Assessment of water availability for wet cooling at potential locations for solar thermal power generation in India

ABSTRACT

This study presents the results of a preliminary attempt to assess water availability for wet-cooled solar thermal power plants at potential locations in India. A total of 95 locations with sufficient wastelands and annual average DNI more than 2000?kWh/m² have been considered for the analysis. Options of rainwater harvesting and groundwater extraction have been explored. It was observed that with rainwater harvesting, only 12 locations in different states are suitable for adoption of wet cooling. Further, with only groundwater extraction option, only one location in the state of Madhya Pradesh is found to be suitable for adoption of wet cooling. By combining both the approaches, it is observed that 28 of the 95 locations would have sufficient water available to meet the requirements of the plant. In the remaining 67 potential locations, the adoption of other available cooling options with relatively lesser water requirements may be appropriate.     

Effect of thermal pretreatment on recovery of nickel and cobalt from Sukinda lateritic nickel ore using microorganisms

Experimental investigation made previously on microbiological leaching of nickel and cobalt from the laterite nickel ore of Sukinda Valley reveals that the recovery was not very much promising under any favorable conditions. Therefore, in order to improve the efficiency for bioleaching, the homogenized lateritic ore in palletized form is thermally pretreated by roasting at different temperatures. The parameters studied for the bioleaching experiments were the four types of pretreated ore which were roasted at different temperatures, i.e., 300 °C, 400 °C, 600 °C and 800 °C, in shake flask by using a mixed mesophilic acidophilic bacterial consortium consisting predominantly of the Acidithiobacillus ferrooxidans strain. It was observed that the pretreated ore at 600 °C with 10% (w/v) pulp density showed maximum recovery of nickel and cobalt, i.e., 59.18% (4.556 ppm) and 65.09% (0.546 ppm), using 10% (v/v) (2.5 × 10⁸ cells/ml) consortium concentration at 1.5 pH, 30 °C, and 150 rpm after an incubation period of 31 days.     

Split variable-length input Huffman code with application to test data compression for embedded cores in SOCs

In this article, a run length encoding-based test data compression technique has been addressed. The scheme performs Huffman coding on different parts of the test data file separately. It has been observed that up to a 6% improvement in compression ratio and a 29% improvement in test application time can be achieved sacrificing only about 6.5% of the decoder area. We have compared our results with the other contemporary works reported in the literature. It has been observed that for most of the cases, our scheme produces a better compression ratio and that the area requirements are much less.     

A new analytical subthreshold model of SRG MOSFET with analogue performance investigation

For the first time, a pseudo-two-dimensional (2D) approach is extended from a rectangular device structure to a cylindrical one. A pseudo-2D model applying Gauss's law in the cylindrical channel depletion region for undoped or lightly doped surrounding gate (SRG) silicon metal oxide semiconductor field effect transistor (MOSFETs) working in subthreshold regime is presented. From this pseudo-2D analysis, electrostatic potentials, current characteristics, the threshold voltage roll-off, the drain-induced barrier lowering and the subthreshold swing are explicitly modelled. The obtained analytical model has been extended to develop a model for transconductance-to-drain current ratio (g _m/I _d) in weak inversion regime. Analogue figures of merit of SRG MOSFETs are studied, including transconductance efficiency g _m/I _d, intrinsic gain and output resistance. The trends related to their variations along the downscaling of dimension are provided. In order to validate our model, the modelled expressions are compared with the simulated characteristics obtained from ATLAS device simulator.     

Improved extraction of humic acids from vermicomposted organic waste by a column-based continuous elution method

A column-based continuous elution (CCE) method was developed for extracting humic acids (HA) from vermicomposted organic waste. Dissolution of HA by passing extractant (0.2 M NaOH) through vermicompost in a column followed by elution under gravity resulted in yields of 47.5% and 74.7% extractable HA in 24 h by International Humic Substance Society (IHSS) method and CCE method, respectively. These results were 63.3% and 97.9% in 48 h, respectively. The extracted HA showed similar FTIR absorption spectra and chemical compositions. Rate of oxidative degradation of HA during extraction by the CCE method was lower as compared with the IHSS method indicating improvement in extraction without altering the quality.     

Preparation of ordered porous carbon from tea by chemical activation and its use in Cr(VI) adsorption

Ordered porous carbon was prepared from a new carbon precursor??the tea leaves, the most widely used beverage worldwide by a chemical activation process. We obtained well developed spherical interlinked meso and micro pores with uniform pore morphology and high surface area from green, black and waste tea by NaOH as well as H₃PO₄ activation process. The carbon obtained from green tea by H₃PO₄ activation had the highest BET surface area of 1,285?m²g^?1 with total pore volume of 0.6243?mL?g^?1. The as prepared porous carbon showed high adsorption efficiency of Cr(VI) adsorption from aqueous solution.     

Overview of design and thermal–hydraulic analysis of Indian solid breeder blanket concept

India has developed two concepts of breeding blanket for the DEMO reactor: one is Lead Lithium Ceramic Breeder (LLCB), and the other one is Helium-cooled Ceramic Breeder (HCCB) concept. Indian HCCB concept is having edge on configuration of helium-cooled solid breeder with RAFMS structure. Li₂TiO₃/Li₄SiO₄ and beryllium are used as the tritium breeder and neutron multiplier, respectively. 2D thermal–hydraulic simulation studies using ANSYS have been performed based on the heat load obtained from neutronics calculations to confirm heat removal under ITER pulsed operation. Transient thermal analysis has been simulated in ANSYS for the ITER relevant operational conditions. Thermal analysis provides important information about the temperature distribution in different materials used and their temperature–time histories. Result of thermal–hydraulic simulations shows that in each cycle, the maximum temperature of all materials remains same. The peak temperatures of all materials are well within their limiting value. Concept designs of HCCB blanket and its thermal hydraulic analysis will be presented in this paper.     

Quantum Dot–Carbon Nanotube Hybrid Phototransistor with an Enhanced Optical Stark Effect

Enhanced carrier–carrier interactions in hybrid nanostructures exhibit exceptional electronic and optoelectronic properties. Carbon nanotubes demonstrate excellent switching behavior with high on/off ratio and high mobility but do not show photoresponse in the visible range, whereas quantum dots (QDs) shows excellent optical response in various optical ranges which can be tuned with diameter. Here, a simple and effective way to develop hybrid phototransistors with extraordinary optoelectronic properties is presented by decorating semiconducting QDs on the surface of a single‐walled carbon nanotube (SWCNT). This hybrid structure demonstrates clear negative photoresponse and optical switching behavior, which could be further tuned by applying external gate bias in the future. A clear type conversion of SWCNT transistor from p‐type to n‐type caused by a charge transfer from attached QDs to CNT is demonstrated. Moreover, this hybrid structure also demonstrates an enhancement in ‘optical Stark effect’ without applying any external electric field. Charged SWCNT surface plays a key role behind the enhancement of optical Stark effect in QDs. The carrier dynamics of the QD and CNT heterostructures system highlights the potential application opportunity of the quantum dot systems, which can be adaptable to the current technologies.     

A simple digital control algorithm for three phase shunt active filter: simulation and experimentation

A novel and simple i _freal control algorithm using digital signal processor (DSP) has been proposed and realized for a three phase shunt active filter (SAF). The simulation and prototype construction of SAF is conducted to compensate the reactive power and harmonics in a distribution system. The major feature of the proposed i _freal algorithm is that it does not require unit vector templates and any transformations for the reference current generation of SAF. This reduces the computational complexity and makes the control flexible and faster. The simulation is conducted in MATLAB/SIMULINK while DSP TMS320LF2407 is employed in the digital implementation of hysteresis current control (HCC) for experimentation. The hardware results correlate with the simulation results in reducing the total harmonic distortion (THD) of the source current and achieving unity power factor.