1,720,978 research outputs found
Optimizing Trombe Wall performances: The impact of L-shaped fins on solar heating efficiency and building thermal comfort
No full textThis study delves into optimizing the thermal efficiency of Trombe Wall (TW) systems through the strategic
integration of L-shaped fins, offering a novel approach to enhancing solar heating capabilities in buildings. By
meticulously examining the effects of fin geometry-including thickness, length, and number-on the system’s
performance, the research provides valuable insights into the design and operational optimization of TW sys-
tems. Using CFD simulations, the investigation reveals that specific fin configurations significantly improve heat
transfer and air circulation within the TW, thereby augmenting the system’s thermal efficiency. Main results
suggest that a fin thickness of 0.01 m and a fin length of 0.2 m, combined with an optimal number of fins, can
achieve the most effective thermal performance, enhancing room temperature homogeneity while adhering to
comfort standards. This comprehensive analysis underscores the critical role of fin geometry in solar heating
technologies and paves the way for future innovations in sustainable building designs. The study’s implications
extend beyond immediate energy savings, suggesting avenues for further research into material efficiencies and
architectural integra
Numerical investigation on performance of a solar chimney power plant with different absorber configurations
No full textA solar tower system is a nonpolluting solar thermal power plant that utilizes acombination of a wind turbine and generator to convert thermal energy generatedfrom a solar collector into electrical energy. The study focuses on a system compris-ing a solar collector that transforms solar energy into thermal energy, a chimney thatconverts thermal energy into kinetic energy, and a wind turbine that further convertskinetic energy into electrical energy. The system's performance is evaluated throughthe implementation of a numerical model, which is validated by comparing it withexperimental data. Four different types of meshes are tested to determine the mostsuitable mesh for the system. The discrete ordinate radiation model is used to solvethe radiative transfer equation, and the RNG k-ε turbulence model is implemented tocalculate turbulence. In a subsequent study, the effect of absorber configuration onthe system's performance is investigated. Three different absorber configurations—sinusoidal, square, and triangular—are proposed, and the numerical results showed thatthe system's performance is affected by the absorber configuration. The velocity in thechimney inlet increases for all proposed configurations compared to the standard con-figuration, with the triangular configuration showing the highest velocity increase.Additionally, the newly proposed configurations enhance the thermal efficiency of thesystem, leading to a thermal efficiency of 12.18%, 12.2%, and 13.65% for the sinusoi-dal, triangular, and square configurations, respectively. Overall, the solar tower systemdemonstrates its potential as a clean and efficient source of electrical power
OPTIMIZING MESH CONFIGURATIONS IN SOLAR CHIMNEY SYSTEMS: A COMPUTATIONAL FLUID DYNAMICS (CFD) BASED APPROACH FOR ENHANCED ENERGY EFFICIENCY AND PERFORMANCE
Full text linkThe present study investigates the effect of mesh configurations on the performance of a solar chimney (tower) system using Computational Fluid Dynamics (CFD) simulations. This research focuses on optimizing mesh density to enhance the accuracy of temperature, velocity, and pressure predictions in the solar tower, which significantly impact energy efficiency. Unlike previous studies, which primarily focused on geometrical design and system layout, this article introduces a novel meshing strategy that balances computational efficiency and simulation accuracy. Four different mesh types were analyzed, with the finest meshes (M3and M4) showing the closest alignment to experimental data, achieving an error margin below 4%. The results revealed that finer meshes provided more accurate representations of temperature profiles, pressure gradients, and velocity distributions, particularly near the chimney’s axis, optimizing the overall system’s performance. The minimum total pressure values for meshes were 5.61Pa, 6.25 Pa, 6.61 Pa, and 6.86 Pa, respectively, indicating how mesh density influences internal pressure dynamics. This study highlights the importance of mesh selection in CFD simulations and recommends future designs to incorporate adaptive mesh refinement techniques for better simulation efficiency. The findings offer valuable insights into the design and optimization of solar tower systems, promoting enhanced power generation and efficiency, which are essential for scaling renewable energy projects. Future research could explore broader applications of this methodology to optimize other renewable energy systems.
Key words: Computational Fluid Dynamics, mesh effect, numerical analysis, solar energy, solar tower
A Review on the Water Sector in Iran: Current Forecasts, Scenario and Sustainability Issues
No full textThe water sector in Iran has to date paid scrimpy attention to the issue of climate and is often unaware of its effects on future water resources. Studies will be needed to determine the effects of water shortage and draw up adaptation solutions. Forecasts are not optimistic. Models for Iran water resources indicate that amount of water per capita will decrease than 1000 cubic meters in 2025 and Iran will enter s serious water crisis. In this paper weather conditions, precipitations and water resources state of six main basins of Iran are discussed. Main reasons of water issue in Iran are population growth, ineffective agriculture and poor management of water resources and the effect of each one of them are studied. Finally, effective strategies to collation and prevent the adverse socio-economic and political conditions, result of mismanagement and inefficient use of water resources are discussed. It is necessary to create a national action plan to ensure the security of access to safe water for all.
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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