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[en] Highlights: • The effect of Cr on the solubility of H in Ta is investigated for the first time. • Hydrogen solubility in Ta decreases with increase in Cr content. • The Heat of reaction for solution of H in Ta–Cr alloys is exothermic in nature. • The relative change in enthalpy for the solution of H in Ta increases with Cr content. -- Abstract: Isothermal pressure–composition–temperature, (P–C–T) equilibrium study for the solubility of hydrogen is investigated over the temperature range of (673 to 873) K to evaluate the relative change in Gibbs energy, enthalpy and entropy for the solution of hydrogen in the Ta–Cr solid solution alloys. The inert gas fusion technique and pressure drop method are used for hydrogen analysis. It is observed that the solubility of hydrogen in tantalum decreases as the Cr content increases. The change in hydrogen solubility in tantalum with increase in Cr content could be explained on the basis of change in strain energy of dissolved hydrogen due to presence of different size interstitial sites around a substituted atom and due to increase in e/a ratio and it may be attributed to repulsive interaction between H and Cr atoms. The exothermic heat of reaction is observed for solution of hydrogen in all the samples
[en] Highlights: • Solid solubility of hydrogen in Pb83Li17 increases with pressure and temperature. • Hydrogen-Pb83Li17 solid solution is exothermic. • Hydrogen solubility in Pb83Li17 is less than the expected value. • No hydride phase is precipitated in the range of 373–473 K at all the pressure investigated. - Abstract: Lead–lithium alloy Pb83Li17 (0.6 wt.% lithium) is a potential candidate to be used as a neutron multiplier, tritium (fuel) breeder and heat transfer agent (coolant) in the International Thermonuclear Experimental Test Reactor (ITER). The tritium produced in the alloy could be soluble in the alloy or appear as a new phase. During reactor shut down condition, Pb83Li17 will be solidified and stored in a storage tank. Investigation on the solubility of tritium in solid Pb83Li17 is essential to quantify the trapped tritium in solid Pb83Li17 alloy to estimate the extent of radioactive contamination (with respect to tritium) and valuable tritium loss. Tritium being the isotope of hydrogen behaves more or less similar to hydrogen. In the present study solid-solubility of hydrogen in Pb83Li17 alloy has been investigated as a function of temperature and pressure. It was found that the hydrogen solubility increases with temperature (373–473 K) and follows the Sieverts law. Hydrogen solution enthalpy has been calculated using Seiverts constant and found to be −4.81 kJ/mole of hydrogen
[en] Hydrogen interaction with lithium titanate (Li2TiO3) pebbles of diameter in the range of 300–600 μm has been studied at various temperatures and pressures. It was found that solid solubility of hydrogen in Li2TiO3 is substantially less. Thermogravimetric study of the pebbles in hydrogen atmosphere indicates substantial mass losses. Pebbles change its original brilliant white colour to dark blue in hydrogen atmosphere. Microstructural analysis of pebbles exposed in hydrogen atmosphere indicates the development of multiple micro cracks on the pebbles surface which significantly degrades the mechanical integrity of the pebbles. It was found that the hydrogen exposed pebbles regain its mass and original colour when re-heated in open atmosphere. However, the microcracks developed on the pebbles surface remain unaffected. The effect of hydrogen on the density of the Li2TiO3 pellets has also been studied and found that it is decreasing with exposure time of hydrogen atmosphere
[en] In the era of fast paced development, energy sector is also looking for methodologies which can diligently investigate the thermodynamics as well as economics of power utilities. The methodology need to be so designed that it is able to analyze the effect of operating parameters on plant performance and its costing. In this regard thermoeconomic investigation is a tool which combined thermodynamic concepts and economic principles to analyze thermal systems. Present paper deals with comparative thermoeconomic investigation of basic gas turbine (BGT) and intercooled recuperated gas turbine (IcRcGT) cycle based power utilities featuring air film cooling of turbine blades. The work also represents the effect of operating parameters on thermoeconomics of two aforesaid cycles. In present work Average-Cost-Theory approach has been adopted for the investigation. The results so obtained from calculation reports that IcRcGT offers 50% higher plant specific work with 27.8% higher fuel flow rate as compared to BGT for base case parameters (rpc = 30, TIT = 1500 K, ηAC = 88% and ηGT = 90%). The total cost rate for IcRcGT is 16.33% higher and at the same time related cost of electricity is 20% lower as compared to BGT for same operating parameters due to higher plant specific work. - Highlights: • Comparative analysis of basic and complex cooled gas turbine cycle is reported. • Intercooled recuperated GT cycle offers higher efficiencies over basic GT cycle. • The total cost rate of complex GT cycle is 16.33% higher. • Electricity cost for complex GT cycle is 20% lower compared to the basic GT cycle.
[en] The rotationally inelastic cross sections, integral and differential, are computed as quantum processes using a published interaction potential and are compared with recently available experimental data at low collision energies. Different coupling approximations are analysed and the mainly repulsive interaction potential is confronted with the one exhibited by the H + H2 system. It is found that a full coupling of angular momenta is needed for accurate comparisons and that the long-range anisotropy of the employed interaction is still not adequate to quantitatively reproduce the experimental data. (author)
[en] A procedure for assessing the techno-economic viability of solar thermal systems in a dynamic economic environment is developed. It is shown analytically that the period for replacement of these systems depends upon the nature of their use. While determining investment viability, it is necessary to ascertain the exact life of the system. The life of a solar thermal system for non-commercial use is determined by optimum life for replacement, which is not influenced by energy inflation and energy saved. It is a function of maintenance cost and decreases with increases with increase in maintenance cost. For commercial purposes, the lifetime of the system is governed by optimum return on investment mode (Ζ), which is a strong function of energy inflation and energy saved per unit capital cost. (author)
[en] Samples of phosphate, soda and quartz glass detectors have been exposed vertically to different heavy ion beams such as Si25, Ar40, Ti50, Fe56, Ni59, Kr84 and Xe132 with energies ranging from 0.9 MeV/N to 6.5 MeV/N from a heavy ion accelerator. The exposed samples have been etched under the optimum etching conditions. The variation of etchpit diameter with etching time has been studied and the values of total etchable range for these heavy ions in these glasses have been determined. The energy loss rate, dE/dX, and range of the heavy ions have been computed theoretically using the Mukherjee and Navak Stopping power equations. By comparing the experimental and theoretical range values, the values of the critical threshold for etchable track formation for these glass detectors have been found. Finally, the response of these glasses to different heavy ions has been studied. (author)
[en] In this paper we investigated the feasibility of using the higher-frequency waveforms to characterize the seismicity in the Koyna–Warna region, globally well-known for its reservoir-triggered earthquakes. The local seismicity and source parameters have been extensively explored by many researchers using various types of data, e.g. analog data, broadband seismological data, and deep seismic sounding data. However, here we have utilized the seismological data recorded by 97 temporary 4.5-Hz geophones to locate the local seismicity in the region. We first investigated an appropriate 1-D P-wave velocity model through the inversion of P- and S-times. In order to compensate for the thick and laterally heterogeneous basalt, we incorporated the station corrections in the 1-D velocity inversion process. The station correction varies from + 0.09 to − 0.20 s for the P-waves, with clear demarcations of positive and negative station corrections corresponding to the northern and southern regions, respectively. The patterns of positive and negative station corrections suggested that the northern part is characterized by lower velocity, while slighter higher velocities present in the southern part of the study area are relative to the estimated 1-D velocity model. The earthquake locations are further improved by using the double-difference (hypoDD) approach, which enabled us to accurately map shallow subsurface seismogenic faults in the region. The data comprises 10,062 P-wave and 9049 S-wave catalog differential times from 348 earthquakes (1.0 ≤ ML ≤ 4.5). The precisely relocated earthquakes (ERH < 0.05 km ERZ < 0.5 km and rms < 0.02 s) form the three clusters of earthquakes in the NW–SE direction along the lineaments close to Warna Reservoir. The observed seismicity trends on the surface could be due to the vertical manifestations of faults or fractures. Their alignments are confirmed by the analysis of focal mechanism which exhibits a predominant normal type of faults with one nodal plane consistent with the main alignment of the seismic events.
[en] This paper presents the model equations governing the nonlinear dynamics of the dispersive Alfven wave (DAW) in the low-β plasmas (β<
e/mi; known as inertial Alfven waves) applicable to solar corona and intermediate-β plasmas (me/mi<<β<<1; kinetic Alfven waves) applicable to solar wind in Earth's magnetosphere. The pump DAW is perturbed by a low-frequency fast wave (FW). When the ponderomotive nonlinearities are incorporated in the DAW and FW dynamics, the model equations of DAW and FW turn out to be the modified Zakharov system of equations. Growth rate and threshold field for modulational (filamentation) instability have been calculated. The dependence of the growth rate on the perturbation wave number and the pump wave parameters (such as perpendicular wave number) has also been presented.