• Journal of Biosystems Engineering
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• 제16권4호
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• pp.399-407
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• 1991

In Korea, the cultivation area under the plastic greenhouse was 1,746 ha in 1975, and 36,656 ha in 1989, it shows that the greenhouse cultivation area was increased by 21 times during last 14 years. The greenhouse cultivation area of 90~93% has been kept warm with double layers of plastic film and thermal curtain knitted with rice straw, and the rest area of 7~10% has been heated by fossil fuel energy. The use of rice straw thermal curtain is inconvenient to put it on and off, on the other hand the use of fossil fuel heating system results in the increase of production cost. To solve these problems, at first the heating load and the storable solar energy in greenhouse during the winter season were predicted to design solar utilization system, secondly a solar thermal storage system filled with latent heat storage materials was developed in this study. And then finally the thermal performance of greenhouse-solar energy storage system was analyzed theoretically and experimentally.

• 한국태양에너지학회 논문집
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• 제21권4호
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• pp.47-54
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• 2001

This study has been conducted to verify the possibility of adaptation of a latent storage type air-conditioning system, shifting the peak load of electronic power to a building. In this paper, an energy equation to evaluate performance of PEM(phase change material) has been suggested and solved, after discretization. As a result, it is confirmed that the results from the energy equation are correspond with those from present studies to analysis of one-dimensional solidification and to analysis of two-dimensional solidification.

• 대한기계학회논문집B
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• 제27권7호
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• pp.845-852
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• 2003

Liquid desiccant dehumidification system can be used effectively to save energy consumed in air conditioning as an alternative compared with conventional air conditioning systems by reducing latent heat load. The dehumidifier and the regenerator from the heart of this system. The latent part of the cooling load is handled using liquid desiccant. In this study, the experimental regenerator has been designed to study the regeneration characteristics of the aqueous triethylene glycol(TEG) system. The performance factors of the regenerator with finned tube heat exchanger were evaluated by a series of experimental runs. The regeneration process is highly dependent on the liquid desiccant conditions, such as, temperature, concentration and flow rate. In addition, the effects of the inlet air temperature, humidity and flow rate were discussed. Data obtained are useful for design guidance and performance analysis of a regenerator, particularly for a liquid desiccant cooling system.

• 플랜트 저널
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• 제17권2호
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• pp.42-47
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• 2021

지역난방의 운영적 측면에서 특정시간의 피크부하 완화를 통한 효율적인 열생산과 공급 및 지역난방 공급 중단 시 급탕 공급은 난방 대비 대체가 어려워 사용자 측면의 불편함과 공급자 측면의 애로사항을 해결할 수 있는 적용 기술이 요구되고 있다. 본 연구에서는 이러한 문제점을 해결할 수 있는 기술 중 열저장 능력과 급탕공급에 적합한 78℃급 수화물계 잠열축열조를 제작하여 지역난방 사용자 아파트 급탕공급설비에 현장 적용하였다. 본 시스템의 적용 결과 기존 공급방식 대비 급탕온도의 변화가 거의 없이 일정하게 사용자에게 공급됨을 확인하였으며, 피크 열부하는 평균 35% 감소와 비상열원으로서의 활용 가능성을 확인하였다. 또한 부하균등화에 따른 피크부하 감소로 기존 열 공급시설에서 10%의 열공급 여유와 신규 열공급시설 건설비용 및 열사용자의 공사비부담금이 각 5%와 10%가 감소됨을 확인하였다.

• 수산해양기술연구
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• 제55권4호
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• pp.411-418
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• 2019

In this study, to investigate the effect of physical and chemical properties of butanol on the engine performance and combustion characteristics, the coefficient of variations of IMEP (indicated mean effective pressure) and fuel conversion efficiency were obtained by measuring the combustion pressure and the fuel consumption quantity according to the engine load and the mixing ratio of diesel oil and butanol. In addition, the combustion pressure was analyzed to obtain the pressure increasing rate and heat release rate, and then the combustion temperature was calculated using a single zone combustion model. The experimental and analysis results of butanol blending oil were compared with the those of diesel oil under the similar operation conditions to determine the performance of the engine and combustion characteristics. As a result, the combustion stabilities of D.O. and butanol blending oil were good in this experimental range, and the indicated fuel conversion efficiency of butanol blending oil was slightly higher at low load but that of D.O. was higher above medium load. The premixed combustion period of D.O. was almost constant regardless of the load. As the load was lower and the butanol blending ratio was higher, the premixed combustion period of butanol blending oil was longer and the premixed combustion period was almost constant at high load regardless of butanol blending ratio. The average heat release rate was higher with increasing loads; especially as butanol blending ratio was increased at high load, the average heat release rate of butanol blending oil was higher than that of D.O. In addition, the calculated maximum. combustion temperature of butanol blending oil was higher than that of D.O. at all loads.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.24-29
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• 2013

An automotive cooling system is designed sufficiently large enough to endure the excessive heat load. In general driving condition, the cooling systems are too large to operate optimally. An experimental study was performed to evaluate a novel automotive cooling strategy using the latent heat of a phase change material (PCM). The strategy is expected to reduce the cooling system size up to around 35% and the engine warm-up time around 60%. The strategy will help improve fuel economy and emissions characteristics of vehicles as a result of reduced total body weight and shortened engine warm-up time by a smaller radiator, as well as more stable combustion mode due to constantly maintained coolant temperature.

• 설비공학논문집
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• 제9권2호
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• pp.112-121
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• 1997

This study is focused on the development and selection of optimal cool tube system to maximize its thermal performance. Cool tube is devised to reduce the heating and cooling load of building by preheating or refreshing of intake air. Finite volume method was adopted to solve the conduction problem between the cool tube and earth. We examine the cool tube system for two operating periods, a short term(12 hours) and a long term(3 months). The results of short term operations reveal that condensation significantly influences and raises the exit air temperature. For long term operations, optimum conditions of cool tube system are obtained with variations of flow-rate, depth, length and diameter of cool tube.

• 설비공학논문집
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• 제9권4호
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• pp.517-526
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• 1997

This study is focused on the development and selection of the optimal cool tube system to maximize its thermal performance. Cool tube is devised to reduce the heating and cooling load of building by preheating or refreshing of intake air with buried pipes. Finite volume method is adopted to solve the conduction problem between the cool tube and earth. We examine the cool tube system for two operating periods, a short term(12 hours) and a long term(3 months). The results of short term operations reveal that condensation significantly influences and raises the exit air temperature. For long term operations, optimum conditions of cool tube system are obtained with variations of flow-rate, depth, length and diameter of cool tube.

• 한국산업융합학회 논문집
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• 제12권3호
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• pp.163-169
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• 2009

A preheating module for domestic heating facility will increase a energy efficiency. That collects the wasted heat of exhaust gas and saves the energy. So a heating load is decreased because of a preheating that has a heating energy. Using of a preheating module, a boiler can reduce frequent operation of a burner. So it is increased persistence, decreased discharging noxious gases. Therefore we will intend to develop a heating facility that is a convenient system for the saving energy.

• 설비공학논문집
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• 제26권11호
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• pp.529-534
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• 2014

This research developed a hybrid heat pump system with the functions of dehumidification and heating, which uses simulated air that is like underground air, from an environmental chamber as a heat source. The system consisted of three evaporators and three condensers that were installed in series in the air passage, between the underground and load space. As results, the total amount of dehumidification was 2.726 kg/h, and the heating $COP_h$ was 1.84 at air intake temperature $17^{\circ}C$ and relative humidity 70%, which is a similar condition to underground air. We found that the total amount of dehumidification also increased with the air temperature and humidity. The system $COP_s$ was reached at 2.5, if we include the latent heat of dehumidification in the conventional heat pump system's COP.