Search NASA⌕ Search

SEARCH · Search NASA

Results for “Engine efficiency”

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.

At least 1,297 records · Page 72
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Three Way Catalyst-Selective Catalytic Reduction Aftertreatment System Evaluation for a Lean Burn Gasoline Engine Operating in Homogenous Charge Compression Ignition, Spark-Assisted Compression Ignition, and Spark-Ignited Combustion Modes

Low temperature and dilute homogenous charge compression ignition (HCCI) and spark-assisted compression ignition (SACI) can improve fuel efficiency and reduce engine-out NO x emissions, especially during lean operation. However, under lean operation, these combustion modes are unable to achieve Environmental Protection Agency (EPA) Tier 3 emissions standards without the use of lean aftertreatment. The three way catalyst (TWC)-SCR lean aftertreatment concept investigated in this work uses periodic-rich operation to produce NH 3 over a TWC to be stored on a selective catalytic reduction (SCR) catalyst for NO x conversion during subsequent lean operation. Experiments were performed with a modified 2.0 L gasoline engine that was cycled between lean HCCI and rich SACI operation and between lean and rich spark-ignited (SI) combustion to evaluate NO x conversion and fuel efficiency benefits. Different lambda values during rich operation and different times held in rich operation were investigated. Results are compared to a baseline case in which the engine is always operated at stoichiometric conditions. SCR system calculations are also presented to allow for comparisons of system performance for different levels of stored NH 3 . With the configuration used in this study, lean/rich HCCI/SACI operation resulted in a maximum NO x conversion efficiency of only 10%, while lean/rich SI operation resulted in a maximum NO x conversion efficiency of 60%. If the low conversion efficiency of HCCI/SACI operation could be improved through higher brick temperatures or additional SCR bricks, calculations indicate that TWC-SCR aftertreatment has the potential to provide attractive fuel efficiency benefits and near-zero tailpipe NO x . Calculated potential fuel efficiency improvement relative to stoichiometric SI is 7–17% for lean/rich HCCI/SACI with zero tailpipe NO x and -1 to 5% for lean/rich SI with zero tailpipe NO x emissions. Although the previous work indicated that the use of HCCI/SACI increases the time for NH 3 to start forming over the TWC during rich operation, reduces NH 3 production over the TWC per fuel amount, and increases NH 3 slip over the SCR catalyst, if NO x conversion efficiency could be enhanced, improvements in fuel efficiency could be realized while meeting stringent tailpipe NO x standards.

Engineering↗
DOE OSTI2018

Bioprocess development for muconic acid production from aromatic compounds and lignin

Muconic acid (MA) is a bio-based platform chemical that can be converted into the commodity petrochemical building blocks adipic acid or terephthalic acid, or used in emerging, performance-advantaged materials. MA is a metabolic intermediate in the ß-ketoadipate pathway, and can be produced from carbohydrates or other traditional carbon sources via the shikimate pathway. MA can also be produced from lignin-derived aromatic compounds with high atom efficiency through aromatic-catabolic pathways. Metabolic engineering efforts to date have developed efficient muconic acid-producing strains of the aromatic-catabolic microbe Pseudomonas putida KT2440, but the titers, productivities, and yields from aromatic compounds in most cases remain below the thresholds needed for industrially-relevant bioreactor cultivations. To that end, this work presents further process and host development towards improving MA titers, yields, and productivities, using the hydroxycinnamic acids, pcoumaric acid and ferulic acid, as model aromatic compounds. Coupling strain engineering and bioprocess development enabled the discovery of new bottlenecks in P. putida that hinder MA production from these compounds. A combination of gene overexpression and removal of a global catabolic regulator resulted in highyielding strains (100% molar yield). Maximum MA titers of 50 g/L, which is near the lethal toxicity limit in this bacterium, and productivities over 0.5 g/L/h were achieved in separate process configurations. Additionally, a high-pH feeding strategy, which could potentially reduce the salt load and enable higher titers by decreasing product dilution, was tested with model compounds and lignin-rich streams from corn stover and a complete conversion of the primary monomeric aromatic compounds to MA was demonstrated, obtaining a titer of 4 g/L. Overall, this study presents a step forward for the production of value-added chemicals from lignin and highlights critical needs for further strain improvement and bioprocess development that can be applied in the biological valorization of lignin.

09 BIOMASS FUELS↗
DOE OSTI2018

Engineering a highly dispersed core@shell structure for efficient photocatalysis: A case study of ternary novel BiOI@MIL-88A(Fe)@g-C3N4 nanocomposite

Highlights: • Novel ternary BiOI@MIL-88A(Fe)@g-C{sub 3}N{sub 4} core@shell photocatalyst is reported. • Photocatalytic degradation mechanism of organic pollutants is investigated. • It is divulged that the photodegradation is increased by BiOI supporting. • Core@shell structure of MIL-88A(Fe)@g-C{sub 3}N{sub 4} causes high activity. • Strong visible light absorption and electron transfer improve activity. - Abstract: Ternary novel BiOI@MIL-88A(Fe)@g-C{sub 3}N{sub 4} nanocomposite with core@shell structure was successfully synthesized by hydrothermal method. Fabricated photocatalysts were characterized and results confirmed the formation of MIL-88A(Fe)@g-C{sub 3}N{sub 4} core@shell structure and subsequently BiOI decoration on the surface of MIL-88A(Fe)@g-C{sub 3}N{sub 4}. Photocatalytic performances of prepared samples were investigated for degradation of Acid Blue 92 (AB92), Rhodamine B (RhB) and phenol under visible irradiation. It is clearly demonstrated that the as-prepared ternary BiOI@MIL-88A(Fe)@g-C{sub 3}N{sub 4} composites exhibits exceptional visible-light photocatalytic activities for cationic, anionic as well as neutral pollutant molecules compared to the widely accepted outstanding g-C{sub 3}N{sub 4}. It is mainly proved that the exceptional photocatalytic efficiencies are comprehensively ascribed to the porous structure of MIL-88A(Fe)@g-C{sub 3}N{sub 4}, greatly promoted charge separation and introduced catalytic functions to the carrier-related redox reactions by decorating BiOI and coupling g-C{sub 3}N{sub 4}, to modulate holes and electrons. Additionally, studies performed using radical scavengers showed the main reactive species in the photocataytic reaction for all chemical pollutant degradation.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Building Efficiency Targeting Tool for Energy Retrofits (BETTER) Analytical Engine

This is an open-source, empirical data-driven, virtual building energy analysis and retrofit targeting tool. The open-source tool will provide a fully-automated, "no-cost/no-touch" approach to screen large volumes of buildings for operational improvement and equipment upgrade opportunities and quantify associated potential energy and cost savings.

Szum, Carolyn↗
NASA NTRS1976

Small-scale test program to develop a more efficient swivel nozzle thrust deflector for V/STOL lift/cruise engines

The installed performance degradation of a swivel nozzle thrust deflector system obtained during increased vectoring angles of a large-scale test program was investigated and improved. Small-scale models were used to generate performance data for analyzing selected swivel nozzle configurations. A single-swivel nozzle design model with five different nozzle configurations and a twin-swivel nozzle design model, scaled to 0.15 size of the large-scale test hardware, were statically tested at low exhaust pressure ratios of 1.4, 1.3, 1.2, and 1.1 and vectored at four nozzle positions from 0 deg cruise through 90 deg vertical used for the VTOL mode.

Schlundt, D. W.↗
NASA NTRS2015

Efficient, Low Pressure Ratio Propulsor for Gas Turbine Engines

A gas turbine engine includes a spool, a turbine coupled to drive the spool, and a propulsor that is coupled to be driven by the turbine through the spool. A gear assembly is coupled between the propulsor and the spool such that rotation of the turbine drives the propulsor at a different speed than the spool. The propulsor includes a hub and a row of propulsor blades that extends from the hub. The row includes no more than 20 of the propulsor blades.

Gallagher, Edward J.↗
NASA NTRS2016

Efficient, Low Pressure Ratio Propulsor for Gas Turbine Engines

A gas turbine engine includes a spool, a turbine coupled to drive the spool, and a propulsor that is coupled to be driven by the turbine through the spool. A gear assembly is coupled between the propulsor and the spool such that rotation of the turbine drives the propulsor at a different speed than the spool. The propulsor includes a hub and a row of propulsor blades that extends from the hub. The row includes no more than 20 of the propulsor blades.

Gallagher, Edward J.↗
NASA NTRS2018

Efficient, Low Pressure Ratio Propulsor for Gas Turbine Engines

A gas turbine engine includes a core flow passage, a bypass flow passage, and a propulsor arranged at an inlet of the bypass flow passage and the core flow passage. The propulsor includes a row of propulsor blades. The row includes no more than 20 of the propulsor blades. The propulsor has a pressure ratio between about 1.2 and about 1.7 across the propulsor blades.

Gallagher, Edward J.↗
NASA NTRS2018

Efficient, Low Pressure Ratio Propulsor for Gas Turbine Engines

A gas turbine engine includes a bypass flow passage that has an inlet and defines a bypass ratio in a range of approximately 8.5 to 13.5. A fan is arranged within the bypass flow passage. A first turbine is a 5-stage turbine and is coupled with a first shaft, which is coupled with the fan. A first compressor is coupled with the first shaft and is a 3-stage compressor. A second turbine is coupled with a second shaft and is a 2-stage turbine. The fan includes a row of fan blades that extend from a hub. The row includes a number (N) of the fan blades, a solidity value (R) at tips of the fab blades, and a ratio of N/R that is from 14 to 16.

Gallagher, Edward J.↗
NASA NTRS2018

Efficient, Low Pressure Ratio Propulsor for Gas Turbine Engines

A gas turbine engine includes a gear assembly and a bypass flow passage that includes an inlet and an outlet that define a design pressure ratio between 1.3 and 1.55. A fan is arranged at the inlet. A first turbine is coupled with a first shaft such that rotation of the first turbine will drive the fan, through the first shaft and the gear assembly, at a lower speed than the first shaft. The fan includes a row of fan blades. The row includes 12-16 (N) fan blades, a solidity value (R) that is from 1.0 to 1.3, and a ratio of N/R that is from 10.0 to 16.

Gallagher, Edward J.↗