Showing papers by "Sreenivas Jayanti published in 2011"
TL;DR: In this paper, the growth of three-dimensional cavity geometries in underground coal gasification has been simulated using experiments carried out in three configurations: (i) sublimation experiments in camphor simulating primarily the heat transfer aspects, (ii) bore hole combustion in Acacia nilotica wood bringing in chemical reaction into play, and (iii) borehole combustion a coal block bringing into consideration the effect of ash on the cavity formation.
59 citations
TL;DR: Conventional chemical-based soaking and stirring methods are compared here to ultrasonic methods of de-sulfurization, which have the main advantages of ultrasonic de-Sulfurized over conventional methods, the mechanism involved in ultrasonicDe-solfurization and the difference between aqueous-based and solvent-based (2N HNO(3), 3-volume percentage H(2)O(2)) de-magnifying methods are investigated experimentally.
58 citations
TL;DR: In this paper, a flow field design based on the improvement of the local cross-flow conditions in a split serpentine flow field is proposed, which offers the quadruple advantage of uniform reactant distribution over the entire cell active area, low overall pressure drop, and effective liquid water evacuation in the U-bends.
58 citations
TL;DR: In this article, a detailed surface reaction mechanism for the decomposition of NH 3 to H 2 and N 2 on a Ni surface is presented for temperatures ranging from 700 to 1500 K and pressures from 5.3 to 100kPa.
48 citations
TL;DR: In this article, the authors investigated utilization of ultrasound in reagent-based coal de-ashing and de-sulfurization and derived an empirical model for the prediction of total sulfur removal.
Abstract: The present work investigates utilization of ultrasound in reagent-based coal de-ashing and de-sulfurization. The coal under study was received from Girald mine, Rajasthan, India. Three different ultrasonic frequencies (25 kHz, Dual (58/192 kHz) and 430 kHz) and three reagents (HCl, HNO 3 and H 2 O 2 ) were used. The study employed a Taguchi fractional-factorial L 27 DOE. Experimental data were used to derive an empirical model for the prediction of total sulfur removal. The model incorporates cavitational intensity, reagent concentration, sonication time, coal particle size and coal concentration as key parameters. Effects of above factors on reagent-based ultrasonic coal-desulfurization are presented here. An optimum set of process parameters are identified and validated. Larger-scale trial with high-ash and high-sulfur coals is strongly recommended.
45 citations
TL;DR: While ultrasonic coal-wash is not entirely new in many countries, it has not yet been practiced in India, though it would appear that the relatively high-ash content of Indian coals would render th...
Abstract: While ultrasonic coal-wash is not entirely new in many countries, it has not yet been practiced in India, though it would appear that the relatively high-ash content of Indian coals would render th...
39 citations
TL;DR: In this article, a comprehensive one-dimensional, single phase, isothermal mathematical model is developed for a liquid-feed PEM-DEFC, taking into account all the necessary mass transport and electrochemical phenomena on both the anode side and the cathode side.
34 citations
TL;DR: In this paper, the authors attributed the formation of thick oxide agglomerates in the case of Li and Na through the pores of which oxygen/metal vapour has to diffuse for combustion to occur.
13 citations
TL;DR: A nonisothermal thermogravimetric analysis technique was used to evaluate the effect of CO2 concentration on the overall reactivity of Indian coal chars during CO2/O2 combustion as discussed by the authors.
Abstract: A nonisothermal thermogravimetric analysis technique was used to evaluate the effect of CO2 concentration on the overall reactivity of Indian coal chars during CO2/O2 combustion. The study was carr...
11 citations
TL;DR: In this paper, a pseudo-transient numerical model is used for the simulation of a multi-functional catalytic plate reactor (CPR), which mainly addresses the problems associated with on-board reforming for solid-oxide fuel cells.
6 citations
03 Nov 2011
TL;DR: In this article, the authors proposed an underground coal gasification (UCG) and solid oxide fuel cell (SOFC) system for a nominal 500 MWt coal-powered power plant.
Abstract: Underground coal gasification (UCG) is a cl ean coal technology which converts coal into a combustible gas in situ without mining and without bringing up the ash contained in the coal. Thus, the attendant problems of coal washing, ash handling and disposal can be avoided. The combustible gas mixture, consisting primarily of hydrogen, methane, carbon monoxide--all of which are fuels for an solid oxide fuel cell (SOFC) system-and carbon dioxide, can be fed to a battery of SOFC after gas cleaning to remove hydrogen sulphide and other impurities. A large portion, typically 50%, of the chemical energy contained in the product gas can be converted into electrical energy by the SOFC. The exhaust gases from the SOFC are typically at a temperature of the order of 600 to 800 deg C. Heat energy from these will be extracted to produce steam, part of which will be used for UCG and the rest will be sent for SOFC internal reforming and shifting reactions. The exhaust gases, consisting primarily of carbon dioxide and steam, will be finally fed through a condenser and will then be sent for compression and sequestration. Thus, the overall system envisaged makes use of oxygen-fed UCG and SOFC to generate electrical energy and an exhaust gas consisting primarily of carbon dioxide and the easily condensable steam which enables CO2 sequestration. The overall integrated system can be divided into five units namely underground coal gasification, UCG product gas purification, electrical power generation from SOFC, heat recovery system and carbon sequestration unit. An energy analysis with heat integration of all the systems for a nominal 500 MWt will be discussed.