Exergetic, exergoeconomic and exergoenvironmental analysis of intercooled gas turbine engine

Exergetic and exergoeconomic and exergoenvironmental analyses have been performed for an advanced aero-derivative intercooled gas turbine engine. The proposed system was modelled using the IPSEpro software package and validated using manufacturer’s published data. The exergoeconomic model evaluates the cost-effectiveness of the gas turbine engine based on the Specific Exergy Costing [SPECO] method. The CO2 emissions per KWh were estimated using a generic combustor model, HEPHAESTUS, developed at Cranfield University. It is well known that the exergetic analysis can determine the magnitudes, locations and types of losses within an energy system. The effect of load and ambient temperature variations on gas turbine performance were investigated for two different configurations. The first system, Case-I, was a simple gas turbine (SCGT) engine, and the second, Case-II, an intercooling gas turbine (ICGT) system. The latter enhances gas turbine efficiency but, at the same time, has an adverse effect on the combustion chamber due to reduced compressed air temperature. It was confirmed that full load and low ambient temperature are preferable due to the low waste exergy. The unit exergy cost rate for both SCGT and ICGT have been calculated as 8.59 and 8.32 US$/GJ respectively. The exergoenvironmental results show the ICGT achieved lower emission levels and is more environmentally friendly than the SCGT

A map and a pipe : a new approach to characterizing erosion-corrosion regimes of Fe in three dimensions using CFD modelling

In studies of erosion-corrosion, much work has been carried out in recent years to identify regimes of behaviour. Such regimes describe the transition between the erosion and corrosion dominated mechanisms. They can also be used, by assigning various criteria, to identify other regimes of behaviour such as extent of "synergy/antagonism" in the process, so-called "additive" behaviour and the extent of wastage. Despite this work, there has been very little effort to combine the two dimensional erosion-corrosion map with CFD modelling approaches, in which the characteristics of the fluid are accounted for in the regime description. This means that extrapolation of such maps in two dimensions to a three dimensional real surface presents some difficulties. However, it is these surfaces that corrosion engineers are required to tailor, either through modification of the material composition, the surface or the process parameters, for optimum erosion-corrosion resistance. In this paper, a methodology is generated to combine the concepts of CFD modelling, and the erosion-corrosion regime map for a specific geometry and for a range of pure metals in descending order in the Galvanic series. The changes in regimes are presented as a function of variation in the erosion and corrosion variables i.e. particle size, hardness and solution pH. Erosion-corrosion regimes are presented, based on the model results, showing the wide range of mechanistic and wastage mechanisms possible over the component surface

Selection and experimental evaluation of low-cost porous materials for regenerator applications in thermoacoustic engines

This paper aims at evaluating three selected low-cost porous materials from the point of view of their suitability as regenerator materials in the design of thermoacoustic travelling wave engines. The materials tested include: a cellular ceramic substrate with regular square channels; steel “scourers”; and stainless steel “wool”. Comparisons are made against a widely used regenerator material: stainless steel woven wire mesh screen. For meaningful comparisons, the materials are selected to have similar hydraulic radii. One set of regenerators was designed around the hydraulic radius of 200 μm. This included the ceramic substrate, steel “scourers”, stainless steel “wool” and stacked wire screens (as a reference). This set was complemented by steel “scourers” and stacked wire screens (as a reference) with hydraulic radii of 120 μm. Therefore six regenerators were produced to carry out the testing. Initial tests were made in a steady air flow to estimate their relative pressure drop due to viscous dissipation. Subsequently, they were installed in a looped-tube travelling-wave thermoacoustic engine to test their relative performance. Testing included the onset temperature difference, the maximum pressure amplitude generated and the acoustic power output as a function of mean pressure between 0 and 10 bar above atmospheric. It appears that the performance of regenerators made out of “scourers” and steel “wool” is much worse than their mesh-screen counterparts of the same hydraulic radius. However cellular ceramics may offer an alternative to traditional regenerator materials to reduce the overall system costs. Detailed discussions are provided

Energetic and exergetic analysis of combined cycle power plant: Part-1 operation and performance

Energetic and exergetic analyses are conducted using operating data for Sabiya, a combined cycle power plant (CCPP) with an advanced triple pressure reheat heat recovery steam generator (HRSG). Furthermore, a sensitivity analysis is carried out on the HRSG using a recent approach to differentiate between the sources of irreversibility. The proposed system was modelled using the IPSEpro software and further validated by the manufacturer’s data. The performance of the Sabiya CCPP was examined for different climatic conditions, pressure ratios, pinch point temperatures, high-pressure steam, and condenser pressure values. The results confirmed that 60.9% of the total exergy destruction occurs in the combustion chamber, which constitutes the main source of irreversibilities within a system. The exergy destruction was significantly affected by both the pressure ratio and the high-pressure steam, where the relation between them was seen to be inversely proportional. The high-pressure stage contributes about 50% of the exergy destruction within the HRSG compared to other stages and the reheat system, due to the high temperature difference between the streams and the large number of components, which leads to high energy loss to the surroundings. Numerous possibilities for improving the CCPP’s performance are introduced, based on the obtained results

Analysis of alkaloids from plant cell tissue cultures and other sources

Specific and sensitive new analytical procedures for the separation and identification of Cinchona and opium alkaloids have been developed using online high performance liquid chromatography/mass spectrometry (HPLC/MS) with a thermospray (TSP) interface connected to a quadrupole instrument. The Cinchona alkaloid separation was based on the extraction of the alkaloids from Cinchona ledgeriana cells using acid base extraction followed by isocratic reversed-phase HPLC. The eluent consisted of ammonium acetate buffer, methanol, and acetic acid, and a Cie stationary phase was used. The assays will allow the selection of high yielding plant strains and optimisation of the culture process for the production of these and other valuable compounds. The method developed for opium alkaloids allowed simultaneous separation of codeine, thebaine, papaverine, noscapine, morphine and its mono and diacetyl conjugates, using an ammonium acetate buffer and acetonitri1e, an application that has not previously been reported. Morphine was selectively acetylated to 3-monoacetyImorphine and the other metabolites were obtained commercially. This assay will be of value to both clinicians and basic scientists, The TSP spectra of these alkaloids showed only the protonated molecular ions and single ion monitoring provided sensitive and selective detection of the separated compounds. Tandem mass spectrometry experiments were carried out on the protonated molecular ions to allow multiple ion monitoring. Alternative ionisation methods including fast atom bombardment were also investigated, The mass spectra and tandem mass spectra showed significant differences in the stability of the stereoisomers. These differences were used to identify the structural features responsible for their fragmentation in the ion source and they were also related to the biological activity, the epimers being modelled by molecular graphics. It was confirmed that H-bonding is possible in the stable isomers, and the differences in their activities agree with small differences in the Cheng's distances calculated

Systematic review and meta-analysis of efficacy and safety of combinational therapy with metformin and dipeptidyl peptidase-4 inhibitors

AbstractCombinational therapies are often required in the management of type 2 diabetes mellitus (T2DM). Among the important candidates, dipeptidyl peptidase-4 inhibitors (DPPIs) and metformin combination (DPPI-MET) have shown promising endeavors. In order to examine the efficacy and safety of such a combination therapy in T2DM patients finding inadequate control with metformin, this systematic review and meta-analysis has been conducted. Literature search was made in multiple electronic databases. Inclusion criteria included; RCTs examining the efficacy and safety of DPPI-MET against placebo-MET or MET-only groups of T2DM patients by observing changes in disease endpoints including HbA1c and FPG, and the length of trial be at least 12weeks. Mean differences based meta-analyses were performed and heterogeneity assessment was carried out. Nineteen studies were selected and included in the meta-analyses. DPPI-MET significantly improved all disease endpoints and the difference could be noticed up to 2years in the majority of outcome measures. In comparison with PBO-MET, the DPPI-MET combinational therapy resulted in the percent HbA1c changes from baseline with a mean difference [95% CI] of −0.77 [−0.86, −0.69] in 3-month (P<0.00001), −0.67 [−0.76, −0.59] in 6-month (P<0.00001), −0.67 [−0.88, −0.47] in 1-year (P<0.00001) and −0.36 [−0.53, −0.20] in 2-year trials (P<0.0003). Reduction in body weight and safety profile in the treated and control groups were not different. A combinational therapy with DPPI and metformin significantly improves diabetes clinical indicators and this effect has been observed for up to 2years herein. Safety and tolerability of DPPI-MET combination have been found well-manageable with a very similar adverse event profile in both treated and control groups

The role of nutraceuticals in the management of autism

AbstractAutism and related disorders are increasingly prevalent behavioral syndromes of impaired verbal and nonverbal communication and socialization owing to neurodevelopmental abnormalities. The most recent estimate for the prevalence of autistic disorders is about 1% on a global scale. Etiology of autism is multifactorial and multidimensional that makes therapeutic intervention even harder. Heterogeneity of genetic factors, oxidative stress, autoimmune mechanism, and epigenetic mechanisms complicate the nature of pathogenesis of the disease. Nutraceutical approach to treat this disease is a promising strategy, especially in some areas, it is more attractive than others. This review critically analyzes the roles of vitamins and cofactors, dietary modifications and gut abnormalities, probiotics and prebiotics, phytochemicals, and environmental factors in order to determine the state of evidence in nutraceutical-based autism management practices. This article presents a systematic review of randomized- and placebocontrolled trials to examine the evidence supports the use of autism nutraceu10.1016/j.jsps.2012.10.001ticals. The results will be discussed in the light of all relevant evidence generated from other clinical and exploratory studies

How Language Creates Bonds among Cross-Cultural Communities

The objective of this thesis is to evaluate how the use of language creates bonds among cross-cultural communities. Language is an important aspect of human relationships because it is the primary way of communication. The use of language becomes more vital and intricate in cross-cultural communities due to the fact that language reflects culture. Another objective that will be evaluated is the challenges faced when using different languages in cross-cultural communities and how these barriers impact the bond created in cross-cultural communities. The significance of language in cross-cultural communities is becoming a more prominent topic in development literature and social studies on a global scale. The operational principles and mindset of a community are developed and expressed in their methods of thinking, behaving, and engaging with the outside world through language and culture. Language has an essential role in integrating economic, political, and social changes, as well as other developing towns, which are intertwined with the cultures of these communities. The concepts of cross-cultural communities are built on the interconnections of various cultural and environmental elements. Secondary data were used to gather information for the topic of interest in this thesis and content analysis was used to examine the data gathered. The preservation of indigenous languages is vital to many people today because it protects their cultural heritage, just as language has always been a significant force in communities as a means of preserving one's own culture or controlling other people groups

Effect of Fused Filament Fabrication Process Parameters on the Mechanical Properties of Carbon Fiber Reinforced Polymers

Carbon fiber reinforced polymer manufactured using additive manufacturing process is relatively a new process. The ability to predict the mechanical properties of these parts with high confidence will spread the use of these high-strength materials in more applications. The purpose of this research was to determine the effect of the build time between successive layers, arrangement of fiber and nylon layers, fiber start location, and the use of support material on the mechanical properties CFRP produced by additive manufacturing process using the MarkForged (MarkOne) 3D printer. A design of experiment (DOE) we preformed to develop a mathematical model describing the functional relationship between the tensile strength of additively manufactured composites and the selected additive manufacturing build process parameters. Testing was performed in accordance with ASTM standard D3039 using the 25 manufactured specimens. The mechanical properties were measured in the experiment were tensile strength, and tensile stress. A liner regression analysis was preformed to determine the relation between the ultimate tensile strength and the main level interactions of the four build parameters. The results showed a significant positive relation longer the build time between successive layers, and negative relation with the other fiber and nylon layer arrangement. However, the two other build parameters showed negative, but not significant results