• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.191-194
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• 2011

Low-grade waste heat has generally been discarded in industry due to lack of efficient recovery methods. In recent years, organic Rankine cycle(ORC) has become a field of intense research and appears as a promising technology for conversion of heat into useful work of electricity. In this work thermodynamic performance of ORC with superheating of vapor is comparatively assessed for various working fluids. Special attention is paid to the effects of system parameters such as the evaporating temperature on the characteristics of the system such as maximum possible work extraction from the given source, volumetric flow rate per 1 kW of net work and quality of the working fluid at turbine exit as well as thermal efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.12
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• pp.1057-1064
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• 2014

Recently, there has been a growing interest in sustainable energy. One method that has been used is an organic Rankine cycle using conventional turbine technology with a low-temperature waste heat source. A 200-kW organic Rankine cycle (ORC) system was designed for a waste heat recovery application using R245fa as the working fluid. A radial turbine running at 15,000 rpm was employed to generate more than 200 kW with an expansion ratio of nine. Because an ORC turbine uses a refrigerant as the working fluid, the ideal gas law was not employed to design the turbine. In addition, the complexity of the molecular structure of R245fa made it difficult to design the turbine. Because R245fa has an Ma value of one at a low velocity for the working fluid (about 1/3 of the speed of sound in air) at about $100^{\circ}C$, it easily reaches a supersonic flow condition with a small pressure expansion. To increase the efficiency of the turbine, a dual stage radial-type turbine with a subsonic speed was suggested. This paper will describe the design procedure and performance evaluation of the ORC turbine using R245fa.

• Journal of the Korean Institute of Gas
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• v.21 no.5
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• pp.27-35
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• 2017

The amount and quality of waste heat from a resource recovery facility were measured. The temperature of exhaust gas was $176.6^{\circ}C$ and the amount of that was 13.8 kg/s. This research designed a waste heat recovery system whose working fluid is R-245fa. It simulated three study cases as follows. In simulation of a basic ORC system, the turbine power output and thermal efficiency were respectively 96.56 kW, 14.3%. In simulation of a superheater connection, 0.09% of efficiency could be improved due to the increase of enthalpy by overheating of working fluid, but the obtained output was decreased with 16.58kW because of the decrease of working fluid mass. In simulation of a process heater connection, efficiency was increased up to 38.51%.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.647-655
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• 2021

The IMO (International Maritime Organization) is discussing the improvement of energy ef iciency of ships in order to reduce greenhouse gas emissions from ships. Currently, by applying an ORC power generation system using waste heat generated from ships, high energy conversion efficiency can be expected from ships. This technology uses an organic medium based on Freon or hydrocarbons as the working fluid, which evaporates at a lower temperature range than water. Through this, it is possible to generate steam (gas) and generate power at a low and low temperature relatively. In this study, the analysis of heat flow between the refrigerant and waste heat in the ORC power generation system, which is an organic Rankine cycle, is analyzed using 3D simulation techniques to determine the temperature change, velocity change, pressure change, and mass change of the fluid flowing of the WHRU (Waste Heat Recovery Unit) inside and the outside the structure. The purpose of this study is to analyze how the mass change affects the structure, and this study analyzed the heat transfer of the heat exchanger from the refrigerant and the exhaust gas of the ship's main engine in the ORC power generation system using this technique.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.12
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• pp.1137-1145
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• 2013

In this study, exergy analysis of a thermally activated refrigeration cycle, a combined organic Rankine cycle (ORC), and a vapor compression cycle (VCC) were conducted. It is considered that a system uses a low-temperature heat source in the form of sensible heat, such as various renewable energy sources or waste heat from industries, and one of eight working fluids: R143a, R22, R134a, propane, isobutane, butane, R245fa, or R123. The effects of turbine inlet pressure and the working fluid selected on the exergy destructions (anergies) at various system components as well as the COP and exergy efficiency of the system were analyzed and discussed. The results show that the component of the greatest exergy destruction in the system varies sensitively with the turbine inlet pressure and/or working fluid.

• Transactions of the KSME C: Technology and Education
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• v.1 no.1
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• pp.107-113
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• 2013

This paper presents the process of turbine development for Organic Rankine Cycle(ORC) system. Development of turbine for ORC system is hot issue in the electric generation market due to the characteristic of organic refrigerant which the evaporate temperature is lower than general refrigerant. Recently, the industry have an interest about ORC turbine development in Korea, and they presented numerous research results. In developing the turbine, several processes can be considered. However, there was few document about ORC turbine development because of the trade secret. This paper can be used as a reference in developing ORC turbine.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.6
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• pp.637-645
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• 2020

In this paper, entransy analysis is carried out for combined heat and power (CHP) generation system driven by low-grade heat source compared with energy and exergy analyses. The system consists of a regenerative organic rankine cycle (ORC) and an additional process heater in a series circuit. Special attention is paid to the effects of the turbine inlet pressure, source temperature, and the working fluid on the thermodynamic performance of the system. Results showed that the work efficiency of entransy is higher than that of energy but lower than that of exergy, wheress the process heat efficiency of entransy is lower than that of energy but higher than that of exergy. Entrance analysis showed the potential to complement the exergy analysis in the optimal design of the energy system.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.1
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• pp.77-85
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• 2021

In this paper, entransy analysis is carried out for combined heat and power (CHP) generation system driven by low-grade heat source compared with energy and exergy analyses. The system consists of an organic Rankine cycle (ORC) and an additional process heater in a parallel circuit. Special attention is paid to the effects of the source temperature, turbine inlet pressure, and the working fluid on the thermodynamic performance of the system. Results showed that the work efficiency of entransy is higher than that of energy but lower than that of exergy, wheress the process heat efficiency of entransy is lower than that of energy but higher than that of exergy. Entrancy analysis showed the potential to complement the exergy analysis in the optimal design of the energy system.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.6
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• pp.590-599
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• 2015

In this paper a performance analysis is carried out based on the first and second laws of thermodynamics for heat exchanger in organic Rankine cycle (ORC) for the recovery of low-temperature finite thermal energy source. In the analysis, effects of the selection of working fluid and pinch temperature difference are investigated on the performance of the heat exchanger including the effectiveness of the heat exchanger, exergy destruction, second-law efficiency, number of transfer unit (NTU), and pinch point. The temperature distribution are shown depending on the working fluids and the pinch temperature difference. The results show that the performance of the heat exchanger depends on the pinch temperature difference sensitively. As the pinch temperature increases, the exergy destruction in the evaporator increases but the effectiveness, second law efficiency and NTU decreases.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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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.