http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Li, Longnan,Kim, Daejoong Elsevier 2016 Journal of membrane science Vol.520 No.-
<P><B>Abstract</B></P> <P>We investigated the effect of poly-dispersed nanostructures on concentration polarization (CP) phenomena in ion exchange membranes through fabrication of poly-dispersed interconnecting channels (Pd-ICs) integrated microfluidic chip and characterized the CP phenomena which happens near the interconnecting channel and main microchannel interface. Current-voltage (<I>I-V</I>) characteristics and depletion (enrichment) layer formation behavior within Pd-IC system are examined. We found that “Electric field focusing” affects the <I>I-V</I> characteristics of Pd-IC system, and Pd-IC system follows the “Limiting current occurrence” criterion. The visualization results show that the depletion layer thickness at the anodic side decreases with an increasing dispersity and also for increasing bulk concentration. We attribute this phenomena to the high electroosmotic flow in the sub-microchannel and “Electroosmosis of the second kind” at the electrolyte-membrane (Pd-IC) interface. The perm-selectivity of interconnecting channels also play an important role. At the cathodic side, we observed that fluorescent dye depleted at the microchannel and sub-microchannel interface due to the ejecting flow and current balance at the corner wedge of sub-microchannels. We hope these working mechanisms of Pd-IC system to be beneficial to model pseudo-ion exchange membrane and to develop high efficiency ion exchange membranes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Investigation of effect of poly-dispersed nanostructures on concentration polarization (CP) phenomena through poly-disperse interconnecting channels (Pd-IC) integrated microfluidic chip. </LI> <LI> Electric field focusing” affects the <I>I-V</I> characteristics of Pd-IC system. </LI> <LI> Pd-IC system follows the “Limiting current occurrence” criterion. </LI> <LI> Depletion layer thickness at the anodic side decreases with an increasing dispersity and bulk concentration. </LI> <LI> Concentration depleted at the microchannel and sub-microchannel interface at the cathodic side. </LI> </UL> </P>
Air supply using an ionic wind generator in a proton exchange membrane fuel cell
Kwon, Kilsung,Li, Longnan,Park, Byung Ho,Lee, Seung Jun,Kim, Daejoong Elsevier 2015 Journal of Power Sources Vol.284 No.-
<P><B>Abstract</B></P> <P>A new air supply is demonstrated for a portable polymer electrolyte membrane fuel cell (PEMFC). The air supply is an ionic wind generator (IWG) with a needle-to-cylinder configuration. The IWG supplies air to the portable PEMFC owing to momentum transfer to the air by charged molecules generated by the corona discharge from a high applied potential. There is no difference in the performance of the PEMFC when compressed air and the IWG are used as the air supply. For the varying interelectrode distance, IWG performance is varied and measured in terms of the flow rate and current. At the interelectrode distance of 9.0 mm, the air flow rate is a suitable for the portable PEMFC with low power consumption. When the IWG is used to supply air to the portable PEMFC, it is found that the flow rate per unit power consumed decreases with the applied voltage, the gross power generation monotonously increases with the applied voltage, and the highest net power (268 mW) is obtained at the applied voltage of 8.5 kV. The parasitic power ratio reaches a minimum value of ∼0.06 with the applied IWG voltage of 5.5 kV.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Portable PEMFC integrated with ionic wind generator was demonstrated. </LI> <LI> IWG performance was evaluated with varying interelectrode distance and voltage. </LI> <LI> Influence of applied IWG voltage on PEMFC performance was evaluated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Numerical investigation of LNG gas dispersion in a confined space: An engineering model
Longnan Li,최진욱,방주원,이소영,이성혁,김대중 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.9
The present study has numerically investigated a dynamic methane leak and dispersion in a confined space. To establish a numerical prediction based engineering model of dynamic gas leak and dispersion in a confined space, numerical experiments are conducted for variation of a key parameter – leak hole size. Based on the numerical results data, an engineering model is developed. The parameters related to lower flammable limit of the methane were quantitatively analyzed to compare the potential risk due to a gas leak. To quantitatively investigate the flammable region, the longitudinal and transverse directional length is defined and studied. We found that the ratio between longitudinal and transverse directional length can be a bridge to model the flammable region. The aspect ratio of the flammable region is fitted by an exponential function to show the relation with time. Then, an oval-shape model is presented to predict flammable region. Oval-shape model is completed by the combination of aspect ratio relation and a function for transverse length. Finally, we compared the developed engineering model (oval-shape model) and numerical results. The engineering model can predict the flammable region quite well when it reaches steady state. It is expected that the established engineering model is valuable for the Quantitative risk assessment (QRA), initial emergency strategy preparation when a fuel gas leak accident happened in a Combined cycle power plant (CCPP). We hope it is also can be a kind of data base for power plant operation manual.
전극간 거리가 이온풍 발생에 미치는 영향에 대한 실험적 연구
Li Longnan,이승준(Seungjun Lee),김대중(Daejoong Kim) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
In this study, ion wind generator was fabricated with a needle electrode and a cylindrical copper electrode. The velocity generated by ion wind relates to the parameters such as applied voltage, distance of electrode gap and electrode type. The onset voltage and breakdown voltage of corona discharge increased with the electrode spacing and the best performance of wind velocity was obtained at 10㎜ electrode gap.
농도분극현상을 이용한 담수화 과정에서의 나노채널 개수 및 운전조건 영향에 대한 실험 적 연구
이용남(Longnan Li),정정열(Jung-Yeul Jung),김대중(Daejoong Kim) 한국가시화정보학회 2015 한국가시화정보학회지 Vol.13 No.2
Concentration polarization(CP) phenomena show great potential on desalination technology. As we can control the dimension of silicon based nanochannel system, it can be used to model ion exchange membrane. In this study, to investigate the effect of nanochannel number and working conditions on the CP based desalination process, nanochannel based microfluidic system is fabricated. First, we optimized nanochannel number and working conditions to conduct visualization study on CP based desalination process. Second, we visualized the desalination process with fluorescent dye in the desalination chip. We also visualized that the particles also can be removed by the CP based desalination process.
나노유체역학 시스템에서 부동한 조건하의 농도분극 현상에 대한 수치해석적 연구
이용남(Longnan Li),김대중(Daejoong Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
In this paper, we studied the concentration polarization phenomena in nanofluidic system.In this system, two microchannels are connected by one nanochannel. When electric field applied through the nanochannel, concentration polarization phenomena occures at the inteface of microchannel and nanochannel. In this study, we applied finite element method to describe concentration phenomena with different applied voltage and surface charge density