Wyniki wyszukiwania - Biblioteka Nauki

1

Wall temperature prediction in annular geometry during post-dryout heat transfer

100%

Anghel I. G. , Anglart H.

Journal of Power Technologies

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2014

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tom Vol. 94, nr 5

1--7

EN

In this paper a new approach to predict wall temperature during post-dryout heat transfer in annuli with flow obstacles is presented. The proposed approach takes into account the obstacle specifics and location in the channel to determine the onset of post-dryout patch. The wall temperature in the dry patch area is predicted from a correlation that takes into account the developing post-dryout heat transfer regime. The method is applied to post-dryout conditions in an annulus with pin spacers and achieves a significant improvement in prediction accuracy compared to other reference methods.

2

Three dimensional flow and heat transfer through a porous medium

100%

Chaudhary R. C. , Chand T.

International Journal of Applied Mechanics and Engineering

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2002

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tom Vol. 7, no 4

1141-1156

EN

The effect of permeability on the heat transfer and the flow through a highly porous medium bounded by an infinite porous surface is investigated. The periodic transverse suction velocity is applied to the surface due to which the flow becomes three-dimensional. The surface is kept at oscillating wall temperature. Analytical expressions for velocity, temperature, skin friction and rate of heat transfer are obtained. The important characteristics of the problem, the skin friction and the rate of heat transfer are discussed in detail with the help of graphs and tables.

3

Interactions of the artificial light sources and the window glazing of buildings

100%

Flimel M.

Przegląd Elektrotechniczny

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2013

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tom R. 89, nr 8

116--119

EN

The article focuses on the issue of determining the real value of the heat transfer coefficient on the window glazing Ug in interaction of the window glazing and the artificial lighting. Measurements by the method of measuring the heat flow in situ conditions showed certain effects of the artificial lighting on the value Ug of the transparent constructions of a building. This knowledge can be used for energy performance evaluation of buildings.

PL

W artykule podjęto probe określenia współczynnika transferu ciepła wynikającego z interakcji oszklenia i sztucznego oświetlenia. Współczynnik transferu ciepła zależy między innymi od konstrukcji budynku.

4

Unsteady MHD heat transfer in Couette flow of water at 4°c in a rotating system with ramped temperature via finite element method

100%

Reddy G. J. , Raju R. S. , Rao J. A. , Gorla R. S. R.

International Journal of Applied Mechanics and Engineering

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2017

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tom Vol. 22, no. 1

145--161

EN

An unsteady magnetohydromagnetic natural convection on the Couette flow of electrically conducting water at 4°C (Pr = 11.40) in a rotating system has been considered. A Finite Element Method (FEM) was employed to find the numerical solutions of the dimensionless governing coupled boundary layer partial differential equations. The primary velocity, secondary velocity and temperature of water at 4°C as well as shear stresses and rate of heat transfer have been obtained for both ramped temperature and isothermal plates. The results are independent of the mesh (grid) size and the present numerical solutions through the Finite Element Method (FEM) are in good agreement with the existing analytical solutions by the Laplace Transform Technique (LTT). These are shown in tabular and graphical forms.

5

Variable thermal conductivity in micropolar thermoelastic medium without energy dissipation possessing cubic symmetry

100%

Ailawalia P. , Priyanka

International Journal of Applied Mechanics and Engineering

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2023

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tom Vol. 28, no. 1

1--10

EN

This investigation deals with the effect of variable thermal conductivity in a micropolar thermoelastic medium without energy dissipation with cubic symmetry. The normal mode technique is employed for obtaining components of physical quantities such as displacement, stress, temperature distribution and microrotation.

6

Analysis of coupled heat and water vapour transfer in textile laminates with a membrane

100%

Sybilska W. , Korycki R.

Fibres & Textiles in Eastern Europe

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2010

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tom Vol. 18, no. 3 (80)

65--69

EN

Clothing materials coated with semi-permeable membranes were analysed as products protecting the organism against heat loss as well as ensuring the drainage of sweat. Both physical and mathematical models of the coupled heat and water vapour transfer within the multilayer structures were discussed. Material parameters should be determined for different numbers of layers, compositions of the raw material and thicknesses of the laminate with a membrane. The heat transfer resistance and resistance of the water vapour transfer were determined, which helped to design material for clothing that fulfils the user’s expectations and ensures thermal comfort.

PL

Scharakteryzowano materiały odzieżowe, powleczone membranami półprzepuszczalnymi, pod kątem ich zdolności do ochrony organizmu przed utratą ciepła oraz zdolnością do odprowadzania potu wydzielonego przez człowieka. Wytypowane do badań materiały były zróżnicowane pod względem liczby warstw, składu surowcowego i grubości. Wyznaczono wartości oporu cieplnego i oporu pary wodnej, które stanowią podstawową wiedzę dla projektantów odzieży. Znajomość ta pozwala na świadome projektowanie materiałowe wyrobów odzieżowych, tak aby uzyskać wyrób, który pozwoli z jednej strony na optymalne wypełnianie funkcji określonych charakterem odzieży, z drugiej zaś zapewni użytkownikowi odzieży odpowiedni komfort w warunkach przyszłego użytkowania.

7

Analysis of a chemically reactive MHD flow with heat and mass transfer over a permeable surface

100%

Fenuga O. J. , Aroloye S. J. , Popoola A. O.

International Journal of Applied Mechanics and Engineering

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2019

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tom Vol. 24, no. 1

53--66

EN

This paper investigates a chemically reactive Magnetohydrodynamics fluid flow with heat and mass transfer over a permeable surface taking into consideration the buoyancy force, injection/suction, heat source/sink and thermal radiation. The governing momentum, energy and concentration balance equations are transformed into a set of ordinary differential equations by method of similarity transformation and solved numerically by Runge- Kutta method based on Shooting technique. The influence of various pertinent parameters on the velocity, temperature, concentration fields are discussed graphically. Comparison of this work with previously published works on special cases of the problem was carried out and the results are in excellent agreement. Results also show that the thermo physical parameters in the momentum boundary layer equations increase the skin friction coefficient but decrease the momentum boundary layer. Fluid suction/injection and Prandtl number increase the rate of heat transfer. The order of chemical reaction is quite significant and there is a faster rate of mass transfer when the reaction rate and Schmidt number are increased.

8

An unsteady electro-magnetohydrodynamic two-liquid plasma flow along a channel of insulating porous plates with Hall currents

84%

Rao V. G. S. , Raju T. L.

International Journal of Applied Mechanics and Engineering

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2023

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tom Vol. 28, no. 2

90--112

EN

It is proposed to use the Hall currents to model the transient magneto-hydrodynamic two liquid flows and heat transfer of ionized gases propelled by a common pressure gradient via a horizontal channel consisting of parallel porous plates. For the distributions of velocity and temperature, the principal partial differential equations that explain heat transfer flow under the chosen constraints are resolved. Graphical representations are given for the distributions of velocity, temperature, and heat transfer rates. This research will be carried out using non-conducting porous plate’s channel.

9

Effects of radiation and Eckert number on MHD flow with heat transfer rate near a stagnation point over a non-linear vertical stretching sheet

84%

Fenuga O. J. , Hassan A. R. , Olanrewaju P. O.

International Journal of Applied Mechanics and Engineering

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2020

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tom Vol. 25, no. 1

27--36

EN

This work investigates the effects of radiation and Eckert number on an MHD flow with heat transfer rate near a stagnation-point region over a nonlinear vertical stretching sheet. Using a similarity transformation, the governing equations are transformed into a system of ordinary differential equations which are solved numerically using the sixth order Runge-Kutta method with shooting technique. Tabular and graphical results are provided to examine the physical nature of the problem. Heat transfer rate at the surface decreases with radiation, Eckert number and as radiation increases, the flow temperature also increases for velocity ratio parameters […].

10

3D Numerical Simulation of Laminar Flow and Conjugate Heat Transfer through Fabric

84%

Zhu G. , Kremenakova D. , Wang Y. , Militky J. , Mishra R. , Wiener J.

Autex Research Journal

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2017

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tom Vol. 17, no. 1

53--60

EN

The air flow and conjugate heat transfer through the fabric was investigated numerically. The objective of this paper is to study the thermal insulation of fabrics under heat convection or the heat loss of human body under different conditions (fabric structure and contact conditions between the human skin and the fabric). The numerical simulations were performed in laminar flow regime at constant skin temperature (310 K) and constant air flow temperature (273 K) at a speed of 5 m/s. Some important parameters such as heat flux through the fabrics, heat transfer coefficient, and Nusselt number were evaluated. The results showed that the heat loss from human body (the heat transfer coefficient) was smallest or the thermal insulation of fabric was highest when the fabric had no pores and no contact with the human skin, the heat loss from human body (the heat transfer coefficient) was highest when the fabric had pores and the air flow penetrated through the fabric.

11

Influence of slip parameter, viscous dissipation and Joule heating effect on boundary layer flow and heat transfer over a power-law stretching wedge-shaped surface with the correlation coefficient and multiple regressions

84%

Ali M. , Alim M. A.

International Journal of Applied Mechanics and Engineering

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2022

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tom Vol. 27, no. 2

1--21

EN

The influence of slip parameter, viscous dissipation, and Joule heating parameter on MHD boundary layer nanofluid flow over a permeable wedge-shaped surface was analysed. The PDEs and the associated boundary conditions were transformed to a set of non-similar ODEs and the obtained system of equations was solved numerically with the help of the spectral quasi-linearization method (SQLM) by applying suitable software. This method helps to identify the accuracy and convergence of the present problem. The current numerical results were compared with previously published work and are found to be similar. The fluid velocity, fluid temperature, and nanoparticle concentration within the boundary layer region for various values of the parameters such as the slip effect, magnetic strength, Prandtl number, Lewis number, stretching ratio, viscous dissipation, suction, Brownian motion, Joule heating, heat generation, and thermophoresis are studied. It is observed that the Brownian motion, Joule heating, viscous dissipation, and thermophoresis lead to decreases in the heat and mass transfer rate. The skin friction coefficient enhances with slip, magnetic, permeability, and suction parameters, but reduces with the Brownian motion, wedge angle, and stretching ratio parameters whereas there is no effect of mixed convection, thermophoresis, heat generation parameters, the Prandtl and Eckert number.

12

A theoretical study of heat transfer to flowing granular materials

84%

Massoudi M. , Anand N. K.

International Journal of Applied Mechanics and Engineering

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2004

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tom Vol. 9, no 2

383-398

EN

The mechanics of flowing granular materials such as coal, sand, agricultural products, fertilizers, dry chemicals, metal ores, etc., and their flow characteristics have received considerable attention in recent years. In a number of instances these materials are also heated prior to processing or cooled after processing. In this paper, the governing equations for the flow of granular materials, taking into account the heat transfer mechanism are derived using a continuum model proposed by Rajagopal and Massoudi (1990). For a fully developed flow down a heated inclined plane, the governing equations reduce to a system of non-linear ordinary differential equations for the case where the material properties are assumed to be constants. The boundary value problem is solved numerically and the results are presented for the volume fraction, velocity, and temperature profiles.

13

Analytical solution of the dual phase lag equation describing the laser heating of thin metal film

84%

Ciesielski M.

Journal of Applied Mathematics and Computational Mechanics

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2017

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tom Vol. 16, nr 1

33--40

EN

Heat transfer processes occurring in the micro-domains can be described using the dual-phase lag equation (DPLE). This equation can be applied as a model of heating of the thin metal film subjected to the femtosecond laser pulse. In the paper, the 1D dual phase lag equation containing the additional internal heat source resulting from the laser pulse irradiation and supplemented by the appropriate boundary and initial conditions is considered. Appearing in this equation two lag times τq the phase lag of the heat flux) and τT (the phase lag of the temperature gradient) are taken into account. An analytical solution of this equation under the assumption that τT > τq is presented. The separation of the variables technique and the Green’s function method are used in order to find this solution. In the final part of the paper, the example of computations is presented.

14

On the heat transfer influence on dynamical damper self-vibrations

84%

Awrejcewicz J. , Pyryev Y.

Vibrations in Physical Systems

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2006

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tom Vol. 22

65--71

15

Odzysk i transfer ciepła z Data Center

84%

Żuk M.

Chłodnictwo i Klimatyzacja

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2022

|

tom nr 6

48--50

PL

Jakie rozwiązania dotyczące chłodzenia serwerowni są w ostatnim czasie coraz częściej rozważane przez inwestorów i dlaczego? Co mówią prognozy na przyszłość? Jako projektant postaram się w tym artykule odpowiedzieć na te i kilka innych pytań związanych z projektowaniem systemów chłodzenia pomieszczeń Data Center oraz wskazać zalecenia, które warto wziąć pod uwagę przy w procesie planowania.

16

Heat transfer effects on carbon nanotubes along a moving flat plate subjected to uniform heat flux

84%

Ferdows M. , Shamshuddin M. , Reza M. , Ara Quadir R.

International Journal of Applied Mechanics and Engineering

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2022

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tom Vol. 27, no. 4

66--81

EN

In the present paper, a theoretical analysis is made to investigate fluid flow and heat energy transformation features of single and multi-walled water functionalized carbon nanotubes (CNTs) with uniform heat inconstancy boundary conditions onward a flat plate. The liquid motion and momentum transfer of carbon nanotubes (CNTs) have been analyzed using a homogeneous flow model. Both single-wall CNTs (SWCNTs) and multi-wall CNTs (MWCNTs) used base fluids, namely, water. The thermophysical characteristics of CNTs regarding the solid volume fraction of CNTs are studied by applying empirical correlations. Similarity transformations have been used to the governing partial differential equations turning them into ordinary differential equations. The outcome of similarity transformations which are nonlinear ordinary differential equations subjected to reconstructed boundary conditions, are subsequently solved numerically using bvp4c. The effects of the governing parameters on the dimensionless velocity, temperature, and skin friction are investigated numerically and graphically. An increase in the volume fraction and the velocity ratio parameter increase the flow, the velocity, and the temperature profile. Regardless of any physical parameter, SWCNTs give better heat transfer than MWCNTs.

17

An analysis of the boundary conditions model influence on the ground temperature profile determination

84%

Jaszczur M.

Computer Assisted Methods in Engineering and Science

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2015

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tom Vol. 22, no. 3

243--253

EN

In this work, the influence of boundary conditions model (environmental model) on the ground temperature profile is analyzed. A numerical model for transport phenomena in the area above the top ground surface and below in the ground is presented. The results of simulation – ground temperature profile and mean seasonal temperature which estimate the energy potential of the ground are presented. In addition, the results of implementation of five different environmental models for the area above the top ground surface are presented. It is found that none of the models is able to reproduce the temperature variation similar to the reference (most complex) model accuracy. On the other hand, it is found that with a slight error a similar result for low ground depth can be obtained using the simplest Model 1.

18

The Caputo vs. Caputo-Fabrizio operators in modeling of heat transfer process

84%

Oprzędkiewicz K. , Mitkowski W. , Gawin E. , Dziedzic K.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2018

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tom Vol. 66, nr 4

501--507

EN

In the paper two non-integer order, state space models of heat transfer process are compared. The first uses a known Caputo operator and the second – a new operator proposed by Caputo and Fabrizio in 2015. Both discussed models are modifications of a known, integer order, state space, semigroup model of heat transfer process. Parameters of both models were identified by means of optimization of MSE cost function with the use of simplex method, available in MATLAB. Both proposed models have been compared in the aspect of accuracy and convergence. Analytical and numerical results show that the Caputo-Fabrizio model is faster convergent and easier to implement than the Caputo model. However, its accuracy in the sense of MSE cost function is worse.

19

Hot Layer Formation during the Crude Oil Fires

84%

Jarosz W. , Stawczyk J.

Zeszyty Naukowe SGSP / Szkoła Główna Służby Pożarniczej

|

2016

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tom Nr 58 (tom 1) (2)

5--16

EN

The paper presents the research results on hot layer formation during the crude oil fires, the conditions for creating a hot layer, mechanisms of the boilover and its accompanying dangerous phenomena. The research was carried out in The Main School of Fire Service in Warsaw. In the experiments, crude oil was burned in tanks with the diameter of 1.4 m and two different heights – 0.7 and 1.4 m.

PL

W artykule przedstawiono wyniki badań nad formowaniem się warstwy gorącej, warunków tworzenia się warstwy gorącej, mechanizmu wyrzutu i zjawisk towarzyszących podczas pożarów ropy naftowej, które zostały przeprowadzone w Szkole Głównej Służby Pożarniczej w Warszawie. W eksperymentach spalano ropę naftową w zbiornikach o średnicy 1,4 m i dwóch różnych wysokościach – 0,7 i 1,4 m.

20

Impacts of chemical reactions on inclined isothermal vertical plate

84%

Sundar Raj M. , Nagarajan G. , Murugan V. P. , Muthucumaraswamy R.

International Journal of Applied Mechanics and Engineering

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2023

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tom Vol. 28, no. 2

64--76

EN

An accurate parameterization of an irregular surge across a continuously propelled circulation through an endless isothermal inclined plate has been investigated in the presence of a first-degree uniform chemical reaction. Both the plate’s temperature and the proximal intensity are increased systematically. To evaluate non-dimensional equations, the Laplace transform is utilized. The effect of velocity components on a range of physical parameters is investigated which include Sc, Pr, Gr, Gc, α, K and t. A proportionate increase of velocity with Gr and Gc was prominent. τ and Sh were mathematically determined.