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저온 지열발전의 출력 극대화를 위한 흡수식 동력 사이클의 시뮬레이션
백영진(Young-Jin Baik),김민성(Minsung Kim),장기창(Ki-Chang Chang),이영수(Young-Soo Lee),윤형기(Hyung-Kee Yoon) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.2
본 연구에서는 지열발전 등과 같은 저온 열원을 에너지원으로 하는 발전에 응용될 수 있는 흡수식 동력 사이클의 출력 최적화를 수행하였다. 이를 위해 정상상태 사이클 시뮬레이션을 수행하여 사이클의 성능을 고찰하였다. 시뮬레이션은 열원과 열침의 입구온도 및 유량을 고정한 상태에서 수행하였으며, 일반적인 발전소의 열원-열침 유량비를 고려하였다. 사이클의 성능은 두 개의 독립변수를 이용하여 나타내었는데, 이는 분리기 입구 암모니아 농도와 터빈 입구 압력이다. 시뮬레이션 결과, 100℃의 지열수와 20℃의 냉각수(지열수 유량의 5배) 조건에서, 흡수식 동력 사이클을 이용하면 지열수 유량 1 ㎏/s 당 최대 약 14 ㎾의 출력을 얻을 수 있음을 보였다. In this study, an absorption power cycle, which can be used for a low-temperature heat source driven power cycle such as geothermal power generation, was investigated and optimized in terms of power by the simulation method. A steady-state simulation model was adopted to analyze and optimize its performance. Simulations were carried out for the given heat source and sink inlet temperatures, and the given flow rates were based on the typical power plant thermal-capacitance-rate ratio. The cycle performance was evaluated for two independent variables: the ammonia fraction at the separator inlet and the maximum cycle pressure. Results showed that the absorption power cycle can generate electricity up to about 14 ㎾ per 1 ㎏/s of heat source when the heat source temperature, heat sink temperature, and thermal-capacitance-rate ratio are 100℃, 20℃, and 5, respectively.
열펌프 직렬운전을 통한 근사-로렌츠 사이클 구현에 의한 성능 향상 가능성
백영진(Young-Jin Baik),강병찬(Byung-Chan Kang),김민성(Minsung Kim),장기창(Ki-Chang Chang),나호상(Ho-Sang Ra) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
In this study, the performance enhancement potential of an approximate-Lorenz cycle, which was implemented by series operation of two heat pumps, was investigated by comparison between the performance of parallel operation and that of series operation, for a heating supply temperature of 60°C. To fairly compare the performance of each configuration, the inlet temperatures and the flow rates of both the heat source and the load were fixed. Heat transfer and pressure drop characteristics were also considered to achieve more realistic comparison. Results show that a heating COP of the approximate-Lorenz cycle, which was implemented by series operation of two heat pumps, is about 5% higher than that of the parallel operation under the simulation conditions considered in the present study.
세계 최초 축류형 초임계 이산화탄소 터빈 발전기 시험운전
백영진(Young-Jin Baik),조준현(Junhyun Cho),신형기(Hyung-Ki Shin),조종재(Jongjae Cho),노철우(Chul Woo Roh),이길봉(Gilbong Lee),이범준(Beomjoon Lee),최봉수(Bongsoo Choi),강영석(Youngseok Kang),허재성(Jaesung Huh) 대한기계학회 2018 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.6 No.2
초임계 이산화탄소(sCO2) 발전기술은 소형화 및 고효율 잠재력 때문에 최근 관심이 증가하고 있으며, 화력, 원자력 및 태양열(CSP) 등 재생에너지 발전 분야에서 활발히 연구되고 있다. 한국에너지기술연구원은 향후 재생에너지 분산발전 적용을 목표로 지난 2013 년 연구에 착수, 3 기의 터빈과 2 기의 시험 루프를 개발하였으며, 특히 최근에는 축류형 sCO2 터빈 발전기를 개발 및 시험운전 하였다. 기존연구와는 달리, 본 연구에서는 터빈을 축류 충동형으로 설계하여 축력을 줄이고자 하였으며, 마찰손실 감소를 위하여 씰과 누설 관리 시스템을 도입하였다. 시험운전 결과, 205℃/100 bar 입구 조건에서 터빈운전이 가능함을 확인하였으며, 최대 11 kWe 의 출력을 얻었다. 이것은 초임계 이산화탄소를 작동유체로 하는 축류형 터빈으로서는 세계 최초의 실험 결과이다. Because of the growing interest in supercritical carbon dioxide power cycle technology owing to its potential enhancement in compactness and efficiency, supercritical carbon dioxide (sCO2) power generation technology has been studied in the fields of fossil fuel power, nuclear power, and renewable power generation such as concentrated solar power (CSP). Targeting renewable distributed power generation applications, Korea Institute of Energy Research (KIER) has been developing three sCO2 turbines and two test loops, since 2013. Recently, KIER built and tested an axial sCO2 turbine generator. In contrast to previous studies, KIER designed the turbine as an axial impulse type to reduce the axial force and introduced a mechanical seal and leakage management system to reduce windage loss. Initial test results showed that the turbine can be operated at the inlet conditions of 205℃/100 bar while the maximum power output of 11 kWe was obtained, which is the world"s first test result of an axial turbine in the area of sCO2 technology.
초월임계 운전에 의한 저온 열원 동력사이클의 출력 향상 가능성에 관한 연구
백영진(Young-Jin Baik),김민성(Minsung Kim),장기창(Ki-Chang Chang),이영수(Young-Soo Lee),나호상(Ho-Sang Ra) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
본 연구에서는 100℃의 저온 열원을 이용하여 구동되는 랭킨 동력 사이클에 대하여, HFC-134a를 이용한 아임계 운전을 할 경우의 출력과 HFC-125를 이용한 초월임계 운전을 할 경우의 출력을 서로 비교함으로써, 초월임계 운전에 의한 출력 향상 가능성을 연구하였다. 서로 다른 두 사이클들의 출력을 공정하게 비교하기 위하여, 각 사이클들을 3개의 설계인자를 이용하여 최적화 하였다. 이 때, 보다 현실적인 결과를 위하여 기존의 연구와는 달리, 열교환 과정에서 작동유체의 열전달 및 압력강하 특성을 고려하였다. 시뮬레이션 결과, HFC-125 초월임계 사이클의 출력이 HFC-134a 아임계 사이클의 출력에 비해 본 연구의 시뮬레이션 조건 하에서 9.4% 향상 될 수 있음을 보였다. In this study, the power enhancement potential of a transcritical cycle was investigated by comparison between the power of a HFC-134a subcritical cycle and that of a HFC-125 transcritical cycle, for a low-grade heat source of about 100℃. To fairly compare the power of the cycles by using different working fluids, each cycle was optimized from the view point of power by three design parameters. In contrast to conventional approaches, to achieve more realistic comparison, the working fluid’s heat transfer and pressure drop characteristics were considered. Results show that the HFC-125 transcritical cycle yields 9.4% more power than does the HFC-134a subcritical cycle under the simulation conditions considered in the present study.
백영진(Young-Jin BAIK),신형기(Hyung-Ki SHIN),이길봉(Gilbong LEE),이범준(Beomjoon LEE),조준현(Junhyun CHO),노철우(Chul Woo ROH),나호상(Ho-Sang RA) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
In response to the growing interest in supercritical carbon dioxide (S-CO2) power cycle technology because of its potential enhancement in compactness and efficiency, the S-CO2 cycles have been studied intensively in the fields of nuclear power, concentrated solar power (CSP), and fossil fuel power generation. By utilizing carbon dioxide’s property changes near the critical point, the compression work can be reduced, which results in a significant efficiency improvement. In this study, the current status of the research project on the supercritical carbon dioxide power cycle in KIER (Korea Institute of Energy Research) was introduced. During the first phase of the project, the un-recuperated supercritical Brayton cycle, which was designed to have a net power of 12.6 ㎾, was built. The cycle was composed of the turbo-alternator-compressor unit (TAC) of maximum speeds of 70,000 rpm, two PCHEs (Printed Circuit Heat Exchangers) and a thermal oil heater of capacity of 697 ㎾. The maximum design pressure and temperature of the cycle was 135 bar and 180℃, respectively, while the minimum of those was 79 bar and 35.9℃, respectively. After a successful cold-run test of the TAC unit at a target spin speed of 70,000 rpm, the cycle test loop was test-run up to the spin speed of 30,000 rpm with supercritical CO2. In the second phase of the project, the recuperated supercritical Brayton cycle has been being optimized and designed.
백영진(Young-Jin Baik),김민성(Minsung Kim),장기창(Ki-Chang Chang),윤형기(Hyung-Kee Yoon),이영수(Young-Soo Lee),나호상(Ho-Sang Ra) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
In this study, an absorption power cycle was investigated and optimized by simulation method. An absorption power cycle can be used for the utilization of a low-temperature heat sources such as geothermal and industrial waste heat that are not hot enough to produce steam. The sea/river water can be considered as a cooling media. A steady-state simulation model was developed to analyze and optimize its performance. The model contains a turbine, a pump, an expansion valve and heat exchangers. The turbine and pump were modelled by an isentropic efficiency. The effect of the ammonia fraction at the separator inlet and the maximum cycle pressure on the cycle performance is investigated in detail.