• 설비공학논문집
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• 제4권2호
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• pp.65-71
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• 1992

In most absorption machines, absorption enhancement has been achieved by adding small amount of surfactant additive, which introduced the surface tension difference between absorbent and surfactant droplets in the vapor absorption. The aim of this study is to understand a basic mechanism of Marangoni convection and its effectiveness in the vapor absorption enhancement. In this study, nonflowing aqueous solution of LiBr 60 mass% was exposed to saturated water vapor under the condition that two dropwises surfactant were fixed on the absorbent surface. Our experiments achieved to visualize the enhanced heat and mass transfer phenomena by the effect of Marangoni convection through the laser holographic interferometry. Also, Marangoni convection behavior was obtained by using tracer method.

• 설비공학논문집
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• 제13권1호
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• pp.48-58
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• 2001

For the past few decades the vapor compression cycle with a solution circuit (VCCSC) has been known to provide high efficiency and variable capacity. In this study performance of a VCCSC cycle is examined through computer simulation. In the simulation heat exchangers were modelled by specifying UA or effectiveness values while the compressor performance was specified by an isentropic efficiency. Aqua/ammonia solution was chosen as the working fluid which can be used in the high temperature range. The results show that there exists an optimum operation condition which is dependent upon the temperatures of the external heat transfer fluids(HTFs). Besides the HTF\`s temperature, the maximum system pressure and the size of the solution heat exchanger are shown to have an influence on the optimum operation condition. Finally, as compared to a simple vapor compression heat pump with HFC134a, the COP of the VCCSC is shown to be 2∼22% higher.

• Journal of Biosystems Engineering
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• 제27권1호
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• pp.39-44
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• 2002

In order to obtain the information of bio-environment control, the thermal characteristics of soil in the greenhouse heated by the heat pump and latent heat storage system were experimentally analyzed. The experimental systems were composed of the greenhouse with a heat pump and a latent heat storage system (system I), the greenhouse with a heat pump (system II), the greenhouse with a latent heat storage system (system III), and the greenhouse without auxiliary heating system (system IV). The thermal characteristics experimentally analyzed in each system were temperature of soil layers, soil heat storage and release, soil heat capacity and soil heat storage ratio. The results could be summarized as follows. 1. Time to reach the highest temperature at 20cm deep in soil layers of the crop routs in case of system I was shown to be delayed by 6 hours in comparison to the time of the highest temperature at the soil surface. 2. In the clear winter days, the stored heat capacity values fur the system I and the system II were shown to be 22.3% and 11.0% higher than the released heat capacity respectively, and the stored heat capacity values for the system III and the system IV were shown to be 6.2% and 29.6% lower than the released heat capacity respectively This confirms that the system I provided the best heat storage effect. j. The heat quantity values stored or released were shown to be highest at 5 cm depth of soil layers. And it was reduced with increasing of depth of soil layers until 20 cm and was not changed under the soil layer of 20 cm depth. 4. The heat absorption rates of soil, the ratio between supplied and stored heat energy, fur both the system I and system II were lower than 23%.

• 설비공학논문집
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• 제17권9호
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• pp.808-815
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• 2005

A technical analysis was conducted to predict the development trends for heat pump system. This study was based on submitted patents from 1983 to 2002 in Korea, USA, and Japan. The total number of raw data from the registered database was 19,261 and the obtained data to be analyzed through the filtering process was 5,143. Japan's technical development for the heat pump system was more dominant than the other countries. Approximately $54\%$ of the total patents related with the heat pump system was registered by Japan. The number of patents for the heat pump system registered by Korea was very low in 1980's, but it increased rapidly in 1990's. As a result, the number of patents applied by Korea was $21\%$ of all patents. When the patent was categorized into compression, absorption/ad-sorption, and chemical type, the technology of compression type made up over $80\%$ in each country. Approximately $93\%$ of the patents surveyed in this study was developed for air or water source heat pumps because of easy applications compared with other heat sources. The $89\%$ of all patents was applied by companies when applicants were divided into three groups of company, individual, and the others (national institute, university, and so on).

• 한국기계연구소 소보
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• 통권18호
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• pp.115-123
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• 1988

• 대한설비공학회지:설비저널
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• 제22권5호
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• pp.348-370
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• 1993

• 청정기술
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• 제7권4호
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• pp.273-280
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• 2001

흡수기는 흡수식 열펌프 시스템에서 중요한 구성요소일 뿐만 아니라 흡수기의 성능은 전체 시스템에 중요한 영향을 미친다. 본 연구에서는 기포분사형 흡수기에서의 암모니아기체의 흡수열의 효과적 제거를 위한 냉각수 방향으로의 열전달에 대해 실험적 연구를 수행하였다. 흡수기에 유입되는 암모니아 기체의 유속, 암모니아 수용액의 유속, 농도, 온도, 흡수기의 지름, 높이, 기체와 용액의 유입 방향등 여러 가지 변수에 대하여 열전달 성능의 특성을 살펴본 결과, 기체의 주입량, 용액의 주입량 증가는 열전달 성능 향상에 기여하며, 용액의 온도나 농도의 상승은 열전달 성능에 방해요소로 작용하였으며 흐름방향이 향류인 경우 열전달 성능에 향상이 있었다. 본 실험의 데이터를 이용하여 상관관계식을 유도하여 열전달에 대한 복잡한 관계를 일반화 하였다.

• 설비공학논문집
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• 제26권1호
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• pp.1-7
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• 2014

A field test of a 70 kW heat pump system with flue gas heat recovery was performed by an experiment at the Korea Institute of Energy Research. The flue gas is exhausted from a 320 RT absorption chiller-heater in the heating season. Using this flue gas, source water of the heat pump is heated by a condensed-type heat exchanger in the chimney. The operating characteristics of the heat recovery heat pump system were analyzed. Based on the results of the experiments, operating maps were obtained, and an optimum operating range is suggested, in which the return and heat source water temperature are $51^{\circ}C$ and $31^{\circ}C$, respectively. Additionally, economic analysis of this system was conducted and about 50% energy cost savings can be expected in the heating season.

• 대한기계학회논문집B
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• 제34권2호
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• pp.191-196
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• 2010

기존의 증기압축식과 흡수식을 결합한 하이브리드 히트펌프는 $50^{\circ}C$정도의 저열원에서 $80{\sim}90^{\circ}C$의 온수를 효과적으로 생산할 수 있다. 본 연구에서는 EES를 사용하여 2단 압축 하이브리드 히트펌프와 1단 압축 하이브리드 히트펌프의 성능을 비교하였다. 동일한 작동조건에서 2단 압축 하이브리드 히트펌프는 1단 압축 하이브리드 히트펌프보다 약간 높은 COP를 가지며 더 안정적인 상태에서 운전이 가능한 것으로 나타났다. 2단 압축 하이브리드 히트펌프에서 작동 유체의 최대 온도는 1단 압축 하이브리드 히트펌프보다 40K정도 낮게 나타났으며 이는 윤활유의 작동에 무리없는 운전상태를 가능하게 한다. 1단과 2단 하이브리드 히트펌프 모두 UA값이 증가할 때 COP는 감소하였으며 열출력은 증가하였다.

• 한국태양에너지학회 논문집
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• 제25권3호
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• pp.27-35
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• 2005

In this paper, a thermodynamic analysis was performed to provide design data for a double-effect absorption heating system with water-LiBr-LiSCN mixture which utilizes solar energy as evaporator heat source. In addition, a comparative study of the water-LiBr-LiSCN mixture against the water-LiBr pair was conducted by a computer simulation. The computer simulation is based on mass, material and heat balance equations for each part of the system. Coefficients of performance and flow ratios for effects of different operating temperatures are investigated. It is found that the heating COP is higher for the water-LiBr-LiSCN mixture than for the water-LiBr pair, and FR is lower for the former.