scholarly journals A New Method to Estimate Fuel Surface Area-to-Volume Ratio Using Water Immersion.

1998 ◽  
Vol 8 (3) ◽  
pp. 121 ◽  
Author(s):  
PM Fernandes ◽  
FC Rego
Keyword(s):  
Surface Area ◽  
Particle Density ◽  
Low Cost ◽  
Water Immersion ◽  
Volume Ratio ◽  
Adsorbed Water ◽  
General Technique ◽  
Fuel Surface ◽  
Before And After

A fast, simple, low cost and general technique for estimating fuel surface area-to-volume ratio is presented. The technique requires particle density, the determination of fuel weight before and after immersion in water and the theoretical thickness of the adsorbed water pellicle that is assumed constant. Estimates by the technique were consistent and in good agreement with published surface area-to-volume ratios for the same fuels obtained through other methods, and its performance was judged appropriate for current fire behaviour modelling needs. This water immersion technique was applied to various shrubs and trees grown in Portugal. Limitations and possibilities for improvement of the newly developed technique are discussed.

scholarly journals A New Method to Estimate Fuel Surface Area-to-Volume Ratio Using Water Immersion

1998 ◽  
Vol 8 (2) ◽  
pp. 59 ◽  
Author(s):  
PM Fernandes ◽  
FC Rego
Keyword(s):  
Surface Area ◽  
Particle Density ◽  
Low Cost ◽  
Water Immersion ◽  
Volume Ratio ◽  
Adsorbed Water ◽  
General Technique ◽  
Fuel Surface ◽  
Before And After

A fast, simple, low cost and general technique for estimating fuel surface area-to-volume ratio was developed. It requires the knowledge of particle density, the determination of fuel weight before and after immersion in water, and theoretical thickness of the adsorbed water pellicle that is assumed constant. Estimates by the technique were consistent and in good agreement with published surface area-to-volume ratios for the same fuels obtained through commonly used methods, and its performance is judged appropriate for the current fire behaviour modeling needs. The water immersion technique was applied to five common shrub species in Portugal. Limitations and possibilities for improvement of the newly developed technique are discussed.

scholarly journals Antioxidant Determination with the Use of Carbon-Based Electrodes

Chemosensors ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 72
Author(s):  
Aurelia Magdalena Pisoschi ◽  
Aneta Pop ◽  
Florin Iordache ◽  
Loredana Stanca ◽  
Liviu Bilteanu ◽  
...  
Keyword(s):  
Surface Area ◽  
Oxidation Process ◽  
Low Cost ◽  
Oxidative Enzymes ◽  
Adaptation Mechanisms ◽  
Chain Breaking ◽  
Nanomolar Range ◽  
Quench Singlet Oxygen ◽  
Carbon Based

Antioxidants are compounds that prevent or delay the oxidation process, acting at a much smaller concentration, in comparison to that of the preserved substrate. Primary antioxidants act as scavenging or chain breaking antioxidants, delaying initiation or interrupting propagation step. Secondary antioxidants quench singlet oxygen, decompose peroxides in non-radical species, chelate prooxidative metal ions, inhibit oxidative enzymes. Based on antioxidants’ reactivity, four lines of defense have been described: Preventative antioxidants, radical scavengers, repair antioxidants, and antioxidants relying on adaptation mechanisms. Carbon-based electrodes are largely employed in electroanalysis given their special features, that encompass large surface area, high electroconductivity, chemical stability, nanostructuring possibilities, facility of manufacturing at low cost, and easiness of surface modification. Largely employed methods encompass voltammetry, amperometry, biamperometry and potentiometry. Determination of key endogenous and exogenous individual antioxidants, as well as of antioxidant activity and its main contributors relied on unmodified or modified carbon electrodes, whose analytical parameters are detailed. Recent advances based on modifications with carbon-nanotubes or the use of hybrid nanocomposite materials are described. Large effective surface area, increased mass transport, electrocatalytical effects, improved sensitivity, and low detection limits in the nanomolar range were reported, with applications validated in complex media such as foodstuffs and biological samples.

Increasing Condenser Capacity Without Adding Tubes to Support a Station Uprate

2010 ◽  
Author(s):  
Warren C. Welch ◽  
Timothy J. Harpster ◽  
Joseph W. Harpster
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Surface Area ◽  
Low Cost ◽  
Cooling Water ◽  
Steam Generation ◽  
Before And After ◽  
Generation Capacity ◽  
Almost All

A station uprate provides an economical opportunity to improve the generation capacity of a power plant if all the major system components are able to handle the effects of increased generation. The magnitude of uprate from increased steam generation will be limited by the maximum capacity of the weakest link in the cycle, which for many plants is the condenser. The condensers on many units are already pushed to their limit. This is especially true if a cooling tower is employed, where the condenser inlet cooling water temperatures are high on high wet-bulb temperature days. This condition forces many units to throttle down load to prevent excursions above the backpressure limits on their turbines. For condensers limited by the present duty, however, the options have been historically limited to rebundling the whole condenser with a larger surface area design and perhaps changing the tube material to a material with a higher heat transfer coefficient. Recently, a very low cost option has been demonstrated that should be considered by any plant looking to increase condenser duty or prevent station power reductions. Advances in the proper management of steam, condensate and noncondensable flows have permitted an upgrade for almost all vintage condensers, unlocking inactive surface area without a bundle replacement or complete redesign. This paper reports the results of a condenser retrofit effort, with emphasis on an upgrade applied to a load limited condenser concurrent with a major reduction in its operating backpressure. The performance of the condenser is presented before and after the upgrade showing significant backpressure reduction and heat transfer improvement accompanied by exceptional condensate chemistry results. It will be shown that 30% of the effective condenser surface area (or similarly, an additional 30% average heat transfer coefficient) was unlocked by activating the previously idle surface area.

Pyric properties of some dominant Mediterranean vegetation species

2001 ◽  
Vol 10 (1) ◽  
pp. 23 ◽  
Author(s):  
A. P. Dimitrakopoulos ◽  
P.I. Panov
Keyword(s):  
Surface Area ◽  
Mediterranean Basin ◽  
Particle Density ◽  
Heat Content ◽  
Volume Ratio ◽  
Ash Content ◽  
Mediterranean Vegetation ◽  
The Mediterranean ◽  
Vegetation Species ◽  
The Mediterranean Basin

The chemical and physical pyric properties of several species, dominant in the Mediterranean Basin, are quantified and compared with each other. Heat content and total and mineral (silica-free) ash content are measured and analysed for 13 species, while surface area-to-volume ratio and particle density are measured for 8 species.

scholarly journals Measuring the specific surface area of wet snow using 1310 nm reflectance

2014 ◽  
Vol 8 (4) ◽  
pp. 1139-1148 ◽  
Author(s):  
J.-C. Gallet ◽  
F. Domine ◽  
M. Dumont
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Volume Ratio ◽  
Liquid Water Content ◽  
Optical Methods ◽  
Integrating Sphere ◽  
Wet Snow ◽  
The Difference

Abstract. The specific surface area (SSA) of snow can be used as an objective measurement of grain size and is therefore a central variable to describe snow physical properties such as albedo. Snow SSA can now be easily measured in the field using optical methods based on infrared reflectance. However, existing optical methods have only been validated for dry snow. Here we test the possibility to use the DUFISSS instrument, based on the measurement of the 1310 nm reflectance of snow with an integrating sphere, to measure the SSA of wet snow. We perform cold room experiments where we measure the SSA of a wet snow sample, freeze it and measure it again, to quantify the difference in reflectance between frozen and wet snow. We study snow samples in the SSA range 12–37 m2 kg−1 and in the mass liquid water content (LWC) range 5–32%. We conclude that the SSA of wet snow can be obtained from the measurement of its 1310 nm reflectance using three simple steps. In most cases, the SSA thus obtained is less than 10 {%} different from the value that would have been obtained if the sample had been considered dry, so that the three simple steps constitute a minor correction. We also run two optical models to interpret the results, but no model reproduces correctly the water–ice distribution in wet snow, so that their predictions of wet snow reflectance are imperfect. The correction on the determination of wet snow SSA using the DUFISSS instrument gives an overall uncertainty better than 11%, even if the LWC is unknown. If SSA is expressed as a surface to volume ratio (e.g., in mm−1), the uncertainty is then 13% because of additional uncertainties in the determination of the volume of ice and water when the LWC is unknown.

Color Development Reaction Research of Melamine in Milk

2011 ◽  
Vol 393-395 ◽  
pp. 1133-1138
Author(s):  
Xi Quan Sun ◽  
Sheng Lin Qiao ◽  
Zheng Xiao Liu ◽  
Ling Le Kong
Keyword(s):  
Exchange Resin ◽  
Detection Method ◽  
Low Cost ◽  
Cation Exchange Resin ◽  
Volume Ratio ◽  
Centrifugal Separation ◽  
Resin Column ◽  
Color Development ◽  
Extraction Agent

According to the color development reaction between starch/iodine reagent and products which obtained by fumigating melamine with chlorine, a method for determination of melamine in milk was put forward. The conditions of method were researched. The best conditions are as follows. Volume ratio of milk and extraction agent is 1:1. 5, dissolved with ultrasonic washer for 5 minutes, centrifugal separation 4000r/min for 5 minutes, extracted by C008 cation exchange resin column. The results are as follows: detection limit is 10mg/L, the linear range is 25-250 mg/L, related coefficient r is 0.994, coefficient of recovery is 94%-110%, and relatively standard deviation is 0.9%. This method is easy handling, cheap equipment, good practicability and recovery, can be used as low cost detection method.

scholarly journals NM R Determination of the Fractal Geometry of Gels Around the Collapse Transition

1989 ◽  
Vol 44 (2) ◽  
pp. 163-164 ◽  
Author(s):  
R. Blinc ◽  
O. Jarh ◽  
A. Zidanšek ◽  
A. Blinc
Keyword(s):  
Fractal Dimension ◽  
Fractal Geometry ◽  
Relaxation Times ◽  
Volume Ratio ◽  
Liquid Component ◽  
Collapse Transition ◽  
Spin Lattice ◽  
Before And After ◽  
The Masses

Abstract The increase in the surface to volume ratio at the collapse transition of gels can be exploited to allow for an NMR determination of the fractal dimension of the gel surface in the liquid state where this quantity is hard to measure with other techniques. The measured quantities are the ratio be­tween the spin-lattice and spin-spin relaxation times T1/T2 of the liquid component and the ratio of the masses or volumes of the gel before and after the collapse transition. The technique has been used to determine the surface fractal dimen­sion of a blood plasma gel.

scholarly journals Comparison of the observed size-dependent melting point of CdSe nanocrystals to theoretical predictions

2018 ◽  
Vol 9 (1) ◽  
pp. 39-43
Author(s):  
Albert Demaine Dukes III ◽  
Christopher Dylan Pitts ◽  
Anyway Brenda Kapingidza ◽  
David Eric Gardner ◽  
Ralph Charles Layland
Keyword(s):  
Melting Point ◽  
Surface Area ◽  
Melting Temperature ◽  
Volume Ratio ◽  
Melting Point Depression ◽  
Cdse Nanocrystals ◽  
Size Dependent ◽  
Theoretical Predictions

Cadmium selenide nanocrystals were observed to have a size-dependent melting point which was depressed relative to the bulk melting temperature. The observed size-dependent melting point ranged from 500-1478 K, while a model based on the surface area to volume ratio predicted that is should range between 774-1250 K. The nanocrystals were heated in situ in the electron microscope, and the melting point was almost immediately followed by the vaporization of the CdSe nanocrystals, allowing for straightforward determination of the melting temperature. The differences between the observed melting point of CdSe nanocrystals and the values predicted by the surface area to volume ratio model indicates that additional factors are involved in the melting point depression of nanocrystals.

scholarly journals Determination of Optimal Surface Area to Volume Raio for Thin-Layer Drying of Breadfruit (Artocarpus altilis)

2007 ◽  
Vol 2 (2) ◽  
Author(s):  
C. George ◽  
R. McGruder ◽  
K. Torgerson
Keyword(s):  
Surface Area ◽  
Volume Ratio ◽  
Optimal Size ◽  
Drying Characteristics ◽  
Artocarpus Altilis ◽  
Sun Drying ◽  
Thin Layer Drying ◽  
Optimal Surface ◽  
The Caribbean

Experiments to determine the optimal size shred of breadfruit for sun drying in the Caribbean were conducted and verified. To determine optimal shred size, ease of shredding and handling as well as the drying characteristics were considered. Additional experiments compared the drying characteristics of breadfruit to several types of produce more readily available for use in the laboratory and examined the effect of alternative bases or backgrounds for sun drying. An optimal surface area to volume ratio is recommended and found to dry breadfruit under average Caribbean conditions (27-30 ˚C, 60-65% RH, ~800 W/m2 solar radiation and 1.5-2.0 m/s prevailing winds) in about three hours.

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