• 대한환경공학회지
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• 제32권4호
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• pp.341-348
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• 2010

유중 건조 공정의 기본 원리는 수분과 비열차이가 있는 오일을 가열할 때 온도 차이에 따라 형성되는 슬러지 내부의 급격한 압력 변화를 이용한다. 즉 슬러지 내부에 발생하는 급격한 압력 상승이 이루어질 때 슬러지 공극을 통하여 수분이 빠르게 배출하도록 하는 것이다. 본 연구의 목적은 유중 건조공정 중 다양한 운전 변수가 건조효율에 미치는 영향을 구체적으로 규명하기 위한 것이다. 변수 연구를 위하여 일련의 건조 실험과 수치해석을 시도하였으며 그 결과 건조온도, 건조시간, 폐오일종류, 슬러지 종류 등 중요 실험변수에 따른 건조곡선이 얻어졌다. 건조 온도 변화에 따른 연구 결과는 폐오일의 종류에 관계없이 $140^{\circ}C$ 이상으로 운전하는 것이 건조효율에 유리한 것으로 나타났으며 이 결과는 수치 해석적 결과로도 확인되었다. 그리고 슬러지 직경의 경우 직경이 감소할수록 효율적으로 건조되는 경향으로 보였으며 이는 비표면적의 증가에 기인하는 것으로 판단되었다. 오일 종류나 물성의 변화에 대한 연구에서는 오일의 점도가 가시적인 영향을 주는 것으로 나타났다. 특히 점도가 높은 오일의 경우 건조 초반에 수분 증발이 현저히 지체되는 현상이 나타났다. 그러나 건조온도 $140^{\circ}C$ 이상에서는 이러한 지체 현상이 감소하는 결과를 나타내었다. 슬러지 종류에 따른 연구에서는 전체적으로 큰 차이를 나타내지는 않았으나 하수슬러지가 다른 종류의 슬러지에 비하여 좀 더 가시적으로 양호한 수분제거 양상을 나타내었다. 수치 해석적 연구는 실험적 연구에 대한 상호보완적인 연구로서 가능성을 보였으나 복잡한 세부모델에 대한 경험적인 모델개발의 필요성이 제기되었다.

• 태양에너지
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• 제9권3호
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• pp.3-12
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• 1989

Semi-greenhouse type solar-dehumidification drying of oak was carried out to investigate the possibility to dry wood using solar energy in Korea. The energy balance equation was set up, considering all the energy requirements, and the solar radiation was calculated to analyze the efficiencies of solar dryer with and without the dehumidifier. The average temperature inside dryer and collector rose up to $52^{\circ}C$ and $70^{\circ}C$, respectively. The average daily total beam, diffuse, and ground-reflected radiations were 7.27MJ, 8.70MJ, and 0.33MJ on the roof and 2.08MJ, 4.84MJ, and 5.37MJ on the south wall collector, respectively. Heat efficiency of solar dryer was 14.04% with dehumidifier and 13.13% without dehumidifier. The energy required to remove 1g of water from wood was 0.0289MJ/g in solar-dehumidification drying and 0.0310 MJ/g in semi-greenhouse type solar drying.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.103.2-108
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• 2003

The purpose of this study is to understand the Physical characteristics of cement mortar about humidity control on indoors and wall crack restraint. Experiments were conducted on the strength, water absorption coefficient, drying-shrinking crack, length change, cracks of mortar plaster bases according to mixture rate by mixing cellulose fiber and diatomite into cement mortar. The excellent tensile & bending reinforcement efficiency of cellulose fiber and void filling ability of diatomite proved to be suppressing cracks of cement. And diatomite seems to improve moisture-protection efficiency of cement mortar because of its high water absorption ratio and slow drying speed.

• 대한기계학회논문집B
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• 제33권8호
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• pp.629-634
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• 2009

In this paper, drying mechanism is analyzed for improving the energy efficiency of an electric clothes dryer which consumes more electric power than other appliances. For the purpose, characteristic curves of the dryer such as temperature, relative humidity, evaporation rate, mass transfer coefficient, remaining moisture content curves are experimentally obtained. Based on the experimental results and analysis of drying mechanism, the effect of power of a heater and heat loss on the power consumption of an electric clothes dryer are systematically presented. These results demonstrate the feasibility of controlling heat loss at the heater as well as the backduct component to decrease the power consumption of an electric clothes dryer.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2262-2267
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• 2008

In this paper, drying mechanism is analyzed for improving the energy efficiency of an electric clothes dryer which consumes more electric power than other appliances. For the purpose, characteristic curves of the dryer such as temperature, relative humidity, evaporation rate, mass transfer coefficient, remaining moisture content curves are experimentally obtained. Based on the experimental results and analysis of drying mechanism, the effect of power of a heater and heat loss on the power consumption of an electric clothes dryer are systematically presented. These results demonstrate the feasibility of controlling heat loss at the heater as well as backduct component to decrease the power consumption of an electric clothes dryer.

• 설비공학논문집
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• 제21권1호
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• pp.1-8
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• 2009

The simulation of a heat pump dryer has been carried out to figure out the effect of air flow rate on the drying performance represented by MER, SMER, and so on. The simulation includes the analyses of one-stage heat pump cycle and simple drying process using the drying efficiency. The heat pump cycle with Refrigerant 134a has been considered. In the dryer, some of drying air from the drying chamber flows through the heat pump system, the rest of air bypasses the heat pump system. The two air flows joins before the drying chamber inlet. The performance parameters considered in the present study are MER, SMER, the temperature and humidity of drying air. Those parameters are compared for different total air flow rate or bypass air flow rate.

• 생물환경조절학회지
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• 제27권4호
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• pp.356-362
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• 2018

고추는 조미채소의 한 종류로 우리나라 채소시장에서 큰 비중을 차지하는 품목이다. 대부분 고추의 이용은 건고추의 분말형태인 고춧가루로 가공하여 이용되고 있으므로, 고추건조에 대한 품질과 생산성 향상이 중요한 부분이다. 따라서 본 연구에서는 고추의 건조방법에 따라 고춧가루의 품질을 좌우할 수 있는 성분의 변화에 대하여 비교하고, 생산비를 고려하여 적정 건조방법을 제시하고자 실험을 수행하였다. 건조방법으로는 관행으로 많이 이용되는 양건과 화건을 이용하였으며, 제습기를 이용한 제습건조방식을 추가 적용하여 건고추 생산성과 품질을 비교하였다. 고추의 건조방식에 따른 건조율은 화건이 85.1%로 제일 높았고, 이에 따라 고춧가루의 수분함량도 13.5%로 가장 낮게 나타났다. 고추의 색택을 좌우하는 ASTA(American Spice Trade Association) 색도는 양건처리에 비해 화건과 제습건조처리가 높은 결과를 보였다. 고춧가루의 신미성분인 capsaicinoid 함량은 양건처리에 비하여 화건과 제습건조처리에서 모두 낮게 나타나 이에 대한 추가적인 적정 건조조건에 대한 연구가 추가되어야 된다. 당함량은 건조시간이 비교적 짧았던 화건과 제습건조처리에서 양건에 비해 높게 나타났으나 두 처리간에는 유의한 차이를 보이지 않았다. 건고추 생산비용은 제습건조처리가 화건처리에 비해 9.9% 효율이 높은 것으로 나타났다. 본 연구를 통해 화건과 제습건조가 당함량의 증진과 건고추의 색 발현 측면에서는 효과적 이었음을 알 수 있었다. 고추의 신미성분인 capsaicinoid 함량 증진을 위해서는 화건과 제습건조처리에서 적정한 건조온도와 건조시간에 대한 연구가 추가되어야 될 것으로 판단되었다.

• 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.

• 환경위생공학
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• 제22권1호
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• pp.57-66
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• 2007

Changes in the alliinase activity during the hot air drying and vacuum freeze drying of garlic samples treated as the whole, sliced and crushed state were investigated. The specific activity of alliinase in raw garlic was 8.52 units/mg protein. The activity in the whole garlic prepared by the hot air drying for 8 hrs was reduced remarkably to 5.22 units/mg protein with 61% remaining and to 4.25 units/mg protein with 50% remaining for 36 hrs. The activity in the sliced garlic prepared by the hot air drying for 36 hrs was reduced to 3.55 units/mg protein with 42% remaining and the activity in the crushed garlic prepared by the hot air drying for 36 hrs was reduced to 3.12 units/mg protein with 37% remaining. The garlic sample sliced or crushed was higher than the whole state in the efficiency of drying but was lower in the remaining activity of alliinase. The activity in the whole garlic prepared by the vacuum freeze drying for 8 hrs was reduced to 7.21 units/mg protein with 85% remaining and to 5.53 units/mg protein with 65% remaining for 36 hrs. The activity in the sliced garlic prepared by the vacuum freeze drying for 36 hrs was reduced to 4.55 units/mg protein with 53% remaining and the activity in the crushed garlic prepared by the vacuum freeze drying for 36 hrs was reduced to 4.16 units/mg protein with 49% remaining. The remaining activity of alliinase in the garlic samples prepared by the vacuum freeze drying was higher than the remaining activity in the garlic samples prepared by the hot air drying.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.187-192
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• 2000

The textile which is rotated in the tumbler dryer is dried by the heated air. the energy consumption for drying textile depends on various parameters. The objective of this study is to save the energy and the drying time. One of the various methods for energy saving is EGR(exhaust gas recirculation). We set the drying equipment for this study and perform the experimental study with the changes of the recirculation rate, the input power, and the air mass flow rate. We found the optimal drying conditions.