• Journal of Biosystems Engineering
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• 제39권2호
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• pp.96-100
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• 2014

Purpose: The objective of this study was to develop a classification index and the grade levels for a five-grade energy efficiency classification of agricultural dryers in Korea. Methods: The classification index and the grade levels were determined by using the performance test data published by the FACT over the last eight years to reflect a state of the art technology for agricultural dryers in Korea. The five grades were designed to have the classified dryers distributed normally over the grades with 15% for the $1^{st}$ grade, 20% for the $2^{nd}$ grade, 30% for the $3^{rd}$ grade, 20% for the $4^{th}$ grade and 15% for the $5^{th}$ grade. Results: The classification index was defined as the total amount of fuel and electrical energy consumed per 1% of the wet basis moisture content evaporated from a unit mass of grain or agricultural crops during the drying process: 1 MT of paddy rice for grain dryers and 1 kg of red pepper for agricultural crop dryers as the standard mass. Conclusions: The grade levels for the five-grade energy efficiency classification of grain dryers, kerosene dryers, and electric dryers were proposed in terms of the classification index value.

• Journal of Biosystems Engineering
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• 제13권2호
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• pp.51-62
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• 1988

Bulk-type dryers which are widely used for drying special agricultural products such as tobaco leaf, red pepper, mushroom, ginseng, medicinal herb, etc, began to be distributed on a full scale since 1980 and the total number of dryers introduced to farms reached to about 36,600 units as of the end of 1986. In this study a survery was carried on the farmers cultivating special crops, dryer manufacturers and related administrative institutes and associations by means of on-the-spot investigation, mail or interview to collect data on scales and patterns of farming, utilization of bulk-type dryers, production and price streams of the special crops etc. Based on the analysis of the data surveyed predictions were made for the total demand on the bulk-type dryers and for annual demand over five-year span.

• Journal of Biosystems Engineering
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• 제6권2호
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• pp.48-57
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• 1982

In order to improve the quality of traditionally sun-dried red peppers and to increase the efficiency of drying performance, three types of solar dryers were designed and built, and drying performance of the solar dryers was compared to traditional sun drying. Results obtained from the experiment are summarized as fallows: 1. The air temperature and relative humidity profiles over a 8-hour period measured at the specified locations in the drying chamber of solar dryers appeared to have large variation in each dryer. The rate of drying increased with the temperature rise in the drying chamber of the solar dryer. 2. In general. drying with solar dryers proceeded faster than traditional sun drying. With A'-type of solar dryer developed in the second experiment it was possible to dry red peppers in seven days from an initial moisture content of 80% to safe storage conditions. The drying time with the A'-type solar drier was 50% shorter compared to traditional sun drying. 3. Red peppers appeared to have an increasing or constant-rate drying period until the weight of the product was reduced to about one half the initial weight, followed by a falling-rate drying period. When the dried red peppers were exposed to the atmospere during the night, the moisture content increased as much as 6%, which is much higher than for the grains. 4. It was suggested from the experiment that either a heat storage system or a supplemental heating system in the solar dryer was desirable for more efficient drying operation. 5. It was shown that the solar dryer developed in this study may be suitable for drying other vegetables and fishes, and also offered additional advantages of saving in drying time, maintaining sanitation and minimizing contamination by dust, insects and unfavorable weather condition.

• 한국산학기술학회논문지
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• 제13권9호
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• pp.3827-3834
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• 2012

최근 많은 열에너지를 필요로 하는 열풍식 건조기 대신 에너지 효율이 높은 히트펌프 건조기가 제지, 섬유, 목재, 식품 등 다양한 분야에서 사용되고 있다. 본 논문에서는 냉동 농산물 건조 초기에 전기히터 사용을 최소화하여 에너지 효율을 높이고자, 압축기 출구 고온가스 우회 시스템에 대한 히트펌프 사이클 특성을 이론적으로 고찰하였다. 또한, 추가 열을 확보하기 위하여 외부공기 유입을 위한 댐퍼를 고려하였고 이의 최적화를 통해 에너지 효율 향상이 가능함을 보였다.

• 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.

• 한국잠사곤충학회지
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• 제53권2호
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• pp.101-109
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• 2015

본 연구는 장기 냉동저장 오디에 대해 현재 사용하고 있는 방법이 보관 및 유통비용 등이 커 농가에 부담이 되므로, 이에 고가 건조기를 대체할 수 있는 값이 저렴한 상용화된 다목적농산물건조기를 통한 건조기 개량 및 반건조기술을 개발하였다. 연료와 히터의 건조온도를 $60^{\circ}C$로 설정하고, 상온통풍은 상온보다 온도를 낮추어 건조시험 한 결과 연료 3시간, 히터 1시간, 상온통풍 51시간인 조건에서 다른 조건과 비교해서 연료소모 및 전기사용량 면에서 가장 양호하였고, 품질에 있어서도 다른 조건에 비해 현저히 끈기가 있는 반 건조 특성을 나타내었으며, 완료된 건조시료의 상태도 상품성이 뚜렷한 암갈색을 나타냈다. 경도(압축력)은 건조 전보다 건조 후에, 항온보다는 변온에서 높게 나타났다.

• Agricultural and Biosystems Engineering
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• 제7권1호
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• pp.1-7
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• 2006

A need exists to monitor and control the localized high temperatures often experienced in solar grain dryers, which result in grain cracking, reduced germination and loss of cooking quality. A verified finite element model would be a useful to monitor and control the drying process. This study examined the feasibility of the finite element method (FEM) to predict temperature distribution in solar grain dryers. To achieve this, an indirect solar grain dryer system was developed. It consisted of a solar collector, plenum and drying chambers, and an electric fan. The system was used to acquire the necessary input and output data for the finite element model. The input data comprised ambient and plenum chamber temperatures, prevailing wind velocities, thermal conductivities of air, grain and dryer wall, and node locations in the xy-plane. The outputs were temperature at the different nodes, and these were compared with measured values. The ${\pm}5%$ residual error interval employed in the analysis yielded an overall prediction performance level of 83.3% for temperature distribution in the dryer. Satisfactory prediction levels were also attained for the lateral (61.5-96.2%) and vertical (73.1-92.3%) directions of grain drying. These results demonstrate that it is feasible to use a two-dimensional (2-D) finite element model to predict temperature distribution in a grain solar dryer. Consequently, the method offers considerable advantage over experimental approaches as it reduces time requirements and the need for expensive measuring equipment, and it also yields relatively accurate results.

• 한국지열·수열에너지학회논문집
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• 제14권4호
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• pp.7-12
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• 2018

Energy performance of electric heater and geothermal source heat pump type hot air dryers are compared in this study. For set temperatures of $30^{\circ}C$, $35^{\circ}C$ and $40^{\circ}C$, radish is dried from initial mass 60 kg until it gets 5 kg, where the difference equals the amount of water removed. As set temperature is increased, drying time is shortened for both electric heater and heat pump types, however energy efficiency is decreased due to increasing electricity consumption. Moisture extraction rate(MER) of electric heater is 2.58~2.84 kg/h, and for heat pump type 2.56~2.71 kg/h, showing little difference between the two types. Specific moisture extraction rate (SMER) of electric heater is 0.94~0.96 kg/kWh, and for heat pump type 1.72~2.21 kg/kWh. SMER of heat pump type is greater by 0.78~1.25 kg/kWh than the electric heater hot air dryer, which is 1.8~2.3 times better in terms of energy efficiency.

• Journal of Biosystems Engineering
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• 제40권3호
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• pp.186-192
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• 2015

Background: Various solar energy collecting systems have been developed and analyzed for agricultural applications. They include solar thermal and electric devices such as solar crop dryers, solar water pumps, solar greenhouse heating, ventilation for livestock, solar aeration pumps, solar electricity, and many more. Purpose: This review provides the current status of research and development in the field as well as the solar energy systems that are currently in use in the agriculture sector across the globe. Review: Solar energy is the largest and cheapest energy resource on earth; one hour of solar radiation exceeds the complete global energy consumption in one year. The potential annual total solar radiation in South Korea is $3.58-5.4 kWh/m^2/day$. The available solar energy is sufficient for agricultural applications across the entire country. Conclusion: The scope of solar energy utilization in agricultural machinery engineering in South Korea and in other countries is promising.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.877-885
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• 1993

Three types of solar grain dryers, namely , the solar grain bin dryer, the solar greenhouse rotary drum dryer and small scale solar green house tray dryer, have been tested. The results showed that each type of solar grain dryer has its feature. These solar drying units have three main advantages : (1) Required commercial energy to remove 1Kg moist from rough rice is only 5.3% to 15.8% of the energy consumed by common heated dryer : 2) The area of solar drying system is only about 10% of the area of the sunny ground to give equal drying capacity ; (3) There are good drying quality in the moisture uniform , germination percentage, and grain color.