Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “KNO3”

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.

14 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.82–3.01 Å. N5+ is bonded in a trigonal planar geometry to three O2- atoms. All N–O bond lengths are 1.27 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one N5+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.89–2.97 Å. N5+ is bonded in a trigonal planar geometry to three O2- atoms. All N–O bond lengths are 1.27 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one N5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.78–3.03 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.76–3.00 Å. There are two inequivalent N5+ sites. In the first N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.27 Å) and one longer (1.28 Å) N–O bond length. In the second N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.26 Å) and two longer (1.27 Å) N–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two K1+ and one N5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two K1+ and one N5+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N5+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 is Calcite-like structured and crystallizes in the trigonal R32 space group. The structure is three-dimensional. K1+ is bonded to six equivalent O2- atoms to form distorted corner-sharing KO6 octahedra. The corner-sharing octahedral tilt angles are 67°. All K–O bond lengths are 2.78 Å. N5+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All N–O bond lengths are 1.27 Å. O2- is bonded in a trigonal planar geometry to two equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 crystallizes in the trigonal R3m space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine equivalent O2- atoms. There are three shorter (2.84 Å) and six longer (2.96 Å) K–O bond lengths. N5+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All N–O bond lengths are 1.27 Å. O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of K–O bond distances ranging from 2.82–3.23 Å. N5+ is bonded in a trigonal planar geometry to three O2- atoms. All N–O bond lengths are 1.27 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to four equivalent K1+ and one N5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS2003

Individual Aerosol Particles from Biomass Burning in Southern Africa Compositions and Aging of Inorganic Particles: Compositions and Aging of Inorganic Particles - 2

Individual aerosol particles collected over southern Africa during the SAFARI 2000 field study were studied using transmission electron microscopy and field-emission scanning electron microscopy. The sizes, shapes, compositions, mixing states, surface coatings, and relative abundances of aerosol particles from biomass burning, in boundary layer hazes, and in the free troposphere were compared, with emphasis on aging and reactions of inorganic smoke particles. Potassium salts and organic particles were the predominant species in the smoke, and most were internally mixed. More KCl particles occur in young smoke, whereas more K2SO4 and KNO3 particles were present in aged smoke. This change indicates that with the aging of the smoke, KCl particles from the fires were converted to K2SO4 and KNO3 through reactions with sulfur- and nitrogen- bearing species from biomass burning as well as other sources. More soot was present in smoke from flaming grass fires than bush and wood fires, probably due to the predominance of flaming combustion in grass fires. The high abundance of organic particles and soluble salts can affect the hygroscopic properties of biomass-burning aerosols and therefore influence their role as cloud condensation nuclei. Particles from biomass burning were important constituents of the regional hazes.

Li, Jia↗
DOE OSTI2022

Chemical compatibility of hollow ceramic cenospheres as thermal insulation for high-temperature thermal energy storage applications with molten nitrate salt

An effective insulation material that is both thermally and chemically stable in molten salts could transform the design of molten-salt-based thermal energy storage (TES) tanks. Most current molten salt TES tanks hold the metallic tank structure in direct contact with hot salt inventory, a design which leads to thermal expansion of the tank and triggers stresses that can lead to thermomechanical failures. With an internal insulation to lower the temperature at the tank structure, the extent of thermal expansion can be reduced, thereby reducing expansion-induced stresses and allowing for consideration of lower-cost tank structure materials. Conventional insulation materials are either 1) too porous and allow molten salts to permeate into the matrix, which significantly increases the thermal conductivity or 2) too dense and have a thermal conductivity that cannot provide sufficient thermal insulation. This paper presents an alternative thermal insulation concept using cenospheres which have an alumino-silicate structure. The cost analysis suggests that the low-density cenospheres can be one of the cheapest materials to provide cost-effective thermal insulation. The chemical compatibility of cenospheres is investigated in molten 60 wt% NaNO3/40 wt% KNO3 salt which is close to industrial-grade Solar Salt. This paper shows that diffusion of the sodium and potassium cations from the salt into the cenospheres occurs based on weight analysis, energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The cation diffusion breaks the bridging oxygen bonds and causes volume expansion of the microstructure which is responsible for the failure of the cenosphere particles. The chemical composition of the cenospheres is found to affect their compatibility with molten nitrate salt. A cenosphere product with low iron content showed the best compatibility with an average survival rate of 77.9% +/- 9.8% after 7 days of immersion in the molten nitrate salt. While even the low-iron cenospheres appear to require protection from direct molten salt contact, their slow degradation rate, closed-cell porosity, and low cost hold potential for effective use as internal tank insulation.

14 SOLAR ENERGY↗
DOE OSTI2022

Corrosion resistance of high nickel alloys in solar salt at 600 °C for up to 4000 h

This study focuses on the time dependent performance of the corrosion resistance of IN625, H230 and 740H alloys in the solar salt (60 wt% NaNO3, 40 wt% KNO3, at 600 °C) for up to 4000 h. Alloy IN625 showed the lowest mass change with parabolic oxidation kinetics that tends to stabilize with exposure time. Both 740H and H230 alloys deviated from the parabolic oxidation behavior beyond the 3000 h of exposure. Alloy 740H showed the highest mass loss due to the nonuniform surface oxidation and the high chromium dissolution rate. Internal oxidation was noticed with Alloy H230 due to the high tungsten concentrations.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K8NO3 by Materials Project

K8NO3 is Fluorite-derived structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. K1+ is bonded to one N2- and three equivalent O2- atoms to form a mixture of edge and corner-sharing KNO3 tetrahedra. The K–N bond length is 2.88 Å. All K–O bond lengths are 2.83 Å. N2- is bonded in a body-centered cubic geometry to eight equivalent K1+ atoms. O2- is bonded in a body-centered cubic geometry to eight equivalent K1+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1978

Space Shuttle SRM Ignition System

This paper presents the Space Shuttle SRM Ignition System, which consists of a large solid propellant main igniter, a small solid propellant initiating igniter and an electromechanical safety and arming device containing two NASA Standard Initiators and a B-KNO3 pyrotechnic booster charge. In development motors, the igniter also has a valve through which CO2 is injected for post-firing quench of the SRM. The igniter has redundant, testable seals at all pressurized joints and three major reusable components; the case, the adapter, and the S&A device. Two development problem areas are discussed. One problem area was transverse mode combustion instability in the main igniter with maximum amplitude of 340 psi peak-to-peak at a frequency of 1500 Hz, which was reduced by a propellant grain configuration change and a change from a 2% aluminum content propellant to a formulation containing 10% aluminum. The other problem area was an excessively rapid rise of thrust in the SRM, which was reduced by reducing the igniter mass flow rate. This mass flow rate reduction was accomplished by removing portions of the grain starpoints in the head end.

Bolieau, C. W.↗
NASA NTRS1979

A solar thermal electric power plant for small communities

A solar power plant has been designed with a rating of 1000-kW electric and a 0.4 annual capacity factor. It was configured as a prototype for plants in the 1000 to 10,000-kWe size range for application to small communities or industrial users either grid-connected or isolated from a utility grid. A small central receiver was selected for solar energy collection after being compared with alternative distributed collectors. Further trade studies resulted in the selection of Hitec (heat transfer salt composed of 53 percent KNO3, 40 percent NaNO2, 7 percent NaNO3) as both the receiver coolant and the sensible heat thermal stroage medium and the steam Rankine cycle for power conversion. The plant is configured with road-transportable units to accommodate remote sites and minimize site assembly requirements. Results of the analyses indicate that busbar energy costs are competitive with diesel-electric plants in certain situations, e.g., off-grid, remote regions with high insolation. Sensitivity of energy costs to plant power rating and system capacity factor are given.

Holl, R. J.↗
NASA NTRS1983

Microstructural characterization of SiC (SCS) filaments

Microstructural features of SiC('SCS') fibers demonstrating growth properties have been investigated using scanning and transmission electron microscopy. An etchant of fused KOH:KNO3 was developed which adequately brought out previously undetermined features.

Wawner, F. W.↗
NASA NTRS2016

Temperature-Staged Thermal Energy Storage Enabling Low Thermal Exergy Loss Reflux Boiling in Full Spectrum Solar Systems

Hybrid full spectrum solar systems (FSSS) designed to capture and convert the full solar wavelength spectrum use hybrid solar photovoltaic/thermodynamic cycles that require low thermal exergy loss systems capable of transferring high thermal energy rates and fluxes with very low temperature differentials and losses. One approach to achieving this capability are high-heat-flux reflux boiling systems that take advantage of high heat transfer boiling and condensation mechanisms. Advanced solar systems are also intermittent by their nature and their electrical generation is often out-of-phase with electric utility power demand, and their required power system cycling reduces efficiency, performance (dispatch ability), lifetime, and reliability. High temperature thermal energy storage (TES) at 300-600°C enables these reflux boiling systems to simultaneously store thermal energy internally to increase the energy dispatch ability of the associated solar system, as this can increase the power generation profile by several hours (up to 6-10 hours) per day. Many TES phase change materials (PCM’s) exist including KNO3, NaNO3, LiBr/KBr, MgCl2/NaCl/KCl, Zn/Mg, and CuCl/NaCl, which have various operating melting points and different latent heats of fusion. Common, cost effective TES PCM's are FeCl2/NaCl/KCl mixtures, whose phase change temperature can be varied and controlled by simple composition adjustments. This paper presents and discusses unique "temperature-staged" thermal energy storage configurations using these TES materials and analysis of such systems integrated into high-heat-flux reflux boiling systems. In this specific application, the TES materials are designed to operate at staged temperatures surrounding an operating design point near 350°C, while providing 18 kW of source heat transfer to operate a thermoacoustic power system during off-sun conditions (e.g., temporary cloud conditions, after sun-down). This work discusses relevant configurations, and critical thermal and entropy models of the TES configurations, which show the inherent minimization of thermal exergy during critical heat transfers within the configurations and systems envisioned.

Hendricks, Terry J.↗