Design and Characterization of Micropost-Filled Reactor to Minimize Pressure Drop While Maximizing Surface-Area-to-Volume-Ratio

2006 ◽  
Author(s):  
J. Yeom ◽  
J.-H. Han ◽  
B. Bae ◽  
M. A. Shannon ◽  
R. I. Masel
Keyword(s):  
Pressure Drop ◽  
Surface Area ◽  
Figure Of Merit ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Knudsen Flow ◽  
Total Analysis System ◽  
Dimensionless Figure Of Merit ◽  
Analysis System

Micropost-filled reactors are commonly found in many micro total analysis system applications because of their high surface area for the surrounding volume. Design rules for micropost-filled reactors are presented here to optimize the performance of the micro-preconcentrator, which is a component of a micro gas chromatography system. The dimensionless figure of merit is proposed to be used to minimize the pressure drop while maximizing the surface-area-to-volume-ratio for a given overall channel geometry of the micropost-filled preconcentrator. Two independent models from the literature are used to predict the pressure drop across the micropost-filled channels for low Reynolds number flows. The pressure drop can be expressed solely as a function of a design parameter, β = a/s, a ratio of a radius of each post and a half-spacing between two adjacent posts. Pressure drop measurements are performed to experimentally corroborate the pressure drop model and the optimization using the dimensionless figure of merit. As the number of microposts; for a given β increases in a given channel size, a greater surface-area-to-volume-ratio will occur for a fixed pressure drop. Therefore, increasing the arrays of posts with smaller diameters and spacing will optimize the microreactor for higher surface area for a given flow resistance, at least until Knudsen flow begins to dominate.

scholarly journals Enhanced photoelectrochemical water splitting performance using morphology-controlled BiVO4 with W doping

2017 ◽  
Vol 8 ◽  
pp. 2640-2647 ◽  
Author(s):  
Xin Zhao ◽  
Zhong Chen
Keyword(s):  
Surface Area ◽  
Light Absorption ◽  
Charge Separation ◽  
High Surface ◽  
High Surface Area ◽  
Charge Injection ◽  
Volume Ratio ◽  
Solvent Ratio ◽  
Photoelectrochemical Performance ◽  
Interfacial Charge

Nanostructures exhibit numerous merits to improve the efficiency in solar-to-energy conversion. These include shortened carrier collection pathways, an increased volume ratio between depletion layer and bulk, enhanced light capture due to multiple light scattering in nanostructures, and a high surface area for photochemical conversion reactions. In this study, we describe the synthesis of morphology-controlled W-doped BiVO4 by simply tuning the solvent ratio in precursor solutions. Planar and porous W-doped BiVO4 thin films were prepared and compared. The porous film, which exhibits increased surface area and enhanced light absorption, has displayed enhanced charge separation and interfacial charge injection. Our quantitative analysis showed an enhancement of about 50% of the photoelectrochemical performance for the porous structure compared to the planar structure. This enhancement is attributed to improved light absorption (13% increase), charge separation (14% increase), and interfacial charge injection (20% increase).

scholarly journals Nanotechnology and Its Applications to Medicine: an over view

QJM ◽  
2020 ◽  
Vol 113 (Supplement_1) ◽  
Author(s):  
H Ibrahim
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Electrospinning Process ◽  
Nano Particles ◽  
High Production Rate ◽  
Nano Fiber ◽  
Nano Medicine ◽  
Bio Compatibility

Abstract Nowadays there are more interesting with nanotechnology and its applications in several sectors specially in medicine for diagnoses, therapeutic and research biomedical tools. It can be defined as any process or technique used to produce material in nano-scale structure with particle size ranged from 1-100 nm. The utilization of nanotechnology in human health benefits known as nano medicine. So that nanotechnology has firmly entered the drug delivery realm to maximize drug therapeutic activity and minimize its undesirable side effects. Herein we deal with both nanoparticles and nano-fibers and their applications in medical field. Nano-particles have unique properties from its small size with high surface area therefore it provides larger than particle numbers from that prepared with convention methods. In addition, nanoparticles can be used to improve various drug bio-availability from its biodegradability and bio-compatibility. Nano-fibers have huge surface area to volume ratio which increase its performance in several applications. Nano-fiber produced via electrospinning process (simple and have high production rate). It can be used in many applications such as water filtration, tissue engineering scaffold, wounds, fiber composites, drug release and protective clothes.

Growth of Carbon Nanotubes on Carbon Toray Paper for Bio-Fuel Cell Applications

2007 ◽  
Author(s):  
Bhupesh Chandra ◽  
Joshua T. Kace ◽  
Yuhao Sun ◽  
S. C. Barton ◽  
James Hone
Keyword(s):  
Carbon Nanotubes ◽  
Fuel Cell ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Multiwall Carbon Nanotubes ◽  
Volume Ratio ◽  
Carbon Paper ◽  
Heating Process ◽  
Scale Production

In recent years carbon nanotubes have emerged as excellent materials for applications in which high surface area is required e.g. gas sensing, hydrogen storage, solar cells etc. Ultra-high surface to volume ratio is also a desirable property in the applications requiring enhanced catalytic activity where these high surface area materials can act as catalyst supports. One of the fastest developing areas needing such materials is fuel-cell. Here we investigate the process through which carbon nanotubes can be manufactured specifically to be used to increase the surface area of a carbon paper (Toray™). This carbon support is used in bio-catalytic fuel cell as an electrode to support enzyme which catalyzes the redox reaction. Deposition of nanotubes on these carbon fibers can result in great enhancement in the overall surface area to support the enzyme, which increases the reaction rate inside the fuel cell. The present paper describes a method to achieve ultra-thick growth of multiwall carbon nanotubes (MWNT) on a carbon Toray™ paper using a joule heating process and gas-phase catalyst. Using this method, we are able to achieve rapid, high-density, and uniform MWNT growth. This method is also potentially scalable toward larger-scale production.

PRODUCTION AND PROPERTIES OF 2,3-BUTANEDIOL: X. THE EFFECTS OF SURFACE–VOLUME RATIO AND REDUCED PRESSURE ON THE FERMENTATION OF CARBOHYDRATES BY AEROBACILLUS POLYMYXA AND AEROBACTER AEROGENES

1946 ◽  
Vol 24f (2) ◽  
pp. 107-116 ◽  
Author(s):  
G. A. Adams ◽  
J. D. Leslie
Keyword(s):  
Carbon Dioxide ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Reduced Pressure ◽  
Aerobacter Aerogenes ◽  
Fermentation Rate ◽  
Per Se ◽  
Reduced Pressures

The rate of fermentation of wheat mashes by Aerobacillus polymyxa was markedly increased by providing a high surface-area–volume ratio. Exposure to air or oxygen per se was not a controlling factor since an atmosphere of nitrogen gave the same effect. Inhibition of fermentation of shallow layers of mash by exposure to carbon dioxide suggested that escape of fermentation gases (mainly carbon dioxide) might be the major factor affecting the fermentation rate. Support has been given to this hypothesis by the marked increase in rate obtained when wheat mashes were fermented under reduced pressures.Fermentation of 15% wheat mashes, normally requiring 72 to 96 hr., were complete in 48 hr. under 5 in. pressure (absolute). The fermentation rate was accelerated by decreasing pressures but was retarded slightly by increasing depths of mash. The butanediol–ethanol ratio became progressively lower with decreasing pressures, showing that such conditions favour ethanol formation.Fermentation of sugar media by Aerobacter aerogenes was only mildly stimulated by reduced pressures. This treatment compares unfavourably with aeration as a means of increasing the fermentation rate of this organism.

scholarly journals Innovation of Critical Bubble Electrospinning and Its Mechanism

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 304 ◽  
Author(s):  
Ya Li ◽  
Aixue Dong ◽  
Jihuan He
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Increasing Demand ◽  
Critical Bubble

Along with the advent of an ever-increasing demand for the nano-industrialization, nanofibers become a unique class with many fascinating properties due to their nanoscale diameters and high surface area to volume ratio [...]

scholarly journals Morphological evolution of Pt-modified nanoporous gold after thermal coarsening in reductive and oxidative environments

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
A. A. El-Zoka ◽  
B. Langelier ◽  
G. A. Botton ◽  
R. C. Newman
Keyword(s):  
Surface Area ◽  
Morphological Evolution ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Atom Probe ◽  
Nanoporous Gold ◽  
Atomic Scale ◽  
Thermal Coarsening

AbstractNanoporous gold made by dealloying AgAuPt (NPG-Pt) has been shown to exhibit several interesting catalytic properties, tied to its exceptionally high surface area; however, structural degradation may occur owing to thermal coarsening. To understand the effect of atmosphere chemistry on thermal coarsening and degradation, and means of limiting it, this study focuses on the high-resolution characterization of NPG-Pt layers coarsened in reductive Ar-H2 atmosphere, and in oxidative air. Atom probe tomography (APT) analysis is performed on NPG-Pt, coarsened separately in either Ar-H2 or air, to characterize the atomic-scale chemical changes in the nanoligaments and to develop a mechanistic view of the inherent processes. A tendency of Ag to segregate to the surface during coarsening is found to lead to complete elimination of the nanoligament core-shell structures in both cases. Large Pt segregates form during coarsening in Ar-H2, but under the surface of the ligaments, having relatively little effect on the coarsening rate. The oxygen-induced segregation of Pt was observed to cause the inhibition of thermal coarsening after minor loss in surface area-to-volume ratio. Findings in this paper help in understanding further the thermal coarsening of heterogeneous nanomaterials made by dealloying, and the pertinent factors that come into play in different chemical environments.

scholarly journals The Role of Temperature on the Degree of End-Closing and Filling of Single-Walled Carbon Nanotubes

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3365
Author(s):  
Magdalena Kierkowicz ◽  
Elzbieta Pach ◽  
Julio Fraile ◽  
Concepción Domingo ◽  
Belén Ballesteros ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Surface Area ◽  
Density Functional ◽  
Annealing Temperature ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Density Functional Theory Calculations ◽  
Nitrogen Adsorption

Carbon nanotubes (CNTs), owing to their high surface area-to-volume ratio and hollow core, can be employed as hosts for adsorbed and/or encapsulated molecules. At high temperatures, the ends of CNTs close spontaneously, which is relevant for several applications, including catalysis, gas storage, and biomedical imaging and therapy. This study highlights the influence of the annealing temperature in the range between 400 and 1100 °C on the structure and morphology of single-walled CNTs. The nitrogen adsorption and density functional theory calculations indicate that the fraction of end-closed CNTs increases with temperature. Raman spectroscopy reveals that the thermal treatment does not alter the tubular structure. Insight is also provided into the efficacy of CNTs filling from the molten phase, depending on the annealing temperature. The CNTs are filled with europium (III) chloride and analyzed by using electron microscopy (scanning electron microscopy and high-resolution transmission electron microscopy) and energy-dispersive X-ray spectroscopy, confirming the presence of filling and closed ends. The filling yield increases with temperature, as determined by thermogravimetric analysis. The obtained results show that the apparent surface area of CNTs, fraction of closed ends, and amount of encapsulated payload can be tailored via annealing.

Preparation and Properties of Hydrophobic Silica Aerogels by Ambient Pressure Drying Method

2011 ◽  
Vol 71-78 ◽  
pp. 1040-1043
Author(s):  
Hui Wang ◽  
Shi Ming Liu ◽  
Ling Ke Zeng
Keyword(s):  
Surface Area ◽  
Ambient Pressure ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Hydrophobic Properties ◽  
Large Pore Volume

Silica alcogels were prepared by hydrolysis with hydrochloric acid and condensation with NH4OH of ethanol diluted tetraethylorthosilicate (TEOS) precursor and trimethylchlorosilane and hexane as surface modifying agent. The physical properties such as density, appearance, hydrophobicity, surface area, pore size distribution and thermal stability were measured. It was found that the physical and hydrophobic properties of the silica aerogels depend on the TMCS/hexane (V) volume ratio. The density decreased with increase ofV, and the aerogels are more hydrophobic asV=3%. The aerogels were thermally stable up to a temperature of 350 °C, and the aerogel prepared has a high surface area and large pore volume.

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