Reheat Factors for Expansions of Superheated and Wet Steam

1938 ◽  
Vol 5 (4) ◽  
pp. A161-A168
Author(s):  
Charles G. Thatcher
Keyword(s):  
Moisture Content ◽  
Superheated Steam ◽  
Moisture Removal ◽  
Wet Steam ◽  
Step Method ◽  
Maximum Value ◽  
Stage Efficiency

Abstract For superheated-steam expansions, charts show the reheat factors plotted against the ratio of P1/P2 up to a maximum value of 50 for this ratio. The probabilities are that these values of reheat factor are accurate to within one part in a thousand. The effect of stage efficiency is considered and results presented. Within the superheat region all stage efficiencies are considered to be constant. Wet-region values are worked out by the step-by-step method, and are presented entirely separate from those for the superheat region. Here also the effect of stage efficiency is included, as well as the effect of decreasing stage efficiency due to increasing moisture content in the expanding steam. The lack of uniformity in practice on this latter issue is pointed out and a suggestion made which should lead to clearer understanding. Moisture removal, which is prevalent in modern turbines, causes discontinuity in the condition curve, and a suggestion is made for the construction of the curve for such a case. Finally, there is given a method of calculating a condition curve for an expansion from any point in the superheat region and terminating in the wet region. It was found impractical to present a chart of reheat factors for such expansions.

Prediction of Trifluralin Diffusion Coefficients

Weed Science ◽  
1973 ◽  
Vol 21 (5) ◽  
pp. 485-489 ◽  
Author(s):  
L. E. Bode ◽  
C. L. Day ◽  
M. R. Gebhardt ◽  
C. E. Goering
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Diffusion Coefficients ◽  
Moisture Diffusion ◽  
Soil Parameters ◽  
Void Space ◽  
Exponential Relationship ◽  
Maximum Value ◽  
Soil Temperatures ◽  
Dry Soil

In the range of 4.4 to 49 C, there is an exponential relationship between temperature and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) diffusion coefficients. Diffusion is low in air-dry soil for all temperatures. It increases to a maximum value when the soil has between 8 and 15% w/w soil moisture content and then decreases steadily as moisture content increases. When the air-filled fraction of soil void space is reduced below approximately 40% v/v by either compression or addition of moisture, diffusion begins to decrease. An equation was developed to predict trifluralin diffusion coefficients from a factorial experiment with seven soil moisture contents, five soil temperatures, and two bulk densities. Diffusion coefficients range from 3.8 X 10-11 cm2/sec to 2.8 X 10-6 cm2/sec. Fifteen terms are required in the prediction model to describe accurately the response surface of trifluralin diffusion coefficients. With the equation it is possible to predict trifluralin diffusion coefficients for any combination of measured soil parameters as long as they are represented by the range of the variables used in the experiment.

The Effect of the Drying Temperature on the Moisture Removal and Mechanical Properties of Sisal Fibers

2017 ◽  
Vol 380 ◽  
pp. 66-71 ◽  
Author(s):  
D. Gomes dos Santos ◽  
A.G. Barbosa de Lima ◽  
P. de Sousa Costa
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Moisture Content ◽  
Raw Material ◽  
Moisture Removal ◽  
Heating Rates ◽  
Drying Temperature ◽  
Vegetable Fibers ◽  
Drying Condition ◽  
Sisal Fibers

Vegetable fibers have been used in most several applications, as raw material, for manufacturing of different products or directly as reinforcement in composite materials. Green fibers are wet, what requires its drying before their use.In this sense, the aim of this work is to study drying of the sisal fibers in oven. Drying experiments were carried out at different drying condition. It was evaluated the curves of moisture content, drying and heating rates and temperature, as well as the influence of the drying temperature on the mechanical properties of the fibers. It was found that the drying temperature (60 - 105°C) had no significant influence on the tensile mechanical properties, elongation at rupture and modulus of elasticity of the sisal fibers.

On the performance of a cascade of turbine rotor tip section blading in wet steam Part 1: Generation of wet steam of prescribed droplet sizes

1997 ◽  
Vol 211 (7) ◽  
pp. 519-529 ◽  
Author(s):  
F Bakhtar ◽  
H Mashmoushy ◽  
J R Buckley
Keyword(s):  
Superheated Steam ◽  
Turbine Rotor ◽  
Phase Flow ◽  
Wet Steam ◽  
Flow Conditions ◽  
Two Phase ◽  
Lower Efficiency ◽  
Blow Down ◽  
Droplet Sizes ◽  
Phase Mixture

During the course of expansion in turbines steam nucleates to become a two-phase mixture consisting of a very large number of extremely small droplets carried by the vapour. Turbine stages operating in a two-phase regime have a lower efficiency than those working on superheated steam. To reproduce turbine two-phase flow conditions realistically requires a supply of supercooled steam which can be generated under blow-down conditions by the equipment employed. To generate wet steam the supercooled steam can be passed through a venturi. This paper is one of a set describing an investigation of the performance of a cascade of turbine rotor tip section profiles in wet steam and is concerned with the generation of a supply of wet steam of prescribed droplet sizes for admission to the cascade.

scholarly journals Effect of Pads and Thickness of Paddy on Moisture Removal under Sun Drying

2021 ◽  
Author(s):  
A. Narmilan ◽  
G. Niroash ◽  
M.I.M. Mowjood ◽  
A.T.A. Akram
Keyword(s):  
Sri Lanka ◽  
Moisture Content ◽  
Removal Rate ◽  
Initial Moisture Content ◽  
Storage Period ◽  
Moisture Removal ◽  
Drying Time ◽  
Sun Drying ◽  
Regular Time ◽  
Paddy Farmers

Background: Sun drying is a popular post-harvest operation to maintain rice quality during the storage period. Farmers use different pads and thicknesses for sun drying of paddy in Ampara district, Sri Lanka. A study was conducted to evaluate the suitability and effectiveness of the drying pad and thickness as practiced by local paddy farmers during the sun drying process.Methods: The grain with an initial moisture content of 28% (dry basis) was sun dried with four types of drying pads and five levels of thickness of grain. This experiment was conducted between 8.30 am and 4.30 pm at the South Eastern University of Sri Lanka in August 2020. The moisture contents of the grain were measured at regular time intervals.Result: It was found that the duration of drying of paddy from 28% to 13% moisture content on a dry basis was 300 to 540 minutes depending upon the drying pad and thickness. The tarpaulin is reasonable at shallow thickness with less time to reach the necessary moisture level than other drying pads. Black polythene and fertilizer bag can be utilized for sun drying of paddy at 4 cm thickness with 130 minutes. It was found that with an increase in the thickness of paddy from 0.5 cm to 4 cm, the drying time increases. A statistically significant interaction was obtained between drying pads and thickness level on moisture removal of paddy. Therefore, the moisture removal rate differs with the drying pad and thickness of the paddy under open sun drying.

Pre-Drying Effect and Quality Change of Rough Rice under Hot Air-Assisted Radio Frequency Disinfestation Treatment

2021 ◽  
Vol 37 (6) ◽  
pp. 1045-1054
Author(s):  
Windi Damayanti ◽  
Meiji Liao ◽  
Yuanrong Xu ◽  
Pu Jing ◽  
Shunshan Jiao
Keyword(s):  
Moisture Content ◽  
Radio Frequency ◽  
Moisture Loss ◽  
Total Phenolic ◽  
Moisture Removal ◽  
Drying Method ◽  
Quality Change ◽  
Hot Air ◽  
Rough Rice

HighlightsHA-RF disinfestation treatment had better pre-drying effect of rough rice than that of HA treatmentHighest moisture loss (8.7%) was obtained for samples with highest IMC (39.6% d.b.)Initial moisture content (IMC) correlated negatively with milling quality of rough riceHA-RF can be used as a pre-drying method to partially reduce the moisture contentAbstract.Hot air-assisted radio frequency (HA-RF) is an environmentally friendly disinfestation method, which can completely control the insects and meanwhile maintain quality of rough rice. In this study, the pre-drying effect of HA-RF disinfestation treatment of rough rice with different initial moisture contents (IMCs) (16.7%, 24.8%, 34.7%, and 39.6% d.b.) was investigated along with associated quality change. HA-RF treatments had better pre-drying effect of rough rice with various IMCs than that of hot air (HA) treatment and larger electrode gap obtained lower moisture removal. IMCs of rough rice also influenced the moisture removal for HA-RF treatments, and the corresponding moisture loss were 4.3%, 5.3%, 6.1%, and 8.7% for the treated rough rice with IMC of 16.7%, 24.8%, 34.7%, and 39.6%, respectively. More quality loss was observed for the rough rice with higher IMC, especially for broken rate, fissure, and water uptake ratio. HA-RF treatment had no influences on total phenolic acids, protein, and fat contents, but amylose and vitamin E contents were affected. Non-milled rice treated by HA-RF had an obvious decrease in the lightness (L*) except for the samples with highest IMC (39.6%). RF disinfestation treatment can be used as a pre-drying method to partially reduce the moisture content (MC) of rough rice. Keywords: Disinfestation, Moisture content, Pre-drying, Quality, Rough rice.

Mass Diffusivities of Radiata Pine in Superheated Steam Drying

2010 ◽  
Vol 146-147 ◽  
pp. 357-360
Author(s):  
Hua Wu Liu ◽  
Zhen Yun Wang ◽  
Ping Xu
Keyword(s):  
Superheated Steam ◽  
Analytic Solution ◽  
Waste Heat ◽  
Radiata Pine ◽  
Moisture Removal ◽  
Superheated Steam Drying ◽  
Higher Temperature ◽  
Drying Technology ◽  
Steam Drying ◽  
Low Temperature Drying

Superheated steam drying is an energy saving and effective drying technology, in which the waste heat is recycled with the loop system and the moisture removal is much faster than that of conventional low temperature drying. The computation methods for the estimation of wood mass diffusivities were evaluated and the first ten terms of the analytic solution of Fick’s Second Law was considered sufficiently accurate, but Crank’s method was rejected, due to its large errors. The experimental data show that higher temperature significantly accelerated the drying rate. In addition, no visible surface or internal checks have been found in the superheated steam dried samples (dry-bulb temperature 160, 180, 200, 220 oC). The highly effective super heated steam drying is definitely an advantage. However, samples were browned when dried above 220 oC, which may be regarded as the critical temperature for quality control.

scholarly journals Electrochemical Properties of La2Mg17/Ni Electrodes Prepared via TiF3-Catalysed Mechanical Milling

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
T. Li ◽  
Z. Liu ◽  
G. Zhang ◽  
F. Ruan ◽  
R. Guo ◽  
...  
Keyword(s):  
Storage Capacity ◽  
Hydrogen Diffusion ◽  
High Energy ◽  
Electrochemical Reactions ◽  
Hydrogen Storage Capacity ◽  
Step Method ◽  
Maximum Value ◽  
Electrochemical Capacity ◽  
Energy Ball ◽  
Diffusion Of Hydrogen

In order to improve the hydrogen storage capacity of conventional La2Mg17electrode alloys, a nanocrystalline/amorphous-structured La2Mg17-Ni composite material was produced by high energy ball milling in the presence of TiF3. Subsequent analysis of the discharge/charge cycle performances of this electrode material revealed that its cycle stability and electrochemical capacity were greatly improved, with the latter reaching a maximum value of 787.07 mAh/g with optimisation of the TiF3addition. Moreover, a remarkable enhancement in the reversibility of electrochemical reactions on the material’s surface was also observed. Hydrogen diffusion coefficients for the material were calculated by means of a potential step method, confirming that TiF3markedly improves the long-range diffusion of hydrogen within the material.

Improved Sawdust Briquette: An Alternative Source of Fuel

2009 ◽  
Vol 62-64 ◽  
pp. 769-773
Author(s):  
J.O. Osarenmwinda ◽  
S. Imoebe
Keyword(s):  
Moisture Content ◽  
Calorific Value ◽  
Ash Content ◽  
Alternative Source ◽  
Maximum Value ◽  
Alternate Source

The production of an improved sawdust briquette, as an alternate source of fuel has been achieved. In addition to sawdust other constituents of the briquette were silica (sharp sand), starch and kerosene. The density, ash content, calorific values and moisture content of briquette were determined. The composition of starch and kerosene was constant throughout the experiment. It was observed that as silica percentage was increased, there was an increase in the briquette calorific value until maximum value of 20%. The sample which gave the best calorific value was with percentage compositions of 60% sawdust, 20% silica (sharp sand), 5% kerosene and 15% starch with a calorific value of 12.68mJ/kg .The produced briquette had a higher calorific value than wood and other agro waste it was compared with.

scholarly journals Studies of the Combined Modes of Microwave Grain Drying

2018 ◽  
Vol 12 (6) ◽  
pp. 25-30
Author(s):  
Sergey A. Pavlov ◽  
Igor A. Pekhalsky ◽  
Nikolay G. Nikolay G. Kynev
Keyword(s):  
Moisture Content ◽  
Microwave Pulse ◽  
Raw Materials ◽  
Removal Rate ◽  
Pause Duration ◽  
Microwave Drying ◽  
Flow Density ◽  
Moisture Removal ◽  
Moisture Movement ◽  
Vegetable Raw Materials

Abstract. To ensure the high quality of the materials being dried, one of the most promising ways to dehydrate vegetable raw materials is drying under the action of electromagnetic radiation (microwave drying). Microwave drying is widely used in various industries, in particular, in the food and woodworking industries. (Research purpose) Calculation of the microwave pulse and pause duration; their experimental determination, as well as the determination of the moisture removal rate at the pulse moment and the depth of pulse penetration into the layer. (Materials and methods) When drying in a microwave field, the gradient of moisture content in the material prevents the moisture movement towards the surface, internal cracks can be formed as well. Therefore, the combined methods of drying can yield the best results. The pulse duration has been calculated by the permissible increment of the grain temperature, the pause duration has been determined by assuming that during the pulse, moisture from the caryopsis kernel is pushed out and cooled under isothermal conditions by an air flow. (Results and discussion) It has been confirmed that at a microwave pulse energy duration of 4, 6, and 10 s, the speed of blow-off and blowdown of the layer with external air was 0.5 m per second. When grain is cooled by natural convection, the pulse time is 10 s, the pause time is 1, 2, 3, and 5 min. For the blow-off mode, the pulse exposure time was 6 and 10 s, that of blow-off - 0.5, 1.0, and 1.5 minutes. The maximum duration of the microwave pulse was determined by the flow density of allowable grain heating and the fraction of heat required for the evaporation of moisture when heated to 20-25 degrees. (Conclusions) The pause duration is determined by the grain cooling time to the temperature preceding the pulse. It has been experimentally established that the calculated values of the pulse and pause duration with an accuracy of 15 percent for grain with a moisture content of 20-24 percent at a microwave flow density of 0.7 kilowatts per square meter, at a depth of the microwave energy penetration into the grain by 70 percent, do not exceed 20-22 mm, and the moisture removal rate is 0.1-0.15 percent.

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