Analysis of a 115MW, 3 shaft, helium Brayton cycle

This research theme is originated from a development project that is going on in South Africa, for the design and construction of a closed cycle gas turbine plant using gas-cooled reactor as the heat source to generate 115 MW of electricity. South African Power utility company, Eskom, promotes this developmental work through its subsidiary called PBMR (Pebble Bed Modular Reactor). Some of the attractive features of this plant are the inherent and passive safety features, modular geometry, small evacuation area, small infrastructure requirements for the installation and running of the plant, small construction time, quick starting and stopping and also low operational cost. This exercise is looking at the operational aspects of a closed cycle gas turbine, the finding of which will have a direct input towards the successful development and commissioning of the plant. A thorough understanding of the fluid dynamics in this three-shaft system and its transient performance analysis were the two main objectives of this research work. A computer programme called GTSI, developed by a previous Cranfield University research student, has been used in this as a base programme for the performance analysis. Some modifications were done on this programme to improve its control abilities. The areas covered in the performance analysis are Start-up, Shutdown and Load ramping. A detailed literature survey has been conducted to learn from the helium Turbo machinery experiences, though it is very limited. A critical analysis on the design philosophy of the PBMR is also carried out as part of this research work. The performance analysis has shown the advantage, disadvantage and impact of various power modulation methods suggested for the PBMR. It has tracked the effect of the operations of the various valves included in the PBMR design. The start-up using a hot gas injection has been analysed in detail and a successful start region has been mapped. A start-up procedure is also written based on this. The analysis on the normal and emergency load rejection using various power modulation devices has been done and it stress the importance of more control facilities during full load rejection due to generator faults. A computational fluid dynamics (CFD) analysis, using commercial software, has been carried out on some geometry of the PBMR design to find out whether its flow characteristic will have any serious impact on the performance on the cycle during the load control of the plant. The analysis has demonstrated that there will not be much impact on the performance, during load control using pressure level changes, from this geometry. However, some locations in the geometry have been identified as areas where the flow is experiencing comparatively high pressure losses. Recommendations, which include modification in the physical design, were made to improve this. The CFD analysis has extended to a cascade to compare the flow behaviour of Air and Helium with an objective of using air, being inexpensive, to test the helium flow characteristic in a test rig to simulate the behavioural pattern of helium in the PBMR pressure vessel. The specification of a hypothetical test rig and the necessary scaling parameters has been derived from this exercise. This will be useful for designing test rigs during the developmental and operational stage of the PBMR project

An Isolated Multiport DC-DC Converter for Different Renewable Energy Sources

ABSTRACT: This paper presents a new isolated multiport dc-dc converter for concurrent power management of several renewable energy sources which can be of similar types. The proposed dc-dc converter uses only one controllable switch in each port to which a source is connected. It has simple configuration and minimum number of power switches. The proposed converter is applied for simultaneous maximum power point tracking (MPPT) control of a wind/solar hybrid generation system consisting of one Wind Turbine Generator (WTG) and two different Photovoltaic (PV) panels. The experimental results are provided to validate the incisiveness of using the proposed converter to achieve MPPT simultaneously for the WTG and both PV panels. KEYWORDS: Multiport converter, maximum power point tracking (MPPT), photovoltaic (PV), wind turbine generator (WTG) solar energy, wind energy. I.INTRODUCTION Nowadays, there is a growing interest in generating electricity from distributed renewable energy sources. In numerous applications, it is required to connect multiple renewable energy sources of different types to a power grid or load. The multiport DC-DC converter has been proposed to efficient power management and grid integration for the multiple origins and development in a new era in a demand quality power in remote communities[8] The proposed isolated multiport dc-dc converter for simultaneous power management of multiple renewable energy sources uses only one power electronic switch in each input port connected to a source. The proposed converter does not use any controllable switch on the secondary side of the transformer [2]-[4]. The proposed converter has the least number of switches and thereby a lower cost. The newly introduced converter is applied for power management of a wind/solar hybrid generation systems, which consists of a WTG and two varied PV panels. The power generation from solar and wind energy are designed using perturbation and observation (P&O) MPPT algorithm, in which the WTG and PV panels can be controlled at the same time and extract the maximum power. II.PROPOSED ISOLATED MULTIPORT DC-DC CONVERTER Th

A comparative single dose study of oral acetaminophen 650 mg to its standard 500 mg dose in adult pyrexia patients in a tertiary care hospital

Background: Acetaminophen commonly called as paracetamol is the most used ‘over-the-counter’ analgesic for headache, musculoskeletal pain, dysmenorrhoea etc. It is the best drug to be used as antipyretic for fever due to any cause and safest to be prescribed in all age groups. Antipyretic dose of acetaminophen is 325 to 650 mg; 3 to 4 times a day and is available in the strength of 650 mg and 500 mg tablets. This study was conducted to analyse the antipyretic efficacy and safety profile of two different doses of acetaminophen in patients with low grade fever.Methods: 300 hospitalised patients aged more than 18 years, in department of General Medicine, having low grade fever (38º to 39º C) were randomly allocated into two groups of 150 each, group A received 500 mg and group B received 650 mg of single oral dose of acetaminophen tablets. Oral temperature was measured before dosing, 30 minutes after dosing, one hour, two hourlies thereafter for 6 hours after the dose. Safety was assessed by monitoring for adverse effects during the study and 24 hours after administration of the assigned drug.Results: There was a statistically significant decrease in temperature in group B patients from baseline 39.06±0.87º C to 37.02±0.89º C at the end of 6th hour as compared with 39.18±0.80º C to 38.03±0.77º C in Group A patients (p=0.031).Conclusions: Our study concluded that acetaminophen in a dose of 650 mg is highly efficacious antipyretic drug compared to acetaminophen 500 mg with no adverse effects

USING HYDROGEN AS A FUEL IN AUTOMOTIVE ENGINES - AN INVESTIGATION

In the fast moving world, hydrocarbon based fuels have become significant for a century’s development. The fuels derived from crude oil are critical source of energy for fueling vehicles. However, crude oil based fuels are non renewable. The present investigation of using hydrogen was carried out in a direct injection diesel engine having a compression ratio of 17.5:1 and a capacity of 5.9 kW at a rated speed of 1800 rpm. In this investigation, the hydrogen was fed to the engine through the inlet manifold along with intake air during suction stroke of the engine. In order to maintain safety, the flame trap and flame arrestor were also used in the experimental setup. The results shows that there is an increase in brake thermal efficiency of the engine and reduction in carbon monoxide emission when, the hydrogen is used as a dual fuel, in the operation of the diesel engine

Meteorite impact craters as hotspots for mineral resources and energy fuels: A global review

The ever-increasing recovery rate of natural resources from terrestrial impact craters over the last few decades across the globe offers new avenues for further exploration of mineral and hydrocarbon resources in such settings. As of today, 60 of the 208 terrestrial craters have been identified to host diverse resources such as hydrocarbons, metals and construction materials. The potential of craters as plausible resource contributors to the energy sector is therefore, worthy of consideration, as 42 (70%) of the 60 craters host energy resources such as oil, gas, coal, uranium, mercury, critical and major minerals as well as hydropower resources. Among others, 19 craters are of well-developed hydrocarbon reserves. Mineral deposits associated with craters are also classified similar to other mineral resources such as progenetic, syngenetic and epigenetic sources. Of these, the progenetic and syngenetic mineralization are confined to the early and late excavation stage of impact crater evolution, respectively, whereas epigenetic deposits are formed during and after the modification stage of crater formation. Thus, progenetic and syngenetic mineral deposits (like Fe, Ni, Pb, Zn and Cu) associated with craters are formed as a direct result of the impact event, whereas epigenetic deposits (e.g. hydrocarbon) are hosted by the impact structure and result from post-impact processes. In the progenetic and syngenetic deposits, the shock-wave induced fracturing and melting aid the formation of deposits, whereas in the epigenetic deposits, the highly fractured lithostratigraphic units of higher porosity and permeability, like the central elevated area (CEA) or the rim, act as traps. In this review, we provide a holistic view of the mineral and energy resources associated with impact craters, and use some of the remote sensing techniques to identify the mineral deposits as supplemented by a schematic model of the types of deposits formed during cratering process

Synthesis, gene silencing, and molecular modeling studies of 4 '-C-aminomethyl-2 '-O-methyl modified small interfering RNAs.

The linear syntheses of 4′-C-aminomethyl-2′-O-methyl uridine and cytidine nucleoside phosphoramidites were achieved using glucose as the starting material. The modified RNA building blocks were incorporated into small interfering RNAs (siRNAs) by employing solid phase RNA synthesis. Thermal melting studies showed that the modified siRNA duplexes exhibited slightly lower Tm (1 °C/modification) compared to the unmodified duplex. Molecular dynamics simulations revealed that the 4′-C-aminomethyl-2′-O-methyl modified nucleotides adopt South-type conformation in a siRNA duplex, thereby altering the stacking and hydrogen-bonding interactions. These modified siRNAs were also evaluated for their gene silencing efficiency in HeLa cells using a luciferase-based reporter assay. The results indicate that the modifications are well tolerated in various positions of the passenger strand and at the 3′ end of the guide strand but are less tolerated in the seed region of the guide strand. The modified siRNAs exhibited prolonged stability in human serum compared to unmodified siRNA. This work has implications for the use of 4′-C-aminomethyl-2′-O-methyl modified nucleotides to overcome some of the challenges associated with the therapeutic utilities of siRNAs

The Tertiary sequence of Varkala coastal cliffs, southwestern India: An ideal site for Global Geopark

Varkala, along the southwestern coast of Peninsular India, has a unique place in Indian geology and geomorphology due to the presence of coastal lateritic cliffs, which exposes the entire Mio-Pliocene sequence of Warkalli Formation, and is declared as the type area. Stratigraphically, this formation exposes carbonaceous clay with lenses of lignite and sticks of marcasite, followed by variegated clays and sandstone. The presence of variegated lithounits endows beauty to these cliffs. Varkala cliffs, edging the Arabian Sea, run for a length of 7.5 km. These cliffs, together with confined beaches, made Varkala a popular tourist destination. Several geodiversity spots within the Varkala Cliff geoheritage site make Varkala geologically unique, just like the vestiges of the last separation of Indian subcontinent from the Mascarene Plateau; showcasing lateritization and distribution of beach placers, and jarosite, formed as a diagenetic replacement mineral from marcasite and considered as a Martian analog, are distinctiveness of the cliff. Additionally, Varkala is an internationally acclaimed beach tourist destination. Furthermore, there are several geoheritage sites as well as socio-cultural-historical sites in the hinterland of Varkala Cliff geoheritage site, which are within the proposed Varkala Global Geopark jurisdiction. Thus, this area fulfills all the criteria to be a Global Geopark. The socio-economic-environmental analysis showcases the changes that have occurred in these 3-end members. When the economic sphere was unaffected, the social scenario was slightly affected (25%) whereas the environmental aspect then drastically deteriorated by 75%. But, the SWOT analysis still elects Varkala as a potential Global Geopark. The concept of geopark contributes to at least one of the 17 goals in Agenda 2030 Sustainable Development Goals (SDG) of the United Nations (UN). Consequently, this work also aims at propagating, not only the need for converting the geologically prominent areas to a geopark, but also attaining SDG, whatever is possible through geoparks

Clonal variability in black pepper hybrid Panniyur 1

Forty two clones of twenty year old Panniyur 1 plants, grown as a monocrop of black pepper, were analyzed for variations in yield contributing factors as well as quality paralTIeters over a period of three years. The analysis of the data has revealed that the plants exhibited considerable amount of variability for characters under study and the standard deviation was lnore for berries spike-1 and yield. Among the quality characteristics, oleoresin exhibited more variability than piperine. From the non hierarchical Euclidean cluster analysis it is observed that the plants can be clustered ideally in to five clusters based on their mean performance. The intra and inter cluster distance was more for cluster number 4, which later culminated in Inaximuln nUlnber of plants (13) having high yield and oleoresin. &nbsp

Stability analysis of ginger (Zingiber officinale Rose.) genotypes

Ten genotypes of ginger (Zingiber officinale) were subjected to stability analysis based on their evaluation for 6 years at Regional Agricultural Research Station, Ambalavayal (Kerala, India). All the genotypes differed significantly for tiller number, leaf number and yield. Stability analysis revealed the superiority. of Ernadan and Kuruppampady as they expressed high mean yield, non significant S2di values and a regression nearing unity. &nbsp

Stability analysis of ginger (Zingiber officinale Rose.) genotypes

Ten genotypes of ginger (Zingiber officinale) were subjected to stability analysis based on their evaluation for 6 years at Regional Agricultural Research Station, Ambalavayal (Kerala, India). All the genotypes differed significantly for tiller number, leaf number and yield. Stability analysis revealed the superiority. of Ernadan and Kuruppampady as they expressed high mean yield, non significant S2di values and a regression nearing unity. &nbsp