• 한국유체기계학회 논문집
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• 제18권4호
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• pp.13-21
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• 2015

The system design of the Organic Rankine Cycle(ORC) is greatly influenced by the thermal properties such as the temperature or the thermal capacity of heat source. Typically waste heat, solar energy, geothermal energy, and so on are used as the heat source for the ORC. However, thermal energy supplying from these kinds of heat sources cannot be provided constantly. Hence, an experimental study was conducted to utilize fluctuating thermal energy efficiently. For this experiment, an impulse turbine and supersonic nozzles were applied and the supersonic nozzle was used to increase the velocity at the nozzle exit. In addition, these nozzles were used to adjust the mass flowrate depending on the amount of the supplied thermal energy. The experiment was conducted with maximum three nozzles due to the capacity of thermal energy. The experimented results were compared with the predicted results. The experiment showed that the useful output power could be producted from low-grade thermal energy as well as fluctuating thermal energy.

• 에너지공학
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• 제21권4호
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• pp.393-397
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• 2012

본 연구에서는 산업용 가스 엔진의 배기 폐열을 회수하여 발전하는 유기랭킨사이클을 구성하고 시스템 성능 분석 실험을 수행하였다. 엔진 배기가스 열을 작동유체(냉매 R134a)에 흡수시키기 위해 Shell & Tube 방식 열교환기를 엔진 배기 매니폴드 후단에 장착하였다. 엔진출력 60 kW인 조건에서 약 63 kW의 배기가스 열을 배출하였으며, 열교환기를 통해 작동유체에 흡수된 열량은 43~46 kW로서 배기가스 열회수율은 68~73%, 최대출력은 4.6 kW로서 배기가스 열량에 대한 최대출력의 비는 7.3%을 나타내었다.

• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.223-231
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• 2011

The thermal efficiency of energy-to-power conversion becomes uneconomically low when the temperature of heat source drops below $370^{\circ}C$. ORC (Organic Rankine Cycle) has attracted much attention in last few years due to its potential in reducing consumption of fossil fuels and relaxing environmental problems, and its favorable characteristics to exploit low-temperature heat sources. In this work thermodynamic performance of ORC using nine working fluids is comparatively assessed. Special attention is paid to the effect of system parameters such as turbine inlet temperature and pressure on the characteristics of the system such as volumetric flow rate and quality at turbine exit, latent heat, net work as well as thermal efficiency. Results show that in selection of working fluid it is required to consider various criteria of performance characteristics as well as the thermal efficiency. Results also show that the system efficiencies become same irrespective of kind of working fluid when the temperature of heat source decreases to low range.

• 한국수소및신에너지학회논문집
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• 제25권2호
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• pp.200-208
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• 2014

This paper presents thermodynamic performance analysis of organic Rankine cycle (ORC) using low temperature heat source in the form of sensible energy and using liquefied natural gas (LNG) as heat sink to recover the cryogenic energy of LNG. LNG is able to condense the working fluid at a very low condensing temperature in a heat exchanger, which leads to an increased power output. Based on the mathematical model, a parametric analysis is conducted to examine the effects of eight different working fluids, the turbine inlet pressure and the condensation temperature on the system performance. The results indicate that the thermodynamic performance of ORC such as net work production or thermal efficiency can be significantly improved by the LNG cold energy.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.699-705
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• 2011

A combined heat and power cogeneration system driven by low-temperature sources is investigated by the first and second laws of thermodynamics. The system consists of Organic Rankine Cycle (ORC) and an additional process heater as a series circuit. Seven working fluids of R152a, propane, isobutane, butane, R11, R123, isopentane and n-pentane are considered in this work. Maximum mass flow rate of a working fluid relative to that of the source fluid is considered to extract maximum power from the source. Results indicate that the second-law efficiency can be significantly increased due to the combined heat and power generation. Furthermore, higher source temperature and lower turbine inlet pressure lead to lower second-law efficiency of ORC system but higher that of combined system. Results also show that the optimum working fluid varies with the source temperature.

• 한국태양에너지학회 논문집
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• 제31권6호
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• pp.49-56
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• 2011

In this study a novel cogeneration system driven by low-temperature sources at a temperature level below $190^{\circ}C$ is investigated by first and second laws of thermodynamics. The system consists of Organic Rankine Cycle(ORC) and an additional heat generation as a parallel circuit. Seven working fluids of R143a, R22, R134a, R152a, $iC_4H_{10}$(isobutane), $C_4H_{10}$(butane), and R123a are considered in this work. Maximum mass flow rate of a working fluid relative to that of the source fluid and optimum turbine inlet pressure are considered to extract maximum power from the source. Results show that due to a combined heat and power generation, both the efficiencies by first and second laws can be significantly increased in comparison to a power generation, however, the second law efficiency is more resonable in the investigation of cogeneration systems. Results also show that the working fluid for the maximum system efficiency depends on the source temperature.

• 동력기계공학회지
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• 제18권6호
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• pp.120-125
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• 2014

In this paper, suitable working fluid of 1MW Organic Rankine Cycle(ORC) with liquid-vapor ejector using effluent from power plant is selected. The results of comparison performance of 5 refrigerants are as follows; R600a, R134a, R1270, R236fa, R235fa. The operating parameters considered in this study include the condensation capacity evaporation capacity and efficiency. As a result of comparison of basic ORC system and with liquid-vapor ejector, with ORC system presents the higher system efficiency since the ejector makes the turbine outlet pressure lower than condensation pressure through its pressure recovery. Also, this ejector ORC system is advantageous in miniaturizing the size of components owing to decrease of evaporation capacity and condensation capacity.

• 신재생에너지
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• 제19권4호
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• pp.61-71
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• 2023

The necessity of energy utilization using livestock manure has been proposed with the decrease in domestic agricultural land. Livestock manure solid fuel has been investigated as a promising energy resource owing to its convenient storage and use in agricultural and livestock fields. Additional electricity production is possible through the integration of a biomass combustion boiler with the organic Rankine cycle (ORC). In this study, a mathematical system model of the cattle manure solid fuel boiler integrated with the ORC was developed to analyze the components' performance under variable operating conditions. A sensitivity analysis was conducted to confirm the electrical efficiency of the ORC turbine and the applicability of this system. The minimum required waste heat recovery rate was derived considering the system marginal price and levelized cost of electricity of the ORC. The simulation results showed that, in Korea, more than 77.98% of waste heat recovery and utilization in ORC turbines is required to achieve economic feasibility through ORC application.

• 대한기계학회논문집 C: 기술과 교육
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• 제3권1호
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• pp.55-62
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• 2015

국내에서는 천연가스 공급국가와 수입국가의 거리, 공급시설 투자, 국가 간 협력 등 여러 가지 제약에 따라 액화천연가스를 수입하고 있다. 수입한 액화천연가스를 수요처로 공급하기 위해 해수를 이용한 기화과정에서 냉열이 낭비되고 있다. 본 연구에서는 이러한 냉열을 효율적으로 활용하는 냉열발전시스템에서 직접팽창과 유기랭킨사이클 방식의 운전성능을 비교 연구하였다. 시뮬레이션은 Aspen HYSYS를 이용하여 수행하였으며, 운전성능 분석은 T-S 선도 및 시스템 성능 해석을 토대로 비교분석하였다. 시뮬레이션 결과로부터 발전시스템의 운전 측면에서는 유기랭킨사이클 방식이 유리한 것을 확인하였다.

• 대한기계학회논문집B
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• 제37권12호
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• pp.1137-1145
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• 2013

본 연구에서는 열 구동 냉동사이클로서 유기 랭킨사이클 (ORC)과 증기 압축 냉동사이클(VCC)의 복합 사이클에 대한 엑서지 해석을 수행하였다. 시스템의 열원으로는 다양한 재생 에너지 열원이나 산업체에서의 폐열 등 현열 형태의 저온 열원을 고려하였으며 작동유체로서 R143a, R22, R134a, 프로판, 이소부탄, 부탄, R245fa 및 R123 등 여덟가지 작동유체들을 고려하였다. 터빈 입구 압력의 변화나 작동유체의 종류에 따라 시스템의 COP 나 엑서지 효율은 물론 시스템의 각 요소에서의 엑서지 파괴 (아너지)에 미치는 다양한 영향에 대해 분석하고 논의하였다. 해석 결과는 주어진 열원 온도에 대해 시스템에서 가장 엑서지 파괴가 큰 구성 요소는 터빈 입구 압력과 작동유체에 따라 민감하게 변화하는 사실을 보여준다.