1 sun are 8 and 7 mA cm -2 with degradation rates of 0.60 and 0.47 mA cm -2 day -1 , during unbiased operation for the 1 and 8 cm 2 devices, respectively. Additionally, evaluating under outdoor and indoor conditions at two U.S. National Laboratories reveals similar results, evidencing the reproducibility of this design's performance. Furthermore, the emerging degradation mechanisms during scale-up are investigated and the knowledge gained from this work will provide feedback to the broader community, since PEC device durability is a limiting factor in its potential future deployment.

25 ENERGY STORAGE↗
NASA NTRS1981

Fabrication of multijunction high voltage concentrator solar cells by integrated circuit technology

Standard integrated circuit technology has been developed for the design and fabrication of planar multijunction (PMJ) solar cell chips. Each 1 cm x 1 cm solar chip consisted of six n(+)/p, back contacted, internally series interconnected unit cells. These high open circuit voltage solar cells were fabricated on 2 ohm-cm, p-type 75 microns thick, silicon substrates. A five photomask level process employing contact photolithography was used to pattern for boron diffusions, phorphorus diffusions, and contact metallization. Fabricated devices demonstrated an open circuit voltage of 3.6 volts and a short circuit current of 90 mA at 80 AMl suns. An equivalent circuit model of the planar multi-junction solar cell was developed.

Valco, G. J.↗
DOE OSTI2022

Design and characterization of “flow-cell” integrated-flow active cooling for high-average-power ceramic optics

We used COMSOL Multiphysics to design a prototype actively cooled “flow-cell” substrate targeted at high-average-power applications, fabricated the prototype from cordierite ceramic, and tested the substrate under load in our thermal loading test stand. Sub-aperture testing revealed average-power handling up to 3.88-W/cm 2 absorbed power density, in excellent agreement with model predictions. Gratings fabricated on 2-in.-diam cordierite coupons were subjected to laser-damage testing and showed a damage threshold of 250 mJ/cm 2 .

47 OTHER INSTRUMENTATION↗
NASA NTRS2006

Fuel Cell Airframe Integration Study for Short-Range Aircraft: Aircraft Propulsion and Subsystems Integration Evaluation - Volume 1

The objective of this study is to define the functionality and evaluate the propulsion and power system benefits derived from a Solid Oxide Fuel Cell (SOFC) based Auxiliary Power Unit (APU) for a future short range commercial aircraft, and to define the technology gaps to enable such a system. United Technologies Corporation (UTC) Integrated Total Aircraft Power System (ITAPS) methodologies were used to evaluate a baseline aircraft and several SOFC architectures. The technology benefits were captured as reductions of the mission fuel burn, life cycle cost, noise and emissions. As a result of the study, it was recognized that system integration is critical to maximize benefits from the SOFC APU for aircraft application. The mission fuel burn savings for the two SOFC architectures ranged from 4.7 percent for a system with high integration to 6.7 percent for a highly integrated system with certain technological risks. The SOFC APU itself produced zero emissions. The reduction in engine fuel burn achieved with the SOFC systems also resulted in reduced emissions from the engines for both ground operations and in flight. The noise level of the baseline APU with a silencer is 78 dBA, while the SOFC APU produced a lower noise level. It is concluded that a high specific power SOFC system is needed to achieve the benefits identified in this study. Additional areas requiring further development are the processing of the fuel to remove sulfur, either on board or on the ground, and extending the heat sink capability of the fuel to allow greater waste heat recovery, resolve the transient electrical system integration issues, and identification of the impact of the location of the SOFC and its size on the aircraft.

Gummalla, Mallika↗
DOE OSTI2021

Boosting photovoltaic performance of ternary organic solar cells by integrating a multi-functional guest acceptor

Constructing ternary structure is one of the most effective design strategies to break the efficiency ceiling of traditional binary organic solar cells (OSCs). Here, a new Y-series non-fullerene acceptor (Y-T) featuring 1,3-diethyl-2-thiobarbituric acid (DTBA) end groups is developed as a third component for the classical PM6:Y6 binary system. The champion power conversion efficiency of ternary OSCs is increased from 15.64% to 17.37% via incorporating 10 wt% Y-T, with the simultaneously enhanced open-circuit voltage (Voc) of 0.865 V, a short-circuit current density (Jsc) of 26.90 mA/cm 2 , and a fill factor (FF) of 74.97%. The positive contribution of Y-T in the ternary blend can be ascribed to the improved spectroscopic complementarity and enhanced exciton utilization ratio due to the additional energy transfer process. Moreover, Y-T guest acceptor plays a critical role in adjusting the active layer morphology and facilitating three-dimension phase separation, resulting in a balanced charge transport and enhanced FF of ternary OSCs. Overall, this work provides insight into the molecular design of non-fullerene acceptor and suggest guidelines to rationally select guest component for ternary OSCs.

14 SOLAR ENERGY↗
DOE OSTI2020

Water Splitting: Emergent Degradation Phenomena Demonstrated on Resilient, Flexible, and Scalable Integrated Photoelectrochemical Cells (Adv. Energy Mater. 48/2020)

We report Photoelectrochemical (PEC) water splitting provides a pathway to generate sustainable clean fuels using the two most abundant resources on Earth: sunlight and water. Currently, most of the successful models of PEC cells are still fabricated on small scales near 1 cm 2 , which largely limits the mass deployment of solar-fuel production. Here, the scale-up to 8 cm 2 of an integrated PEC (IPEC) device is demonstrated and its performance compared to a 1 cm 2 IPEC cell, using state-of-the-art iridium and platinum catalysts with III-V photoabsorbers. The initial photocurrents at 1 sun were 8 and 7 mA cm -2 with degradation rates of 0.60 and 0.47 mA cm -2 day -1 , during unbiased operation for the 1 and 8 cm 2 devices, respectively. Evaluating under outdoor and indoor conditions at two US National Laboratories revealed similar results, evidencing the reproducibility of this design’s performance. Furthermore, the emerging degradation mechanisms during scale-up are investigated and the knowledge gained from this work will provide feedback to the broader community, since PEC device durability is a limiting factor in its potential future deployment.

25 ENERGY STORAGE↗
NASA NTRS1978

Solar cells having integral collector grids

A heterojunction or Schottky barrier photovoltaic device is described, comprising a conductive base metal layer. A back surface field region was formed at the interface between the device and the base metal layer, a transparent, conductive mixed metal oxide layer in integral contact with the n-type layer of the heterojunction or Schottky barrier device. A metal alloy grid network was included. An insulating layer prevented electrical contact between the conductive metal base layer and the transparent, conductive metal oxide layer.

Evans, J. C., Jr.↗
NASA NTRS1979

Method for fabricating solar cells having integrated collector grids

A heterojunction or Schottky barrier photovoltaic device comprising a conductive base metal layer compatible with and coating predominately the exposed surface of the p-type substrate of the device such that a back surface field region is formed at the interface between the device and the base metal layer, a transparent, conductive mixed metal oxide layer in integral contact with the n-type layer of the heterojunction or Schottky barrier device having a metal alloy grid network of the same metal elements of the oxide constituents of the mixed metal oxide layer embedded in the mixed metal oxide layer, an insulating layer which prevents electrical contact between the conductive metal base layer and the transparent, conductive metal oxide layer, and a metal contact means covering the insulating layer and in intimate contact with the metal grid network embedded in the transparent, conductive oxide layer for conducting electrons generated by the photovoltaic process from the device.

Evans, J. C., Jr.↗
DOE OSTI2024

Gas turbine combustion section having an integrated fuel cell assembly

A combustion section defines an axial direction, a radial direction, and a circumferential direction. The combustion section includes a casing that defines a diffusion chamber. A combustion liner is disposed within the diffusion chamber and defines a combustion chamber. The combustion liner is spaced apart from the casing such that a passageway is defined between the combustion liner and the casing. A fuel cell assembly is disposed in the passageway. The fuel cell assembly includes a fuel cell stack having a plurality of fuel cells each extending between an inlet end and an outlet end. Each fuel cell of the plurality of fuel cells includes an air channel and a fuel channel each fluidly coupled to the combustion chamber.

Hong, Seung-Hyuck↗
NASA NTRS1986

Thermally-Integrated Fuel-Cell/Electrolyzer Systems

New and more efficient method of thermally integrating fuel cell and electrolyzer designed. Design addresses thermal integration of fuel cell and water electrolyzer in regenerative fuel-cell system. System configuration provides thermal integration with single coolant loop. Configuration does not have thermal limitations associated with trying to transfer heat between two coolant loops. Design less complex and more reliable than prior designs. Adaptable to standalone power systems in conjunction with solar panels for remote-area applications.

Garow, J.↗
DOE OSTI2024

Differential roles of kinetic on- and off-rates in T-cell receptor signal integration revealed with a modified Fab’-DNA ligand

Antibody-derived T-cell receptor (TCR) agonists are commonly used to activate T cells. While antibodies can trigger TCRs regardless of clonotype, they bypass native T cell signal integration mechanisms that rely on monovalent, membrane-associated, and relatively weakly binding ligand in the context of cellular adhesion. Commonly used antibodies and their derivatives bind much more strongly than native peptide major histocompatibility complex (pMHC) ligands bind their cognate TCRs. Because ligand dwell time is a critical parameter that tightly correlates with physiological function of the TCR signaling system, there is a general need, both in research and therapeutics, for universal TCR ligands with controlled kinetic binding parameters. To this end, we have introduced point mutations into recombinantly expressed α-TCRβ H57 Fab to modulate the dwell time of monovalent Fab binding to TCR. When tethered to a supported lipid bilayer via DNA complementation, these monovalent Fab’-DNA ligands activate T cells with potencies well-correlated with their TCR binding dwell time. Single-molecule tracking studies in live T cells reveal that individual binding events between Fab'-DNA ligands and TCRs elicit local signaling responses closely resembling native pMHC. The unique combination of high on- and off-rates of the H57 R97L mutant enables direct observations of cooperative interplay between ligand binding and TCR-proximal condensation of the linker for activation of T cells, which is not readily visualized with pMHC. This work provides insights into how T cells integrate kinetic information from TCR ligands and introduces a method to develop affinity panels for polyclonal T cells, such as cells from a human patient.

Science & Technology - Other Topics↗