Retrofitting of Pressurized Sand Traps in Hydropower Plants

Abstract Urban climate experimental results from the Comprehensive Outdoor Scale Model (COSMO) were used to estimate roughness lengths for momentum and heat. Two different physical scale models were used to investigate the scale dependence of the roughness lengths; the large scale model included an aligned array of 1.5-m concrete cubes, and the small scale model had a geometrically similar array of 0.15-m concrete cubes. Only turbulent data from the unstable boundary layers were considered. The roughness length for momentum relative to the obstacle height was dependent on wind direction, but the scale dependence was not evident. Estimated values agreed well with a conventional morphometric relationship. The logarithm of the roughness length for heat relative to the obstacle height depended on the scale but was insensitive to wind direction. COSMO data were used successfully to regress a theoretical relationship between κB−1, the logarithmic ratio of roughness length for momentum to heat, and Re*, the roughness Reynolds number. Values of κB−1 associated with Re* for three different urban sites from previous field experiments were intercompared. A surprising finding was that, even though surface geometry differed from site to site, the regressed function agreed with data from the three urban sites as well as with the COSMO data. Field data showed that κB−1 values decreased as the areal fraction of vegetation increased. The observed dependency of the bulk transfer coefficient on atmospheric stability in the COSMO data could be reproduced using the regressed function of Re* and κB−1, together with a Monin–Obukhov similarity framework.

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Prefabricated Futures: Adaptable and productive construction methods for New Zealand dwellings

10.26686/wgtn.17072756.v1 ◽

2021 ◽

Author(s):

◽

Mitchell Holden

Keyword(s):

New Zealand ◽

Scale Model ◽

Package Design ◽

Home Owner ◽

Construction Methods ◽

Physical Scale ◽

Scale Models ◽

Building Information ◽

Roof Panel ◽

Traditional Construction

<p>The traditional construction method of the New Zealand home has remained largely unchanged over the last century. These housing solutions that have supported our nation no longer suffice and the ‘young home owner’ is becoming a distant dream. New Zealand needs homes, and fast. Specialised trades create fragmentation in construction. This results in inefficient processes that divide the stages of constructing a home. What lacks in these instances is accessibility to design. Architects tend to focus on one-off, bespoke builds, whilst transportable home companies create generic, minimum spec designs. It can be argued that current prefabricated solutions are not complete, requiring sub-trades and work onsite that causes delays and construction related setbacks. Investigation into a key historic precedent has driven this research. This demonstrates that attempts have been made to change the housing model in New Zealand with some success. The precedent aligns with past notions in considering core parts of the home as products. This can create efficiencies in construction. The current demand for housing provides the perfect opportunity to reboot the method in which we build. This thesis questions how offsite panel assemblies can create a complete prefabricated housing product and improve construction efficiencies. This will still offer architectural choice. BIM (Building Information Modelling) and parameter driven design are used as a vehicle to demonstrate how more efficient, more collaborative and more controlled design approaches can be developed in order to create a complete construction package. Design-led research involving constant scale model testing and development led to my prefabricated wall panel design. Named the LapLock panel, I have developed a complete wall, floor and roof panel product system. Designed to be fully fabricated from structure to claddings and services in factory. This produces ruthless efficiencies onsite. The work utilises BIM in the form of Revit and takes advantage of parameter driven families to allow for fast manipulation and output of drawings for panels. A constant conversation between analogue and digital tools (in the form of physical scale models and Revit) strengthened the understandings of the limitations throughout the research. This thesis offers a new way of considering how New Zealand builds homes. By introducing adaptable and efficient panels that are complete on arrival to site, the Laplock solution provides accessible architectural choice to clients. This future-proofs the construction of the New Zealand home.</p>

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Investigations of Rake and Rib Structures in Sand Traps to Prevent Sediment Transport in Hydropower Plants

Energies ◽

10.3390/en14133882 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3882

Author(s):

Mads Mehus Ivarson ◽

Chirag Trivedi ◽

Kaspar Vereide

Keyword(s):

Three Dimensional ◽

Flow Distribution ◽

Head Loss ◽

Total Weight ◽

Hydropower Plant ◽

Trap Efficiency ◽

Hydropower Plants ◽

Sand Trap ◽

Sst Turbulence Model ◽

Three Dimensional Models

In order to increase the lifespan of hydraulic turbines in hydropower plants, it is necessary to minimize damages caused by sediment erosion. One solution is to reduce the amount of sediments by improving the design of sand trap. In the present work, the effects on sand trap efficiency by installing v-shaped rake structures for flow distribution and rib structures for sediment trapping is investigated numerically using the SAS–SST turbulence model. The v-shaped rake structures are located in the diffuser near the inlet of the sand trap, while the ribs cover a section of the bed in the downstream end. Three-dimensional models of the sand trap in Tonstad hydropower plant are created. The present study showed that integrating rib type structure can reduce the total weight of sediments escaping the sand trap by 24.5%, which leads to an improved sand trap efficiency. Consequently, the head loss in the sand trap is increased by 1.8%. By additionally including the v-shaped rakes, the total weight of sediments escaping the sand trap is instead increased by 48.5%, thus worsening the sand trap efficiency. This increases head loss by 12.7%. The results also show that turbulent flow commencing at the sand trap diffuser prevents the downstream settling of sediments with a diameter of less than one millimeter. The hydraulic representation of the numerical model is validated by comparison with particle image velocimetry measurements of the flow field from scale experiments and ADCP measurements from the prototype. The tested rib design has not previously been installed in a hydropower plant, and can be recommended. The tested v-shaped rakes have been installed in existing hydropower plants, but this practice should be reconsidered.

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CONSTRUINDO MAQUETES - UMA ESTRATÉGIA DIDÁTICA INTERDISCIPLINAR NO EIXO GEOMETRIAS: ESPAÇO E FORMA

EAD em FOCO ◽

10.18264/eadf.v5i2.238 ◽

2015 ◽

Vol 5 (2) ◽

Author(s):

Carla Denize Ott Felcher ◽

Crisna Daniela Krause Bierhalz ◽

Lisete Funari Dias

Keyword(s):

Teaching Strategy ◽

Collaborative Work ◽

Cultural Knowledge ◽

Virtual Learning Environment ◽

Assessment Tools ◽

Scale Model ◽

Learning Centers ◽

Physical Scale ◽

Scale Models ◽

Interdisciplinary Theory

Este trabalho tem por objetivo socializar e discutir os resultados de aprendizagem relacionados a uma estratégia didática: a construção de maquetes virtuais e físicas propostas no Curso de Licenciatura em Matemática a Distância (CLMD), da Universidade Federal de Pelotas, Projeto Universidade Aberta do Brasil (UAB3/ PARFOR), no segundo semestre de 2012. O currículo, organizado por Eixos Temáticos, tem seu planejamento com enfoque interdisciplinar. O foco deste trabalho é o Eixo Geometrias: Espaço e Forma. A base teórica deste trabalho utiliza a teoria da interdisciplinaridade, apoiada em Almeida e Passini (2002), Oliveira e Velasco (2007), Lenoir (2012), Trindade (2013) e Mello (1998). A pesquisa caracteriza-se metodologicamente como um estudo de caso, com análise qualitativa sobre dados coletados no Ambiente Virtual de Aprendizagem (Moodle), tais como os blogs dos polos e os registros nos portfólios virtuais, um dos instrumentos de avaliação propostos. Utiliza-se, para esta análise, a metodologia da Análise Documental (Ludke e Andre, 1986). Destaca-se, como resultado, que a estratégia didática ultrapassou os objetivos estabelecidos pelos professores, pois além dos conceitos geométricos, de física e de educação ambiental, a construção da maquete envolveu conhecimentos históricos e culturais da região em um trabalho colaborativo. Foi uma experiência significativa, segundo os registros dos próprios alunos pois, além de servir para construção da sua aprendizagem, a maquete foi utilizada pelos alunos que já atuam como professores nas suas práticas pedagógicas.Palavras-Chave: Educação a Distância; Maquete; Interdisciplinaridade. Aprendizagem significativa. Building Maquetes: Interdisciplinary Teaching Strategy in Axle and Shape of Space Geometry UFPel Abstract This paper aims at socializing and discussing the learning outcomes related to a teaching strategy: the construction of virtual and physical scale models proposed in the Mathematics Degree Distance Course (CLMD), from Universidade Federal de Pelotas, Project Open University in Brazil (UAB3/PARFOR) in the second half of 2012. The curriculum is organized by Thematic Groups, with interdisciplinary focus. The focus of this work is the Axis Geometries: Space and Shape. The theoretical basis of this work uses the interdisciplinary theory, supported by Almeida and Passini (2002), Oliveira and Velasco (2007), Lenoir (2012), Trindade (2013) and Mello (1998). The research is conducted methodologically as a case-study with a qualitative analysis of data collected in the Virtual Learning Environment (Moodle), such as learning centers blogs and records from the virtual portfolios, which are some of the proposed assessment tools. For this analysis, it is used the Document Analysis (LUDKE and ANDRE, 1986) methodology. It is important to emphasize that, as a result, the teaching strategy exceeded the objectives set by teachers, because, besides the geometrical concepts, physical and environmental education, the process of building a scale model has involved the places historical and cultural knowledge in a collaborative work. It was a meaningful experience, according to the students because, besides serving for the construction of their learning, the scale model was used by students who are working already as teachers in their pedagogical practice.Keywords: Distance Education; Mockup; Interdisciplinary; Meaningful learning.

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Tank Diaphragm Kinematic Behavior and Conditions for Safe Tank Withdrawal

Volume 2: Plant Systems, Structures, and Components; Safety and Security; Next Generation Systems; Heat Exchangers and Cooling Systems ◽

10.1115/icone20-power2012-55024 ◽

2012 ◽

Author(s):

Ludwig C. Haber ◽

Amie Humphrey-Facendola

Keyword(s):

Storage Tank ◽

Nuclear Power ◽

Power Plants ◽

Failure Modes ◽

Atmospheric Conditions ◽

Kinematic Behavior ◽

Physical Scale ◽

Scale Models ◽

Potential Failure ◽

Gas Volume

Power plants, including nuclear power plants regularly employ tanks whose contents need to be kept isolated from atmospheric conditions. One way to satisfy these requirements is to provide a liner for the tank which completely fits the interior shape of the tank but floats on top of the tank contents when the tank contains fluid. As the volume in the tank changes, the liner or diaphragm accommodates the changes in volume by sliding along the tank walls. To allow free movement of the diaphragm, management of the gas volume above the fluid and behind the diaphragm is of prime importance. The work described in this paper elaborates on the conditions required to prevent the tank diaphragm from becoming damaged. To develop potential failure modes, the kinematics of the diaphragm and the interaction with the gas volume between the diaphragm and the tank fluid are considered in detail. The developed model is applied to the case of a condensate storage tank at Comanche Peak Nuclear Power Plant (CPNPP). Two physical scale models of the tank were constructed and tested to validate the model and allow the safe operation principles to be quantified for use in the operation of the condensate storage tank at CPNPP. The work allowed CPNPP to design appropriate periodic checks and maintenance activities to ensure the diaphragm will not be damaged due to tank volume changes while still ensuring the required water chemistry criteria for the tank contents can be met.

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Prefabricated Futures: Adaptable and productive construction methods for New Zealand dwellings

10.26686/wgtn.17072756 ◽

2021 ◽

Author(s):

◽

Mitchell Holden

Keyword(s):

New Zealand ◽

Scale Model ◽

Package Design ◽

Home Owner ◽

Construction Methods ◽

Physical Scale ◽

Scale Models ◽

Building Information ◽

Roof Panel ◽

Traditional Construction

<p>The traditional construction method of the New Zealand home has remained largely unchanged over the last century. These housing solutions that have supported our nation no longer suffice and the ‘young home owner’ is becoming a distant dream. New Zealand needs homes, and fast. Specialised trades create fragmentation in construction. This results in inefficient processes that divide the stages of constructing a home. What lacks in these instances is accessibility to design. Architects tend to focus on one-off, bespoke builds, whilst transportable home companies create generic, minimum spec designs. It can be argued that current prefabricated solutions are not complete, requiring sub-trades and work onsite that causes delays and construction related setbacks. Investigation into a key historic precedent has driven this research. This demonstrates that attempts have been made to change the housing model in New Zealand with some success. The precedent aligns with past notions in considering core parts of the home as products. This can create efficiencies in construction. The current demand for housing provides the perfect opportunity to reboot the method in which we build. This thesis questions how offsite panel assemblies can create a complete prefabricated housing product and improve construction efficiencies. This will still offer architectural choice. BIM (Building Information Modelling) and parameter driven design are used as a vehicle to demonstrate how more efficient, more collaborative and more controlled design approaches can be developed in order to create a complete construction package. Design-led research involving constant scale model testing and development led to my prefabricated wall panel design. Named the LapLock panel, I have developed a complete wall, floor and roof panel product system. Designed to be fully fabricated from structure to claddings and services in factory. This produces ruthless efficiencies onsite. The work utilises BIM in the form of Revit and takes advantage of parameter driven families to allow for fast manipulation and output of drawings for panels. A constant conversation between analogue and digital tools (in the form of physical scale models and Revit) strengthened the understandings of the limitations throughout the research. This thesis offers a new way of considering how New Zealand builds homes. By introducing adaptable and efficient panels that are complete on arrival to site, the Laplock solution provides accessible architectural choice to clients. This future-proofs the construction of the New Zealand home.</p>

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Radial Turbine Design for Solar Chimney Power Plants

Energies ◽

10.3390/en14030674 ◽

2021 ◽

Vol 14 (3) ◽

pp. 674

Author(s):

Paul Caicedo ◽

David Wood ◽

Craig Johansen

Keyword(s):

Power Plants ◽

Reference Frames ◽

Three Dimensional ◽

Discrete Ordinates ◽

Large Area ◽

Solar Chimney ◽

Cfd Simulations ◽

Radial Turbine ◽

Design Changes ◽

Turbine Design

Solar chimney power plants (SCPPs) collect air heated over a large area on the ground and exhaust it through a turbine or turbines located near the base of a tall chimney to produce renewable electricity. SCPP design in practice is likely to be specific to the site and of variable size, both of which require a purpose-built turbine. If SCPP turbines cannot be mass produced, unlike wind turbines, for example, they should be as cheap as possible to manufacture as their design changes. It is argued that a radial inflow turbine with blades made from metal sheets, or similar material, is likely to achieve this objective. This turbine type has not previously been considered for SCPPs. This article presents the design of a radial turbine to be placed hypothetically at the bottom of the Manzanares SCPP, the only large prototype to be built. Three-dimensional computational fluid dynamics (CFD) simulations were used to assess the turbine’s performance when installed in the SCPP. Multiple reference frames with the renormalization group k-ε turbulence model, and a discrete ordinates non-gray radiation model were used in the CFD simulations. Three radial turbines were designed and simulated. The largest power output was 77.7 kW at a shaft speed of 15 rpm for a solar radiation of 850 W/m2 which exceeds by more than 40 kW the original axial turbine used in Manzanares. Further, the efficiency of this turbine matches the highest efficiency of competing turbine designs in the literature.

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Development of a Hydropower Turbine Using Seawater from a Fish Farm

Processes ◽

10.3390/pr9020266 ◽

2021 ◽

Vol 9 (2) ◽

pp. 266

Author(s):

Md Rakibuzzaman ◽

Sang-Ho Suh ◽

Hyoung-Ho Kim ◽

Youngtae Ryu ◽

Kyung Yup Kim

Keyword(s):

Power Plants ◽

Guide Vane ◽

Cross Flow ◽

Synchronous Generator ◽

Fish Farm ◽

Hydropower Plant ◽

Fish Farms ◽

Data Simulation ◽

Small Hydropower ◽

Hydropower Plants

Discharge water from fish farms is a clean, renewable, and abundant energy source that has been used to obtain renewable energy via small hydropower plants. Small hydropower plants may be installed at offshore fish farms where suitable water is obtained throughout the year. It is necessary to meet the challenges of developing small hydropower systems, including sustainability and turbine efficiency. The main objective of this study was to investigate the possibility of constructing a small hydropower plant and develop 100 kW class propeller-type turbines in a fish farm with a permanent magnet synchronous generator (PMSG). The turbine was optimized using a computer simulation, and an experiment was conducted to obtain performance data. Simulation results were then validated with experimental results. Results revealed that streamlining the designed shape of the guide vane reduced the flow separation and improved the efficiency of the turbine. Optimizing the shape of the runner vane decreased the flow rate, reducing the water power and increasing the efficiency by about 5.57%. Also, results revealed that tubular or cross-flow turbines could be suitable for use in fish farm power plants, and the generator used should be waterproofed to avoid exposure to seawater.

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The Winter Habitat Selection of Red Deer (Cervus elaphus) Based on a Multi-Scale Model

Animals ◽

10.3390/ani10122454 ◽

2020 ◽

Vol 10 (12) ◽

pp. 2454

Author(s):

Yue Sun ◽

Yanze Yu ◽

Jinhao Guo ◽

Minghai Zhang

Keyword(s):

Habitat Selection ◽

Environmental Factors ◽

Cervus Elaphus ◽

Red Deer ◽

Scale Model ◽

Winter Habitat ◽

Multi Scale ◽

Optimal Scale ◽

Scale Models ◽

Selection Of

Single-scale frameworks are often used to analyze the habitat selections of species. Research on habitat selection can be significantly improved using multi-scale models that enable greater in-depth analyses of the scale dependence between species and specific environmental factors. In this study, the winter habitat selection of red deer in the Gogostaihanwula Nature Reserve, Inner Mongolia, was studied using a multi-scale model. Each selected covariate was included in multi-scale models at their “characteristic scale”, and we used an all subsets approach and model selection framework to assess habitat selection. The results showed that: (1) Univariate logistic regression analysis showed that the response scale of red deer to environmental factors was different among different covariate. The optimal scale of the single covariate was 800–3200 m, slope (SLP), altitude (ELE), and ratio of deciduous broad-leaved forests were 800 m in large scale, except that the farmland ratio was 200 m in fine scale. The optimal scale of road density and grassland ratio is both 1600 m, and the optimal scale of net forest production capacity is 3200 m; (2) distance to forest edges, distance to cement roads, distance to villages, altitude, distance to all road, and slope of the region were the most important factors affecting winter habitat selection. The outcomes of this study indicate that future studies on the effectiveness of habitat selections will benefit from multi-scale models. In addition to increasing interpretive and predictive capabilities, multi-scale habitat selection models enhance our understanding of how species respond to their environments and contribute to the formulation of effective conservation and management strategies for ungulata.

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Multiphasic Study of Fluid-Dynamics and the Thermal Behavior of a Steel Ladle during Bottom Gas Injection Using the Eulerian Model

Metals ◽

10.3390/met11071082 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1082

Author(s):

Antonio Urióstegui-Hernández ◽

Pedro Garnica-González ◽

José Ángel Ramos-Banderas ◽

Constantin Alberto Hernández-Bocanegra ◽

Gildardo Solorio-Díaz

Keyword(s):

Heat Exchange ◽

Thermal Behavior ◽

Gas Flow ◽

Fluid Dynamic ◽

Steel Slag ◽

Scale Model ◽

Discrete Ordinates ◽

Transfer Model ◽

Steel Ladle ◽

Physical Scale

In this work, the fluid dynamic and thermal behavior of steel was analyzed during argon gas stirring in a 140-t refining ladle. The Eulerian multiphase mathematical model was used in conjunction with the discrete ordinates (DO) thermal radiation model in a steel-slag-argon system. The model was validated by particle image velocimetry (PIV) and the analysis of the opening of the oil layer in a physical scale model. The effect of Al2O3 and Mg-C as a refractory in the walls was studied, and the Ranz-Marshall and Tomiyama models were compared to determine the heat exchange coefficient. The results indicated that there were no significant differences between these heat exchange models; likewise, the radiation heat transfer model adequately simulated the thermal behavior according to plant measurements, finding a thermal homogenization time of the steel of 2.5 min for a gas flow of 0.45 Nm3·min−1. Finally, both types of refractory kept the temperature of the steel within the ranges recommended in the plant; however, the use of Al2O3 had better heat retention, which would favor refining operations.

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