• 연구논문집
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• s.22
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• pp.141-150
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• 1992

A basic study on the batch type freeze dryer has been carried out. The operating principles, merits and demerits of the freeze dryer were described. And the kinds of major components and their roles were also invesigated. As a fundamental study, using the Differential Scanning Calorimeter(DSC), the determination of unfrozen water in the specimens and invesigation of effects of cooling rate on the freeze drying were performed. To provide a guidline of basic design for a freeze dryer, a parametric study about the drying conditions was carried out.

• Journal of Biosystems Engineering
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• v.41 no.1
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• pp.43-50
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• 2016

Purpose: The present study is aimed at examining the drying characteristics of sea tangle through a combination of microwave and far-infrared drying experiment and finding the optimal drying conditions. Methods: Sea tangle was cleaned and cut into fine pieces (5mm) before they were subjected to combinational drying by microwave and far-infrared ray. The amount of specimen per drying is 2 kg. The finely cut pieces of sea tangle were preheated in a microwave dryer for three different lengths of time (10, 15, and 20 min). Subsequently, they were dried using a far-infrared dryer at tow temperatures ($90^{\circ}C$ and $100^{\circ}C$) at an air velocity of 0.8 m/s until the final moisture content reduced to 10%. Results: Sea tangle dried under the condition of 20 min of preheating in the microwave dryer and drying at $100^{\circ}C$ by the far-infrared dryer. Of the drying models verified in this study, the logarithmic model showed high accuracy with the coefficient of determination $R^2>0.7825$ and RMSE<0.1095. The rehydration ratio of sea tangle was the highest (12.87 g water/g dry matter) under the condition of 15 min of preheating in the microwave dryer and drying at $100^{\circ}C$ by the far-infrared dryer. The energy consumption for the combination of microwave and far-infrared drying was the lowest (4.78 kJ/kg water) under the condition of 20 min of preheating in the microwave dryer and drying at $100^{\circ}C$ by the far-infrared dryer. Conclusions: Considering the drying time, discoloration during drying, rehydration ratio, and energy consumption for the drying of sea tangle, the optimal drying conditions for high-quality sea tangle are 15 min of preheating in a microwave dryer and drying at $100^{\circ}C$ by a far-infrared dryer.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.4
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• pp.1-6
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• 2015

In this study, energy performance of two types of food dryers which are electric heater and heat pump is studied experimentally. With drying chamber temperatures controlled at 45, 50 and $55^{\circ}C$, sliced radish is dried from an initial mass of 90 to final 7 kg. Moisture content, drying time, total power consumption, MER (moisture extraction rate, kg/h) and SMER (specific moisture extraction rate, kg/kWh) are measured and analyzed. As the drying chamber temperature is increased, drying time is shortened but energy efficiency is reduced for both types. For an electric heater dryer, the effect of chamber temperature on drying time is significant but less significant on energy efficiency. For a heat pump dryer, the dependence of chamber temperature on drying time is weak but strong on energy efficiency. Temperature levels have little effect on electric heater dryer performance but strong effect on heat pump dryer which operates on a vapor compression refrigeration cycle. The energy performance of the heat pump dryer is superior with an average SMER of 2.175 kg/kWh which is 2.22 times greater than that of the electric heater dryer with SMER of 1.224 kg/kWh.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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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.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.10
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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 the Korean Society of Industry Convergence
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• v.6 no.2
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• pp.103-108
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• 2003

This study was performed to find out drying characteristics and develop waste heat recovery dryer. this system was initiated in order to recover discharged waste heat of drying air from drying chamber in agricultural products dryer and recycle for additional heat source that could save drying cost. The system consists of drying chamber, fan, burner, circulation pump and heat exchanger made of fins and tubes. For the system performance, drying experiments with fresh pepper were conducted, and comparisons on fuel consumption amount and drying performance were made between conventional dryer and the heat recovery system attached dryer.

• Membrane Journal
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• v.14 no.1
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• pp.1-17
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• 2004

Dehumidification systems have been developed for the various applications, especially for the production of dry compressed air. Compressed air producing system attach $\varepsilon$ d with dehumidification unit have advantages such as high reliability, low error ratio, comfortable working conditions, etc. Conventional dehumidification systems have several economical drawbacks like high electric cost, high cost of adsorbent and it is not environmentally friendly system because freezing agent like a Freon has been used. Membrane dryer is emerging system which have economical advantages and environmental merits.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.419-423
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• 2008

엔진 성능의 시험에 있어서 작동유체인 압축공기의 물성중 수분은 매우 중요한 부분으로, 엔진의 작동과 성능에 영향을 미치는 대표적인 요인이다. 특히 고공환경 시험에서는 습도의 조건에 따라 성능의 차이가 커지므로 엔진의 정확한 성능과 운용성을 파악하는데 작동유체인 압축공기중에 포함된 수분의 조건은 대단히 중요하다. 압축상태인 작동유체의 수분 함유량을 고공의 조건과 같은 $-40^{\circ}C$ 이하의 이슬점(Dew Point) 상태로 제습 하기 위한 장치인 흡착식 Air Dryer의 개발을 위해 흡착과정 및 재생과정에 대한 이해와 흡착제의 흡착효율을 극대화하고, 재생비용을 최소화하여 에너지를 저감 할 수 있는 Air Dryer System에 대하여 기술한다.

• Journal of Biosystems Engineering
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• v.33 no.6
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• pp.390-395
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• 2008

Current high oil price and the agreement on global climate change prevention have increased worldwide investment and research on renewable energy. In Korea, development of a rapeseed dryer for bio-diesel production has been started in 2007. Usually, rapeseeds are harvested in early summer, because rice cultivation is followed right after rapeseed harvesting. Early harvest and bad summer results in highly moistured rapeseed and development of artificial drying system is required to dry great amount of rapeseed that couldn't be processed by sun drying alone. The rapeseed dryer was modified from an existing circulation type grain dryer. Modification of the dryer was performed with the aid of CFD simulation. Drying test showed that drying rate of rapeseed was 1.51%/h and germination rate reduction was 4.5%p for the drying temperature of $60^{\circ}C$.

• Journal of information and communication convergence engineering
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• v.13 no.1
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• pp.21-26
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• 2015

A wireless sensor network (WSN) is designed and implemented for a freeze dryer. Freeze-drying technology is widely used in the fields of pharmacy and biotechnology as well as the food and agriculture industries. Taking into account the demand for high-resolution pressure and temperature measurements in a freeze dryer, the proposed WSN has a significant advantage of creating a monitoring environment in a freeze dryer. The proposed WSN uses a ZigBee/IEEE 802.15.4 network with an altimeter module that contains a high-resolution pressure and temperature sensor with a serial digital data interface. The ZigBee network is suitable for low-energy and low-data-rate applications in the field of wireless communication. The altimeter module is capable of sensing pressure in the range of 7.5-975 Torr (10-1300 mbar) and temperature in the range of $-40^{\circ}C$ to $125^{\circ}C$ with a DC power consumption of $3{\mu}W$. The implemented WSN is installed in a commercial laboratory freeze dryer in order to demonstrate its functionality and efficiency. A comparison with the temperature profile measured by a thermocouple installed in the freeze dryer reveals that the resolution of the temperature profile measured by WSN is superior to that measured by the thermocouple.