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원전용 능동기기 주요 성능특성 평가를 위한 수치해석 연구
김재형(Jaehyung Kim),김대환(Dae-Hwan Kim),이상혁(Sang Hyuk Lee) 한국전산유체공학회 2019 한국전산유체공학회지 Vol.24 No.1
The active components such as valve, pump and snubber to used in nuclear power plants shall be qualified according to ASME QME-1. For the qualification of valve assembly among various active components, the valve operation must be verified with considering the flow conditions. But the limitation of the test facility leads to the engineering evaluation on the valve operation. In general, the evaluation is related to the force such as the bearing torque, seating torque, packing torque, hydrostatic torque and hydrodynamic torque. Especially, the hydrodynamic torque coefficient is important, because the hydrodynamic torque is generally acquired from the test. This situation makes the valve maker difficult in design and qualification. And the evaluation of flow coefficient is also in same difficult situation to the valve maker. In this study, the hydrodynamic torque coefficient and flow coefficient are measured from the flow test and analyzed with CFD. And the CFD results have the engineering meanings within small error in comparison to the real test result. It is confirmed that the CFD is useful tools to get the performance parameter of valve, such as the hydrodynamic torque coefficient and flow coefficient.
외장형 연료펌프를 사용한 LPLi 연료공급시스템에서의 연료상태량 변화 예측
김재형(Jaehyung Kim),윤여빈(Yubin Yoon),송춘섭(Chunsub Song),박영준(Youngjoon Park),이성욱(Seangwock Lee),조용석(Yongseok Cho) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
The LPG(Liquefied Petroleum Gas) fuel attracts attention as a clean alternative fuel. In order to further reduce the exhaust emission and improve performance in LPG engines, the LPLi(Liquid Phase LPG Injection) system is used. In LPLi system, the fuel pump performance is important for keeping the LPG over its saturated vapor pressure. An external fuel pump is needed to improve the durability and the ease of maintenance for LPG engines. This paper predicted the variation of fuel properties on the LPLi system with an external fuel pump. From each components thermodynamic model, an 1-D simulation is developed for LPLi systerm with an external fuel pump. Then the 1-D simulation data analyzed and compared with the rig-test and chassis dynamometer test. The 1-D simulation, the rig-test and the chassis dynamometer test produced similar results.
원전용 게이트 밸브의 성능특성 분석을 위한 유동해석 모델링 연구
김재형(Jaehyung Kim),임태묵(Taemook Lim),이정희(Jung Hee Lee) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.4
The 3D flow analysis model on gate valve in nuclear power plant is made and validated by known experimental equation, which is the requirement of ASME QME-1 standard. The major loss on valve is calculated and compared to Swamee-Jain equation, where the error of pipe friction coefficient is within 7% error bound. The minor loss on valve is calculated but cannot be compared because of no experimental equation. So the orifice is inserted on pipe instead of valve and the differential pressure and flow rate is used to calculate the discharge coefficient (Cd value) with various size of flow passage. With the validated mesh and model, the flow analysis of gate valve was performed with changing stoke and reynolds number. The minor loss in valve is dominant when the valve is operated and the force on disk is larger with increasing reynolds number. Valve factor, which accounts the loss effect by differential pressure force, is calculated with the flow analysis result. The valve factor can be used in calculation of valve force in design and functional qualification.
김재형(Jaehyung Kim),이상혁(Sang Hyuk Lee),이정희(Jung Hee Lee) 한국전산유체공학회 2021 한국전산유체공학회지 Vol.26 No.3
Valve assembly must be qualified with technical guide of ASME QME-1 before using in nuclear power plant. In general, the qualification is to be performed by experiment, but lately the new version of ASME QME-1 is to require the qualification by the test based methodology. This study shows that the differential force on disk by fluid flow is to generate the contact force and frictional force on seat ring and guide bar. The last frictional force is to be transferred to the stem nut. The related mechanics is to be solved by multi-body dynamics. The fluid force on disk, named as differential pressure force, is to be calculated using interpolation of dimensionless differential pressure force by computational fluid dynamics(CFD). And the interpolation equation is to be made in multi-body dynamics solver and be applied for the force calculation using dimensionless stroke as dependent variable. This study shows that the contact model on disk, seat ring, and guide bar is to generate similar and proper data on thrust, torque, and stem factor. This study may be useful to evaluate the contact force on the gate valve in detail, that has been considered by simple assumption using limited experiment.
Saccharomyces cerevisiae 효모를 이용한 동시당화에서의 에탄올 생산
김재형(Jaehyung Kim),이준철(Juncheol Lee),박홍선(Hongsun Park),최용근(Yongkeun Choi),이선영(Sunyoung Lee),챠토패드히야제이타(Chattopadhy Jayeeta),박대원(Daewon Pak) 한국에너지학회 2008 한국에너지공학회 학술발표회 Vol.2008 No.-
바이오매스를 생물학적인 방법을 이용하여 바이오에탄올을 생산하는 과정은 크게 2가지로 나누어진다. 첫 번째로는 바이오매스의 고분자당류를 저분자당류로 전환시키는 당화단계와 두 번째로는 전환된 저분자당류를 에탄올로 전환하는 에탄올발효단계이다. 본 연구에서는 바이오매스인 음식물쓰레기를 이용하여 에탄올 생산효율을 극대화시키고자 당화단계에서 효소가수분해를 이용하였다. 효소는 glucoamylase와 complex carbohydrase를 이용하여 비교하였으며, 이때 complex-carbohydrase의 glucose생산량이 0.81g/g-dry foodwastes 이었다.. 발효과정에서의 에탄올생산 미생물(Saccharomyces cerevisiae)의 특성을 확인하고자, hexose를 이용하여 실험을 진행한 결과 0.48g ethanol/g hexose를 생산하였으며, 음식물쓰레기의 염분농도에 의한 S. cerevisiae의 영향을 확인하고자, 각각의 Cl-가 주입된 실험을 진행한 결과 약 5%이상의 Cl-농도에서 현저히 낮은 에탄올 생산량을 나타내었다. 음식물쓰레기를 이용하여 앞선 연구의 최적 당화조건을 적용한 당화과정 이후 S. cerevisiae를 접종한 결과 0.34g/g-dry food wastes를 생산량을 확인하였다.