Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “drying methods”

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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Mathematical modelling for the drying method and smoothing drying rate using cubic spline for seaweed Kappaphycus Striatum variety Durian in a solar dryer

The solar drying experiment of seaweed using Green V-Roof Hybrid Solar Drier (GVRHSD) was conducted in Semporna, Sabah under the metrological condition in Malaysia. Drying of sample seaweed in GVRHSD reduced the moisture content from about 93.4% to 8.2% in 4 days at average solar radiation of about 600W/m{sup 2} and mass flow rate about 0.5 kg/s. Generally the plots of drying rate need more smoothing compared moisture content data. Special cares is needed at low drying rates and moisture contents. It is shown the cubic spline (CS) have been found to be effective for moisture-time curves. The idea of this method consists of an approximation of data by a CS regression having first and second derivatives. The analytical differentiation of the spline regression permits the determination of instantaneous rate. The method of minimization of the functional of average risk was used successfully to solve the problem. This method permits to obtain the instantaneous rate to be obtained directly from the experimental data. The drying kinetics was fitted with six published exponential thin layer drying models. The models were fitted using the coefficient of determination (R{sup 2}), and root mean square error (RMSE). The modeling of models using raw data tested with the possible of exponential drying method. The result showed that the model from Two Term was found to be the best models describe the drying behavior. Besides that, the drying rate smoothed using CS shows to be effective method for moisture-time curves good estimators as well as for the missing moisture content data of seaweed Kappaphycus Striatum Variety Durian in Solar Dryer under the condition tested.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Efficiency Limits of Evaporative Fabric Drying Methods

Cloth drying is a major consumer of energy, and most drying is conducted by evaporative methods. The evaporative drying energy efficiency limit is commonly assumed to be 100%: one unit of latent heat removed per unit of energy expended. However, this ignores the “free drying” available from unsaturated ambient air and the possible role of heat pumping. We demonstrate that efficiency limits for evaporative drying are fundamentally related to both drying rate and ambient psychrometric conditions. A relationship among efficiency, drying rate, and ambient conditions is quantified for several evaporative drying technologies, and a comparison among evaporative technologies is provided. In addition, a comparison is provided between efficiency limits and state of the art device performance. This research will help guide future research in the most promising directions.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2015

Synthesis of nickel oxide nanospheres by a facile spray drying method and their application as anode materials for lithium ion batteries

Graphical abstract: NiO nanospheres prepared by a facile spray drying method show high lithium ion storage performance as anode of lithium ion battery. - Highlights: • NiO nanospheres are prepared by a spray drying method. • NiO nanospheres are composed of interconnected nanoparticles. • NiO nanospheres show good lithium ion storage properties. - Abstract: Fabrication of advanced anode materials is indispensable for construction of high-performance lithium ion batteries. In this work, nickel oxide (NiO) nanospheres are fabricated by a facial one-step spray drying method. The as-prepared NiO nanospheres show diameters ranging from 100 to 600 nm and are composed of nanoparticles of 30–50 nm. As an anode for lithium ion batteries, the electrochemical properties of the NiO nanospheres are investigated by cyclic voltammetry (CV) and galvanostatic charge/discharge tests. The specific reversible capacity of NiO nanospheres is 656 mA h g{sup −1} at 0.1 C, and 476 mA h g{sup −1} at 1 C. The improvement of electrochemical properties is attributed to nanosphere structure with large surface area and short ion/electron transfer path.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Freeze-drying method as a new approach to the synthesis of polyurea aerogels from isocyanate and water

Polyurea (PUA) aerogels were prepared as the polycondensation product of triisocyanate and water. PUA aerogels were formed through supercritical drying (SC) and, for comparison, by freeze-drying (FD). The effect of isocyanate concentration, catalyst concentration, and drying method on properties like density, specific surface area, pore volume, compressive strength, and morphology was investigated. The properties of aerogels strongly depend on the concentration of the isocyanate in the parent solution and, to a lesser extent, on catalyst concentration. For example, aerogels with higher isocyanate concentration exhibited a higher surface area and modulus. Depending on the formulation, the materials had a density between 0.128 and 0.220 g/cm 3 , surface area between 140 and 210 m 2 /g, pore volume between 0.593 and 1.500 cm 3 / g, compressive modulus between 6.5 and 25 MPa, and thermal conductivity between about 0.028 and 0.033 W/m K. Most importantly, the drying method did not strongly affect the properties of the materials. These were within ~15% for SC and FD. Furthermore the results indicate that freeze-drying can be successfully used to fabricate aerogels in a cost-effective way.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Recovery of valuable components from waste LCD panel through a dry physical method

Highlights: • This paper aims at harmless treatment and resource recovery of waste LCD panel. • Indium tin oxide (ITO) was enriched from CF and TFT glass through mechanical exfoliation. • Vibrated gas-solid fluidized bed separation was introduced to investigate the separation of polarizing film and glass. •One flowsheet for recycling waste LCD panel synthetically which combine dry methods is proposed. - Abstract: A waste liquid crystal display (LCD) panel was recycled synthetically and cleanly by using dry physical methods, namely, mechanical exfoliation, dry crushing and vibrated gas–solid fluidized bed separation. Results of elemental and phase analyses show that indium and tin contents were enriched greatly in indium tin oxide concentrate obtained from colour filter and thin-film transistor glass. The results of crushing, ash content and scanning electron microscopic analyses show that when the LCD panel was crushed into particles smaller than 0.25 mm, the polarizer film is nearly completely liberated from the glass. Moreover, the results of vibrated gas–solid fluidized bed separation show that gas velocity and separation time are the main factors influencing the separation. The vibration intensity of 6.8, gas velocity of 13.6 cm/s and fluidizing time of 30 s are the optimum operating parameters, and the degree of separation and recovery of polarizing film reached up to 37.69 and 72.3%, respectively. Based on these results, the combination of dry enrichment, dry crushing and dry separation in a flowsheet is proposed for recycling of waste LCD panel.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Drying and Analysis of Aluminum (Oxy)hydroxide Films for Dry Storage of Aluminum-Clad Spent Nuclear Fuels

In aluminum-clad spent nuclear fuels, an (oxy)hydroxide layer on the surface of the cladding hosts chemisorbed water formed during reactor and post-discharge exposure to water. Any residual water is susceptible to generating hydrogen via radiolysis, which can be a risk associated with dry fuel storage. Engineering-scale forced helium dehydration (FHD) and vacuum drying tests were conducted on mock-up fuel assemblies that included corroded aluminum surrogate plates to assess the removal of bulk and chemisorbed water. Thermogravimetric analysis was performed on samples of the surrogate plates, both undried control samples used to determine onset temperatures associated with a phase change occurring in the oxide layer and samples from drying tests used to determine the effectiveness of each drying method. Both vacuum drying and FHD processes were capable of removing bulk water. However, FHD was determined to provide additional drying capabilities, including partial removal of chemisorbed water from bayerite due to the higher temperatures during drying. In conclusion, the temperature threshold for partial dehydroxylation of the oxide layer was determined to be around 220°C, meaning any drying methods attempting to remove chemisorbed water must exceed 220°C.

chemisorbed water↗
DOE OSTI2013

Effect of scandia doping method on the emission uniformity of scandate cathode with Sc{sub 2}O{sub 3}–W matrix

Graphical abstract: Emission uniformity of the cathodes prepared by mechanical mixing (a) and spray drying method (b). - Highlights: • The emission uniformity of scandate cathodes has been quantitively obtained. • The nanoparticles on the cathode surface lead to the electric field enhancement. • The cathode prepared by spray drying method exhibits good emission uniformity. - Abstract: Scandia doped tungsten matrix dispenser cathodes were manufactured using scandia doped tungsten powder prepared by mechanical mixing, liquid–solid doping and a spray drying method. It is found the macrostructure of the cathode depended on the powder preparation method. The cathode prepared using the powder prepared by spray drying method had a homogenous and porous matrix characterized with grains with a diameter of less than 1 μm and with many nanoparticles distributing uniformly around these grains. The cathode with submicron structure and uniform distribution of scandia exhibited good emission uniformity. The emission uniformity ΔJ/J of the cathode prepared by spray drying method was 0.17, about 6 times lower than that of the cathode prepared by mechanical mixing method. The calculation results showed that the nanoparticles led to electric field enhancement. A Ba–Sc–O multilayer on the cathode surface and nanoparticles distributing mainly on W grains contributed to the emission property of the cathode.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Methods for dry etching semiconductor devices

The present invention provides methods for etching semiconductor devices, such aluminum nitride resonators. The methods herein allow for devices having improved etch profiles, such that nearly vertical sidewalls can be obtained. In some examples, the method employs a dry etch step with a primary etchant gas that omits BCl.sub.3, a common additive.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Fast synthesis of La-substituted apatite by the dry mechanochemical method and analysis of its structure

Compared to pure apatite, La-substituted apatites have improved thermal, mechanical and biological characteristics. In this article, a fast synthesis of La-substituted apatites by a dry mechanochemical method is presented. Structural studies by X-ray diffraction and Fourier transform infrared spectroscopy indicated the formation of a single-phase nanosized product after 30 min of high-energy ball milling of the reaction mixtures. The dry mechanochemical method is technologically attractive for the preparation of La-substituted apatites, as it allows reducing the processing time down to half an hour and does not require prolonged high-temperature annealing normally used in the synthesis practice of the substituted apatite. As the mechanochemically synthesized samples are nanosized, it is difficult to determine the details of their crystal structure by the Rietveld refinement method. Therefore, a series of the mechanochemically synthesized samples with different concentrations of lanthanum were annealed at 1000 °C for 5 h. It was found that the annealed powders are microcrystalline La-substituted apatites Ca{sub 10−x}La{sub x}(PO{sub 4}){sub 6}O{sub x}(OH){sub 2−x}, where 0 ≤ x ≤2. In their structure, the Ca{sup 2+} ions are replaced by the La{sup 3+} ions localized near the Ca2 sites, and the OH{sup -} groups are replaced by the O{sup 2-} ions in the hexagonal channels. - Highlights: • a new approach to the synthesis of La-substituted apatites is proposed. • dry mechanochemical method allows reducing the synthesis time down to 30 min. • the product of synthesis is single-phase with an average crystallite size of 20 nm. • the parameters and volume of the unit cell increase with dopant concentration. • La-substituted apatites are Ca{sub 10−x}La{sub x}(PO{sub 4}){sub 6}O{sub x}(OH){sub 2−x}, where 0 ≤ x ≤ 2.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Characterization and photo-chemical applications of nano-ZnO prepared by wet chemical and thermal decomposition methods

Graphical abstract: - Highlights: • Nano-ZnO particles were synthesized by soft-wet precipitation and dry methods. • ZnO nanoparticle with different morphologies was obtained. • Nano ZnO samples showed a high photocatalytic activity. • ZnO nanoparticle showed strong ultraviolet emission at room temperature. • The samples showed high biological activity depending on their synthetic method. - Abstract: Nano-crystalline ZnO particles were synthesized using two different routes: soft-wet and dry methods. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to identify the particles structures and morphologies, while X-ray diffraction (XRD) was used for verifying the particles crystal structure. The thermal stabilities of the particles were examined through thermal gravimetric analysis technique and their surface areas were calculated using BET method. Moreover, the photocatalytic activities were evaluated using UV–vis spectroscopy and photoluminescence (PL) characterization. The results showed that all the prepared ZnO samples possess a hexagonal wurtzite structure with high purity. Different particle sizes and morphologies of spheres, rods and wires were obtained depending on the preparation method used. Particle sizes obtained by the dry method are smaller than that found by the wet chemical method. The effects of both particle size and morphology on each of surface as well as optical properties, photocatalytic activity, dye/ZnO solar cell efficiency and biological activity have been studied and discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Supercritical drying of cementitious materials

Techniques to characterize the microstructure of hydrated cement require dried materials. However, the microstructure of hydrated products is significantly altered by high capillary forces during drying when using the conventional drying methods. To avoid drying stresses when preparing samples, we have employed supercritical drying (SCD) which has been used for decades to prepare aerogels that undergo no shrinkage during drying, but has rarely been used for cementitious materials. The pore solution is first replaced with isopropanol, and then with trifluoromethane (R23). The temperature and pressure are raised above the critical point, where no menisci or capillary pressure can exist; therefore, the dried samples are free of artifacts created by stresses. Images from scanning electron microscope show less compact morphology for supercritically dried samples than that dried by conventional methods, while BET surface areas of SCD samples are very close to samples dried by the isopropanol replacement method. This can be explained by the fact that isopropanol and supercritical fluid enter the micropores and block them. The nature of the chemical interactions of isopropanol and R23 with cement pastes are still not clear, but no reaction products were identified in the present study.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Morphology of cementitious material during early hydration

Morphology of hydration products, mainly calcium-silicate-hydrate (C-S-H), has a strong influence on the mechanical and transport properties of hardened cementitious materials. This paper examines the effect of curing conditions and drying methods during specimen preparation on C-S-H morphology. It shows that an appropriate drying method, either supercritical drying (SCD) or isopropanol (IPA) replacement, is able to preserve the delicate microstructure on both macro and micro scales. On the surface of the specimen, the structure is fibrillar for specimens cured in high relative humidity (RH) chamber or reticular for specimens cured in pore solution/limewater. A thin layer with cluster-like structure was found for specimens cured in high RH. By observing the fracture surface, it is found that the interior morphology is complex and varies with depth and curing methods. Consequently, one must take into account the effect of ion transport during the curing and drying when preparing specimens for microstructure analysis. We proposed that the basic units of C-S-H are fine fibers and thin sheets.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Development of multifunctional nylon 6,6-based nanocomposites with high electrical and thermal conductivities by scalable melt and dry blending methods for automotive applications

With the advent of intelligent automobile technology, the demand for multifunctional composites with higher electrical and thermal conductivities is increasing. We have herein reported for the first time the effect of polyolester on the dispersion of carbon nanotube (CNT) in the short-carbon fiber (CF)/nylon 6,6 (PA66) composite using a scalable melt-mixing and dry-blending method and its subsequent improvement in electrical and thermal conductivities. Masterbatches were prepared with a higher concentration of CNT (both untreated and polyolester-treated) followed by dry blended with reference composite (30 wt% CF and 10 wt% mineral fiber filled PA66) before making coupons via injection molding. A 500% and 63% improvements in electrical (3.14 S cm -1 ) and thermal conductivities (in-plane) (1.99 W m -1 K -1 ) conductivities were observed by adding 1.5 wt% treated CNT compared to the reference composite. The improvements were even higher than that of untreated CNT due to better dispersion. Furthermore, the electromagnetic shielding effectiveness reached 61 dB for 1.5 wt% treated CNT-filled composite (39% enhancement). In conclusion, these results are significant in imparting multiple functionalities to the automotive composite parts.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Dry Deposition Methods Based on Turbulence Kinetic Energy: 1. Evaluation of Various Resistances and Sensitivity Studies Using a Single‐Point Model

Different functions are used to account for turbulence strength in the atmospheric boundary layer for different stability regimes. These functions are one of the sources for differences among different atmospheric models' predictions and associated biases. Also, turbulence strength is underrepresented in some of the resistance formulations. Here, to address these issues with dry deposition, firstly we take advantage of three‐dimensional (3‐D) turbulence information in estimating resistances by proposing and validating a 3‐D turbulence velocity scale that is relevant for different stability regimes of boundary layer. Secondly, we hypothesize and validate that friction velocity measured by 3‐D sonic anemometer can be effectively replaced by the new turbulence velocity scale multiplied by the von Karman constant. Finally, we (a) present a set of resistance formulations for ozone (O 3 ) based on the 3‐D turbulence velocity scale; (b) intercompare estimations of such resistances with those obtained using existing formulations; and, (c) evaluate simulated O 3 fluxes using a single‐point dry deposition model against long‐term observations of O 3 fluxes at the Harvard Forest (MA) site. Results indicate that the new resistance formulations work very well in simulating surface latent heat and O 3 fluxes when compared to respective existing formulations and measurements at a decadal time scale. Findings from this research may help to improve the capability of dry deposition schemes for better estimation of dry deposition fluxes and create opportunities for the development of a community dry deposition model for use in regional/global air quality models.

54 ENVIRONMENTAL SCIENCES↗