Bordered Pit Aspiration in the Wood of Cryptomeria Japonica in Relation to Air Permeability

IAWA Journal ◽  
1997 ◽  
Vol 18 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Tomoyuki Fujii ◽  
Youki Suzuki ◽  
Naohiro Kuroda
Keyword(s):  
Moisture Content ◽  
Cryptomeria Japonica ◽  
Initial Moisture Content ◽  
Air Permeability ◽  
Heartwood Formation ◽  
Permeability Measurement ◽  
Air Drying ◽  
Freeze Dried ◽  
Pit Membrane ◽  
Bordered Pits

Aspiration of bordered pits in Cryptomeria japonica (L. f.) D. Don was studied in relation to the air permeability in sapwood, transition zone wood, and heartwood. The percentage of aspirated pits relative to the total number of bordered pits with observable tori was determined in samples that were epoxy-embedded and thin sectioned. Air permeability of air-dried and freeze-dried wood samples was measured following the method described by Siau (1984). Pit membrane structure of air-dried and freeze-dried samples was investigated by scanning electron microscopy on split radial surfaces. It is proposed that pit aspiration progresses during heartwood formation as already reported, but the pit aspiration was frequently incomplete and the percentage varied between individuals. The pit aspiration percentage was not obviously related to the sample's initial green moisture content or heartwood color. The results from permeability measurement and SEM observation on air- and freeze-dried samples suggest that pit aspiration occurred in sapwood samples (the initial moisture content of which ranged from 200 to 300%) during air-drying and caused a significant decrease in permeability confirming the pit aspiration mechanism proposed by Hart and Thomas (1967). In the heartwood, encrustation of pit membranes prevented aspiration during air-drying.

Airflow Drying of Corn Stalks Particles in Straight Horizontal Tube

2013 ◽  
Vol 864-867 ◽  
pp. 499-502
Author(s):  
Xiao Nan Zhang ◽  
Wei Lv ◽  
Xin Hai Wang ◽  
Zhong Xia Zhao ◽  
Xi Yu Lin ◽  
...  
Keyword(s):  
Moisture Content ◽  
Feed Rate ◽  
Initial Moisture Content ◽  
Horizontal Tube ◽  
Single Factor ◽  
Airflow Velocity ◽  
Air Drying ◽  
Orthogonal Experiments ◽  
Drying Curves

For analyzing initial moisture content of corn stalks, feed rate, airflow temperature and airflow velocity which affect drying, the experiment bench of air drying was established, industrial analysis, single factor and multi-factors orthogonal experiments for corn stalks were done. The drying curves about various factors were summed up to conclude airflow temperature is the most important factor which affects drying effect.

Kinetics of forced convective air drying of potato and squash slabs / Cinética del secado de rodajas de patatas y calabacin con corriente de aire

1997 ◽  
Vol 3 (4) ◽  
pp. 251-261 ◽  
Author(s):  
C.O. Rovedo ◽  
C. Suárez ◽  
P.E. Viollaz
Keyword(s):  
Moisture Content ◽  
Surface Area ◽  
Initial Moisture Content ◽  
Three Dimensional ◽  
Sorp Tion ◽  
Air Drying ◽  
Solid Diffusion ◽  
Drying Behaviour ◽  
Drying Curves ◽  
Kinetics Of

Moisture content, temperature, and surface area variations of potato and squash slabs were measured during forced convective air drying; the effect of the initial moisture content on drying behaviour was also investigated. A mathematical model that numerically integrated the diffusion equation and the thermal balance for a three-dimensional shrinking slab was used to simulate the drying process. The parameters of the model (surface area, heat transfer coefficient and dry solid density) were experimentally determined. Fitting parameters (activation energy and pre- exponential coefficient in the Arrhenius equation) were found by comparing experimental and predicted drying curves. Good agreement was obtained down to a moisture level of 0.4 kg water/kg dry solid. Diffusion coefficients were independent of their moisture content within the range studied for both products. The activation energies for potato and squash were 2.09 x 104 kJ/kg mol and 3.76 x 10 4 kJ/kg mol, respectively. Changes in the rates of drying and heating curves for potato took place at moisture levels around 0.4 kg water/kg dry solid, but this was not the case for squash. The differences were mainly attributed to the different shapes of the sorp tion isotherms.

ALTERATIONS OF SOIL STRUCTURE UPON FREEZING AND THAWING AND SUBSEQUENT DRYING

1968 ◽  
Vol 48 (2) ◽  
pp. 193-197 ◽  
Author(s):  
W. C. Hinman ◽  
Frederick Bisal
Keyword(s):  
Moisture Content ◽  
Soil Structure ◽  
Room Temperature ◽  
Clay Soil ◽  
Soil Aggregates ◽  
Initial Moisture Content ◽  
Aggregate Size ◽  
Freezing And Thawing ◽  
Initial Size ◽  
Freeze Dried

A laboratory investigation of a clay soil indicated that the percentage of aggregates < 1 mm in diameter might be increased, decreased or unaffected by freezing and thawing depending on the initial moisture content, the initial size of soil aggregates and the method of drying the sample. Little or no changes in aggregate size occurred if the initial moisture content was at 15 atmospheres. At 0.1 atm, aggregates which were initially coarse (> 4 mm) tended to break down slightly when exposed to alternate freezing and thawing followed by air-drying at room temperature. On the other hand, a substantial decrease in aggregates < 1 mm in diameter occurred when aggregates which were originally fine received the same sequence of treatments. However, if the samples were freeze-dried following the same treatments, all aggregates were reduced to < 1 mm in diameter. Similar trends were established with samples which were continuously frozen and when the initial moisture content was at 0.33 atm, although the magnitude of the change was much smaller. It is proposed that forces engendered during freezing disrupt aggregates, but this process is reversed during thawing and drying at room temperatures.

Hot Air Drying and Vacuum Drying Characteristics of Scarlet Runner Beans

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Yoshiki Muramatsu ◽  
Eiichiro Sakaguchi ◽  
Takahiro Orikasa ◽  
Akio Tagawa
Keyword(s):  
Diffusion Coefficient ◽  
Moisture Content ◽  
Initial Moisture Content ◽  
Vacuum Drying ◽  
Drying Method ◽  
Drying Process ◽  
Hot Air Drying ◽  
Air Drying ◽  
Drying Characteristics ◽  
Hot Air

Abstract The drying characteristics and volume changes of scarlet runner beans were measured under various conditions to obtain useful basic information for the optimum drying method and conditions. The sample was dried using two drying methods: hot air drying and vacuum drying. The measured changes in moisture content of the sample with the hot air drying process were in good agreement with the exact solution of the infinite plane sheet model. The estimated diffusion coefficients were 3.8×10 -7 -7.4×10 -7 (m 2 h -1) for hot air drying and were related to absolute temperature by an Arrhenius-type equation. The hull of the scarlet runner bean is hard and thick, and the drying rate of the sample was much slower than that of other beans. To establish an efficient drying method without the quality loss, the vacuum drying characteristics of the sample were measured at several levels for temperature and initial moisture content. For the vacuum drying process, an exponential model could be used to estimate the changes in moisture content of the sample. The values of diffusion coefficient for vacuum drying were approximately twice as much as the values of diffusion coefficient for hot air drying at the same temperature. The effects of drying method, temperature, and initial moisture content on the sample quality were investigated, and the optimum drying method and conditions for scarlet runner beans were proposed. Volumetric changes in the sample were determined by measuring particle density. The specific volume of the sample was represented as a linear function of moisture content.

Mode for hot air drying of alder blanks that retain the colour acquired during the steaming process

2021 ◽  
Vol 114 ◽  
pp. 86-91
Author(s):  
Ladislav Dzurenda
Keyword(s):  
Moisture Content ◽  
Initial Moisture Content ◽  
Bound Water ◽  
Free Water ◽  
Hot Air Drying ◽  
Air Drying ◽  
Water Steam ◽  
Color Changes ◽  
Hot Air ◽  
Relative Air Humidity

Mode for hot air drying of alder blanks that retain the colour acquired during the steaming process. The paper presents a hot-air mode for drying steamed alder in the form of blanks with dimensions: 38x100x800 mm from the initial moisture content W1 ≈ 50 % to the final moisture content W2 = 10%, while maintaining the colour of wood obtained in the process of steaming with saturated water steam. The drying process is divided into two parts: (I) evaporation of free water from wet wood at drying medium temperatures td = 35 - 40 °C and relative air humidity φ = 70 – 60%, when there are no chemical changes in the lignin-saccharide complex of alder wood manifested by a change in colour; (II) evaporation of bound water from alder wood below the hygroscopicity limit is performed at temperatures td = 60 - 80 °C. The color coordinates of steamed alder wood after drying by a given mode in the CIE L* a* b* colour space are: L* = 62.5 ± 1.7; a* = 13.1 ± 0.8; b* = 18.5 ± 0.9. Total colour difference ∆E = 1.6. According to the categorization of wood color changes in thermal processes of wood , this change belongs to small (insignificant) color changes.

The Effects of Drying Techniques on Clay-Rich Soil Texture

1974 ◽  
Vol 32 ◽  
pp. 466-467
Author(s):  
T. G. Naymik
Keyword(s):  
Critical Point ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Drying Methods ◽  
Air Drying ◽  
Freeze Dried ◽  
Critical Point Drying ◽  
Set Up ◽  
The Relationship ◽  
Quartz Grains

Three techniques were incorporated for drying clay-rich specimens: air-drying, freeze-drying and critical point drying. In air-drying, the specimens were set out for several days to dry or were placed in an oven (80°F) for several hours. The freeze-dried specimens were frozen by immersion in liquid nitrogen or in isopentane at near liquid nitrogen temperature and then were immediately placed in the freeze-dry vacuum chamber. The critical point specimens were molded in agar immediately after sampling. When the agar had set up the dehydration series, water-alcohol-amyl acetate-CO2 was carried out. The objectives were to compare the fabric plasmas (clays and precipitates), fabricskeletons (quartz grains) and the relationship between them for each drying technique. The three drying methods are not only applicable to the study of treated soils, but can be incorporated into all SEM clay soil studies.

Examination of Tobacco Hygroscopicity / Über die Hygroskopizität des Tabaks

1965 ◽  
Vol 3 (1) ◽  
Author(s):  
L. Hübschen
Keyword(s):  
Moisture Content ◽  
Sorption Isotherm ◽  
Initial Moisture Content

AbstractThe present paper shows the detectable factors on which a sorption isotherm depends. Even if it is well-known that a sorption isotherm is most essentially conditioned by influences of the respective tobacco variety, other factors, such as temperature, initial moisture content, or fibre dimension, play a part as well. In general, a sorption isotherm constitutes a ''summation'' of such factors and, in the end, a combination of desorption and adsorption if the tobacco is dried or moistened from the average commercial moisture content. The tobacco hysteresis is experimentally investigated and discussed

Pengeringan Biji Kakao dengan Pengering Surya Tipe Terowong Berpenggerak Sel Fotovoltaik di Manokwari

Agrotek ◽  
2018 ◽  
Vol 2 (6) ◽  
Author(s):  
Wilson Palelingan Aman
Keyword(s):  
Moisture Content ◽  
Performance Test ◽  
Initial Moisture Content ◽  
Maximum Temperature ◽  
Photovoltaic Module ◽  
Cocoa Beans ◽  
Drying Time ◽  
Tunnel Dryer ◽  
Heat Collector ◽  
New Construction

<em>A research about cocoa beans drying used solar tunnel dryer with photovoltaic module driven have conducted in Manokwari. Solar tunnel dryer used in this research adapted from type Hohenheim with photovoltaic module and integrated air heat collector has been installed at the Department of Agricultural Technology, Papua State University Manokwari to dried cocoa beans. The objectives of this research were to design solar tunnel dryer and evaluate it�s performance in dryed cocoa beans. The result obtained was a new construction of solar tunnel dryer for cocoa beans with dimensions 6 m of length and 0,9 m of wide. The dryer completed with photovoltaic module to drive the blowers of hot drying air. �Performance test of the dryer showed that drying of 10 kg of cocoa beans with initial moisture content about 70% wet basis needed 13 hours of drying time to achieved final moisture content about 7,17% wet basis. The drying time achieved was faster compared than traditional solar drying that needed 20 hours of drying time. The maximum temperature achieved in drying chamber was 60 <sup>o</sup>C.</em>

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