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Jongin Yang,Hong Hyun Son,Yong Jae Lee,Doyoung Shin,Taejin Kim,Seong Soo Choi Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.6
The load-following operation of small modular reactors (SMRs) requires accurate prediction of transient behaviors that can occur in the balance of plants (BOP) and the nuclear steam supply system (NSSS). However, 1-D thermal-hydraulics analysis codes developed for safety and performance analysis have conventionally excluded the BOP from the simulation by assuming ideal boundary conditions for the main steam and feed water (MS/FW) systems, i.e., an open loop. In this study, we introduced a lumped model of BOP fluid system and coupled it with NSSS without any ideal boundary conditions, i.e., in a closed loop. Various methods for coupling boundary conditions at MS/FW were tested to validate their combination in terms of minimizing numerical instability, which mainly arises from the coupled boundaries. The method exhibiting the best performance was selected and applied to a transient simulation of an integrated NSSS and BOP system of a SMART. For a transient event with core power change of 100-20-100%, the simulation exhibited numerical stability throughout the system without any significant perturbation of thermal-hydraulic parameters. Thus, the introduced boundary-condition coupling method and BOP fluid system model can expectedly be employed for the transient simulation and performance analysis of SMRs requiring daily load-following operations.
MCFC 발전시스템용 촉매연소기의 연소 특성에 관한 실험적 연구
홍동진(Dong Jin Hong),안국영(Kook Young Ahn),김만영(Man Young Kim) 대한기계학회 2012 大韓機械學會論文集B Vol.36 No.4
MCFC 발전시스템에서 연소기는 연료극의 배가스 중에 포함된 미반응 가스를 연료로 사용하여 공기극에 H₂O와 CO₂ 농도가 높은 고온의 혼합가스를 공급하는 역할을 한다. 하지만 이러한 배가스는 가연한계 이하로 내려가게 되어 통상적인 연소방식에 의한 완전연소가 어렵기 때문에 이를 해결하기 위하여 촉매연소기를 사용한다. 완전연소 및 이에 다른 공해물질의 저감 특성에 따라 최근 촉매연소는 환경친화적인 연소방식으로 주목받고 있다. 따라서 본 연구에서는 MCFC 발전시스템의 BOP 시스템에 적용되는 촉매연소기에 대한 실험연구를 수행하였다. 본문에서는 실험장치를 설명한 후 촉매연소 시스템의 설계변수, 즉, H₂ 연료 첨가에 따른 연료조성, 유입가스의 온도, 과잉 공기비, 촉매의 종류, 그리고 시동 스케줄에 따른 촉매연소 특성을 고찰하였다. In the MCFC power generation system, the combustor supplies a high temperature mixture of gases to the cathode and heat to the reformer by using the off-gas from the anode; the off-gas includes high concentrations of H₂O and CO₂. Since a combustor needs to be operated in a very lean condition and avoid local heating, a catalytic combustor is usually adopted. Catalytic combustion is also generally accepted as one of the environmentally preferred alternatives for generation of heat and power from fossil fuels because of its complete combustion and low emissions of pollutants such as CO, UHC, and NOx. In this study, experiments were conducted on catalytic combustion behavior in the presence of Pd-based catalysts for the BOP (Balance Of Plant) of 5 ㎾ MCFC (Molten Carbonate Fuel Cell) power generation systems. Extensive investigations were carried out on the catalyst performance with the gaseous CH₄ fuel by changing such various parameters as H₂ addition, inlet temperature, excess air ratio, space velocity, catalyst type, and start-up schedule of the pilot system adopted in the BOP.
Dynamic behavior modeling of a polymer electrolyte membrane fuel cell power generation system
이정호,강수영,Tong Seop Kim 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.11
This paper presents models for simulating the operation of a polymer electrolyte membrane fuel cell (PEMFC) system and the results of the dynamic simulations. The entire system included a PEMFC stack and balance-of-plant components such as an air supply blower, a membrane humidifier, a fuel supply unit, and a heat management unit. Mathematical modeling for the computation of power generation and heat transfer of the PEMFC stack, the heat and mass transfer of the humidifier, and the energy transfer of the cooling system was set up. Theoretical and experiential data such as the voltage-current density relationship of the cell stack and the performance maps of blowers and pumps, together with semi-theoretical heat and mass transfer equations, were used to represent the characteristics of all the components. The effect of the thermal inertia of solid parts was considered in the fuel cell stack, the membrane humidifier, and the radiator. System dynamic behaviors under various operating conditions due to changes in stack current and ambient temperature were predicted. The sudden abnormal operations of the cooling water circulation pump and the radiator fan were also simulated as an example of component malfunctions.
Development of Active Breathing Micro PEM Fuel Cell
김병희,서영호,김형진,장웅기 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.1 No.2
Air-breathing proton exchange membrane fuel cells (AB-PEMFCs) can reduce the cost, complexity, noise, volume, and weight of fuel cells and can enhance their reliability. However, such cells are still typically characterized by low output power densities. In this study, to overcome the inherent weaknesses of low power density and oxygen concentration without mobility loss, we have adopted a microscale synthetic jet air breather (a crucial balance-of-plant device), which supplies air to the cathode side of the flow field of a planar AB-PEMFC. A synthetic jet air breather consists of a PZT diaphragm actuator, small cylindrical cavity, inlet and outlet channels, and a pump body. The flow rate of the fabricated synthetic jet air breather is more than 400 cc/min at 550 Hz with a power consumption of less than 0.3 W. An AB-PEMFC equipped with a microscale-synthetic jet air breather shows higher performance and stability, obtaining a maximum power density of 188 mW/cm2 at 400 mA/cm2.
김민석(Kim, Minseok),이선호(Lee, Sunho),전희권(Jun, Heekwon),배준강(Bea, Junkang) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
For stationary 1kW-class fuel cell systems to be used widely, it is essential to achieve dramatic improvements in system durability as well as cost reduction. In order to address this engineering challenge, it is important to develop innovative technologies associated with BOP components. According to this background, in 2009, the Korean Government and Korea Institute of Energy Technology Evaluation and Planning(KETEP) launched into the strategic development project of BOP technology for practical applications and commercializations of stationary fuel cell systems, named Technology Development on Cost Reduction of BOP Components for 1kW Stationary Fuel Cell Systems to Promote Green-Home Dissemination Project. The objectives of this project are to develop fundamental technologies to meet these requirements, and to improve the performance and functionality of BOP components with reasonable price. The project consortium consists of Korea's leading fuel cell system manufacturers, BOP component manufacturers which technologically specialized, and several research institutions. This paper is to provide a summary of the project, as well as the achievements made through the 1st period of the project(2009~2010). Several prototypes of BOPs - Cathode air blowers, burner air blowers, preferential oxidation air blowers, fuel blowers, cooling water pumps, reformer water pumps, heat recovery pumps, mass flow meters, valves and power conditioning systems - had been developed through this project in 2010. As results of this project, it is expected that a technological breakthrough of these BOP components will result in a substantial system cost reduction.
정황훈(Hwang-Hun Jeong),윤소남(So-Nam Yun),함영복(Young-Bok Kim),김동건(Dong-Gun Kim),서정균(Jeong-Kyun Seo),허덕열(Duk-Yeal Heo) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
The solenoid valve which was used in fuel cell system needs good performance on sealing because the work fluid can be exploded in the system. And the temperature of work fluid is extremely high to keep the property of rubber ring that seals the solenoid valve. This study deals with the rubber ring that is made by fluoro elastomers. The life cycle of rubber ring was estimated by relational expression of Arrhenius. And the solenoid valve was tested to confirm the sealing characteristic.
윤소남(So Nam Yun),정황훈(Hwang Hun Jeong),함영복,김동건(Dong-Gun Kim),허덕열(Duk-Yeal Heo) 대한기계학회 2011 大韓機械學會論文集A Vol.35 No.10
연료전지 내의 작동유체는 폭발성을 가지고 있기 때문에 솔레노이드 밸브의 실링특성은 일반적인 시스템에 비해 매우 중요하다 할 수 있다. 하지만, 이 시스템의 경우 작동 온도가 일반적인 경우에 비해 비교적 높으며, 작동 유체의 화학적 특성 때문에 실링에 사용되는 재질은 내화학성이 뛰어나면서도 연료전지 시스템에서 요구하는 수명을 보장해야 하는 어려움이 있다. 본 연구에서는 연료전지 내에서 사용가능한 솔레노이드 밸브의 실링 특성을 확인하기 위하여, 내화학성이 뛰어난 실링용 링의 재질인 불소고무에 대한 수명을 아레니우스(Arrhenius) 관계식을 이용하여 예측하였다. 또한, 수상치환법을 이용하여 실제 제작된 연료전지용 솔레노이드 밸브가 제품으로써 충분히 사용가능함을 확인하였다. The solenoid valve used in fuel cell system need to have good sealing performance because the work fluid can explode in the system. Moreover, the temperature of the work fluid is extremely high in order to maintain the properties of the rubber ring that seals the solenoid valve. This study deals with the rubber ring which is made from a fluoro-elastomer. The life cycle of the rubber ring was estimated by the relational expression of Arrhenius, and the solenoid valve was tested to confirm the sealing characteristics.