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DF 엔진의 급기 매니폴드용 폭발 릴리프 밸브의 설치를 위한 유동해석
Li Changchang,고대권(D. K. Koh),황성철(S. C. Hwang),정석호(S. H. Jung) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월
선박의 엔진에서 폭발 사고가 발생하는 경우, 선박 화재뿐만 아니라 인명 사고까지 이어지는 심각한 문제가 될 수 있다. 이중 연료(Dual Fuel) 엔진의 급기 매니폴드는 이러한 폭발 사고가 발생할 가능성이 있기 때문에 폭발 릴리프 밸브를 설치하고 있다. 크랭크케이스에 설치되는 폭발 릴리프 밸브는 디젤엔진에 오래전부터 사용되어오며 많은 선행 연구들이 이뤄졌지만, 급기 매니폴드에 설치하는 것은 최근들어 적용되었기 때문에 아직까지 다양한 연구가 이뤄지지 않고 있다. 급기 매니폴드에서 발생하는 폭발 사고는 급 배기 밸브의 겹침이 발생하는 시점에서 기계적 결함으로 인해 발생하는데, 이러한 상황을 실험을 통해 구현하는데 어려움이 있다. 그렇기 때문에 전산유체역학(CFD)을 이용하여 사고가 발생하는 상황을 시뮬레이션하여 분석해야할 필요가 있다. 본 연구에서는 이중 연료엔진에서 사용되는 액화천연가스 성분 중에서 메탄이 급기 매니폴드에서 폭발을 일으키는 경우를 수치해석하여 압력, 온도 결과 및 폭발 릴리프 밸브의 설치 필요성에 대해 분석하였다. 폭발이 발생하는 경우 압력의 상승으로 인해 충격파가 발생하며, 폭발 릴리프 밸브는 급격한 압력 상승을 방지하기 위해 적합한 위치에 설치되어야 한다. 800 kW 급 7기통 중속엔진의 급기 매니폴드을 대상으로 각 실린더에서 폭발이 발생하는 경우를 분석하였고, 폭발 릴리프 밸브로 인해 압력 및 온도가 감소되는 영향을 확인하였다. 실린더에 따라 압력 및 온도가 감소하는 결과는 다르게 나타났으며, 본 연구의 결과를 활용하여 폭발 릴리프 밸브의 위치 선정 및 엔진의 운전 조건에 따라 발생하는 폭발 사고를 시뮬레이션하는데 활용할 수 있을 것으로 기대된다.
Xin Yao,CHANGCHANG MA,Hai Huang,Zhi Zhu,Hongjun Dong,Chunxiang Li,Wenli Zhang,Yongsheng Yan,Yang Liu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.3
In this paper, the biomass carbon quantum dots (CQDs) modified flower-like BiOI (CQDs/BiOI) composite photocatalyst was synthesized by a facile solvothermal method. Compared with the pristine BiOI, the biomass CQDs/BiOI exhibited outstanding photocatalytic activity for degradation of the typical methylene blue (MB) under visible light irradiation since the biomass CQDs could act as electron acceptors to effectively facilitate the separation efficiency of photon-generated carriers and prolong their lifetime. Furthermore, the mechanism detection experiment showed that the ·O2 - and H+ were major activity species, and the photocatalytic electron transfer mechanism was further investigated. This work provided a new insight into biomass CQDs effects and took an important step toward the development of improving Bi-based semiconductor photocatalyst activity.
Dongyao Wu,Jinze Li,Jingru Guan,Chongyang Liu,Xiaoxu Zhao,Zhi Zhu,CHANGCHANG MA,Pengwei Huo,Chunxiang Li,Yongsheng Yan 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.64 No.-
An Intercalated heterostructural g-C3N4/TiO2/HNTs supported photocatalyst was successfully prepared via sol–gel and calcination methods. The introduction of HNTs and the g-C3N4-TiO2 heterojunction effectively enhanced the charge transfer and separation efficiency of photogenerated electron–hole pairs, which endued the g-C3N4/TiO2/HNTs hybrid material with an outstanding photoelectric performance and good stability. And an obviously enhanced photocatalytic activity was exhibited by photodegrading ciprofloxacin compared with pure TiO2. Furthermore, the main active species were detected through trapping experiment and ESR spin-trap technique with DMPO, which confirmed that the O2− and the h+ were the main active species in the photocatalytic system.
Pengwei Huo,Yanfeng Tang,Mingjun Zhou,Jinze Li,Zhefei Ye,CHANGCHANG MA,Longbao Yu,Yongsheng Yan 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.37 No.-
ZnWO4-CdS heterostructure photocatalysts have been successfully synthesized by hydrothermalmethod with assembling CdS on the surface of ZnWO4. The obtained composite photocatalysts werecharacterized by X-ray diffraction, transmission electron microscopy, Raman, thermo-gravimetricanalysis, UV–vis diffuse reflectance spectroscopy, photoluminescence and photocurrent measurement. The results show that the interface between ZnWO4 and CdS is well formed, and the CdS nanoparticlesare uniformly distributed onto ZnWO4 nanorods which could facilitate charge transfer and reducerecombination of photo-generated electrons and holes. Compared with pure ZnWO4 and CdS, the aspreparedheterostructure photocatalysts exhibit excellent photostability and photodegradation abilityof ciprofloxacin (CIP) under visible light irradiation.
Yu Zhao,Yongjun Zhou,Lingling Wu,Changchang Li,Zhongguo John Ma 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.6
The Longgang Bridge in Shaanxi, China, is a complex continuous hybrid structure composed of two cable-stayed self-anchored suspension parts and one single-pylon cable-stayed part. A 1:20-scaled model was established due to the effect of multiple structural transformation, frequent internal force changes during the construction process, and differences between actual material parameters and theoretical calculation parameters. In this paper, the design, materials, counterweight, experimental instrumentation, and construction stages of the scaled model are introduced. Based on the experimental data, the nonlinear behavior of the self-anchored suspension and cable-stayed hybrid bridge during the structural transformation of the construction process is systematically and comprehensively studied. The evolutions of the hanger force and stayed cable force, the variation in the subcable and back-cable forces, the displacement characteristics of the suspension cable and the deflection of the stiffened girder are analyzed, and the relationships among these variables in different states of the structural system are discussed. This paper will serve as a technical reference for the construction of similar bridges in the future.
Longbao Yu,Zhefei Ye,Jinze Li,Chunhong Ma,CHANGCHANG MA,XINLIN LIU,Huiqin Wang,Lili Tang,Pengwei Huo,Yongsheng Yan 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.6
A series of hamburger-like Ag@ZnO/C core–shell plasmonic photocatalysts have been synthesized via a simple solvothermal method for degradation of tetracycline (TC) under visible light irradiation, possessing high photocatalytic activity and good stability. The presence of localized surface plasmon resonance (LSPR) in the Ag core has increased the photocatalytic activity over an extended wavelength range. The plasmon-induced resonant energy transfer (PIRET) and direct electron transfer (DET) have facilitated the excitation and separation of photogenerated e-/h+pairs, which has been further confirmed by electrochemical investigations. The presences of hydroxyl radicals ( ·OH), superoxide radicals ( · O-2) and singlet oxygen (1O2) in the photocatalytic reaction system of Ag@ZnO/C photocatalyst have been demonstrated by electron spin resonance (ESR) measurements. All of the experiment results indicate that the ternary structure of Ag@ZnO/C can effectively enhance the photocatalytic activity. Furthermore, the effects of introduced Ag contents and carbon source dosage were researched by comparative photocatalytic experiments, and the potential structures of photodegradation products were studied by HPLC-MS.