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CONTENTS
Volume 4, Number 4, December 2016
 

Abstract
This paper presents a novel symbiotic organisms search (SOS) algorithm to optimize both real power loss (RPL) and voltage stability limit (VSL) of a transmission network by controlling the variables such as unified power flow controller (UPFC) location, UPFC series injected voltage magnitude and phase angle and transformer taps simultaneously. Mathematically, this issue can be formulated as nonlinear equality and inequality constrained multi objective, multi variable optimization problem with a fitness function integrating both RPL and VSL. The symbiotic organisms search (SOS) algorithm is a nature inspired optimization method based on the biological interactions between the organisms in ecosystem. The advantage of SOS algorithm is that it requires a few control parameters compared to other meta-heuristic algorithms. The proposed SOS algorithm is applied for solving optimum control variables for both single objective and multi-objective optimization problems and tested on New England 39 bus test system. In the single objective optimization problem only RPL minimization is considered. The simulation results of the proposed algorithm have been compared with the results of the algorithms like interior point successive linear programming (IPSLP) and bacteria foraging algorithm (BFA) reported in the literature. The comparison results confirm the efficacy and superiority of the proposed method in optimizing both single and multi objective problems.

Key Words
symbiotic organisms search algorithm; real power loss minimization; voltage stability limit enhancement; interior point successive linear programming; bacteria foraging algorithm

Address
Balachennaiah Pagidi: Department of Electrical & Electronics Engineering, AITS, New Boyinapalli-516126, Rajampet, A.P., India
Suryakalavathi Munagala, Nagendra Palukuru: Department of Electrical & Electronics Engineering, JNTUH-Kukatpalli-500085, Hyderabad, T.S., India

Abstract
In the present work, ZnO nanoparticles (NPs) have been dispersed alone in the same solvent of the active layer for improving performance parameters of the organic solar cells. Different concentrations of the ZnO NPs have been blended inside active layer of the solar cell based on poly(3-hexylthiophene) (P3HT), which forms the hole-transport network, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which forms the electron-transport network. In the present investigations, the ZnO NPs may represent an efficient tool for improving light harvesting through light scattering inside active layer, electron mobility, and electron acceptance strength which tend to improve photocurrent and performance parameters of the investigated solar cell. The fill factor (FF) of the ZnO-doped solar cell increases nearly 14% compared to the non-doped solar cell when the doping is 50%. The present investigations show that ZnO NPs improve power conversion efficiency of the solar cell from 1.23% to 1.64% with increment around 25% that takes place after incorporation of 40% as a volume ratio of the ZnO NPs inside P3HT:PCBM active layer.

Key Words
organic solar cells; ZnO nanoparticles; device performance parameters

Address
Shanmugam Saravanan, Murugesan Silambarasan: Centre for Photonics and Nanotechnology, Sona College of Technology, Salem 636 005, Tamil Nadu, India
Yasser A.M. Ismail: Third Generation Solar Cells Laboratory, Department of Physics, Faculty of Science, Al-Azhar University, Asyut 71524, Egypt
Yasser A.M. Ismail: Al-Azhar Center of Nanoscience and Applications (ACNA), Al-Azhar University, Assiut, 71524, Egypt
Naoki Kishi, Tetsuo Soga: Department of Frontier Materials, Nagoya Institute of Technology, Nagoya 466-8555, Japan

Abstract
Fundamental understanding of vanadium ion transport and the detrimental effects of cross-contamination on vanadium redox flow battery (VRFB) performance is critical for developing low-cost, robust, and highly selective proton-conducting membranes for VRFBs. The objective of this work is to examine the effect of conductivity and diffusivity, two key membrane parameters, on long-cycle performance of a VRFB at different operating conditions using a transient 2D multi-component model. This single-channel model combines the transport of vanadium ions, chemical reactions between permeated ions, and electrochemical reactions. It has been discovered that membrane selecting criterion for long cycles depends critically on current density and operating voltage range of the cell. The conducted simulation work is also designed to study the synergistic effects of the membrane properties on dynamics of VRFBs as well as to provide general guidelines for future membrane material development.

Key Words
vanadium redox flow battery; CFD simulation; transient; crossover; membrane

Address
Zi Wei, Fuqiang Liu: Department of Mechanical Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA
N.A. Siddique, Dong Liu, Shambhavi Sakri: Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, TX 76019, USA


Abstract
Cylindrical parabolic solar concentrators of small concentration ratio are attractive options for working temperatures around 120oC. The heat gained can be utilized in many applications such as air conditioning, space heating, heating water and many others. These collectors can be easily manufactured and do not need to track the sun continuously. Using a heat pipe as a solar absorber makes the system more compact and easy to install. This study is devoted to modeling a system of cylindrical parabolic solar concentrators of small concentration ratio (around 5) fitted with a heat pipe absorber with a porous wick. The heat pipe is surrounded by evacuated glass tube to reduce thermal losses from the heat pipe. The liquid and vapor flow equations, energy equation, the internal and external boundary conditions were taken into consideration. The system of equations was solved and the numerical results were validated against available experimental and numerical results. The validated heat pipe model was inserted in an evacuated transparent glass tube as the absorber of the cylindrical parabolic collector. A calculation procedure was developed for the system, a computer program was developed and tested and numerical simulations were realized for the whole system. An experimental solar collector of small concentration, fitted with evacuated tube heat pipe absorber was constructed and instrumented. Experiments were realized with the concentrator axis along the E-W direction. Results of the instantaneous efficiency and heat gain were compared with numerical simulations realized under the same conditions and reasonably good agreement was found.

Key Words
parabolic concentrator; concentrator with heat pipe; solar energy; evacuated enveloped heat pipe

Address
Kamal A.R. Ismail, Maurício A. Zanardia, Fátima A.M. Lino: Faculty of Mechanical Engineering, Department of Energy, State University of Campinas, Mendeleiev street, 200, Cidade Universitária \"ZeferinoVaz\", Barão Geraldo, Postal Code 13083-860, Campinas, SP, Brazil

Abstract
Cerbera Odollam (sea mango) is a proven promising feedstock for the production of biodiesel due to its high oil content. Fatty acid methyl esters (FAME) were produced as the final reaction product in the transesterification reflux condensation reaction of sea mango oil and methyl acetate (MA). Potassium methoxide was used as catalyst to study its reacting potential as a homogeneous base catalyst. The initial part of this project studied the optimum conditions to extract crude sea mango oil. It was found that the content of sea mango sea mango oil was 55%. This optimum amount was obtained by using 18 g of grinded sea mango seeds in 250 ml hexane. The extraction was carried out for 24 hours using solvent extraction method. Response surface methodology (RSM) was employed to determine the optimum conditions of the reaction. The three manipulated variables in this reaction were the reaction time, oil to solvent molar ratio, and catalyst wt%. The optimum condition for this reaction determined was 5 hours reaction time, 0.28 wt% of catalyst and 1:35 mol/mol of oil: solvent molar ratio. A series of test were conducted on the final FAME product of this study, namely the FTIR test, GC-FID, calorimeter bomb and viscometer test.

Key Words
cerbera odollam; biodiesel; methyl acetate; potassium methoxide

Address
Sandip Singh Dhillon and Kok Tat Tan: Department of Petrochemical Engineering, Faculty of Engineering and Green Technology, Universiti Tunku Abdul Rahman, Jalan Universiti, Bandar Barat 31900 Kampar, Perak, Malaysia


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