检索结果-南通市图书馆

Trombe walls with porous medium insertion and their influence on thermal comfort in flats in Cusco,Peru

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Energy and Built Environment

Energy and Built Environment 2024年第2期5卷 194-210页

作者： Patrick Facelli Sanchez Lisset Mercado Hancco Department of Civil Engineering Faculty of Architecture and Civil EngineeringUniversidad Nacional de San Antonio Abad del Cusco08003 CuscoPeru

The Trombe wall is a passive indirect heating system which should be used in Cusco,Peru to improve thermal conditions against the typical frosts and low temperatures during winter in the high Andean regions.Due to this problem,the use of a modified Trombe wall with insertion of porous medium is proposed to improve thermal comfort in flat buildings in Cusco.This research aims to analyse and compare the performance of dwellings without Trombe wall,with traditional Trombe wall,and with Trombe wall with glass and plastic pellets insertion in thermal comfort improvement.Autodesk■CFD was used to simulate and analyse the system.The simulation was performed with three prototype flats(55 m^(2),75 m^(2) and 95 m^(2))for six months of the year.From the results obtained,the level of thermal comfort in the traditional scenarios is low with an average PMV of-1.86,in the scenarios with Trombe wall is good and in the scenarios with Trombe wall with insertion of porous medium is slightly better than the previous one,reaching an average PMV of+0.10 and a temperature of 21.90℃.The study carried out is important because it represents an efficient eco-sustainable heating alternative that improves the thermal comfort sensation in houses during the coldest months of the year.

关键词： Trombe wall thermal comfort porous medium residential buildings computational fluid dynamics

Flow and Heat Transfer of a Dusty Williamson MHD Nanofluid Flow over a Permeable Cylinder in a porous medium

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Fluid Dynamics 2024年第2期14卷 100-122页

作者： Oluranti Adejoke Adekanmbi-Akinseye Olugbenga John Fenuga Hamzat Afe Isede Musibau Gbeminiyi Sobamowo Department of Mathematics University of Lagos Lagos Nigeria Department of Mechanical Engineering University of Lagos Lagos Nigeria

This study investigates the flow and heat transfer of dusty Williamson (MHD) Nanofluid flow over a stretching permeable cylinder in a porous medium. Dusty Williamson Nanofluid was considered due to its thermal properties and potential benefits of increasing the heat transfer rate. Firstly, partial differential equations are transformed into coupled non-linear ordinary differential equations through a similarity variables transformation. The resulting set of dimensionless equations is solved analytically by using the Homogony Perturbation Method (HPM). The effects of the emerging parameters on the velocity and temperature profiles as well as skin-friction coefficient and Nusselt number are publicized through tables and graphs with appropriate discussions. The present result has been compared with published papers and found to be in agreement. To the best of author’s knowledge, there has been sparse research work in the literature that considers the effect of dust with Williamson Nanofluid and also solving the problem analytically. Therefore to the best of author’s knowledge, this is the first time analytical solution has been established for the problem. The results revealed that the fluid velocity of both the fluid and dust phases decreases as the Williamson parameter increases. Motivated by the above limitations and the gaps in past works, therefore, it is hoped that the present work will assist in providing accurate solutions to many practical problems in science, industry and engineering.

关键词： Williamson Dusty Particles Homotopy Perturbation Method (HPM) Magneto Hydrodynamic (MHD) Nanofluid porous medium Stretching Cylinder

Influence of variable viscosity and double diffusion on the convective stability of a nanofluid flow in an inclined porous channel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 563-580页

作者： N.HUMNEKAR D.SRINIVASACHARYA Department of Mathematics National Institute of TechnologyWarangal 506004TelanganaIndia

The influence of variable viscosity and double diffusion on the convective stability of a nanofluid flow in an inclined porous channel is investigated.The DarcyBrinkman model is used to characterize the fluid flow dynamics in porous materials.The analytical solutions are obtained for the unidirectional and completely developed flow.Based on a normal mode analysis,the generalized eigenvalue problem under a perturbed state is solved.The eigenvalue problem is then solved by the spectral method.Finally,the critical Rayleigh number with the corresponding wavenumber is evaluated at the assigned values of the other flow-governing parameters.The results show that increasing the Darcy number,the Lewis number,the Dufour parameter,or the Soret parameter increases the stability of the system,whereas increasing the inclination angle of the channel destabilizes the flow.Besides,the flow is the most unstable when the channel is vertically oriented.

关键词： nanofluid inclined channel variable viscosity linear stability double dif-fusion porous medium

Formation Characteristics of CO_(2) Hydrates in the Presence of porous Media and NaCl

在线全文

学校读者我要写书评

暂无评论

China Petroleum Processing & Petrochemical Technology 2024年第2期26卷 168-177页

作者： Han Jianchao Zhu Shuai Gui Xia College of Chemical Engineering Nanjing Tech UniversityNanjing 211816China

Hydrate-based CO_(2) sequestration is an effective method for reducing the greenhouse effect,and the presence of porous media and NaCl can impact the formation characteristics of hydrates.This study uses the constant volume temperature search method to investigate the effects of quartz sand particle size(0.006‒0.03 mm),water saturation(30%–90%),and NaCl concentration(1%‒9%)on the phase equilibrium and kinetics of CO_(2) hydrates within a temperature range of 273‒285 K and pressure range of 1.0‒3.5 MPa.The results indicate that a decrease in quartz sand particle size or an increase in NaCl concentration shifts the hydrate phase equilibrium curve towards lower temperatures and higher pressures,making hydrate generation conditions more demanding.In different particle size systems,there are no significant changes in the rate of CO_(2) hydrate formation or conversion rate.The highest hydrate conversion rate of 71.1%is observed in a 0.015 mm particle size system.With increasing water saturation,both the generation rate and conversion rate of CO_(2) hydrates show a trend of first increasing and then decreasing.Meanwhile,low concentrations of NaCl(1%–3%)are found to enhance the formation and conversion rates of CO_(2) hydrates.However,as NaCl concentration increases,the rate of CO_(2) hydrate formation and conversion rate decrease.

关键词： CO_(2)hydrate porous medium NaCl formation characteristics

Theoretical investigation on submicron particle penetration through circular tubes inside a porous medium

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2022年第11期70卷 55-63页

作者： Yanrong Yu Yongwei Gao Yanming Kang School of Environmental Science and Engineering Donghua UniversityShanghai 201620China School of Physics and Electronic-Electrical Engineering Ningxia UniversityYinchuan 750021China

The analytical infinite series solution of submicron particle transport in a circular tube bounded by a porous wall,such as a pinhole,is determined under the slip velocity boundary condition,and the solution is verified by using the experimental data in the previous studies for the specific cases.The results show that particle penetration rate increases with the increase of the porous parameter,the axial pressure drop,and the pinhole radius,whereas it decreases with increasing the pinhole length.The penetration rate of nano-particles are more sensitive to the variation of these parameters.However,the differences between the penetrations of particles ranging from 0.3μm to 1μm are not evident because the diffusion becomes weak gradually in this size range.In addition,a further comparison is performed between the analytical solution and the existing studies,and approximate expressions are presented for accurate calculation of particle penetration rate through pinholes appearing in porous materials including filter devices and masks.

关键词： porous medium Penetration Submicron particle Circular tube Analytical solution

An In-Situ MRI Method for Quantifying Temperature Changes during Crystal Hydrate Growths in porous medium

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2022年第5期31卷 1542-1550页

作者： ZHANG Lunxiang SUN Mingrui WANG Tian YANG Lei ZHANG Xiaotong ZHAO Jiafei SONG Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education School of Energy and Power EngineeringDalian University of TechnologyDalian116024China Interdisciplinary Institute of Neuroscience and Technology Zhejiang UniversityHangzhou310029China

Given the complexity of the thermo-hydro-chemically coupled phase transition process of hydrates,real-time in-situ observations are required.Thermometry maps are particularly essential in analyzing the heat transfer process during the growth and dissociation of crystal hydrates.In this study,we present the temporally and spatially resolved thermometry of the formation of tetrahydrofuran hydrates based on the temperature dependence of the chemical shift of the water proton.Images of temperature changes were synchronously obtained using a 9.4 T^(1)H magnetic resonance imaging(MRI)system to predict the saturation level of the aqueous solution,phases of the solid hydrates,and the positive temperature anomaly of the exothermic reaction.It was observed that variations in the MRI signal decreased while the temperature rise differed significantly in space and time.The results predicted in this study could have significant implications in optimizing the phase transition process of gas hydrates.

关键词： hydrate phase transition heat transfer porous medium temperature mapping magnetic resonance imaging thermometry thermodynamics and molecular-scale phenomena

Deep bed filtration model for cake filtration and erosion

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 355-372页

作者： L.I.KUZMINA Y.V.OSIPOV A.R.PESTEREV Department of Applied Mathematics HSE UniversityMoscow 101000Russia Department of Computer Science and Applied Mathematics Moscow State University of Civil EngineeringMoscow 129337Russia

Many phenomena in nature and technology are associated with the filtration of suspensions and colloids in porous media. Two main types of particle deposition,namely, cake filtration at the inlet and deep bed filtration throughout the entire porous medium, are studied by different models. A unified approach for the transport and deposition of particles based on the deep bed filtration model is proposed. A variable suspension flow rate, proportional to the number of free pores at the inlet of the porous medium, is considered. To model cake filtration, this flow rate is introduced into the mass balance equation of deep bed filtration. For the cake filtration without deposit erosion,the suspension flow rate decreases to zero, and the suspension does not penetrate deep into the porous medium. In the case of the cake filtration with erosion, the suspension flow rate is nonzero, and the deposit is distributed throughout the entire porous medium. An exact solution is obtained for a constant filtration function. The method of characteristics is used to construct the asymptotics of the concentration front of suspended and retained particles for a filtration function in a general form. Explicit formulae are obtained for a linear filtration function. The properties of these solutions are studied in detail.

关键词： deep bed filtration cake filtration porous medium particle deposition and erosion analytical solution concentration front

Analysis of a Stagnation Point Flow with Hybrid Nanoparticles over a porous medium

在线全文

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2023年第2期19卷 541-567页

作者： U.S.Mahabaleshwar T.Anusha M.Hatami Department of Mathematics Davangere UniversityShivagangothriDavangereIndia Department of Mechanical Engineering Ferdowsi University of MashhadMashhadIran

The unsteady stagnation-point flow of a hybrid nanofluid over a stretching/shrinking sheet embedded in a porous medium with mass transpiration and chemical reactions is considered.The momentum and mass transfer problems are combined to form a system of partial differential equations,which is converted into a set of ordinary differential equations via similarity transformation.These ordinary differential equations are solved analytically to obtain the solution for velocity and concentration profiles in exponential and hypergeometric forms,respectively.The concentration profile is obtained for four different cases namely constant wall concentration,uniform mass flux,general power law wall con-centration and general power law mass flux.The effect of different physical parameters such as Darcy number Da^(1-1),mass transpiration parameter V_(C),stretching/shrinking parameter (d),chemical reaction parameter(β)and Schmidt number (Sc)on velocity and concentration profile is examined.Results show that,the axial velocity will decreases as the shrinking sheet parameter increases,regardless of whether the suction or injection case is examined.The concentration decreases with an increase in the shrinking sheet parameter and the chemical reaction rate parameter.

关键词： Chemical reaction parameter mass transpiration hybrid nanofluid porous medium Schmidt number

Flow and heat transfer of a nanofluid through a porous medium due to stretching/shrinking sheet with suction,magnetic field and thermal radiation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2023年第3期38卷 373-391页

作者： Ubaidullah Yashkun Khairy Zaimi Suliadi Firdaus Sufahani Mohamed REid Mohammad Ferdows Centre of Excellence for Social Innovation and Sustainability Institute of EngineeringUniversiti Malaysia PerlisPauh Putra Campus02600ArauPerlisMalaysia Department of Mathematics Sukkur IBA UniversityAirport RoadSukkur65200SindhPakistan Department of Mathematics and Statistics Faculty of Applied Sciences and TechnologyUniversiti Tun Hussein Onn MalaysiaJohorMalaysia Department of Mathematics Faculty of ScienceNew Valley UniversityAl-Wadi Al-GadidAl-Kharga 72511Egypt Mathematics Department Faculty of ScienceNorthern Border UniversityArar 1321Saudi Arabia Research Group of Fluid Flow Modeling and Simulation Department of Applied MathematicsUniversity of DhakaDhaka-1000Bangladesh

This study investigates the suction and magnetic field effects on the two-dimensional nanofluid flow through a stretching/shrinking sheet at the stagnation point in the porous medium with thermal radiation.The governing partial differential equations(PDEs)are converted into ordinary differential equations(ODEs)using the similarity transformation.The resulting ODEs are then solved numerically by using the bvp4c solver in MATLAB software.It was found that dual solutions exist for the shrinking parameter values up to a certain range.The numerical results obtained are compared,and the comparison showed a good agreement with the existing results in the literature.The governing parameters’effect on the velocity,temperature and nanoparticle fraction fields as well as the skin friction coefficient,the local Nusselt number and the Sherwood number are represented graphically and analyzed.The variation of the velocity,temperature and concentration increase with the increase in the suction and magnetic field parameters.It seems that the thermal radiation effect has increased the local Sherwood number while the local Nusselt number is reduced with it.

关键词： stagnation point flow nanofluid porous medium suction magnetohydrodynamic thermal radiation