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부하추종 운전전략수립을 위한 시스템 코드 기반 질소 브레이튼 사이클의 출력제어 과도해석
정성균(Sungkun Chung),최재현(Jae Hyun Choi),조항진(HangJin Jo) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
Recently, control strategies of power conversion systems are getting important due to coupling energy systems including renewable and nuclear sources. In this study, a power-control transient analysis of a nitrogen Brayton cycle which is one of the realistic and near-term options for a power conversion system of sodium-cooled fast reactors is performed to confirm the flexibility and safety of the system. The transient calculation is performed with a heat source variation scenario which is varied from 100% to 55% determined from a reference. The transient results showed that net power could be controlled from 100% to 0% with a turbine bypass valve. For safe operation of the system, recuperator recirculation and inventory tank valves are used to avoid the local frozen in a heat exchanger and choking events in compressors. From the power-control transient analysis, it is concluded that the nitrogen Brayton cycle is applicable for coupling energy systems with simple control strategies.
부하추종 운전전략수립을 위한 시스템 코드 기반 질소 브레이튼 사이클의 출력제어 과도해석
정성균(Sungkun Chung),최재현(Jae Hyun Choi),조항진(HangJin Jo) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
Recently, control strategies of power conversion systems are getting important due to coupling energy systems including renewable and nuclear sources. In this study, a power-control transient analysis of a nitrogen Brayton cycle which is one of the realistic and near-term options for a power conversion system of sodium-cooled fast reactors is performed to confirm the flexibility and safety of the system. The transient calculation is performed with a heat source variation scenario which is varied from 100% to 55% determined from a reference. The transient results showed that net power could be controlled from 100% to 0% with a turbine bypass valve. For safe operation of the system, recuperator recirculation and inventory tank valves are used to avoid the local frozen in a heat exchanger and choking events in compressors. From the power-control transient analysis, it is concluded that the nitrogen Brayton cycle is applicable for coupling energy systems with simple control strategies.
Jae Hyun Choi,Jung Yoon,Sungkun Chung,Namhyeong Kim,HangJin Jo Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7
In this study, the validity of reducing the number of gas turbine stages designed for a nitrogen Brayton cycle coupled to a sodium-cooled fast reactor was assessed. The turbine performance was evaluated through computational fluid dynamics (CFD) simulations under different off-design conditions controlled by a reduced flow rate and reduced rotational speed. Two different multistage gas turbines designed to extract almost the same specific work were selected: two- and three-stage turbines (mid-span stage loading coefficient: 1.23 and 1.0, respectively). Real gas properties were considered in the CFD simulation in accordance with the Peng-Robinson's equation of state. According to the CFD results, the off-design performance of the two-stage turbine is comparable to that of the three-stage turbine. Moreover, compared to the three-stage turbine, the two-stage turbine generates less entropy across the shock wave. The results indicate that under both design and off-design conditions, increasing the stage loading coefficient for a fewer number of turbine stages is effective in terms of performance and size. Furthermore, the Ellipse law can be used to assess off-design performance and increasing exponent of the expansion ratio term better predicts the off-design performance with a few stages (two or three).
Kwon, Young-Do,Oh, Jung-Mi,La, Minh Thanh,Chung, Hea-Jong,Lee, Sun Joo,Chun, Sungkun,Lee, Sun-Hwa,Jeong, Byung-Hoon,Kim, Hee-Kwon American Chemical Society 2019 Bioconjugate chemistry Vol.30 No.1
<P>Prostate cancer is one of the most common cancers in the world. It is widely known that prostate-specific membrane antigen (PSMA) is highly expressed in prostate cancer, and hypoxia is a common characteristic of many solid tumors, including prostate cancer. In this study, we designed multifunctional fluorescent inhibitors to target PSMA and tumor hypoxia in order to increase the tumor uptake of inhibitors. Novel PSMA inhibitors were prepared using lysine as the backbone to connect three different functional groups: the glutamate-urea-lysine (GUL) structure for inhibiting PSMA, 2-nitroimidazole for the hypoxia-sensitive moiety, and a near-infrared fluorophore (sulfo-Cyanine 5.5). According to the <I>in vitro</I> PSMA binding assay, novel fluorescent inhibitors were demonstrated to have nanomolar binding affinities. Multifunctional inhibitor <B>2</B> with one 2-nitroimidazole had a similar inhibitory activity to inhibitor <B>1</B> that did not contain the hypoxia targeting moiety, but multifunctional inhibitor <B>3</B> with two 2-nitroimidazoles showed lower inhibitory activity than inhibitor <B>1</B> due to the bulky structure of the hypoxia-sensitive group. However, <I>in vivo</I> optical imaging and <I>ex vivo</I> biodistribution studies indicated that both multifunctional inhibitors <B>2</B> and <B>3</B> had higher accumulation in tumors than inhibitor <B>1</B> due to a synergistic combination of PSMA and hypoxia targeting moieties. These observations suggest that this novel multifunctional strategy might be a promising approach to improve the diagnosis and therapy of prostate cancer.</P> [FIG OMISSION]</BR>