检索结果-南通市图书馆

Investigating the Effects of Injection Pipe Orientation on Mixing and Heat Transfer for Fluid Flow Downstream a T-Junction

引用

Journal of Power and Energy Engineering 2024年第10期12卷 1-30页

作者： Vincent Yao Agbodemegbe Seth Kofi Debrah Afia Boatemaa edward shitsi Department of Nuclear Engineering School of Nuclear and Allied Sciences University of Ghana Accra Ghana Nuclear Power Institute Ghana Atomic Energy Commission Legon Accra National Nuclear Research Institute Ghana Atomic Energy Commission Legon Accra

At T-junctions, where hot and cold streams flowing in pipes join and mix, significant temperature fluctuations can be created in very close neighborhood of the pipe walls. The wall temperature fluctuations cause cyclical thermal stresses which may induce fatigue cracking. Temperature fluctuation is of crucial importance in many engineering applications and especially in nuclear power plants. This is because the phenomenon leads to thermal fatigue and might subsequently result in failure of structural material. Therefore, the effects of temperature fluctuation in piping structure at mixing junctions in nuclear power systems cannot be neglected. In nuclear power plant, piping structure is exposed to unavoidable temperature differences in a bid to maintain plant operational capacity. Tightly coupled to temperature fluctuation is flow turbulence, which has attracted extensive attention and has been investigated worldwide since several decades. The focus of this study is to investigate the effects of injection pipe orientation on flow mixing and temperature fluctuation for fluid flow downstream a T-junction. Computational fluid dynamics (CFD) approach was applied using STAR CCM+ code. Four inclination angles including 0 (90), 15, 30 and 45 degrees were studied and the mixing intensity and effective mixing zone were investigated. K-omega SST turbulence model was adopted for the simulations. Results of the analysis suggest that, effective mixing of cold and hot fluid which leads to reduced and uniform temperature field at the pipe wall boundary, is achieved at 0 (90) degree inclination of the branch pipe and hence may lower thermal stress levels in the structural material of the pipe. Turbulence mixing, pressure drop and velocity distribution were also found to be more appreciable at 0 (90) degree inclination angle of the branch pipe relative to the other orientations studied.

关键词： Thermal Fatigue Unsteady Reynolds Averaged Navier-Stokes (URANS) Thermal Stratification T-Junction Pipes Computational Fluid Dynamics (CFD)

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Performance of Heat Transfer Correlations Adopted at Supercritical Pressures: A Review

引用

World Journal of Engineering and Technology 2018年第2期6卷 241-267页

作者： edward shitsi Seth Kofi Debrah Vincent Yao Agbodemegbe Emmanuel Ampomah-Amoako Department of Nuclear Engineering Graduate School of Nuclear and Allied Sciences University of Ghana Accra Ghana

Research activities involving heat transfer at supercritical pressures have attracted attention in recent years because of possibility of increase in thermal output of heat transfer and industrial equipment. Because of high pressure and temperature conditions associated with heat transfer at supercritical pressures, only few experimental heat transfer studies are being carried out at supercritical conditions. The use of numerical tools for heat transfer and other related studies at supercritical pressures is increasing because of the high-pressure-temperature limitation of experimental studies at supercritical conditions. Heat transfer correlations implemented in these numerical tools are used to obtain numerical heat transfer data to complement experimental heat transfer data provided through experimental studies. In order to further broaden the understanding of fluid flow and heat transfer, this review examines the performance of heat transfer correlations adopted at supercritical pressures. It is found from the review that most of the correlations could predict heat transfer quite well in the low enthalpy region and few of the correlations could predict heat transfer in the high enthalpy region near critical and pseudo-critical conditions (heat transfer deteriorated conditions). However, no single heat transfer correlation is able to accurately predict all the experimental results presented in this work.

关键词： Heat Transfer Correlations Supercritical Pressure Heat Transfer Deterioration Supercritical Water Cooled Reactor SCWR

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Flow Instability in Parallel Channels with Water at Supercritical Pressure: A Review

引用

World Journal of Engineering and Technology 2018年第1期6卷 128-160页

Research into flow instability at both subcritical and supercritical pressures has attracted attention in recent years because of its potential of occurrence in industrial heat transfer systems. Flow instability has the potential to affect the safety of design and operation of heat transfer equipment. Flow instability is therefore undesirable and should be avoided?in the design and operation of industrial equipment. Rahman?et al. reviewed studies on supercritical water heat transfer with the aim of providing references for SCWR researchers. It was found out that most of the CFD studies and experimental studies were performed with single tube geometry due to the complexity of parallel channel geometry. Because studies performed with parallel channel geometry could provide detailed information to the design of the SCWR core, they called for more studies in parallel channel geometry at supercritical pressures in the future. In order to help understand how flow instability investigations are carried out and also highlight the need to understand flow instability phenomenon and equip the designers and operators of industrial heat transfer equipment with the needed knowledge on flow instability, this study carried out a review of flow instability in parallel channels with water at supercritical pressures.

关键词： Parallel Channels Supercritical Pressure Flow Instability Supercritical Water Cooled Reactor

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Investigating the Effects of Interface Topology on Flow Development in Rod Bundle Supported by Spacer Grid with Split Mixing Vane Using STAR-CCM+

引用

Journal of Power and Energy Engineering 2022年第11期10卷 45-67页

作者： Vincent Yao Agbodemegbe edward shitsi Felix Ameyaw Henry Cecil Odoi Isaac Kwasi Baidoo School of Nuclear and Allied Sciences University of Ghana Accra Ghana National Nuclear Research Institute Ghana Atomic Energy Commission Accra Ghana Nuclear Power Institute Ghana Atomic Energy Commission Accra Ghana

Flow development downstream of a spacer grid is dependent on the upstream conditions and the imposed interface topology, especially at inlet and outlet boundaries. In STAR-CCM+, all interfaces fall into two groups, direct and indirect. A direct interface directly joins together two boundaries composing the interface either permanently or temporarily, for the case of rigid body motion. An explicit connection is created between cells on each side of the interface, so that mass and energy or either of them will occur across the interface. Three options of interface topology namely, in-place, periodic and repeating are available to be imposed at the inlet-outlet boundaries for a flow problem. In the present work, computational fluid dynamic simulation using STAR-CCM+ was performed for the flow of water at a bundle’s Reynolds number of Re1 = 3.4 × 104 through a 5 × 5 rod bundle geometry supported by spacer grid with and without split mixing vanes for which the rod-to-rod pitch to diameter ratio was 1.33 and the rod to wall pitch to diameter ratio was 0.74. The two-layer k-epsilon turbulence model with an all y+ automatic wall treatment function in STAR-CCM+ was adopted for an isothermal single phase (water) flow through the geometry with and without imposed cyclic periodic interface boundary condition of fully developed flow type at inlet and outlet boundaries. The objectives were to primarily investigate the extent of predictability of the experimental data by the Computational Fluid Dynamic (CFD) simulation as a measure of reliability on the CFD code employed, and also study the effects of the imposed interface topology on flow redistribution in the presence and absence of split mixing vane. Validation of simulation results with experimental data showed a good correlation of mean flow parameters with experimental data. Generally, the agreement of simulation results with data obtained from the experimental investigation confirmed the suitability of the CFD co

关键词： CFD Spacer Grid Split Vane Interface Topology Turbulence STAR-CCM+

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Management System Activities of the Operation and Utilization of GHARR-1

引用

World Journal of Engineering and Technology 2023年第4期11卷 807-826页

作者： edward shitsi Henry Cecil Odoi Kwame Gyamfi Philip Dordoh-Gasu Isaac Kwasi Baidoo edward Oscar Amponsah-Abu Emmanuel Kwesi Boafo Samuel Yao Ganyaglo Samuel Boakye Dampare Henry Kwame Obeng William Osei-Mensah Wilfred Sedofia Massiasta Robert Ekow Quagraine Nuclear Reactors Research Centre National Nuclear Research Institute Ghana Atomic Energy Commission Accra Ghana

The Ghana Research Reactor-1 (GHARR-1) is a 34 kW low enriched uranium (LEU) Miniature Neutron Source Reactor (MNSR), tank-in-pool type and cooled by natural circulation under atmospheric pressure operating conditions. GHARR-1 is owned by Ghana Atomic Energy Commission (GAEC) and operated by National Nuclear Research Institute (NNRI), one of the institutes of GAEC. GHARR-1 is housed by Nuclear Reactors Research Centre (NRRC), one of the Centres of NNRI. Management/Administration, Radiation protection, Reactor operation and maintenance, Reactor utilization and Physical protection are the various systems/units that integrate to manage the activities of operation and utilization of GHARR-1 in addition to the quality assurance and quality control management system of the research reactor facility. The GHARR-1 which is currently in operation follows a robust maintenance culture adopted by the management system and this has made it possible to keep the reactor in operation with minimal interruption. The management system activities adopted at the Centre to ensure safety of the workers, public and the research reactor facility include authorization of the operation of the reactor for any experiments/modifications;providing material and financial resources for maintaining the research reactor facility;following standard procedures while carrying out Neutron Activation Analysis;participation in IAEA proficiency test;irradiation sites/positions characterization;following standard procedures while carrying out reactor operation and maintenance including reactor and pool water purification and other related activities;monitoring radiation levels in the controlled, supervised and uncontrolled areas of the research reactor facility as well as during reactor operation and maintenance;controlling the physical entry of the workers and public into the research reactor facility;and ensuring that the security structures provided to protect the reactor facility are functioning properly.

关键词： Management Systems Quality Assurance and Quality Control Research Re-actor Operation and Utilization Monitoring Forms Ghana Research Reactor-1 (GHARR-1)

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Seismites of the Late Triassic Lockatong Formation,Pennsylvania,USA:implications for Newark Basin border fault movement

引用

Journal of Palaeogeography 2025年第1期14卷 1-14页

作者： edward L.Simpson Michael C.Wizevich David L.Fillmore Department of Physical Sciences Kutztown University of Pennsylvania Department of Earth and Space Sciences Central Connecticut State University

Numerous soft-sediment deformation structures(SSDS) within thin-bedded, heterolithic lacustrine shoreline deposits of the Upper Triassic Tumble Falls Member, Lockatong Formation of eastern Pennsylvania, demonstrate liquefaction, fluidization and shearing features processes affecting sediment. This study employs thin-section analysis of SSDS to interpret them as probable seismites from the Triassic-Jurassic Newark Basin. Sedimentary structures include right-lateral offset of desiccation cracks and ichnofossils, thrust,reverse, and normal faults with mm-scale offsets, horsts and grabens, lateral spreads, and single and complex multiple networks of dikes and sills and associated sedimentary volcanoes, thin mudflows on a paleosurface linked to sediment dikes, load and flame structures, ball and pillow structures, recumbent folds, and incipient breccias. Dike fill consists of mudstone, angular sedimentary clasts, sandstone margins with mudstone cores,and plastically deformed sediment fill. The SSDS indicate that Late Triassic lacustrine shoreline sediments were subjected to forces, probably compressive with a minimal shear component reflected in the offset of the dikes and ichnofossils, that induced liquefaction followed by fluidization and vertical movement of *** forces that altered sediment vertical stability, leading to deformation of the sediment included gravitationally unstable density gradients, vertical shear stress, and gravitational body forces. SSDS can be induced by seismic and aseismic processes. However, this unique combination of forces and resulting sedimentary structures indicate an origin by earthquake activity, likely produced by the nearby, active Newark Basin border fault system. The Lockatong Formation SSDS seismites improve our understanding via thin section analysis of the rheology and preservation potential of SSDS in lacustrine shoreline deposits, critical for the geologic history of Newark Basin, as well as the refinement for paleos

关键词： Seismites Triassic Lockatong Formation Lacustrine Soft-sediment deformation structures

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Effect of Gum Arabic from Acacia senegal var. kerensis and Texturized Soy Protein on Pysico-Chemical Properties of Protein-Rich Snack Stick

引用

Food and Nutrition Sciences 2025年第1期16卷 28-43页

作者： edward Mukundi Njeru Mary Omwamba Symon Maina Mahungu Department of Dairy Food Science and Technology Egerton University Njoro Kenya

Protein-energy malnutrition (PEM) as a result of poor nutrition, especially for deprived resourced households, is a big health concern in the world. According to the World Health Organisation, PEM accounts for 49% of the 10.4 million deaths of children under five that take place in developing countries. The aim of this study was to evaluate the influence of gum Arabic (GA) and texturized soy protein (TSP) and their interactive effect on proximate, functional, and textural properties of the protein-rich snack stick produced from ground green maize, GA powder, and ground TSP. GA varied at 0%, 4%, 8%, and 12%, while TSP varied at 0%, 12%, 24% and 36%. The 5 cm long protein-rich snack sticks were made using a sausage stuffer and baked in an oven at 110˚C for 1 hr 30 minutes. The snack sticks were subjected to proximate, functional and textural analysis using the standard methods. Increasing GA resulted in a significant (p p < 0.05) increased the protein content (32.46%), Ash content (3.6%), fat (11.96%), and moisture content (16.25%) of protein-rich snack sticks. The interactive effect between GA and TSP led to a decrease in fibre and carbohydrates. Results from this study show GA and TSP significantly enhanced the physico-chemical properties of protein-rich snack sticks. A sample with 4% GA and 36% TSP is recommended for the best physico-chemical attributes of the protein-rich snack stick.

关键词： Gum Arabic Protein Snack Hydrocolloids Nutrition

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Perceptions of Sierra Leonean Mango Farmers on the Pest Status and Current Management Practices for the Control of Fruit Fly in Sierra Leone

引用

Advances in Entomology 2025年第1期13卷 94-106页

作者： Paul Borbor Brewah Alusaine edward Samura Abu James Sundufu Vandi Amara Raymonda Adeline Bernadette Johnson Crop Protection Department School of Agriculture and Food Science Njala University Moyamba Sierra Leone

Tephritid fruit flies are considered one of the world’s most notorious pests of horticultural crops, including mango (Mangefera indica L.) in Sierra Leone, causing extensive direct and indirect damage. A survey was conducted among 60 mango farmers in 7 districts in Sierra Leone between June and August, 2022, to assess their perceptions regarding fruit fly pest status and the current management options adopted for the control of this pest. Semi-structured questions designed in an open and closed-ended fashion were used for the study. The majority (83%) of the farmers were already aware of the fruit fly problem in the country with 62% perceiving it to be very severe. The majority (60%) of farmers, however, demonstrated poor knowledge of identifying fruit fly species, especially Bactrocera dorsalis, Ceratitis capitata, and Ceratitis cosyra. Farmers were more conversant about the direct damage symptoms to host fruits and the economic impact of fruit flies. A total of 32% of growers took no action to control fruit flies on their farms. Sixty-nine percent (69%) of the farmers adopted cultural control measures, like practicing prompt harvesting, collection and disposal of infested fruits, and weeding to maintain better sanitary conditions on their farms. Recommended fruit fly management strategies such as the use of botanicals and resistant varieties were either unknown or inaccessible to growers. A total of 52% applied chemicals that were not recommended for the control of fruit flies without considering their environmental and health risks. It is important to train fruit growers to improve their capabilities for fruit fly management through extension agents that are appropriate for helping them acquire basic knowledge of fruit fly pests and their management.

关键词： Fruit Growers Fruit Fly Pests Knowledge Perceptions Sierra Leone

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Mini-Review:Green sustainable processes using supercritical fluid carbon dioxide

引用

Journal of Environmental Sciences 2009年第6期21卷 720-726页

作者： RAMSEY edward University of Science and Technology Liaoning

Environmentally benign carbon dioxide offers significant potential in its supercritical fluid phase to replace current reliance on a range of hazardous, relatively expensive and environmentally damaging organic solvents that are used on an extensive global basis. The unique combination of the physical properties of supercritical fluids are being exploited and further researched to continue the development and establishment of high efficiency, compact plant to provide energy and water efficient manufacturing processes. This mini-review is focused on the use and potential applications of supercritical fluid carbon dioxide for a selected range of key and emerging industrial processes as a sustainable alternative to totally eliminate or greatly reduce the requirement of numerous conventional organic solvents. Examples of the industries include： chemical extraction and purification, synthetic chemical reactions including polymerization and inorganic catalytic processes. Biochemical reactions involving enzymes, particle size engineering, textile dyeing and advanced material manufacture provide further illustrations of vital industrial activities where supercritical fluid technology processes are being implemented or developed. Some aspects relating to the economics of sustainable supercritical fluid carbon dioxide processes are also considered.

关键词： supercritical extraction synthesis catalysis enzymes polymerization particles dyeing

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Sustainable oil-in-water analysis using a supercritical fluid carbon dioxide extraction system directly interfaced with infrared spectroscopy

引用

Journal of Environmental Sciences 2010年第9期22卷 1462-1468页

作者： edward D.Ramsey School of Chemical Engineering University of Science and Technology Liaoning

A direct aqueous supercritical fluid extraction （SFE） system using carbon dioxide provides a sustainable means by which a vast range of industries may continue to depend on well established infrared （IR） techniques to determine oil-in-water. The SFE-IR method provides an environmentally friendly substitute for current national standard IR reference methods for measuring oil-in-water that rely on using increasingly restricted ozone depleting solvents whose manufacture is being phased out in accordance with international law. The SFE-IR analysis of a 500 mL water sample can be accomplished in 15 min. A rapid on-line SFE-IR calibration method has been implemented. With this calibration method, SFE-IR accuracy for determining diesel oil in 500 mL spiked water samples using single wave number measurement was 86.0%-98.8% with precision （RSD） ranging from 2.5%-7.0%. Using a general purpose calculation which involves measuring infrared absorbance values at three different wave numbers, SFE-IR method accuracy for determining diesel oil in 500 mL spiked water samples was 83.7%-92.2% with RSD 1.0%-9.3%. Data is presented that indicates current long established national standard IR reference methods involving three wave number calculations should be reviewed since, without careful consideration, the inclusion of calculated aromatic hydrocarbon species contributions to final oil-in-water concentration values may provide less accurate results.

关键词： oil-in-water supercritical fluid extraction infrared spectroscopy sustainable green technology

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：