• Title, Summary, Keyword: drying method

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A Study on the Thermal Characteristics of the Large Low Temperature Vacuum Dryer for Biological Drying (생체 건조용 대형 저온진공건조기의 열적 특성에 관한 연구)

  • 김경근;성부용;정한식;최순열;문수범
    • Journal of the Korean Society of Marine Engineering
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    • v.24 no.4
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    • pp.427-434
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    • 2000
  • In tradition, there have been two kinds of drying methods, which are sun drying and artificial drying. The sun drying method which has been adopted traditionally has been replaced by the hot-air drying method which is one of the most general methods of artificial drying, with its simple drying system, low initial cost of drying plant, and easy operating method. But the hot-air drying method has some defects; (1) much energy loss happens due to the discharge of hot air during the drying process, (2) control of drying rate is not easy on account of changing relative humidity of inlet air for uniform hot air temperature, (3) high temperature of foods in drying process brings about the production of low-grade drying products. Vacuum drying takes advantage of energy saving and mass production because it reduces the drying time by increasing the drying rate under low temperature condition. The aim of this paper is to develop the low temperature vacum dryer, with low initial investments and operating costs, easy operating method and trouble-free operation.

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Effects of Drying Methods Based on Exhaust Cycle and Time on the Quality and Drying of Red Peppers

  • Nam, Sang Heon;Ha, Yu Shin;Kim, Tae Wook
    • Journal of Biosystems Engineering
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    • v.39 no.2
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    • pp.101-110
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    • 2014
  • Purpose: The purpose of this study is to develop a system to optimize drying potential energy of the exhausted hot air by changing relative humidity of the air. This study modified the conventional drying method into a drying method changing exhaust cycle and time in order to control the relative humidity of the exhausted hot air during drying process. Method: A valve on the vent was controlled according to a preset time to change the exhaust cycle and time. This study analyzed the influence of the two different types of drying method on the drying characteristics, required energy, and quality of the dried peppers: conventional drying method exhausting hot air continuously and new drying method controlling exhaust cycle and time. Results: Drying characteristics based on exhaust time showed that drying time increased with exhaust time, and specific energy consumption was reduced by 28% from 18.39 MJ/kg (conventional method) to 13.24 MJ/kg when exhaust time was set to one minute. Drying characteristics based on heating time showed that drying time increased with heating time and specific energy consumption was reduced by 30% from 18.39 MJ/kg (conventional method) to 12.87 MJ/kg when exhaust time was set to 22 minutes. Drying characteristics based on exhaust cycle showed that drying time increased with exhaust cycle, and specific energy consumption was reduced by 31% from 18.39 MJ/kg (conventional method) to 12.69 MJ/kg when exhaust time was set to one minute and exhaust cycle was set to 22 minutes before drying and 40 minutes after drying. The quality of the dried red peppers showed that capsaicin, color, and sugar content were high as 34.87 mg/100g, 66.33, and 11.87%, respectively, when exhaust time was set to one minute and exhaust cycle was set to 22 minutes before drying and 40 minutes after drying. Conclusions: In order to utilize the drying potential energy of the exhausted air during drying process, the conventional drying method was modified into the drying method controlling exhaust cycle and time. The results showed that drying with exhaust cycle of one minute was more efficient in terms of drying time, required energy, and quality of the dried peppers than the one with exhaust cycle of 20~40 minutes.

Effect of Stem Drying Method during Curing Process on Physico-chemical Properties in Bulk Cured Leaves (Bulk건조에서 주맥건조방법이 잎담배 이화학성에 미치는 영향)

  • 이철환;이병철;진정의
    • Journal of the Korean Society of Tobacco Science
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    • v.22 no.2
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    • pp.133-137
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    • 2000
  • The bulk curing experiment to improve the quality of flue-cured leaves were carried out to evaluate relationship between the modified(3 step-up) drying and conventional drying method in bulk curing process. Modified drying method was somewhat higher values in yellowing color index of cured leaves, and less brittle than those in conventional drying program. As to the chemical properties, there was no difference in chemical component levels in cured leaves between the modified and the conventional methods, while the major chemical compounds in relation to aromatic essential oil of cured leaves showed mostly higher level in the modified method than that in conventional drying method. Additionally 3 step-up drying method increased the tobacco quality by 2 % in price per kg compared with conventional drying method.

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Quality Characteristics of Ginseng Powder using Molecular Press Dehydration Method (분자 압축 탈수방법을 이용한 인삼분말의 품질특성)

  • Lee, H.S.;Kwon, K.H.;Jeong, J.W.
    • Journal of Biosystems Engineering
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    • v.34 no.3
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    • pp.155-160
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    • 2009
  • This study was attempted to quality characteristics of ginseng powder using molecular press dehydration(MD) method. Ginseng powder was dried using maltodextrin as dehydrating agents, and the quality of the ginseng powder was compared with that of freeze-drying and hot air-drying samples in terms of colors, moisture contents and grain size. The colors of ginseng powder using MD-drying and freeze-drying was better than hot air-dried ginseng powder. The moisture contents of ginseng powder using MD-drying was 9.49%, while freeze-drying was 4.14% and hot air-drying 11.71% after 72ball mill times. The grain size of ginseng powder using MD-drying and freeze-drying was better than hot air-drying ginseng powder. These results suggest that drying of ginseng powder using molecular press dehydration method is very efficient, because minimal cell destruction may be achieved.

A Study on the Thermal Characteristics of the Low Temperature Vacuum Dryer by Material Layers (시료 두께에 의한 저온진공건조기의 열적 특성에 관한 연구)

  • 최순열;문수범
    • Journal of the Korean Society of Marine Engineering
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    • v.26 no.2
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    • pp.226-232
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    • 2002
  • In tradition, there have been two kinds of drying methods, which are sun drying and artificial drying. The sun drying method which has been adopted traditionally has been replaced by the hot-air drying method which is one of the most general methods of artificial drying, with its simple drying system, low initial cost of drying plant, and easy operating method. But the hot-air drying method has some defects ; (1)much energy loss happens due to the discharge of hot air during the drying process, (2)control of drying rate is not easy on account of changing relative humidity of inlet air for uniform hot air temperature, (3)high temperature of floods in drying process brings about the production of low-grade drying products. Also, the hot-air drying method is inducing environmental and sanitary problems which are resulting from the emission of high temperature and high humidity air, including stick on the drying progress. Vacuum drying technique, whose drying time and 7uantity of exhausting energy is about 1/3 ~1/4 of hot air drying, is very excellent in the drying efficiency. As the results, it took about 20 hours for material to reach about 18% of the final moisture content in order to store products for a long time, from about 470% of the early moisture content at the beginning of drying, and maximum drying rate comes to about $0.35 kg/m^2hr$ at about 350% of the moisture content.

A fish-drying control method based on skilled worker's performance

  • Nakamura, Makoto;Fujimoto, Masakatsu;Sakai, Yoshiro
    • 제어로봇시스템학회:학술대회논문집
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    • pp.379-384
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    • 1994
  • In this paper, a fish-drying control method is proposed, which utilizes prediction of proper change in- weight of material fish based on skilled worker's performance. The function of the proposed system is largely broken down into two procedures: The procedure before drying and the one during drying. The procedure before drying is the determination of necessary drying conditions and the required drying time. Required drying time and proper changes in weight for a specific product are obtained by using fuzzy inference and regression models. The procedure during drying is the prediction of the state of material at the end of drying, or the state of product and regulation of drying conditions to attain the prescribed goal before drying. The prediction of product is obtained by using a set of linear-differential equations obtained by the authors' previous work. Drying conditions are regulated by using fuzzy inference. A good agreement between the results of simulation and experiments is obtained, which implies the usefulness of the present control method.

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A Fixed Grid Finite Volume Analysis of Multi-Dimensional Freeze Drying Process under Vacuum Condition (고정격자계에서 유한체적법을 이용한 진공동결건조 과정의 열 및 물질전달에 대한 연구)

  • Chi-Sung, Song
    • Journal of the Korean Society of Marine Engineering
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    • v.28 no.6
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    • pp.981-992
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    • 2004
  • Freeze drying under vacuum condition is a complex process that involves simultaneous heat and mass transfer, sublimation of ice, and motion of sublimation front. Proper treatment of the motion of sublimation interface is crucial for an accurate prediction of the freeze drying process. Based on the enthalpy formulation that has been successfully used in liquid/solid phase change problems. a fixed grid method. streamlined for the freeze drying analysis. was developed in this study. The accuracy of the fixed grid method was checked by solving a one-dimensional tray freeze drying and a two-dimensional vial freeze drying problem and then comparing the results with those by the moving grid method. Finally. the freeze drying characteristics of two-dimensional slab and axis-symmetric cylinder was investigated using the fixed grid method.

Quality Change of Cinnamon Extract Prepared with Various Drying Methods (건조 방법에 따른 계피 Extract의 품질 변화)

  • 김나미;김동희
    • The Korean Journal of Food And Nutrition
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    • v.13 no.2
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    • pp.152-157
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    • 2000
  • In order to select the optimum drying method for the production of cinnamon extract, water extract and 70% ethanol extract of cinnamon were prepared. And then several drying method of oven drying, vacuum evaporation, spray drying and freeze drying were performed. Content of cinnamic acid, cinnamic aldehyde, eugenol, tannin and free sugar, and antioxidant activity, degree of browning, pH, color value, turbity and solubility were compared. In water extract, contents of cinnamic acid, cinnamic aldehyde, eugenol were 29.45mg/100g, 94.86mg/100g, 120.75mg/100g and decreased to 4.76%∼44.21%, 5.30%∼48.05%, 3.66%∼21.83% by oven dyring, vaccum drying, spray drying respectively, but freeze drying showed a little decrease of those components. In 70% ethanol extract, effectual components decreased to 76.05%∼88.38% and 26.86%∼78.76% by freeze drying and vacuum evaporation respectively. Antioxidant activity decreased by drying and decreasing rate in 70% ethanol extract was lower than water extract. Degree of browning increased as the drying temperature increased. Tannin and free sugars were little affected by drying temperature. Solubility decreased in oven drying and 70% ethanol extract. Overall data suggested that optimum drying methods of cinnamon extract were freeze drying in case of water extract and freeze drying and vaccum drying in case of 70% ethanol extract.

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Comparison of Dried Hot Pepper Quality and Production Efficiency by Drying Methods (건조방법에 따른 건고추의 품질특성과 생산효율 비교)

  • Jo, Myeoung Hee;Shin, Jong Hwa
    • Protected Horticulture and Plant Factory
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    • v.27 no.4
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    • pp.356-362
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    • 2018
  • Hot pepper is a kind of seasoning vegetables, which is a major item in the Korean vegetable market. Since the use of hot pepper is processed into pepper powder, which is a powder form of dried hot pepper, improvement of quality and productivity of dried hot pepper is important. Therefore, this experiment was conducted to suggest proper drying method by comparing the changes of hot pepper powder ingredients considering production cost according to the drying method. As a drying method, we used sun drying and heat drying which are widely used in practice. We also compared the productivity and quality of dried hot pepper by applying a dehumidifying drying method using a dehumidifier. Drying rate of hot pepper was highest of 85.1% at heat drying. Accordingly moisture content of hot pepper powder was lowest of 13.5% at heat drying. The American Spice Trade Association (ASTA) color value, which influenced the coloring of red pepper, showed higher in heat drying and dehumidified drying treatment than the sun drying treatment. The content of capsaicinoids was higher at sun drying treatment than that of at both heat drying and dehumidified drying treatments. The content of sugar was higher at heat drying and dehumidified drying treatment where drying time was relatively short than that of sun drying treatment. Also, there was no significant difference in sugar content between the two treatments. The production cost of dried hot pepper with dehumidified drying was 9.9% more efficient than heat drying. Through this study, it was found that heat and dehumidified drying method were effective in increasing sugar content and coloring of hot pepper powder. In order to improve the capsaicinoid content of red pepper, it is considered that appropriate drying temperature and drying time should be added in the process of heat drying and dehumidified drying.

Effect of Opening Ratio of Red Pepper Surface on Drying (고추 과피의 천공률이 건조에 미치는 영향)

  • Cho, Y.J.
    • Journal of Biosystems Engineering
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    • v.18 no.3
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    • pp.270-274
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    • 1993
  • Many researches have been performed to shorten drying time and cost of red pepper in Korea. Nevertheless, an effective drying method for red pepper is not developed yet. This study was conducted to analyze the effect of opening ratio of red pepper's surface on drying for development of an effective drying method. The drying method with punching treatment is expected to be effectively utilized for shortening drying time and improving quality of red pepper.

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