• Journal of agriculture & life science
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• v.53 no.5
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• pp.137-143
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• 2019

To manufacturing of solid fuel by reuse of the wastes, the drying unit which have 500 kg/hr of drying capacity was developed and experimentally evaluate the performance. The spinach grown in Nam-hae island were used for the experiments and investigated of the heated-air drying characteristics as the inlet amount of raw materials, raw material stirring status, conveying type and drying time. The drying air heated by the energy derived from the steam which is supplied from the incineration plant. The moisture contents of raw materials were measured 85.65%. The inlet flow rate of drying air made a difference as the depth of the raw materials loaded on the drying unit and temperature has showed 108~144℃. The drying speed of the mixed drying more than doubled as that of non mixed drying under the same drying type, inlet amount, drying time and drying air temperature. In each experiment, the drying capacity have showed over 500 kg/hr. A drying efficiency of the ratio of drying consumption energy to input energy was 33.46%, lower than the average of 57.76% for the 157 conventional dryers. Because developed dryer must have a drying time of less than one hour, it is considered that the dry efficiency has been reduced due to the loss of wind volume during drying. If waste heat from incineration plant is used as a direct heat source, the dry air temperature is expected to be at least 160℃, greatly improving the drying capacity.

• New & Renewable Energy
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• v.5 no.3
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• pp.40-48
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• 2009

Recovered heat has been considered as a renewable energy in Europe since 2008 because its great effect on energy saving and carbon decreasing in plant process. Energy saving and decreasing green gas are critical issue today, so various technologies to save energy and decrease carbon dioxide in plant process have been applied to many industrial area. In this paper, the feasibility of condenser heat recovery by heat pump in power plant for district heating and fuel line preheating were reviewed by verifying energy (heat) balance and mass balance of power plant model. Some ways to compose proper system to recover heat of condenser are suggested and their possibilities are also reviewed. Limitations on heat recovery in power plant are also reviewed. The results are verified by calculating input/output energy based on actual performance test data of Taean Thermal Power Plant in Korea. There is noticeable improvement of plant performance in some cases which demand low temperature (<100 C) heat like distrcit heating, fuel line heating, and so forth.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.244-249
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• 2012

Recently energy crisis and environmental pollution using fossil fuel became social issue. The Fuel Cell, one of the new and renewable energy has great advantage for the former mentioned problems. The PEM Fuel Cell needs highly purified hydrogen for fuel, in many cases CH4 was reformed to H2 basically using steam reforming. The purpose of this paper is to understand the probability of ceramic honeycomb to apply the combustor of STR. We tested the heat accumulation performance of ceramic honeycomb by change of excess air ratio. The results were suitable for our purpose and also these results can be used to make high temperature air at mild combustion field.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.424-431
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• 2002

마이크로파 주파수는 일반적으로 1㎓-30㎓ 정도로서 주파수가 매우 높기 때문에 도체뿐만 아니라 절연체와 공기 중에서도 전류가 흐르는 성질을 갖는다. 자유공간에서의 마이크로파를 전자파라고도 하며 그 속도는 빛의 속도와 동일하며 자유공간에서 1cm-30cm 파장 범위를 가지므로 센티파라고도 한다. 전자방사(electromagnetic radiation)은 공간을 통하여 시간에 따라 변하는 전자계(electric and magnetic field)에 의한 에너지의 전파(propagation)이며 파동이론과 (wave theory)와 미립자이론(corpuscular theory)에 의해 해석될 수 있다. 전자파 이론(electromagnetic wave theory)의 기초는 1864년 Maxwell이 전자기 현상에 관하여 지배방정식을 수립함으로써 정립되었으며 1888년 Hertz에 의해 마이크로파의 존재가 실험적으로 증명되었다. 이후 마이크로파 기술은 2 차 세계대전을 거치면서 크게 발전하였으며 초기의 레이더 및 통신 등과 같은 군용 기술에서 마이크로파 건조 및 센싱과 같은 산업응용 기술로 발전하게 되었다. 특히 마이크로파 센서기술 및 가열기술은 농업 및 식품분야에 응용되어 마이크로파 응용제품을 선보이게 되었다. (중략)

• Journal of the Korean Solar Energy Society
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• v.34 no.3
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• pp.115-121
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• 2014

With increment on interesting about improving renewable energy efficiency, many research have been conducted and the research about hybrid air-water heater using solar energy that can make heating air and hot water has been conducted also. In this experiment, the temperature difference and thermal efficiency were investigated when two heating medium(air and liquid) was working simultaneously. As a result, thermal efficiency showed 44% to 88% when these heating medium was working simultaneously depending on operation condition and it is better than traditional solar collector. Also possibility of application into building equipment also was confirmed based on temperature and thermal efficiency. But necessity of additional studies about proper operation condition according to purpose of use and heat load was confirmed because change of thermal efficiency by air velocity and flux of liquid was shown a huge difference.

• Journal of Energy Engineering
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• v.11 no.3
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• pp.276-282
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• 2002

The process of energy separation in a low Pressure vortex tube with compressed air as a work-ing medium is studied in detail. Experimental data of the temperature of the cold and hot air leaving the vortex tube are presented. The variation of the maximum wall temperature along the inner surface of the vortex tube and the temperature distribution in a vortex tube provide useful information about the location of the stagnation point of the flow field at the axis of the vortex tube. Analysis of the results enabled to find the optimum length of the vortex tube, the optimum shape of the Throttle and the usefulness of the Sleeve. In this study Outer tube is used for the exhaust application. The hot gas flow is turned 180$^{\circ}$and passes the out-side of the vortex tube a second time heating it. From this geometric setup of a vortex tube He effects of energy separation and the prediction of the ignition of Diesel Soot is presented by experimental data.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.609-614
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• 2014

In this research, results of measuring temperature and relative humidity of underground-air-heat in Jeju showed $15{\sim}18^{\circ}C$ and 70~80% each which are somewhat high compare to other regions. So the Multi-effect dehumidifying and heating Heat Pump system which has merged functions of dehumidification and heating is made to solve this problem mentioned previously. When the suction air was $15^{\circ}C$ with 60% humidity, the outcome was 1.70 on $COP_h$ and 1.797(kg/h) on total amount of dehumidification, and also showed 1.87 $COP_h$ with 1.87 total amount of dehumidification under the condition of $20^{\circ}C$ and 80% humidity of suction air. Furthermore, $COP_h$ showed increased number which is 1.87 and also total amount of dehumidification increased which was 3.269(kg/h). The highest COP can be achieved at $17^{\circ}C$ and 70% relative humidity condition.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.455-459
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• 2013

The fuel processor for the portable fuel cell includes multi-step processes consisting of hydrogen generator, heat generator and several CO clean-up stages. One of requirements of the fuel processor for portable fuel cell system is a rapid start-up time. Especially, the warm-up time for WGS reactor is crucial factors for total start-up time. In this paper, active heating protocol, which is the heating protocol of WGS reactor supplied by the oxidation of CO rich reformate in the initial stage, is used for a rapid start-up. The air stream fed to the inlet of WGS reactor rapidly oxidize the CO rich reformate in the WGS reactor. Therefore, CO concentration in reformate quickly stabilized at the desired concentration without CO surges.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.6
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• pp.639-646
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• 2012

The characteristics of autoignited lifted flames in laminar jets of carbon monoxide/hydrogen fuels have been investigated experimentally in heated coflow air. In result, as the jet velocity increased, the blowoff was directly occurred from the nozzle-attached flame without experiencing a stabilized lifted flame, in the non-autoignited regime. In the autoignited regime, the autoignited lifted flame of carbon monoxide diluted by nitrogen was affected by the water vapor content in the compressed air oxidizer, as evidenced by the variation of the ignition delay time estimated by numerical calculation. In particular, in the autoignition regime at low temperatures with added hydrogen, the liftoff height of the autoignited lifted flames decreased and then increased as the jet velocity increased. Based on the mechanism in which the autoignited laminar lifted flame is stabilized by ignition delay time, the liftoff height can be influenced not only by the heat loss, but also by the preferential diffusion between momentum and mass diffusion in fuel jets during the autoignition process.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1106-1114
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• 1993

A composite material is composed of a reinforcement and a matrix, which determine mechanical characteristics of the molded part. There is no doubt that the properties of a composite material depend not only on the characteristics of the matrix but also on the structure of glass fiber mat and a fiber type of reinforcement. Therefore it is very important to study the composites of reinforcement and the matrix, and to control the fiber type in the process of molding of composite materials. In this study, the specimen was made of a glass fiber mat of 6-7mm thickness by scattering it in the air after cutting the glass fiber mat with needle punching makes change according to the type of needle and the number of times of stretching. First the sheet was made by means of a hot-press after accumulating a matrix and a glass fiber according to each mat structure of glass fiber. It was heated the manufactured sheet with the dry oven and molded it a secondary high temperature compression by a 30 ton oilhydraulic press. A definition of a correlation coefficient is showed up during this period and find it out with the relation of the fiber-matrix separation and the fiber orientation. We studied effects of the glass fiber mat structures on the correlation coefficient.