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김현기(Kim Hyun-Gee),선칠령(Seon Chil-Yeong),이채수(Lee Chae-Soo),Falah Alobaid 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
This paper presents a static and dynamic simulation model of a Super Critical Heat Recovery Steam Generator (SC HRSG) and its application to investigate the load changes and start-up processes for the next generation high efficiency combined cycles. To design the modem combined cycle power plants with high pressure and temperature steam requirements, it is necessary to generate detailed computer models. As an important supports for designers this study describes the upgrading of a validated subcritical HRSG model to SC HRSG. The model includes advanced control circuits to achieve a high level of accuracy, especially during startup. The comparison between the simulation results and the designed data in steady state and different load changes are documented. The obtained results demonstrate that the simulation is very reliable to predict the startup procedure for the SC HRSG. And differences in the thermal efficiency between Sub & SC HRSGs during warm start-up process are assessed.
Finned Tube Bundle에 대한 Ash Fouling전산해석
최낙정(Choi Nak-Jeong),김현기(Kim Hyun-Gee),선칠령(Seon Chil-Yeong),김주석(Kim Joo-Suk),전충환(Jeon Chung-Hwan) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
The objective of this paper is to examine ash fouling behavior in a finned tube bundle by CFD simulation. A Finned Tube Bundle as heat exchanger is exposed to medium temperature(<520℃) region. Under the condition, we consider the particulate fouling only and neglect the condensation and chemical reaction. We derived a fouling model which is composed of the deposition and removal process. Capture conditions of ash particles in the deposition model is decided by force balance of van der waals, elastic rebound and gravity force. The removal model is derived from theoretical approach. A combination of both models was coded by UDF(User Defined Function) in FLUENT and can predict asymptotic behavior of the fouling process. Computational domain is a 9-rows finned tube bundle and flow is vertical opposed to the direction of gravity. We conducted a case study such as effects of ash concentration, inlet velocity and ash particle size distribution on fouling behavior.
EN Code 를 적용한 배열회수보일러의 드럼 피로수명평가
황석환(Hwang Sek-hwan),김현기(Kim Hyun-gee),선칠령(Seon Chil-yeong),이채수(Lee Chae-soo),이부윤(Lee Boo-youn) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
The purpose of this study is to confirm the structural reliability of the main component in HRSG by evaluating the structural integrity of HP drum according to EN code. The HP drum is the most thick-walled pressure vessel in HRSG, in which significant thermal stresses occur during the load change and transient operation. In this paper, transient temperatures and pressures determined by the dynamic simulation were taken into consideration, and thermal and structural finite element analyses(FEA) were performed to properly evaluate their effects. Using the results of the FEA, fatigue life of the HP drum was evaluated.
정재헌(Chong Chae Hon),김현기(Kim Hyun GEE),최영준(Choi Young Jun),이채수(Lee Chae Soo),하준욱(Ha Joon Wook) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
The purpose of this study is to propose the guideline of damage calculation for HRSG(Heat Recovery Steam Generator) components in design step. Cyclic, high temperature and pressure operation of the HRSG creates loading that produce stresses in boiler components that ultimately may produce failures in components. Recently, high operating pressure and temperature are required because of efficiency and also frequent startup/shutdown ate demanded to meet the change of electric power load in HRSG. For this study, operation types that may produce fatigue failure were examined and damage instances that are reported from plant were briefly investigated. In addition, several country's Codes that are suitable for life analysis of HRSG were searched. Sample calculation was performed and approaching method of damage calculation was proposed.
웹캐스팅 기법을 이용한 XML기반의 외국어학습 웹 코스웨어 구현
윤호군(Ho-Gun Yun),김천호(Chon-Ho Kim),김지연(Gee-Yeun Kim),김현기(Hyun-Ki Kim),강환수(Hwan-Su Kang),정화영(Hwa-Young Jeong) 한국정보과학회 2000 한국정보과학회 학술발표논문집 Vol.27 No.2Ⅱ
컴퓨터를 이용한 인터넷의 급속한 발전에 따라 이를 교육에 응용하려는 노력은 최근 몇 년 동안 지속적으로 진행되어왔다. 이는 인터넷 이용인구의 급속한 증가로 인하여 웹 상에서의 가상교육 및 원격교육에 관한 필요성이 증대되었고, 이를 실용화하려는 노력은 여러 가지 방법을 통하여 논의되어왔다. 따라서, 웹 코스웨어는 인터넷을 통한 원거리 학습자들에 대하여 학습욕구를 충족시키기 위한 목적으로 구현 및 개발되었다. 그러나, 이를 이용하려면 사용자의 시스템이 정보를 제공하는 서버와의 정보교환을 위하여 온라인 상태를 유지하였으며, 학습자가 서버에서 갱신되는 학습정보를 받아 보려면 온라인 상에서 학습자의 시스템이 서버로 접속이 이루어져야만 확인이 가능하였다. 본 논문은 이에 관하여 XML(eXtensible Markup Language)을 기반으로 한 웹 캐스팅 기법으로 웹 코스웨어를 구현하였으며 이를 위하여 CDF(Channel Definition Format)형식을 이용하였다. 즉, 채널을 이용하여 학습자가 자율적으로 채널을 선택하면, 학습자가 원하는 정보를 자동적으로 갱신되도록 하였다. 또한, 기존의 웹 코스웨어는 정보를 제공하는 서버의 학습내용이 변화 될 때마다 일일이 확인을 하여야 하는 반면 본 논문에서는 갱신되어진 내용을 학습자에게 자동적으로 업데이트 되도록 하였다.
선칠령(Seon Chil-Yeong),황석환(Hwang Sek-Hwan),김현기(Kim Hyun-Gee),조진현(Cho Jin-Hyun) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
This paper presents a static and dynamic simulation models of Heat Recovery Steam Generator (HRSG) with once-through evaporators and its application to investigate the load changes and startup processes for the combined cycles. The outstanding advantages of once-through HRSG (OT HRSG) are the rapid start-up/shutdown and operational flexibility. But it’ control system is more complex than drum type HRSG. Therefore, to design such a system, it is necessary to have computer models in detail. The OT HRSG models were made using commercial simulation software, APROS. The results of simulation for steady state, load changes, startup and shutdown operating processes were compared with the design data and gas turbine operating curves.
이채수(Lee Chae Soo),최영준(Choi Young Jun),김현기(Kim Hyun Gee),양옥철(Yang Ok Chul),정재헌(Chong Chae Hon) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
The once-through heat recovery steam generator is ideally matched to very high temperature and pressure, well into the supercritical range. Moreover this type of boiler is structurally simpler than drum type boiler. In drum type boiler, each tube play a well-defined role: water preheating, vaporization, superheating. Empirical equations are available to predict the average heat transfer coefficient for each regime. For once-through heat recovery steam generator, this is no more the case and mathematical models have to be adapted to account for the disappearance of drum type economizer, boiler, superheater. General equations have to be used for each tube of boiler, and actual heat transfer condition in each tube has to be identified.