• 대한기계학회논문집B
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• 제31권10호
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• pp.860-867
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• 2007

Heat pump drying has a great potential for energy saving due to its high energy efficiency in comparison with conventional air drying. In the present study, the performance simulation for the basic design of a heat pump dryer has been carried out. The simulation includes one-stage heat pump cycle, simple drying process using the drying efficiency. As an example, the heat pump cycle with Refrigerant 134a has been investigated. For the operating conditions such as the average temperature of the condenser, the heat rate released in the condenser, the flow rate of drying air, and drying efficiency, the simulation has been carried out to figure out the performance of the dryer. The parameters considered in the design of the dryer are COP, MER, SMER, the rate of dehumidification, the temperature and humidity of drying air and those parameters are compared for different conditions after carrying out the simulation.

• Journal of Biosystems Engineering
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• 제21권1호
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• pp.72-83
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• 1996

This study was performed to find out drying characteristics and develop drying model for the design of an efficient dryer or drying system of garlic. The basic model which describes drying phenomenon of garlic was first established. A series of drying test were conducted with two varieties of garlic(Uiseong, Namdo) at 9-different drying conditions (drying temperatures ; $40^{\circ}C$, $50^{\circ}C$, $60^{\circ}C$, relative humidities ; 20%, 35%, 50%) and statistical analysis was made to fit the data with exponential equation, approximated diffusion equation, page equation, thompson equation and wang equation, respectively. In this test, the effects of drying air temperature and relative humidity on the drying rate were undertaken. Finally, new drying model based on these experimental results was developed to describe the drying characteristics of garlic. Also, the volatile components of garlic extracts were investigated. For experiment both Uisoeng and Namdo garlic were dried by heated-air-drying, followed by ether extraction. The extracts were analysed by Gas chromatography/Mass spectrometer.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.254-259
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• 2009

The mixed cooling dryer has been developed significantly by adopting both advantages of cooling dryers and desiccant dryers. In this study, it is introduced that the desired effect, such as drying rate period reduction and energy-saving, could be achieved only by adding the desiccant dryer if an existing cooling dryer is used. The experiment should be conducted for quite long time due to the material selection, so it is regrettable that there are not enough data.

• Journal of Biosystems Engineering
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• 제3권2호
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• pp.114-125
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• 1978

The use of petroleum fuels in grain drying causes problems of high cost and management. To solve these problems, it is required to study on soLar energy as an alternative to petroleum fuels for grain drying. The purposes of this study were to find out the optimum received area and air flow rate of a flat-plate solar air collector for grain drying and to assess its effects on grain drying with a small grain bin. The results of this study are summarized as follows ; 1. The calculated optimum tilt angles of the collector in the summer and autumn drying seasons were 20 and 50 degress, respectively, in suwon area. 2. The outlet temperature of the collector was $36^\circ C$ on the daily average with the maximum of $36^\circ C$ at 12:00 o clock. Solar radiation on the collector surface was 1.04 ly( 1 langley = 1 cal/$cm^2$) per minute on the daily average and 1.30 ly per minute on the maximum at 11:00am. The thermal efficiency of the collector was 62.4 percent on the daily average, and the air flow-rate per unit receiving are was 1.03 $m^3$/min/$m^2$.4. The calculated optimum receiving area and the air flow-rate per unit cubic volume for paddy in autumn drying season was 2 $m^2$ and 2$m^3$/min , respectively. 5. not significantly difference in the collector efficiency was appeared between the rotating and fixed type of solar collector. 6. For drying of wheat with 0.6 meter of the depth in the bin, approximately 9 hours were required to reduce the moisture content from 21.6% to 13% with air follow rate of 5 $m^3$/min an initial moisture per cubic meter of wheat and with air temperature of $52^\circ C$. 7. In the drying test of rough rice with a turning operation in a grain bin approximately 21 hours were required to reduced the moisture from 21% to 14.5% with airflow rate of 2 $m^3$/min per cubic meter of rice and the air temperature of $43.5^\circ C$. 8. Over-drying at the bottom and less -drying at the top of the grain mass was resulted from the high -temperature of drying air which was obtained from the flat-plate solar collector in this test. An appropriate operation should be prepared for the uniform moisture of the grain in the bin.

• Journal of Biosystems Engineering
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• 제40권3호
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• pp.232-237
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• 2015

Purpose: In Korea, wheat is dried using circulating cross-flow grain dryers. However, there is no research on wheat drying which can be utilized for the dryers. Therefore, this study developed and evaluated a simulation of the circulating cross-flow dryer, and examined the effects of various factors on drying performance. Methods: The simulation program was developed using drying models and was evaluated against wheat-drying experiments with a dryer having a 30-ton capacity. The influence of drying temperature, air volume, and grain falling rate on drying performance were examined through the simulation. Results: The experimental results validated the simulation program by showing the same root mean square error (RMSE) for moisture content (0.286%) and drying rate (0.056%/h) in both the experimental data and the simulation values. The appropriate wheat-drying parameter values, considering drying conditions, were determined to be $50^{\circ}C$ for drying temperature, $500m^3/min$ for air volume, and a grain falling rate of $36.0m^3/h$. Conclusions: The developed simulation program for circulating cross-flow dryers analyzed the influences of performance factors such as drying temperature, air volume, and falling rate on drying performance.

• Journal of the Korean Wood Science and Technology
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• 제4권1호
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• pp.48-53
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• 1976

This Study was carried out to investigate the course of air-drying and drying defects of red pine (Pinus densiflora S. et Z.) and Italian poplar (Populus eurameriana I-476) boards 1,2 and 3cm thick in the flat pile. The results are as follows. 1. Air-drying curves for red pine and Italian poplar boards were same as figure 1 and 2. These moisture contents were lower in July and August during seasoning periods. 2. Air drying time of red pine board required to dry 15 percent moisture content in one week for 1 cm board, five weeks for 2 cm board and six weeks for 3cm board respectively. In case of Italian poplar boards, in one week for 1 cm board, four weeks for 2 cm and five weeks for 3 cm board. The thickness of board influenced the time for air drying. 3. Drying defects such as checking, warping and staining happened badly in pine than in Italian poplar boards. Especially, checking was severe in thicker board and warping in thinner board.

• Journal of Biosystems Engineering
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• 제9권2호
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• pp.65-73
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• 1984

While most of researches on the performance of high temperature grain dryer have dealt mainly with improving dryer capacity and drying speed during the last twenty years, energy efficiency, in fact, has not been emphasized. Current fuel supplies and energy cost have shifted the emphasis to reducing the energy consumption for grain drying while maintaining dryer capacity and grain quality. Since the energy input for drying is relatively large, the recovery and reuse of at least part of the exhaust energy can significantly reduce the total energy consumption in existing drying systems. Unilization of exhaust heat in grain dryer either through direct recycling or by a thermal coupling in heat exchanger have been subject of a number of investigators. However, very seldom research in Korea has been done in this area. Three drying tests(non-recycling, 0.22 recycle ratio, and 0.76 recycle ratio)were performed to investigate the thermal efficiency and heat loss factors of continuous flow type dryer, and to analyze the effect of recycle ratio (weight of exhaust air recycled/total weight of input air) on the energy requriements for rough rice drying. The test results showed that when the exhaust air was not recycled, the energy lost from furnace was 15.3 percent of input fuel energy, and latent and sensible heat of exhaust air were 61.4 percent and 11.2 percent respectively. The heat which was required in raising grain temperature and stored in dryer was relatively small. As the recycle ratio of exhaust air was increased, the drying rate was suddenly decreased, and thermal efficiency of the kerosene burner was also decreased. Drying test with 0.76 recycle ratio resulted in 12.4% increase in fuel consumption, and 38.4% increase in electric power consumption as compared to the non-recycled drying test. Drying test of 0.22 recycle ratio resulted in 6.8% saving in total energy consumption, 8.0% reduction in fuel consumption, and 2.5% increase in electric power consumption as compared to the non-recycled drying test.

• 한국식품영양과학회지
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• 제27권5호
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• pp.908-913
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• 1998

Chemical components and some physical proeprties of fresh, defrosted and dried yams(Dioscoreab batatas) were determined to obtain basic data for high quality yam processing. Fresh yam showed 81.79% moisture and 15.24% N-free extract. The cohesiveness and adhesiveness of defrosted yam homogenate were significantly higher than those of fresh yam homogenate. Free sugars of yam were mainly composed of sucrose, rhamnose, fructose and glucose, and the contents of fructose and glucose were apparently decreased by hot air drying. Linoleic(45.64%), oleic(8.32%), and arachidic acids(7.40%) were major fatty acids of yam. Hot air drying caused a decrease in unsaturated fatty acids and an increase in saturated acids. Hot air-dried yam powder showed higher gelatinization properties than freeze-dryed yam powder, such asinitial pasting temperature, temperature at maximum viscosity, and viscosity at different parameters. Hot air-dried yam powder showed higher Hunter parameter b and ΔE values and lower L value than freeze-dried one.

• 한국식품조리과학회지
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• 제23권6호
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• pp.800-809
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• 2007

To develope Hanbang beef jerky as health food, six kinds of beef jerky were prepared by adding sugar (A), licorice (B) and three kinds of spice extracts (clove: C, fennel fruit: D and Chungyang green pepper extract: E) and mixture of all extracts (F). The effects of the drying method and added spice extracts on the quality characteristics of the beef jerky were evaluated. In general, the air-blast dried beef jerky contained $31{\sim}33%$ moisture, $50.0{\sim}51.2%$ crude protein, $7.2{\sim}7.8%$ crude lipid and $3.0{\sim}3.3%$ crude ash. For the mineral content of the air-blast dried jerky, the most prevalent mineral was Na $(1540.08{\sim}1838.17$ mg%), followed by K, P, Mg, and Ca. The Ca content of the beef jerky was highest in the mixed extract group (88.53 mg%), and the lowest content was in sugar-added group (53.12 mg%). For the color properties, the L-value (lightness), a-value (redness) and b-value (yellowness) were higher in the air-blast dried beef jerky than in the hot air dried samples. The drying methods showed their greatest affect on the redness (a) for all six jerkies (p<0.001). For the preference by sensory evaluation, the beef jerky samples with added sugar (A) and licorice extract (B) had significantly higher scores than the beef jerky samples with the added spice extracts, for both of air-blast drying and hot air drying (p<0.05). Preference for the air-blast dried beef jerkies with added clove (C) and fennel fruits (D) were significantly higher, in terms of taste, color, softness and aftertaste as compared to the respective hot air dried jerkies (p<0.01). Considering all the obtained results, we concluded that licorice and spice extracts can be used as natural preservatives in the development of health foods and the air-blast drying method is recommended to improve the quality characteristics of beef jerky.

• 동력기계공학회지
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• 제5권1호
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• pp.44-49
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• 2001

Low temperature vacuum drying technique shows very excellent energy efficiency and prominent drying performances compared with the conventional hot air drying technique. This study was focused on the thermal characteristics of the low temperature vacuum drying technique. From the results of this study, it was confirmed that the time consumption for drying with the new drying technique could be shortened to about 1/3 of the time consumption with the conventional hot air drying technique under the same drying conditions for wet products. Also, the maximum drying rate with the new drying technique reached to about $0.35kg/m^2h$ at about 400% of moisture content.