Brayton-Cycle Turbomachinery Rolling-Element Bearings
Performance evaluation of oil lubrication system for antifriction bearing rotor system of Brayton cycle turbomachinery
Cohen, R.↗
SEARCH · Engineering Papers
Results for “Cycle Performance”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Mach 4 Test Results of a Dual-Flowpath, Turbine Based Combined Cycle Inlet
An experimental study was conducted to evaluate the performance of a turbine based combined cycle (TBCC) inlet concept, consisting of a low speed turbojet inlet and high speed dual-mode scramjet inlet. The main objectives of the study were (1) to identify any interactions between the low and the high speed inlets during the mode transition phase in which both inlets are operating simultaneously and (2) to determine the effect of the low speed inlet operation on the performance of the high speed inlet. Tests were conducted at a nominal freestream Mach number of 4 using an 8 percent scale model representing a single module of a TBCC inlet. A flat plate was installed upstream of the model to produce a turbulent boundary layer which simulated the full-scale vehicle forebody boundary layer. A flowmeter/back pressure device, with remote actuation, was attached aft of the high speed inlet isolator to simulate the back pressure resulting from dual-mode scramjet combustion. Results indicate that the inlets did not interact with each other sufficiently to affect inlet operability. Flow spillage resulting from a high speed inlet unstart did not propagate far enough upstream to affect the low speed inlet. Also, a low speed inlet unstart did not cause the high speed inlet to unstart. The low speed inlet improved the performance of the high speed inlet at certain conditions by diverting a portion of the boundary layer generated on the forebody plate.
Albertson, Cindy w.↗
Vanadium Oxide Pillared by Interlayer Mg 2+ Ions and Water as Ultralong-Life Cathodes for Magnesium-Ion Batteries
Magnesium-ion batteries (MIBs) show great potential for large-scale energy storage because of the advantages of low cost and safety, but their application is severely hindered by the difficulty in finding desirable electrode materials. In this work, we develop a bilayer-structured vanadium oxide (Mg 0.3 V 2 O 5 ·1.1H 2 O) with synergistic effect of Mg 2+ ions and lattice water as the cathode material for MIBs. The pre-intercalated Mg 2+ ions provide high electronic conductivity and excellent structural stability. The lattice water enables fast Mg 2+ ions mobility because of its charge shielding effect. As a result, the Mg 0.3 V 2 O 5 ·1.1H 2 O exhibits excellent rate performance and an unprecedented cycling life with capacity retention of 80.0% after 10,000 cycles. Furthermore, the Mg 0.3 V 2 O 5 ·1.1H 2 O exhibits good electrochemical performance in full MIBs. This scalable Mg 2+ host material is an enticing candidate as a cathode for MIBs, and its high performance is expected to meet the requirements for large-scale storage applications.
25 ENERGY STORAGE↗
Performance study of the cross-flow Maisotsenko cycle in humid climate conditions
This paper presents a first numerical analysis of the cross-flow Maisotsenko cycle (M-Cycle) below dew-point evaporative cooler for humid climates with model including the water vapor condensation phenomenon. Proposed solution allows to cool ambient air below its dew-point temperature, by utilizing cooling energy in air extracted from the building, due to that it can be used as effective pre-cooling solution for traditional systems. Proposed unit has significant advantage over traditional counter and cross-flow units operating in heat recovery mode, hence it is almost insensitive on temperature of exhaust air. This is caused by effective pre-cooling of the exhaust air in its initial part. Operation in humid climates using cold extracted air results in condensation occurrence in the primary air channels, and hence partial dehumidification of the primary airflow (which allows to cool the air before its dew- point temperature). The Maisotsenko cycle exchanger used to recover heat in the air-conditioning system is compared with Maisotsenko exchanger that operates only on the ambient airflow and does not allow to recover heat from the exhaust airflow from a conditioned space. Achieved results showed that M-Cycle below dew-point air cooler can operate more effectively in humid climates than traditional cross-flow Maisotsenko cycle exchanger.
Condensation↗
Thermodynamic performance assessment and comparison of IGCC with solid cycling process for CO2 capture at high and medium temperatures
Explore the source record for details and available documents.
CO2 capture↗
Tuning the Morphology and Electronic Properties of Single-Crystal LiNi 0.5 Mn 1.5 O 4-δ : Exploring the Influence of LiCl–KCl Molten Salt Flux Composition and Synthesis Temperature
Single-crystal materials have played a unique role in the development of high-performance cathode materials for Li batteries due to their favorable chemomechanical stability. The molten salt synthesis method has become one of the most prominent techniques used to synthesize single-crystal layered and spinel materials. In this work, the molten salt synthesis method is used as a technique to tune both the morphology and Mn 3+ content of high-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) cathodes. The resulting materials are thoroughly characterized by a suite of analytical techniques, including synchrotron X-ray core-level spectroscopy, which are sensitive to the material properties on multiple length scales. Furthermore, the multidimensional characterization allows us to build a materials library according to the molten salt phase diagram as well as to establish the relationship among synthesis, material properties, and battery performance. The results of this work show that the Mn 3+ content is primarily dependent on the synthesis temperature and increases as the temperature is increased. Additionally, the particle morphology is mostly dependent on the composition of the molten salt flux, which can be tailored to obtain well-defined octahedrons enclosed by (111) facets, plates with predominant ($11\tilde{2}$) facets, irregularly shaped particles, or mixtures of these. The electrochemical measurements indicate that the Mn 3+ content has a larger contribution to the battery performance of LNMO than do morphological characteristics and that a significant amount of Mn 3+ could become detrimental to the battery performance. However, with similar Mn 3+ contents, morphology still plays a role in influencing the battery cycle life and rate performance. The insights of molten salt synthesis parameters on the formation of LNMO, with deconvolution of the roles of Mn 3+ and morphology, are crucial to continuing studies in the rational design of LNMO cathode materials for high-energy Li batteries.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Elucidating Sodium-Sulfur Battery Chemistry using Operando Transmission X-ray Microscopy and X-ray Absorption Spectroscopy
Room-temperature sodium-sulfur (Na-S) batteries offer a beneficial and cost-effective solution for powering modern electric grids and devices. However, Na-S batteries suffer from performance decay during battery cycling due to the sluggish kinetics and polysulfide shuttling. Revealing the conversion mechanism of the Na-S chemistry is critical to designing high-capacity and stable Na-S batteries. In this study, we employed operando X-ray microscopy and operando X-ray absorption spectroscopy to elucidate the sulfur conversion in a carbon host using an ether-based electrolyte. We reveal the structural and chemical evolution of the sulfur cathode during cycling, which results in volume expansion and the dissolution of active material, ultimately affecting the battery performance. Our work provides fundamental insight into the sulfur reaction scheme, addressing the lingering challenges before establishing inexpensive Na-S batteries for broad applications, including portable electronics and large-scale energy storage.
Jagadeesan, Sathya Narayanan [SLAC National Accele↗
Parametric thermodynamic analysis of closed-cycle gas-laser operation in space
Cycle efficiency and radiator area required were calculated for thermally and electrically pumped lasers operating in closed cycles with a compressor and the required heat exchangers. A thermally pumped laser included within a Brayton cycle was also analyzed. Performance of all components, including the laser, was parametrically varied. For the thermally pumped laser the cycle efficiencies range below 10 percent and are very sensitive to the high-pressure losses associated with the supersonic diffuser required at the laser cavity exit. The efficiencies predicted for the electrically pumped laser cycles range slightly higher, but radiator area also tends to be larger.
Burns, R. K.↗
Europa Environmental Testing of Thermal Hardware for the Mapping Imaging Spectrometer for Europa (MISE) Instrument
The Europa Clipper spacecraft, scheduled for launch in June 2022, hosts a suite of instruments including the Mapping Imaging Spectrometer for Europa (MISE). MISE is a high-optical through-put pushbroom infrared imaging spectrometer that can collect measurements within Europa’s challenging radiation environment. It is externally mounted to the spacecraft and as a result is exposed to high radiation levels and cold temperatures. The instrument consists of a scan mirror assembly, an optical bench including a Dyson spectrometer and a telescope, and a structure that supports a cryocooler and a radiator. The cryocooler is used to actively cool the focal plane array and the spectrometer. The heat from the cryocooler is rejected through pyrolytic graphite sheet thermal straps to a honeycomb radiator. MISE will implement thermal hardware that will either not be used on other parts of the spacecraft or have a more extreme environment than the spacecraft. As a result, the MISE instrument performed numerous environmental tests on its thermal hardware. This paper discusses the results of the thermal cycling and radiation tests performed on the MISE thermal hardware including a Lockheed Martin Micro1-2 cryocooler, Pyrolytic graphite sheet thermal straps, Annealed pyrolytic graphite K-Core, Rosemount Platinum Resistance Thermometers, Tayco Kapton Thermofoil heaters, Dale Ohm resistors, and aluminum honeycomb and facesheets.
Strong, Patrick↗
T91 Boiler Tube Oxidation Performance and Oxide Spallation in Supercritical Steam Thermal Cycling Conditions
For presentation at the MS&T 23 Technical Meeting and Exhibition, Columbus, OH, October 1-4, 2023.
Carney, Casey↗
Analysis of a Rocket Based Combined Cycle Engine during Rocket Only Operation
The all rocket mode of operation is a critical factor in the overall performance of a rocket based combined cycle (RBCC) vehicle. However, outside of performing experiments or a full three dimensional analysis, there are no first order parametric models to estimate performance. As a result, an axisymmetric RBCC engine was used to analytically determine specific impulse efficiency values based upon both full flow and gas generator configurations. Design of experiments methodology was used to construct a test matrix and statistical regression analysis was used to build parametric models. The main parameters investigated in this study were: rocket chamber pressure, rocket exit area ratio, percent of injected secondary flow, mixer-ejector inlet area, mixer-ejector area ratio, and mixer-ejector length-to-inject diameter ratio. A perfect gas computational fluid dynamics analysis was performed to obtain values of vacuum specific impulse. Statistical regression analysis was performed based on both full flow and gas generator engine cycles. Results were also found to be dependent upon the entire cycle assumptions. The statistical regression analysis determined that there were five significant linear effects, six interactions, and one second-order effect. Two parametric models were created to provide performance assessments of an RBCC engine in the all rocket mode of operation.
Smith, T. D.↗
Program Computes Performances Of Scramjets
SRGULL, a scramjet-cycle-analysis computer code, engineer's software tool capable of nose-to-tail simulation of hydrogen-fueled, scramjet engine integrated with air-frame. Simulated flow that of real gas with equilibrium thermodynamic properties. Program facilities initial estimates of performance of scramjet cycle by linking code for two-dimensional forebody, inlet, and nozzle with code for one-dimensional combustor. Five computer codes (SCRAM, SEAGUL, INLET, Program HUD, and GASH) integrated in program to provide capability for analysis of changing flow conditions. Written in FORTRAN 77.
Walton, J. T.↗
Improving AHU Performance by Minimizing Approach Temperature, Reducing Air Maldistribution, and Efficiently Handling Sensible and Latent Loads (Phase 1 Interim Final Technical Report)
Residential air handling units (AHUs) have stayed the same in form and efficiency for the past 30+ years, with incremental improvements made to address safety, functionality, and energy-efficiency. The purpose of this research in Phase I, Topic 9a: Next Generation Residential Air Handlers, was to improve AHU performance by minimizing heat exchanger (HX) approach temperature, reducing air maldistribution, and developing alternative system configurations which more efficiently handle sensible and latent loads. In this research Optimized Thermal Systems (OTS) developed, modeled, and evaluated multiple alternative system concepts. A dual vapor compression system separate sensible and latent cooling (SSLC) concept was studied to inform work on alternative concepts and to show best-case performance benefit. System concepts included ejector enhanced vapor compression cycles, desiccant assisted dehumidification, dual evaporator SSLC, and alternative AHU HX configurations. A dual vapor compression system showed COP improvement of 20%, however, required additional components, increased unit size, and increased cost. Two types of ejector enhanced vapor compression cycles with dual evaporators improved system COP by 9 to 11%, and reduced AHU losses by as much as 18%, with design changes limited to the AHU, no unit physical size increase, and a moderate increase to system first cost. Desiccant assisted air-conditioning required increased air flow rate resulting in higher fan power and the desiccant wheel increased sensible heat load leading to increased compressor power and reduced system COP. Dual evaporator cycles were found to degrade performance due to increased expansion losses. Optimized single slab HX designs used in place of the traditional A-coil HX led to 44–49% reduction in aluminum, 47–60% less refrigerant charge, and improved HX velocity distribution.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Transition to a U/Pu Fuel Cycle with Fast and Thermal Reactors
The purpose of this study was to analyze the transition from the current U.S. nuclear system to an advanced fuel cycle involving U/Pu continuous recycle in a fleet of fast and thermal reactors. This fuel cycle, known as 'EG29' in the 2014 Nuclear Fuel Cycle Evaluation and Screening (E and S), was identified as one of the four most promising out of a comprehensive list of fuel cycles that were grouped based on similar physics and performance characteristics. The EG29 fuel cycle involves continuously recycling the co-extracted U/Pu from a fleet of fast reactors represented by sodium-cooled fast reactors (SFRs) and burning the surplus amounts in a fleet of thermal reactors represented by pressurized water reactors with full mixed oxide (U,Pu)O{sub 2} cores (MOX-PWRs). The target energy generation ratio of SFRs to MOX-PWRs for the final EG29 system is 70:30. A 1% annual growth in nuclear energy demand was also assumed to be met during the entire scenario, including after EG29 is fully deployed. Therefore, to maintain system-wide mass balance, the SFR was designed to have a Pu inventory ratio (discharged/charged) of 1.4 compared to the MOX-PWR's 0.7. (authors)
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Burning lithium in CS 2 for high-performing compact Li 2 S–graphene nanocapsules for Li–S–batteries
Here, tremendous efforts have been made to design the cathode of Li–S batteries to improve their energy density and cycling life. However, challenges remain in achieving fast electronic and ionic transport while accommodating the significant cathode volumetric change, especially for the cathode with a high practical mass loading. Here we report a cathode architecture, which is constructed by burning lithium foils in a CS 2 vapour. The obtained structure features crystalline Li 2 S nanoparticles wrapped by few-layer graphene (Li 2 S@graphene nanocapsules). Because of the improvement on the volumetric efficiency for accommodating sulfur active species and electrical properties, the cathode design enables promising electrochemical performance. More notably, at a loading of 10 mg Li 2 S cm –2 , the electrode exhibits a high reversible capacity of 1,160 mAh g –1 s, namely, an area capacity of 8.1 mAh cm –2 . Li 2 S@graphene cathode demonstrates a great potential for Li-ion batteries, where the Li 2 S@graphene-cathode//graphite-anode cell displays a high capacity of 730 mAh g –1 s as well as stable cycle performance.
25 ENERGY STORAGE↗
Flocculant-assisted synthesis of Fe{sub 2}O{sub 3}/carbon composites for superior lithium rechargeable batteries
Highlights: Black-Right-Pointing-Pointer A facile flocculant-assisted fabrication of Fe{sub 2}O{sub 3}/C composite. Black-Right-Pointing-Pointer Carboxymethylcellulose acts simultaneously as the flocculant and carbon source. Black-Right-Pointing-Pointer A high capacity of 497 mA h g{sup -1} at 1000 mA g{sup -1} over 100 cycles is retained. Black-Right-Pointing-Pointer Fe{sub 2}O{sub 3}/C anode exhibits excellent rate capability and cyclability. -- Abstract: High-performance iron oxide/carbon (Fe{sub 2}O{sub 3}/C) composites for lithium-ion batteries are synthesized by the combination of flocculant-assisted process and thermo-chemical treatment. Carboxymethylcellulose is used simultaneously as the flocculant and carbon source. This facile and scalable method lends itself to the fabrication of other metal oxide/carbon composites based on the flocculation mechanism. The lithium storage mechanism and cycling performance of Fe{sub 2}O{sub 3}/C composites are investigated by cyclic voltammetry and charge-discharge tests. As the rates increase from 50 to 1000 mA g{sup -1}, the composites display high charge capacities of 834 mAh g{sup -1} for the first cycle at 50 mA g{sup -1} and 497 mAh g{sup -1} at 1000 mA g{sup -1} over 100 cycles. Excellent rate capability and cyclability are ascribed presumablely to the isolation and buffer functions of the conductive carbon matrix against particle aggregation and large volume variety upon cycling.
36 MATERIALS SCIENCE↗
2016 U.S. Petroleum Fuels Life Cycle Baseline
The National Energy Technology Laboratory (NETL) has performed a well-to-wheels life cycle assessment (LCA) of petroleum production and refining for the United States (US), both from international and domestic oil sources. This analysis largely follows the same methods and framework established by Cooney et al., which performed a greenhouse gas (GHG) LCA of crude products for the 2014 data year (Cooney et al., 2017). Results are presented for six major petroleum products (gasoline, diesel, jet fuel, fuel oil, coke, bunker/residual fuel oil) across each of the five Petroleum Administration for Defense Districts (PADDs) and at the national US level. However, there are at least seven other refinery outputs (liquified petroleum gas, refinery fuel gas, hydrogen, petrochemical feedstocks, asphalt, sulfur) that are modeled but not shown in this report for brevity. Petroleum product amounts are compared against those reported by US Energy Information Administration (EIA) for each region.
02 PETROLEUM↗