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Sharma M.,Amity University | Singh O.,iversity of Technology
Applied Thermal Engineering | Year: 2016

This paper deals with exergy analysis of a dual pressure (DP) heat recovery steam generator (HRSG) having steam generation at high pressure (HP) and low pressure (LP) in the range of 50-70 bar and 2-6 bar respectively in the gas/steam combined cycle power plant for varying dead states. The in-operation plant data for this study are taken from a gas/steam combined cycle power plant at Auraiya (U.P.), India. Results have been obtained for exergy loss and exergy efficiency with varying dead state temperatures for different HP and LP steam generation states in different sections of HRSG. The exergy analysis for chosen conditions/parameters helps in locating the particular sections of the HRSG having maximum exergy loss. It is found that at varying steam generation pressures the HP and LP super heater sections and at higher dead state temperatures the HP evaporator are found to act as major source of irreversibilities. The results obtained are useful in finding the thermodynamic states that will help in reducing the exergy destruction for enhancing HRSG performance which eventually improves the efficiency of combined cycle power plants. © 2015 Published by Elsevier Ltd.

Sharma M.,Amity University | Singh O.,iversity of Technology
International Journal of Ambient Energy | Year: 2015

A heat recovery steam generator (HRSG) is the vital equipment in a gas/steam combined cycle power plant (CCPP) which plays an important role in enhancing the overall performance of the plant. An HRSG is designed on the basis of the size of the gas and steam turbines used in the power plant. Therefore, the HRSG directly affects the performance of the CCPP and its optimisation based on physical design can improve the plant performance. In the present study, the plant data of the CCPP of NTPC Ltd. at Auraiya (U.P.), India, has been considered for study. A segmented finned model has been chosen as it is the preferred arrangement [Ganapathy, V. 2003. Industrial Boiler and Heat Recovery Steam Generator Design, Application and Calculation. New York: Marcel Dekker Inc.] and thermodynamic investigations have been carried out upon a dual pressure HRSG in a gas/steam CCPP from the perspective of maximum heat recovery and minimum pressure loss. The performance investigations of varying physical parameters of a dual pressure HRSG with segmented fins are useful for CCPP designers and for all those who are engaged in the area of heat recovery. © 2015 Taylor & Francis

Bielinski D.M.,Institute for Engineering of Polymer Materials and Dyes | Bielinski D.M.,iversity of Technology | Ostaszewska U.,iversity of Technology | Jagielski J.,Institute Of Electronic Materials Technology of Poland | Jagielski J.,National Center for Nuclear Research andrzej Soltan 7
Polimery/Polymers | Year: 2014

In the paper effects of surface modification of various elastomers upon irradiation withH+, He+, F+ or Ar+ ions are presented. Changes to chemical composition and physical structure of rubber macromolecules are discussed in terms of influence of the treatment on modification of surface layer of the elastomers. Hydrogen release induced graphitization together with post-treatment oxidation of rubber macromolecules increase surfacewettability of the materials, facilitating lowering of "wet" friction. Free radicals being created due to interactions between energetic ions and macromolecules produce additional crosslinking, which manifests itself by increased hardness of the elastomers. Modification of mechanical properties of the surface layer changes mechanism of elastomer friction from the bulk to the surface one, what results in significant reduction of friction. Despite crosslinking induced shrinkage of the surface layer, which results in its micro-cracking, ion beam treated elastomers showed to bewear resistant due to the lack of delamination under stress. Interesting results were obtained for heavy Ar+ ions surface etched butadiene-acrylonitrile rubber/multiwalled carbon nanotube (NBR/MWCNT) composites. Nanotube agglomerates created from rubber substrate resulted in "island" morphology, significantly reducing friction of the material.

Biswas A.,iversity of Technology | Choudhary K.,University of Calcutta | Bandyopadhyay A.K.,Ideal Institute of Technology
Journal of Applied Physics | Year: 2011

We investigate the pinning of domain walls in ferroelectrics on the basis of the two phonon bound state (TPBS) or discrete breather state due to impurity energy levels above the phonon continua in ferroelectrics such as LiNbO 3 in order to show the pinning transition, which indicates the point of easiest switching. We predict, with the help of our quantum calculations, that every ferroelectric material has such a critical point of easy switching. Here we describe the quantum origin of pinning through the findings of analytical and numerical calculations, as interpreted by a TPBS concept by such impurity or nonlinearity induced modes, by plotting various TPBS parameters against the Landau coefficient and percent impurity content. This new approach might lead to many interesting applications for device manufacturing. © 2011 American Institute of Physics.

Chaturvedi P.,iversity of Technology | Daniel A.K.,iversity of Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

Wireless sensor network constitute a class of real time embedded systems having limited resources. Target coverage problem is concerned with the continuous monitoring of a set of targets such that the network lifetime is maximized with the consideration of resource constraints. In this paper we propose a node scheduling protocol for target coverage problem on the basis of node contribution, coverage probability and trust values, where the set covers are computed dynamically using time stamping. The time stamping is a factor of threshold of the coverage level. We have evaluated the performance of the proposed protocol by varying the number of nodes and targets. The results show that the proposed scheme improves the network lifetime in terms of energy consumption and the reliability of the data communicated in comparison to the naïve approach in which all the nodes are activated at once. The results show that the network lifetime is proportional to the energy savings under a constant environment. © Springer International Publishing Switzerland 2016.

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