Optimization of active area of proton exchange membrane fuel cell with better water management

M. Karthikeyan,M. Muthukumar,P. Karthikeyan,C. Mathan 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.5

Water flooding is one of the major issues which is influencing the performance of PEMFC, while scaling up the active area. Water accumulation in between the GDL and cathode flow field landing in PEMFC can be removed by fixing porous inserts along the landing area of the cathode flow field. In this paper, the optimum active area of the PEMFC is found from the experimental investigations of three active area sizes of 25 cm2, 36 cm2 and 70 cm2 with better water management by fixing porous inserts along the landing surface. All three active areas of PEMFCs with three different flow fields viz. Serpentine; Uniform and Stagger patterned pin types having porous inserts on cathode side have been investigated experimentally. The PEMFCs with active area of 25 cm2, 36 cm2 and 70 cm2 with stagger patterned pin types having porous inserts have obtained maximum power densities as 0.270 W/cm2, 0.338 W/cm2and 0.170 W/cm2 respectively. The PEMFC with active area of 36 cm2 yields higher power density compared to 25 cm2 and 70 cm2 PEMFCs. So it is found that the active area of 36 cm2 is the optimum active area of single cell PEMFC for maximum performance.

Self-Excited and Hidden Attractors in a Simple Chaotic Jerk System and in Its Time-Delayed Form: Analysis, Electronic Implementation, and Synchronization

Rajagopal Karthikeyan,Kingni Sifeu Takougang,Kom Guillaume Honoré,Pham Viet-Thanh,Karthikeyan Anitha,Jafari Sajad 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.2

A chaotic simple jerk system (SJS) that belongs to systems with self-excited and hidden attractors is introduced in this paper. The dynamics of the proposed SJS is analytically and numerically investigated. Interestingly, the influence of the time delay on the proposed chaotic SJS is studied. In addition, the physical existence of self-excited and hidden chaotic attractors found in the proposed SJS and in the time-delayed form of SJSs (TDSJSs) are verified by using Orcard-PSpice software. Finally, chaos synchronization of identical, unidirectional, coupled, proposed chaotic TDSJSs is also reported.

Preparation and Cyclic Performance of Li_1.2(Fe_0.16Mn_0.32Ni_0.32)O₂ Layered Cathode Material by the Mixed Hydroxide Method

Karthikeyan, K.,Nam, K.W.,Hu, E.Y.,Yang, X.Q.,Lee, Y.S. Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.7

Layered $Li_{1.2}(Fe_{0.16}Mn_{0.32}Ni_{0.32})O_2$ was prepared by the mixed hydroxide method at various temperatures. Xray diffraction (XRD) pattern shows that this material has a ${\alpha}-NaFeO_2$ layered structure with $R{\bar{3}}m$ space group and that cation mixing is reduced with increasing synthesis temperature. Scanning electron microscopy (SEM) reveals that nano-sized $Li_{1.2}(Fe_{0.16}Mn_{0.32}Ni_{0.32})O_2$ powder has uniform particle size distribution. X-ray absorption near edge structure (XANES) analysis is used to study the local electronic structure changes around the Mn, Fe, and Ni atoms in this material. The sample prepared at $700^{\circ}C$ delivers the highest discharge capacity of 207 $mAhg^{-1}$ between 2-4.5 V at 0.1 $mAcm^{-2}$ with good capacity retention of 80% after 20 cycles.

Union dyeing of cotton/nylon blended fabric by plasma-nano chitosan treatment

Karthikeyan Kaliyamoorthi,Ramachandran Thangavelu 한국의류학회 2015 Fashion and Textiles Vol.2 No.1

Current union dyeing processes rely on one or two dye baths with one or two dyes for cotton/nylon blend fabrics. For 50:50 cotton/nylon fabrics, cotton is dyed first under alkaline condition with reactive dyes and then the nylon is dyed with acid dyes under acidic condition. Atmospheric plasma- nano Chitosan treatment as an environmentally friendly method was employed to modify surface properties of cotton/nylon blend fabrics to develop union dyeing with acid dyes. Cellulose fibers when immersed in water produce a negative electro-kinetic potential. The negative charge on the fiber repels the anionic dye ions and consequently the exhaustion of the dye bath is limited. When the fabric is treated with chitosan, the primary hydroxyl groups of cellulose is partially modified into amide groups, which intern leads the cellulose to act like as polyamide fiber. Experimental work was carried out on finding the possibility of one bath dyeing of plasma- chitosan pretreated cotton/nylon fabric with acid dyes. Plasma treated cotton/nylon surface characteristics were evaluated using FTIR. The surface activation using air plasma introduces different functional groups in cotton/nylon blend fabric. The effect of plasma-nano chitosan pretreatment on dye ability, fastness, and few physicochemical properties has been investigated, and results are presented. The cotton/nylon sample treated with 0.3% of chitosan nanoparticles had higher K/S values, washing, and crocking fastness. New method of union dyeing showed good fastness properties and offers the option of eco-friendly.

Application of Opposition-based Differential Evolution Algorithm to Generation Expansion Planning Problem

Karthikeyan, K.,Kannan, S.,Baskar, S.,Thangaraj, C. The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.4

Generation Expansion Planning (GEP) is one of the most important decision-making activities in electric utilities. Least-cost GEP is to determine the minimum-cost capacity addition plan (i.e., the type and number of candidate plants) that meets forecasted demand within a pre specified reliability criterion over a planning horizon. In this paper, Differential Evolution (DE), and Opposition-based Differential Evolution (ODE) algorithms have been applied to the GEP problem. The original GEP problem has been modified by incorporating Virtual Mapping Procedure (VMP). The GEP problem of a synthetic test systems for 6-year, 14-year and 24-year planning horizons having five types of candidate units have been considered. The results have been compared with Dynamic Programming (DP) method. The ODE performs well and converges faster than DE.

Zinc-Porphyrin Based Dyes for Dye-Sensitized Solar Cells

Karthikeyan, S.,Lee, Jin Yong American Chemical Society 2013 The journal of physical chemistry. A, Molecules, s Vol.117 No.42

<P>We have designed seven efficient sensitizers based on the zinc-porphyrin structure for dye sensitized solar cells (DSSCs). The geometries, electronic properties, light harvesting efficiency (LHE), and electronic absorption spectra of these sensitizers are studied using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. We found that the designed sensitizers have smaller HOMO–LUMO energy with broadened and red-shifted absorption bands (300–1100 nm) having high molar extinction coefficient compared to the so far known best sensitizer (YD2-o-C8). The position of HOMO–LUMO energy level of these sensitizers ensures a positive effect on the process of electron injection and dye regeneration. Our theoretical calculations reveal that the new sensitizer can be used as a potential sensitizer for DSSCs compared to YD2-o-C8.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcafh/2013/jpcafh.2013.117.issue-42/jp408473k/production/images/medium/jp-2013-08473k_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp408473k'>ACS Electronic Supporting Info</A></P>

Synthesis, characterization, and transport properties of single-layer pure and molybdenum-doped vanadium oxide thin films on metallic conductive substrates

Karthikeyan, M.,Um, S. Elsevier Sequoia 2016 THIN SOLID FILMS - Vol.606 No.-

Single-layer undoped and 10mol% molybdenum (Mo)-doped vanadium oxide (V<SUB>2</SUB>O<SUB>3</SUB>) thin films with thicknesses of approximately 342nm are fabricated by an aqueous sol-gel method and then deposited onto 316L stainless steel conductive substrates. The influence of various annealing temperatures (in a nitrogen atmosphere) on the structural and electrical properties of undoped and Mo-doped vanadium oxide thin films is investigated. Through a controlled annealing process, the electrical resistances of the single-layer thin films are optimized to attain the required amount of Joule heating for cold-start fuel cell applications within an ambient temperature range (273.15 to 253.15K). The films show a negative temperature coefficient (NTC) behavior and a transition from a metal to an insulator at sub-zero temperatures. The highest electrical resistivities are measured to be 0.032@?.cm and 0.071@?.cm for undoped and Mo-doped vanadium oxide films, respectively, after annealing under 20sccm N<SUB>2</SUB> at 673.15K. Consequently, the equilibrium surface temperature of the single-layer Mo-doped vanadium oxide thin film increases from 253.15K to 299.46K upon induced Joule heating at a current density of 0.1A.cm<SUP>-2</SUP>. Thus, it is concluded that single-layer NTC Mo-doped vanadium oxides can be effectively used for cold-start fuel cell applications.

A porous activated carbon supported Pt catalyst for the oxidative degradation of poly[(naphthaleneformaldehyde)sulfonate]

Karthikeyan, S.,Jo, Wan-Kuen,Dhanalakshmi, R.,Isaacs, Mark A.,Wilson, Karen,Sekaran, G.,Lee, Adam F. Elsevier 2018 JOURNAL- TAIWAN INSTITUTE OF CHEMICAL ENGINEERS Vol.93 No.-

<P><B>Abstract</B></P> <P>Wet catalytic oxidation of sodium poly[(naphthaleneformaldehyde)sulfonate], a hazardous contaminant of wastewater streams from the textiles industry, by hydrogen peroxide under ambient conditions was explored over platinum supported on a porous activated carbon (PAC). Bulk and surface properties of the Pt/PAC catalyst were investigated by XRD, XPS, SEM, TEM, FTIR, EPR and thermogravimetric analysis. The parent PAC, derived from pyrolysis and subsequent activation of rice husks, exhibited significant micro- and mesoporosity, and a high degree of surface oxidation. Incorporation of 1.7 wt% Pt resulted in mesopore blockage, and a corresponding drop in surface area, associated with the formation of large ∼8 nm metallic nanoparticles. Poly[(naphthaleneformaldehyde)sulfonate] oxidative degradation was studied as a function of reactant concentration and solution pH, revealing first order decomposition kinetics and good activity over pH 3–9 at ambient temperature. Electron Paramagnetic Resonance (EPR)-DMPO spin trapping experiments confirm that oxidation of the organic pollutant proceeded via hydroxyl radical generation. The 1.7 wt% Pt/PAC catalyst showed excellent catalyst stability for five consecutive runs over 25 h in a fluidised bed reactor, delivering > 85% removal of 100 mg/L sulfonate with negligible Pt leaching or activity loss, and comparable performance for treatment of a real tannery effluent stream with a COD equivalent of 1860 mg/L.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A facile route to Pt functionalized biogenically sourced porous activated carbon. </LI> <LI> First heterogeneous catalyst for poly[(naphthaleneformaldehyde)sulfonate] oxidation. </LI> <LI> Excellent activity and stability over a broad concentration and pH range. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Iridium oxide nanoparticles decorated on MnO2 nanorods supported reduced graphene oxide as efficient electrocatalyst towards oxygen evolution reaction

Karthikeyan S C,Dong Jin Yoo 한국에너지학회 2021 한국에너지공학회 학술발표회 Vol.2021 No.11

PV fed Hybrid Power Converter for rural home applications

Karthikeyan A,Praneeth C.V.S,Prabhakaran K. K. 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper proposes a standalone PV fed hybrid power converter for rural home applications. The aim of the proposed system is to simultaneously deliver the power extracted from PV panels to DC and AC home loads using the proposed hybrid converter topology. The system operates in either MPP or Non–MPP mode depending on the total power demanded by the loads. Modified Perturb and Observe (P&O) MPPT algorithm is used to extract maximum power from PV panels. SPWM based modified PWM technique is used for converter operation. In the MPP mode the power distribution to DC load and AC load is in accordance with the duty generated by modified MPPT. In Non MPP mode, power distribution is in accordance with the duty generated by the single loop voltage control for DC load. The simulation studies for the proposed system are carried out in MATLAB/SIMULINK environment.