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CONTENTS
Volume 3, Number 4, December 2015
 

Abstract
The authors consider the technique based on application of air heated in periodic regenerative ceramic heat exchangers by coal powder combustion products as a gas-turbine working medium to be rather promising for being studied. In this case the working medium can be heated to essentially higher temperatures than at coal combustion in the pressurized fluidized bed. Here only a small amount of ash contained in the coal combustion products settles in the ceramic heat exchanger and then penetrates into the heated air. It allows supporting high air temperature before the turbine at an acceptable level of ash concentration at gas turbine inlet. To substantiate the efficiency of this technique the authors have developed the technological scheme of coal-fired combined cycle plant with gas-turbine cycle working medium heated in periodic regenerative heat exchangers; the mathematical models of regenerative ceramic heat exchangers with cylindrical conduits and coal-fired combined cycle plant were developed. The paper introduces the results based on a detailed mathematical model of the optimization technical and economic studies of coal-fired combined cycle plant with gas-turbine cycle working medium heated in periodic regenerative heat exchangers.

Key Words
coal combined-cycle plant; ceramic heat exchanger; mathematical modeling; optimization studies

Address
Elina A. Tyurina and Aleksandr S. Mednikov: Department of Thermal Power Systems, Melentiev Energy Systems Institute of Siberian Branch of the Russian Academy of Sciences, 130, Lermontov Street, Irkutsk 664-033, Russian Federation

Abstract
In the present work, the continuous flow operation of membraneless methanol fuel cell (MLMFC) using Pt-Ru-Sn/C electrocatalysts with different atomic ratios were prepared by alcohol-reduction process. In this membraneless fuel cell, methanol is used as a fuel, sodium percarbonate is used as an oxidant and sulphuric acid is used as the electrolyte. Sodium percarbonate affords hydrogen peroxide in aqueous medium. The synthesized electrocatalysts were characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analyses. The electrocatalytic activities of the catalysts were characterized by cyclic voltammetry (CV) and chronoamperometry (CA). During the experiments performed on single membraneless fuel cells, Pt-Ru-Sn/C (70:20:10) performed better among all the catalysts prepared with power density of 36.5 mWcm-2. The better performance of ternary Pt-Ru-Sn/C catalysts may be due to the formation of a ternary alloy and the smaller particle size.

Key Words
renewable energy; environment-friendly sodium percarbonate; membraneless methanol fuel cells; ternary catalysts; portable power applications

Address
S.M. Nayeemunisa: Department of Chemistry, Justice Basheer Ahmed Sayeed College for Women, Chennai, 600 018, India
S. Kiruthika: Department of Chemical Engineering, SRM University, Chennai, 603 203, India
K. Ponmani, S. Durga and B. Muthukumaran: Department of Chemistry, Presidency College, Chennai, 600 005, India


Abstract
Thermal and electrical analysis of a linear parabolic concentrated photovoltaic/thermal hybrid solar collector (CPVT) was studied in this article. The energy balance equations were written for different parts of the CPVT collector. A non-linear algebraic equations system was derived for determining the temperature of the photovoltaic module, solar collector, the metallic layer and outlet fluid. Because of the presence of electrical efficiency in the energy balance\'s equation, the thermal analysis of PVT collector is dependent on the electrical analysis. The four-parametric current-voltage model was employed for electrical analysis. The CPVT system\'s equations were solved by numerical methods. The result of this simulation had a good conformity with the previous studies. The effect of different operational and design parameters on the electrical and thermal performances was also investigated.

Key Words
thermal efficiency; electrical efficiency; linear parabolic; photovoltaic/thermal collector

Address
Farid Safari and Abtin Ataei: Department of Energy Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran

Abstract
This paper presents a new approach to identify the suitable location for static var compensator in a multi-bus power system for voltage stability enhancement using a unique two-bus u-network equivalent derived with optimal power flow solution of the actual system at different operating conditions. An index named equivalent network based index (ENBI), derived from the parameters of two-bus equivalent of the multi-bus power system is used for positioning the static var compensator. The proposed approach has been tested under simulated condition on a practical power system (203-bus Indian Eastern Grid) for illustration purpose. Simulation results obtained with the proposed approach are compared with the results of well-established L-index method. Improvement in voltage stability margin using static var compensator is also investigated for the test system considered.

Key Words
two-bus u-network equivalent; optimal power flow; static var compensator; L-index; equivalent network based index; global voltage stability indicator

Address
Nagendra Palukuru: Department of Electrical & Electronics Engineering, Technical Education, Andhra Pradesh, India
Sunita Halder nee Dey and Subrata Paul: Department of of Electrical Engineering, Jadavpur University, Kolkata, West Bengal 700032, India

Abstract
In this paper, techno-economic viability of a hybrid Wind/PV system with a battery and inverter was performed using the HOMER international optimization model. A commercial building in Shiraz, Iran was selected as a case study to analyze the feasibility study of installing the proposed hybrid Wind/PV system. Before the optimization process, different key parameters such as the monthly wind and solar resource, monthly and daily electrical load consumption, economic constraints such as interest rate and project lifetime, the components features such as the battery or inverters sizes and costs and other related information were collected and imported into HOMER. The optimization results suggested that the most efficient and economical hybrid energy system is a combination of 9 kW photovoltaic panel, 1 wind turbine (10 kW), 5 batteries and 5 kW converter. The total net present cost (NPC) and the cost of energy (COE) for this system were estimated to be $89,884 and $0.619/kWh. The final results of the study concluded that the employment of the proposed hybrid energy system for electrification of the studied commercial building in Shiraz is highly recommended.

Key Words
renewable energy; hybrid system; PV array; wind turbine; HOMER

Address
Abtin Ataei, Reza Rashidi, Mojtaba Nedaei and Elnaz Kurdestani: Department of Energy Engineering, Graduate School of the Environment and Energy, Science and Research Branch, Islamic Azad University, Tehran, Iran


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