Preparation and electrochemical characteristics of waste-tire char-based CFX for lithium-ion primary batteries

Ha Naeun,Jeong Seo Gyeong,Lim Chaehun,Ha Seongmin,Min Chung Gi,Choi Yusong,Lee Young-Seak 한국탄소학회 2023 Carbon Letters Vol.33 No.4

In this study, we investigate the opportunity of using waste tire char as a cathode material for lithium-ion primary batteries (LPBs). The char obtained by carbonizing waste tires was washed with acid and thermally fluorinated to produce CFX. The structural and chemical properties of the char and CFX were analyzed to evaluate the effect of thermal fluorination. The carbon structure of the char was increasingly converted to CFX structure as the fluorination temperature increased. In addition, the manufactured CFX-based LPBs were evaluated through electrochemical analysis. The discharge capacity of the CFX reached a maximum of 800 mAh/g, which is comparable to that of CFX-based LPBs manufactured from other carbon sources. On the basis of these results, the use of waste tire char-based CFX as a cathode material for LPBs is presented as a new opportunity in the field of waste tire recycling.

Improvement of the electrochemical properties of Li/CFx primary batteries induced by Nitrogen plasma treatment from silica and carbon fluoride

하성민,Lim Chaehun,Myeong Seongjae,이인우,이영석 한국탄소학회 2024 Carbon Letters Vol.34 No.5

The electrochemical properties of a CFX cathode were improved by defluorination of the surface with a N2 plasma and using a silica wafer. Compared to the N2 plasma treatment alone, when the CFX and silica were reacted together, the C-F bonds were modified and the surface was etched efficiently, so defluorination was enhanced. An electrochemical analysis confirmed that Half-cells prepared by treating CFx and silica with nitrogen plasma exhibited a capacity of about 400 mAh/g at 5C. In addition, it was confirmed that the loss of charge transfer was reduced by up to 71% compared to that for pristine CFX. As shown by a GITT analysis, when the CFx and silica were treated with N2 plasma together, the ion conductivity gradually increased due to a decrease in the ion diffusion barriers and the formation of a carbon layer. Therefore, this is a simple and effective way to improve the conductivities of CFX cathode materials with the energy of a N2 plasma and the silica-fluorine reaction.

Plasma treatment of CFX: the effect of surface chemical modification coupled with surface etching

Chaehun Lim,Seongmin Ha,Naeun Ha,Seo Gyeong Jeong,Young‑Seak Lee 한국탄소학회 2024 Carbon Letters Vol.34 No.2

포트란-CFX 연동해석 기법을 이용한 비정상 DC 전기삼투 유동 가시화

허영근(Young Gun Heo),정종현(Jong Hyeon Jeong),서용권(Yang Kweon Sub) 한국가시화정보학회 2011 한국가시화정보학회지 Vol.9 No.4

In this study, we present methods of coupling a commercial code, ANSYS CFX, and the user Fortran codes for solving an unsteady electro-osmotic flow around a pair of electrodes, receiving DC, attached to the top and the bottom walls of a two-dimensional cavity. We developed a module of Fortran programs for solving the ion-transport equations as well as the Poisson equations for the potential to be used in coupling with the CFX. We present how the developed codes are applied to solving the transient DC electro-osmotic flow problem within a simple cavity. We also address various problems encountered during the development process and explain why such problems are raised.

Benchmark Calculations of a Radiation Heat Transfer for a CANDU Fuel Channel Analysis using the CFD Code

KIM, Hyoung Tae,RHEE, Bo Wook,PARK, Joo Hwan Atomic Energy Society of Japan 2006 Journal of nuclear science and technology Vol.43 No.11

<P>To justify the use of a commercial Computational Fluid Dynamics (CFD) code for a CANDU fuel channel analysis, especially for the radiation heat transfer dominant conditions, the CFX-10 code is tested against three benchmark problems which were used for the validation of a radiation heat transfer in the CANDU analysis code, a CATHENA. These three benchmark problems are representative of the CANDU fuel channel configurations from a simple geometry to a whole fuel channel geometry. For the solutions of the benchmark problems, the temperature or the net radiation heat flux boundary conditions are prescribed for each radiating surface to determine the radiation heat transfer rate or the surface temperature, respectively by using the network method.The Discrete Transfer Model (DTM) is used for the CFX-10 radiation model and its calculation results are compared with the solutions of the benchmark problems. The CFX-10 results for the three benchmark problems are in close agreement with these solutions, so it is concluded that the CFX-10 with a DTM radiation model can be applied to the CANDU fuel channel analysis where a surface radiation heat transfer is a dominant mode of the heat transfer.</P>

Application of a Zircaloy/Steam Oxidation Model to a CFD Code and its Validation against a CANDU Fuel Channel Experiment: CS28-2

KIM, Hyoung Tae,RHEE, Bo Wook,PARK, Joo Hwan Atomic Energy Society of Japan 2007 Journal of nuclear science and technology Vol.44 No.11

<P>Oxidation of a Zircaloy cladding exposed to high-temperature steam is an important phenomenon in the safety analysis of CANDU reactors during a postulated loss-of-coolant accident (LOCA), since a Zircaloy/steam reaction is highly exothermic and results in hydrogen production. As part of a computational fluid dynamics (CFD) simulation of the CS28-2 high-temperature experiment for this accident analysis, two Zircaloy/steam reaction models based on a parabolic rate law are implemented in a commercial CFD code (CFX-10) through a user FORTRAN. It is confirmed that the present oxidation models for the CFX-10 reproduce the results of each empirical correlation in the verification tests well. Then the CFX-10 predictions of a temperature rise and hydrogen production due to Zircaloy/steam oxidation are compared with the results of the CS28-2 experiment. From these validation processes, it is shown that the Urbanic-Heidrick model, which is widely used in CANDU fuel channel codes, is also applicable to a CFX-10 simulation of Zircaloy/steam oxidation in a CANDU fuel channel.</P>

Antibacterial Activity of Ciprofloxacin-incorporated Central Venous Catheters and its Mechanism Against Planktonic Bacterial Cells

Sung Min Jeon,Mal Nam Kim 대한의생명과학회 2009 Biomedical Science Letters Vol.15 No.1

Bloodstream infections (BSI) are caused by planktonic microorganisms, sometimes leading to serious infections such as bacteremia and sepsis. BSI occurs more frequently to the patients wearing the central venous catheter (CVC). The ciprofloxacin-incorporated CVC (CFX-CVC) has been reported previously to possess antimicrobial activity. In this study, the antibacterial activity of CFX-CVC and its mechanism against planktonic BSI cells were explored by using the shake flask test and by examining the release rate of 260 nm-absorbing substances from the bacterial cells indicative of the membrane damage of the bacterial cells. CFX-CVC reduced more than 99.9% of the viable planktonic BSI cells demonstrating its potent antibacterial activity. It provoked bacteriolysis causing leakage of a large amount of 260 nmabsorbing materials from the planktonic bacterial cells like S. aureus and E. coli. These results provide evidence that the antibacterial activity of CFX-CVC came from the inhibition of the stability of the planktonic bacterial cells.

상용 및 오픈소스 CFD 코드를 이용한 EFD-CFD 워크샵 Case 3 해석

김종록(Jong Rok Kim) 한국항공우주학회 2017 韓國航空宇宙學會誌 Vol.45 No.3

EFD-CFD 워크샵 중 Case3인 RAE Wing A 형상에 대해 전산유체역학 해석을 수행하였다. 해석자로 3개의 상용 CFD 해석 코드(Star-CCM+, Fluent, CFX)와 오픈 소스 CFD 코드(SU2)를 사용하였다. 격자는 상용 격자 생성 코드인 Pointwise를 이용하여 격자의 수에 따라 4가지를 생성하였다. 마하수 0.4, 0.8에서 는 받음각 2도, 마하수 0.9에서 받음각 1도에서 해석하였다. coarse격자부터 fine 격자까지는 압력계수 곡선과 수직력 계수는 비슷한 결과를 보였으나 항력 계수에서는 차이가 있었다. Star-CCM+과 Fluent의 해석에서 차분법의 차수가 높을수록 충격파의 위치를 앞으로 예측하였다. 수렴에 다다르는 계산시간은 Fluent, Star-CCM+, CFX의 순으로 나타났고 SU2는 이에 비해 수렴하는데 많은 시간이 들었다. Computational fluid dynamics analysis was performed for the case 3 of the EFD-CFD workshop. Solvers were used for three commercial CFD codes(Star-CCM+, Fluent and CFX) and an open source CFD code(SU2). The grid were generated four types depending on the total cells using commercial grid generation code(Pointwise). Mach number of 0.4 and 0.8, 2 degree angle of attack and Mach number of 0.9, 1 degree angle of attack were calculated. Similar pressure coefficient curve and normal force coefficient were showed from the coarse grid to fine grid of four codes. But there is a difference in the drag coefficient. The position of the shock wave was predicted forward as the discretization order increased in calculations using Star-CCM+ and Fluent. The computation time to converge, Fluent, Star-CCM +, CFX are in order, and SU2 takes much time to converge.

배수갑문 주위의 흐름현상에 대한 3차원 난류 수치모형과 수리모형실험의 비교

이상화(Lee, Sang-Hwa),장은철(Jang, Eun-Cheul),하재율(Ha, Jae-Yul) 한국해안해양공학회 2007 한국해안해양공학회 논문집 Vol.19 No.2

본 연구는 갑문 개방시 유출부의 흐름 현상을 수리모형실헐 결과와 3차원 수치모형실험을 비교 분석하는데 역점을 두고 있다. 대상 갑문은 군장(군산-장항)국가산업단지내의 솔리천에서 유입되는 홍수량 218m³/s을 배제하기 위해서 설계된 배수갑문이다. 수치실험에 사용된 모형은 상용 전산유체역학 프로그램인 ANSYS CFX-10의 κ?ε 난류모형이다. CFX-10의 장점은 난류 흐름에 대해 현상을 양호하게 시뮬레이션 할 수 있으며 특히 물과 공기 접촉면(two phase interface)인 경계층에서 흐름 분리현상을 비교적 뚜렷하게 해석할 수 있다. 수치실험에서 해석된 유속 및 수면의 흐름 형태는 수리모형실험과 유사하게 나타났다. This study is focused on the comparison of a 3 dimensional numerical and hydraulic model experiment for the flow phenomenon when a lock gate is opened. The lock gate is designed to discharge the flood flow rate at 218m³/s of Solicheon at the Kun Jang national industry complex. The three dimensional κ?ε turbulent model of ANSYS CFX-10 of the computational fluid dynamics(CFD) program was used. The characteristics of CFX-10 are able to be simulated effectively for turbulent flow, especially the flow separation of the boundary layer of the two phase interface of air and water. The velocity and the flow pattern of the numerical model was showed to be similar to the results of the hydraulic model experiment.

비대칭으로 연결된 도로 합류부에서의 홍수흐름특성에 관한 수치적 연구

하규호,최성진,김종걸,정우창 한국방재학회 2012 한국방재학회 학술발표대회논문집 Vol.11 No.-

본 연구에서는 도로가 비대칭으로 연결되었을때 합류부 및 합류부 주위에서의 홍수흐름특성을 수리실험 및 3차원 유동모의 프로그램을 이용하여 실험적 분석 및 수치적 분석을 수행하였으며, 적용된 수치모형은 1990년대 초반 영국원자력공사(UKAEA)와 캐나다의 ASC(Advance Science Computing)의 TASCflow로부터 개발되어 CFX-4와 CFX-TASCflow를 기반으로 발전된 CFD 해석모형인 ANSYS CFX모형이다. 모의 및 분석결과 본 연구에서 적용된 모형은 유입유량 및 유입각 조건에 따라 도로 합류부에서 변화되는 복잡한 수면양상을 비교적 잘 모의하는 것으로 나타났다. 또한 도로 합류부 내에서의 시간 및 공간적 수심변화와 두 개의 하류경계에서의 유출유량에 대한 모의결과는 측정결과와 비교적 잘 일치하였다.