• Title/Summary/Keyword: Vacuum drying

Search Result 286, Processing Time 0.029 seconds

Comparison of Longitudinal Liquid Permeability of Pinus koraiensis Sapwood Treated by Steaming and Various Drying Methods (증기 및 여러 가지 건조방법으로 처리된 잣나무 변재의 섬유방향 액체투과율 비교)

  • Kang, Ho-Yang;Lu, Jianxiong
    • Journal of the Korean Wood Science and Technology
    • /
    • v.33 no.6 s.134
    • /
    • pp.17-24
    • /
    • 2005
  • Korean pine (Pinus koraiensis Sieb.et Zucc.) boards of 30 mm thickness were treated by steaming and four different drying methods. Small specimens were taken from the sapwoods of the treated boards and their longitudinal liquid permeability was measured according to Darcy's law. The specimens were also extracted with alcohol and aceton solutions to examine the mechanism of liquid flow in wood. It was observed that specific permeability drastically decreases with measurement time, resulting in violation of Darcy's law. It may be due to that air bubbles formed under vacuum block flow paths in resin canals. The average specific permeabilities of non-extracted and extracted specimens are different from one treatment to another. It is supposed that the properties of residual resin in resin canals change depending on the conditions of treatments. Anatomical examination was conducted with a scanning electron microscope.

Characteristics of the Radio-Frequency/Vacuum Drying of Heavy Timbers for Post and Beam of Korean Style Housings Part II : For Korean red pine heavy timbers with 250 × 250 mm, 300 × 300 mm in cross section and 300 mm in diameter, and 3,600 mm in length

  • Lee, Nam-Ho;Zhao, Xue-Feng;Shin, Ik-Hyun;Park, Moon-Jae;Park, Jung-Hwan;Park, Joo-Saeng
    • Journal of the Korean Wood Science and Technology
    • /
    • v.39 no.2
    • /
    • pp.132-139
    • /
    • 2011
  • This study examined the characteristics of radio-frequency/vacuum dried Korean red pine ($Pinus$ $densoflora$) heavy timbers with 250 ${\times}$ 250 mm (S), 300 ${\times}$ 300 mm (L) in cross section and 300 mm in diameter, and 3,600 mm in length, which were subjected to compressive loading after a kerf pretreatment. The following results were obtained : The drying time was short and the drying rate was high in spite of the large cross section of specimens. The moisture gradient inall specimens was gentle in both longitudinal and transverse directions owing to dielectric heating. The shrinkage of the width in the direction perpendicular to was 21 percent ~ 76 percent of that of the thickness of square timbers in the direction parallel to the mechanical pressure. The casehardening for all specimens was very slight because of significantly reduced ratio of the tangential to radial shrinkage of specimens and kerfing. The surface checks somewhat severely occurred although the occurrence extent of the surface checks on the kerfed specimens was slight compared withthat on the control specimen.

Experimental Study on Prediction and Diagnosis of Leakage and Water Absorption in Water-Cooled Generator Stator Windings by Drying Process Analysis (수냉각 발전기 고정자 권선의 건조 과정 분석을 통한 누설 및 흡습 예측 진단에 관한 실험적 연구)

  • Kim, Hee-Soo;Bae, Yong-Chae;Lee, Wook-Ryun;Lee, Doo-Young
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.34 no.9
    • /
    • pp.867-873
    • /
    • 2010
  • The failure of water-cooled generator stator windings as a result of insulation breakdown due to coolant water leaks and water absorption often occurs worldwide. Such failure can cause severe grid-related accidents as well as huge economic losses. More than 50% of domestic generators have been operated for over 15 years, and therefore, they exhibit signs of aging. Leaking and water-absorbing windings are often found during an overhaul. In an existing method for evaluating the integrity of generator stator windings, the drying process of the interior of the windings is ignored and only final leak tests are performed. In this study, it is shown that water leaks and water absorption in stator windings can be detected indirectly through vacuum pattern analysis in the vacuum drying mode, which is the used in the preparation stage of the leak test.

Effect of Drying Methods on Longitudinal Liquid Permeability of Korean Pine

  • Lee, Min-Gyoung;Lu, Jianxiong;Jiang, Jiali;Kang, Ho-Yang
    • Journal of the Korean Wood Science and Technology
    • /
    • v.36 no.5
    • /
    • pp.49-55
    • /
    • 2008
  • This study was carried to investigate the effects of steaming and four different drying methods on the longitudinal liquid permeability of Korean pine (Pinus koraiensis Sieb.et Zucc.) board. Four drying methods were air drying, conventional kiln drying, microwave-vacuum drying and high temperature drying. Darcy equation was used for calculating the specific permeability of the small sapwood specimens taken from the treated boards while capillary rising method was used for the heartwood specimens. The sapwood specimens were extracted with water and benzene-alcohol solution to examine the mechanism of liquid flow in treated wood. No significant correlation was found between specific permeability and the number of resin canals of the sapwood specimens. Extraction decreased the differences of specific permeabilities of the sapwood specimens between the five treatment methods. The effects of extraction on the longitudinal permeability are different between five treatments. The fluid path in heartwood was observed by dynamic observation method.

Characterization of Vacuum Dried Y, Ba, and Cu Oxalate Precipitates (진공건조에 의한 Y, Ba, Cu 질산염의 Oxalate 침전물에 대한 연구)

  • Kim, Bae-Yeon;Lee, Deuk-Yong;Kim, Chul-Min;Lee, Chang-Jae;Jung, Sung-Sik
    • Journal of the Korean Ceramic Society
    • /
    • v.44 no.8
    • /
    • pp.457-463
    • /
    • 2007
  • Y, Ba and Cu nitrates were precipitated by oxalic acid at pH 4. The Y, Ba and Cu oxalate powders were vacuum dried and characterized by XRD, DT/TGA and etc. Yttrium nitrate precipitated as $NH_4Y(C_2O_4){_2}H_2O$ and converted to $Y_2O_3$ above $450^{\circ}C$. Ba precipitated with two phases, $Ba(HC_2O_4){_2}2H_2O\;and\;Ba(C_2O_4)$. The amount of each precipitates was 4 : 1, Cu precipitated non-hydrated form, $Cu(C_2O_4)$. The vacuum drying was successful to characterize precipitated powder, which had been generally known as amorphous gel.

Comparison of the Physicochemical Properties of Meat and Viscera of Dried Abalone (Haliotis discus hannai) Prepared using Different Drying Methods (건조방법에 따른 건조 전복 (Haliotis discus hannai)의 이화학적 특성 비교)

  • Park, Jeong-Wook;Lee, Young-Jae;Park, In-Bae;Shin, Gung-Won;Jo, Yeong-Cheol;Koh, So-Mi;Kang, Seong-Gook;Kim, Jeong-Mok;Kim, Hae-Seop
    • Food Science and Preservation
    • /
    • v.16 no.5
    • /
    • pp.686-698
    • /
    • 2009
  • We sought basic data for product development and storage improvement of abalone. We explored drying methodologies, such as shade drying, cold air drying, and vacuum freeze drying. We also examined various physicochemical features of both meat and viscera. Raw abalone meat had $78.88{\pm}1.01%$ moisture, $9.24{\pm}0.27%$ crude protein, and $10.05{\pm}0.81%$ carbohydrate (all w/w). The moisture level of dried abalone meat was highest after cold air drying, at $18.38{\pm}0.91%$, and lowest after vacuum freeze drying, at $1.05{\pm}0.05%$. The total amino acid content of raw abalone meat was $17,124.05{\pm}493.18\;mg%$, and fell after shade-drying to $12,969.92{\pm}583.65\;mg%$, and to $13,328.78{\pm}653.11\;mg%$ after cold air drying. The total free amino acid content of raw abalone meat was $4,261.99{\pm}106.55\;mg%$, and rose after shade-drying to $6,336.50{\pm}285.15\;mg%$, to $5,072.04{\pm}248.53\;mg%$ after cold air drying, and to $4,638.85{\pm}218.03\;mg%$ after vacuum freeze drying. The fatty acid proportions in raw abalone meat were $47.00{\pm}0.99%$ saturated, $22.18{\pm}1.05%$ monounsaturated, and $30.82{\pm}1.45%$ polyunsaturated. In the viscera, however, the proportions were $36.72{\pm}0.74%$ saturated, $25.44{\pm}1.12%$ monounsaturated, and $37.84{\pm}1.67%$ polyunsaturated. The contents of chondroitin sulfate in raw abalone were $11.95{\pm}0.35%$ in meat and $7.71{\pm}0.19%$ in viscera (both w/w). After shade-drying, the chondroitin sulfate content was $16.57{\pm}0.90%$ in meat and $9.24{\pm}0.50%$ in viscera. The figures after cold air drying were $16.17{\pm}0.79%$ and $12.44{\pm}0.61%$, and those after vacuum freeze drying $25.17{\pm}1.16%$ and $15.22{\pm}0.70%$ (thus including the highest meat content). The level of collagen in raw abalone was $69.80{\pm}3.07\;mg/g$ in meat and $40.62{\pm}1.79\;mg/g$ in viscera. Meat and viscera dried in the shade had $144.05{\pm}7.78\;mg/g$ and $44.16{\pm}2.39\;mg/g$ collagen, respectively, whereas the figures after cold air drying were $133.29{\pm}6.53\;mg/g$ and $69.20{\pm}3.39\;mg/g$, and after vacuum freeze drying $137.51{\pm}6.33\;mg/g$ and $60.61{\pm}2.79\;mg/g$. Volatile basic nitrogen values of raw abalone showed a higher content in viscera, at $19.01{\pm}0.84\;mg%$, compared to meat ($10.10{\pm}0.44\;mg%$). The value for shade-dried abalone meat was $136.77{\pm}7.37\;mg%$ and that of viscera $197.97{\pm}10.69\;mg%$. After cold air drying the meat and visceral values were $27.32{\pm}1.34\;mg%$ and $71.37{\pm}3.50\;mg%$, respectively.

Influence of Freezing Process on the Change of Ice Crystal Size and Freeze-Drying Rate in a Model System (모델 시스템에서 동결속도에 따른 얼음 결정체의 크기 및 동결건조속도의 변화)

  • Byun, Myung-Hee;Choi, Mi-Jung;Lee, Sung;Min, Sang-Gi
    • Food Science of Animal Resources
    • /
    • v.18 no.2
    • /
    • pp.164-175
    • /
    • 1998
  • The objective of this study was to investigate the effects of freezing rate on ice crystal size and freeze-drying rate. Our experiments were carried out with self-manufactured freeze-dryer. Gelatin gels (2% w / w, 80$\times$20mm) were frozen unidirectionally (Neumann's model) from the bottom at -45, -30, -20, and -15$^{\circ}C$ and followed with freeze-drying. Under the upper conditions we measured freezing rate and the change of temperature and pressure during freeze drying. Freeze-dried gelatins were cut horizontally into 5 mm thickness from the bottom and measured their pore sizes. Also freeze-drying rate(primary drying) is estimated by measuring the temperature of sample and pressure of vacuum chamber. During freeze-drying, profiles of pressure and temperature were shown constant tendency regardless of freezing temperature and we could expect the end-point of freeze drying by considering pressure and temperature together. In temperature profiles, the point which temperature increased significantly was observed during freeze-drying. There is no relationship between freeze temperature and drying rate of primary drying in our model system. As freezing temperature increased, ice crystal size(X*) which correspond to 63.2% of cumulative frequency was increased and at the same freezing temperature ice crystal size(X*) was decreased with distance from the bottom of the sample. Freezing conditions have a strong influence on the quality of the final freeze-dried products in freeze-drying system.

  • PDF

Effect of Different Pre-treatments on the Physicochemical and Antioxidant Activities of Cold-Vacuum Dried Peaches (전처리조건에 따른 냉풍감압건조 복숭아의 이화학적 및 항산화 활성)

  • Kwon, Gi-Man;Kim, Jae-Won;Youn, KwangSup
    • Korean Journal of Food Science and Technology
    • /
    • v.45 no.4
    • /
    • pp.466-472
    • /
    • 2013
  • This study was performed to determine the effects of the pretreatment and cold-vacuum drying methods on the physicochemical properties and antioxidant activities of dried peaches. Moisture content was significantly lower with 0.3% NaCl treatment with cold-vacuum drying. The pH, brix and acid ratio (SS/TA) were the lowest with 1.0% soluble Ca treatment, while soluble solid and SS/TA were significantly higher with 0.1% vitamin C treatment compared to those with other treatments. The ${\delta}E$ and browning degree was lower in the pretreated sample compared to the untreated sample. Cutting strength of dried peaches was highest in the pretreated samples, and it was the highest with 1.0% soluble Ca treatment. Total sugar content with 0.1% vitamin C and 1.0% soluble Ca treatment was significantly higher than that with 0.3% NaCl treatment. The free sugar content was lower with 0.3% NaCl treatment but it was higher with 0.1% vitamin C and 1.0% soluble Ca treatment. The sensory evaluation result was highest with 0.1% vitamin C treatment. Phenolic compounds and antioxidant ability were the highest with the 0.1% vitamin C and 0.1% soluble Ca treatment; all the dried peaches showed relatively high antioxidant activities. These results suggest that pretreatment can affect the quality of dried peaches, showing that cold-vacuum drying can be applied for the production of high quality dried peach products.

Drying Properties of Cashew Film by Thinning Conditions (희석조건과 카슈도막의 건조성)

  • 노정관
    • Journal of the Korea Furniture Society
    • /
    • v.11 no.1
    • /
    • pp.37-44
    • /
    • 2000
  • This work was done to investigate problems of cashew coating in a wooden-art industry such as ritual vessels and to improve a curing property of cashew film. The main problem in the cashew coating industry was a small-scale business, insufficiency of facilities, lack of knowledge about cashew resin and painting, and lack of a technology of productivity improvement by accelerated drying time of cashew film. In present, cashew coating for ritual vessels mostly used the petroleum as a thinner. The time of set to touch of cashew film thinning with petroleum on glass plates was increased with the increasement of the thinning proportion, but retarded from 3 to 11 times compared to that of an exclusive thinner according to thinning level. The addition of 20% aceton to petroleum contributed to the high reduction rate up to about 60% at the thinning level of 100%, which was effective to accelerate the drying time of cashew film. Even though only the petroleum or the petroleum-aceton(20%) mixture was used as a thinner, it did not exhibit any distinguishable differences in crack and appearance of cashew-film coated on Frexinus rhynchophylla after 5 cycles of soak under the vacuum-drying treatment.

  • PDF

Homogeneous Shape Forming of Alumina by Pressure-Vacuum Hybrid Slip Casting (가압-진공 하이브리드 주입성형에 의한 알루미나의 균질 성형)

  • Cho, Kyeong-Sik;Song, In-Beom;Kim, Jae
    • Journal of the Korean Ceramic Society
    • /
    • v.49 no.6
    • /
    • pp.592-600
    • /
    • 2012
  • Conventional methods for preparing ceramic bodies, such as cold isostatic pressing, gypsum-mold slip casting, and filter pressing are not completely suitable for fabricating large and thick ceramic plates owing to disadvantages of these processes, such as the high cost of the equipment, the formation of density gradients, and differential shrinkage during drying. These problems can be avoided by employing a pressure-vacuum hybrid slip casting approach that considers not only by the compression of the aqueous slip in the casting room (pressure slip casting) but also the vacuum sucking of the dispersion medium (water) around the mold (vacuum slip casting). We prepared the alumina formed bodies by means of pressure-vacuum hybrid slip casting with stepwise pressure loading up to 0.5 MPa using a slip consisting of 40 vol% solid, 0.6 wt% APC, 1 wt% PEG, and 1 wt% PVA. After drying the green body at $30^{\circ}C$ and 80% RH, the green density of the alumina bodies was about 56% RD. The sintered density of an alumina plate created by means of sintering at $1650^{\circ}C$ for 4 h exceeded 99.8%.This method enabled us to fabricate a $110{\times}110{\times}20$ mm alumina plate without cracks and with a homogeneous density, thus demonstrating the possibility of extending the method to the fabrication of other ceramic products.