Top PDF Natural Convection Heat and Mass Transfer Flow with Hall Current, Rotation, Radiation and Heat Absorption Past an Accelerated Moving Vertical Plate with Ramped Temperature

Natural Convection Heat and Mass Transfer Flow with Hall Current, Rotation, Radiation and Heat Absorption Past an Accelerated Moving Vertical Plate with Ramped Temperature

Natural Convection Heat and Mass Transfer Flow with Hall Current, Rotation, Radiation and Heat Absorption Past an Accelerated Moving Vertical Plate with Ramped Temperature

It is noticed that when the density of an electrically conducting fluid is low and/or applied magnetic field is strong, Hall current plays a vital role in determining flow-features of the fluid flow problems because it induces secondary flow in the flow-field (Sutton and Sherman (1965). Taking into account of this fact, Aboeldahab and Elbarbary (2001) and Seth et al. (2012) investigated the effects of Hall current on hydromagnetic free convection boundary layer flow past a flat plate considering different aspects of the problem. It is noteworthy that Hall current induces secondary flow in the flow-field which is also the characteristics of Coriolis force. Therefore, it is essential to compare and contrast the effects of these two agencies and also to study their combined effects on such fluid flow problems. Narayana et al. (2013) studied the effects of Hall current and radiation- absorption on MHD natural convection heat and mass transfer flow of a micropolar fluid in a rotating frame of reference. Recently, Seth et al. (2013a) investigated the effects of Hall current and rotation on unsteady hydromagnetic natural convection flow of a viscous, incompressible, electrically conducting and heat absorbing fluid past an impulsively moving vertical plate with ramped temperature in a porous medium taking into account the effects of thermal diffusion. Aim of the present investigation is to study unsteady hydromagnetic natural convection heat and mass transfer flow with Hall current of a viscous, incompressible, electrically conducting, temperature dependent heat absorbing and optically thin heat radiating fluid past an accelerated moving vertical plate through fluid saturated porous medium in a rotating environment when temperature of the plate has a temporarily ramped profile. This problem has not yet received any attention from the researchers although natural convection heat and mass transfer flow of a heat absorbing and radiating fluid resulting from such ramped temperature profile of a plate moving with time dependent velocity may have strong bearings on numerous problems of practical interest where initial temperature profiles are of much significance in designing of so many hydromagnetic devices and in several industrial processes occurring at high temperatures where the effects of thermal radiation and heat absorption play a vital role in the fluid flow characteristics.
Mostrar mais

14 Ler mais

Rotating MHD Convective Heat and Mass Transfer Flow of a Viscoelastic Fluid through Porous Medium in a Vertical Channel with Thermal Radiation and Soret Effect

Rotating MHD Convective Heat and Mass Transfer Flow of a Viscoelastic Fluid through Porous Medium in a Vertical Channel with Thermal Radiation and Soret Effect

At the high temperature attained in some engineering devices, for example, gas can be ionized and so becomes an electrical conductor. The ionized gas or plasma can be made to interact with the magnetic field and alter heat transfer and friction characteristic. Recently, it is of great interest to study the effect of magnetic field on the convective flows when the fluid is not only an electrical conductor but also when it is capable of emitting and absorbing thermal radiation. The heat transfer by thermal radiation is becoming of greater importance when we are concerned with space applications, higher operating temperatures and also power engineering. The radiative free convective flows are encountered in countless industrial and environment processes e.g. heating and cooling chambers, fossil fuel combustion energy processes, evaporation from large open water reservoirs, astrophysical flows, and solar power technology and space vehicle re-entry. The radiative heat transfer plays an important role in manufacturing industries for the design of reliable equipment. Nuclear power plants, gas turbines and various propulsion devices for aircraft, missiles, satellites and space vehicles are examples of such engineering applications. Alagoa et al. [β1] analyzed the effects of radiation on free convection MHD flow through porous medium between infinite parallel plates in the presence of time-dependent suction. Mebine [ββ] studied the radiation effects on MHD ωouette flow with heat transfer between two parallel plates. Singh and Kumar [βγ] obtained an exact solution of free convective oscillatory flow through porous medium in a rotating vertical channel. Singh and Garg [β4] have also obtained exact solution of an oscillatory free convection MHD flow in a rotating channel in the presence of heat transfer due to radiation. Recently Garg [β5] studied combined effects of thermal radiations and Hall current on moving vertical porous plate in a rotating system with variable temperature. Very recently, assuming the temperature of one of the plate varying with time, Singh [β6] analyzed an oscillatory MHD convective flow of a viscoelastic fluid through a porous medium in a rotating vertical channel in slip-flow regime with thermal radiation and Hall current.
Mostrar mais

16 Ler mais

Unsteady Hydromagnetic Natural Convection Flow past an Impulsively Moving Vertical Plate with Newtonian Heating in a Rotating System

Unsteady Hydromagnetic Natural Convection Flow past an Impulsively Moving Vertical Plate with Newtonian Heating in a Rotating System

Investigation of hydromagnetic natural convection flow in a rotating medium is of considerable importance due to its application in various areas of geophysics, astrophysics and fluid engineering viz. maintenance and secular variations of Earth’s m agnetic field due to motion of Earth’s liquid core, internal rotation rate of the Sun, structure of the magnetic stars, solar and planetary dynamo problems, turbo machines, rotating MHD generators, rotating drum type separators for liquid metal MHD applications etc. It may be noted that Coriolis and magnetic forces are comparable in magnitude and Coriolis force induces secondary flow in the flow-field. Taking into consideration the importance of such study, unsteady hydromagnetic natural convection flow past an infinite moving plate in a rotating medium has been studied by a number of researchers. Mention may be made of research studies of Singh (1984), Raptis and Singh (1985), Kythe and Puri (1987), Singh et al. (2010) and Seth et al. (2011). Seth et al. (2013) considered effects of rotation on unsteady hydromagnetic natural convection flow of a viscous, incompressible, electrically conducting and heat radiating fluid past an impulsively moving vertical plate with ramped temperature in a porous medium. Recently, Seth et al. (2015) investigated effects of Hall current and rotation on hydromagnetic natural
Mostrar mais

11 Ler mais

The effects of thermal radiation and viscous dissipation on MHD heat and mass diffusion flow past an oscillating vertical plate embedded in a porous medium with variable surface conditions

The effects of thermal radiation and viscous dissipation on MHD heat and mass diffusion flow past an oscillating vertical plate embedded in a porous medium with variable surface conditions

In all the investigations mentioned above, viscous mechanical dissipation is neglected. A number of authors have considered viscous heating effects on Newtonian flows. Mahajan et al. [25] reported the influence of viscous heating dissipation effects in natural convective flows, showing that the heat transfer rates are reduced by an increase in the dissipation parameter. Isreal- Cookey et al. [26] investigated the influence of viscous dissipation and radi- ation on unsteady MHD free convection flow past an infinite heated vertical plate in a porous medium with time dependent suction. Zueco [27] used net- work simulation method (NSM) to study the effects of viscous dissipation and radiation on unsteady MHD free convection flow past a vertical porous plate. Suneetha et al. [28] have analyzed the thermal radiation effects on hydromagnetic free convection flow past an impulsively started vertical plate with variable surface temperature and concentration by taking into account of the heat due to viscous dissipation. Recently Suneetha et al. [29] stud- ied the effects of thermal radiation on the natural conductive heat and mass transfer of a viscous incompressible gray absorbing-emitting fluid flowing past an impulsively started moving vertical plate with viscous dissipation. Very recently Hiteesh [30] studied the boundary layer steady flow and heat trans- fer of a viscous incompressible fluid due to a stretching plate with viscous dissipation effect in the presence of a transverse magnetic field.
Mostrar mais

27 Ler mais

Chemical reaction and radiation effects on MHD free convection from an impulsively started infinite vertical plate with viscous dissipation

Chemical reaction and radiation effects on MHD free convection from an impulsively started infinite vertical plate with viscous dissipation

unsteady MHD free convective heat transfer flow along a vertical porous flat plate with internal heat generation. In many chemical engineering processes, there does occur the chemical reaction between a foreign mass and the fluid in which the plate is moving. These processes take place in numerous industrial applications viz., Polymer production, manufacturing of ceramics or glassware and food procession. Cramer K. R. and Pai, S. I.et al.[11] taken transverse applied magnetic field and magnetic Reynolds number are assumed to be very small, so that the induced magnetic field is negligible. Muthucumaraswamy et al.[12] have studied the effect of homogeneous chemical reaction of first order and free convection on the oscillating infinite vertical plate with variable temperature and mass diffusion. Das et al.[13] have studied the effects of mass transfer on flow past an impulsively started infinite vertical plate with constant heat flux and chemical reaction. K.Sudhakar and R. Srinivasa Raju et al.[14] have studied chemical reaction effect on an unsteady MHD free convection flow past an infinite vertical accelerated plate with constant heat flux, thermal diffusion and diffusion thermo. S. Shivaiah and J. Anand Rao et al.[15] studied chemical reaction effect on an unsteady MHD free convection flow past a vertical porous plate in the presence of suction or injection. Chaudhary and Jha [16] studied the effects of chemical reactions on MHD micropolar fluid flow past a vertical plate in slip-flow regime. Anjalidevi et al.[17] have examined the effect of chemical reaction on the flow in the presence of heat transfer and magnetic field. Moreover, Al-Odat and Al-Azab [18] studied the influence of magnetic field on unsteady free convective heat and mass transfer flow along an impulsively started semi-infinite vertical plate taking into account a homogeneous chemical reaction of first order. The chemical reaction, heat and mass transfer on MHD flow over a vertical stretching surface with heat source and thermal stratification have been presented by Kandasamy et al.[19]. Ahmed Sahin.et al.[20] have studied influence of chemical reaction on transient MHD free convective flow over a vertical plate in slip-flow regime.
Mostrar mais

13 Ler mais

Transient MHD Free Convective Flow of an Optically Thick Gray Gas Past a Moving Vertical Plate in the Presence of Thermal Radiation and Mass Diffusion

Transient MHD Free Convective Flow of an Optically Thick Gray Gas Past a Moving Vertical Plate in the Presence of Thermal Radiation and Mass Diffusion

one dimensional adaptive-grid finite-differencing computer code for thermal radiation magnetohydrodynamic simulation of fusion plasmas. Excellent studies of thermal radiation-convection magnetohydrodynamics include Duwairi and Damseh (2004), Raptis et al. (2004) who considered axisymmetric flow and Duwairi and Duwairi (2005) who studied thermal radiation heat transfer effects on the hydrodynamic Rayleigh flow of a gray viscous fluid. Aboeldahab and Azzam(2005) have described the effects of magnetic field on hydromagnetic mixed free forced heat and mass convection of a gray, optically-thick, electrically conducting viscous fluid along a semi-infinite inclined plane for high temperature and concentration using the Rosseland approximation. Ghosh and Pop (2007) and Jana and Ghosh (2011) have studied thermal radiation of an optically-thick gray gas in the presence of indirect natural convection showing that the pressure rise region leads to slightly increase in the velocity with an increase of radiation parameter. Patra et.al (2012) considered transient approach to radiation heat transfer free convection flow with ramped wall temperature. Rajput and Kumar (2012) examined the radiation effects on MHD flow past an impulsively started vertical plate with variable heat and mass transfer. Ahmed and Kalita (2013) presented an analytical and numerical study for MHD radiating flow over an infinite vertical surface bounded by a porous medium in presence of chemical reaction. Al-Odat and Al-Azab (2007) have examined the influence of chemical reaction on transient MHD free convection over a moving vertical plate. Mbeledogu and Ogulu (2007) have presented the heat and mass transfer of an unsteady MHD natural convection flow of a rotating fluid past a vertical porous plate in the presence of radiative heat transfer. The MHD transient free convection and chemically reactive flow pasta porous vertical plate with radiation and temperature gradient dependent heat source in slip flow regime have been studied by Rao et al. (2013). Reddy et al. (2012) have investigated the heat and mass transfer effects on unsteady MHD free convection flow past a vertical permeable moving plate with radiation.
Mostrar mais

9 Ler mais

Effect of heat source and variable suction on unsteady viscous stratified flow past a vertical porous flat moving plate in the slip flow regime

Effect of heat source and variable suction on unsteady viscous stratified flow past a vertical porous flat moving plate in the slip flow regime

Raptis et al. [11] discussed the effect of thermal radiation on MHD Flow. Saha and Hossain [12] studied the natural convection flow with combined buoyancy effects due to thermal and mass diffusion in a thermally stratified media. Das et al. [13] estimated numerically the effect of mass transfer on unsteady flow past an accelerated vertical porous plate with suction. Mazumdar and Deka [14] analyzed the MHD flow past an impulsively started infinite vertical plate in presence of thermal radiation. Das and his co- workers [15] discussed the magnetohydrodynamic unsteady flow of a viscous stratified fluid through a porous medium past a porous flat moving plate in the slip flow regime with heat source. In a separate paper Das et al. [16] analyzed the mass transfer effects on MHD flow and heat transfer past a vertical porous plate through a porous medium under oscillatory suction and heat source. Recently, Das and his associates [17] reported the hydromagnetic convective flow past a vertical porous plate through a porous medium with suction and heat source. More recently, Das and Tripathy [18] estimated the effect of periodic suction on three dimensional flow and heat transfer past a vertical porous plate embedded in a porous medium.
Mostrar mais

8 Ler mais

Dual Solutions of MHD Boundary Layer Flow past an Exponentially Stretching Sheet with Non-Uniform Heat Source/Sink

Dual Solutions of MHD Boundary Layer Flow past an Exponentially Stretching Sheet with Non-Uniform Heat Source/Sink

moving exponential surface was discussed by Abbas et al. (2014). Ahmad et al. (2014) analyzed the radiation and magnetic effect on the boundary layer viscous flow past an exponential stretching sheet in porous medium. The three-dimensional flow of a waterbased nanofluid past an exponential stretching surface was studied by Nadeem et al. (2014). Hussian et al. (2014) illustrated the viscous dissipation and Brownian motion effects of two dimensional boundary layer flow of Jeffry nanofluid past an exponentially stretching sheet. A numerical Analysis on unsteady MHD mixed convective boundary layer flow of a nanofluid past an exponential stretching sheet through porous medium was presented by Anwar et al. (2014). Steady laminar MHD boundary layer flow of a viscoelastic fluid past a permeable stretching surface in presence of heat absorption/generation was examined by Cortell (2014). The effects of thermal radiation and wall mass transfer of MHD flow through a porous stretching sheet with non- uniform heat source/sink was analytically studied by Abdul Hakeem et al. (2014). A homotopy analysis of convective steady two-dimensional magnetic fluid flow through a permeable vertical stretching surface with existing of radiation and buoyancy effects was presented by Rashidi et al (2014). Singh and Agarwal (2014) discussed the variable thermal conductivity and non-uniform heat source/sink effects on the MHD flow of Maxwell fluid through porous medium. MHD boundary layer flow and heat transfer investigation of a second grade nanofluid past permeable stretching surface with heat generation in the presence of partial slip conditions was theoretically studied by Bhargava and Goyal (2014).
Mostrar mais

9 Ler mais

MHD Free Convective Heat Transfer Flow Past Vertical Plate Embedded in a Porous Medium with Effects of Variable Fluid Properties in the Presence of Heat Source

MHD Free Convective Heat Transfer Flow Past Vertical Plate Embedded in a Porous Medium with Effects of Variable Fluid Properties in the Presence of Heat Source

As a result which drawn from the flow of fluids with constant viscosity is not applicable for those fluids that flow with the temperature dependent on viscosity, in particular at high temperature. A fluid that flows with variable viscosity has a wide range of applications in chemical and Biochemical industries and also useful in many fluid flow problems. Books on Porous media by [6] and [11] stand evident to the fact that convective flows in porous media are of vital importance to these processes. Reference [3] studied the effect of temperature dependent viscosity on natural convection flow as a linear function of temperature and reference [4] studied the effect of variable viscosity on convective heat transfer in three different cases of natural convection, mixed convection and forced convection taking fluid viscosity to vary inversely with temperature. The authors had discussed the effect of the appropriate parameters on the flow and heat transfer quantities. However, the authors had not discussed the hot ------------------------------------------------------------------- -- 1 rajarani72@gmail.com, Mathematics, Aeronautical Engineering
Mostrar mais

6 Ler mais

Convective Heat And Mass Transfer Flow Of A Micropolar Fluid  In A Rectangular Duct With Soret And Dufour Effects And Heat  Sources

Convective Heat And Mass Transfer Flow Of A Micropolar Fluid In A Rectangular Duct With Soret And Dufour Effects And Heat Sources

As high power electronic packaging and component density keep increasing substantially with the fast growth of electronic technology, effective cooling of electronic equipment has become exceptionally necessary. Therefore, the natural convection in an enclosure has become increasingly important in engineering applications in recent years. Through studies of the thermal behavior of the fluid in a partitioned enclosure is helpful to understand the more complex processes of natural convection in practical applications Number of studies, numerical and experimental, concerned with the natural convection in an enclosure with or without a divider were conducted in past years.
Mostrar mais

36 Ler mais

Variable Viscosity, Chemical Reaction and Thermal Stratification Effects on Mixed Convection Heat and Mass Transfer along a Semi-Infinite Vertical Plate

Variable Viscosity, Chemical Reaction and Thermal Stratification Effects on Mixed Convection Heat and Mass Transfer along a Semi-Infinite Vertical Plate

The effects power law index, variable viscosity and thermal stratification parameter on heat and mass transfer of a steady incompressible Newtonian fluid past a vertical plate have been studied numerically using the RK Gill method together with the shooting technique. From the previous results and discussion, we conclude the following:

7 Ler mais

Effect of Air Flow on Tubular Solar Still Efficiency

Effect of Air Flow on Tubular Solar Still Efficiency

This research article summarized a new compound para- bolic concentric-tubular solar still (CPC-CTSS), which has been designed for and tested under the climatic conditions of Coimbatore, India. The effect of cooling air flowing over the condensation surface was studied. The daily yield of CPC-CTSS was found 1445 mL/day and 16.2% efficiency without air flow and 2020 mL/day and 18.9% efficiency with air flow at a constant flow rate of 4.5 m/s. To bound in a nutshell, this innovative approach of concentrator assisted tubular solar still with air flow augments the performance with enhanced rate of evaporation and condensation with safer operation procedures.
Mostrar mais

7 Ler mais

Oscillatory Flow and Heat Transfer Within Parallel-plate Heat Exchangers of Thermoacoustic Systems

Oscillatory Flow and Heat Transfer Within Parallel-plate Heat Exchangers of Thermoacoustic Systems

dimensional model covering the full length and height of the experimental setup was developed. The model was shown to give good predictions of flow structures for a drive ratio of 0.3%, in agreement with experiment [13]. The full length model allows the verification of the phase changes between pressure and velocity from the computational model to follow the definition from the experiment. It was also found that the pressure and velocity in the flow far away from the heat exchanger can be estimated fairly well by the linear thermoacoustic theory. This indicates that the use of a shorter model is also acceptable provided that the boundary is far enough for the incoming/outgoing oscillatory flow not to interfere with plate structure [5, 14]. In this study, the computational domain was developed to cover a length of 270 mm either way from location m of the joint, as shown in Fig. 1
Mostrar mais

6 Ler mais

INVESTIGATION OF CONVECTION AND RADIATION HEAT TRANSFER IN RHOMBUS MICROCHANNELS

INVESTIGATION OF CONVECTION AND RADIATION HEAT TRANSFER IN RHOMBUS MICROCHANNELS

As seen in Figure 3, the variations of Reynolds number have little effect on Poiseuille number for a fixed rarefaction. It can be concluded from this figure that Poiseuille number decreases with increasing value of Knudson number. Figure 4 shows the Poiseuille number as a function of aspect ratio for different Reynolds number and at Kn=0.01. As seen in Figure 4, Poiseuille number increases with increasing value of aspect ratio, and as shown in this figure, the variations of Reynolds number have little influences on Poiseuille number. Variation of fully developed Poiseuille number with aspect ratio for different Knudsen number at Re=10 is the purpose of Figure 5. It is obvious in Figure 5 that Poiseuille increases with increasing value of aspect ratio for a fixed Knudsen number. As seen in this figure the aspect ratio is more effective when it is less than 0.7 and at greater values than this aspect ratio, the Poiseuille number is constant for a fixed rarefaction. This figure also shows that Knudsen number can considerably affect on Poiseuille number, in which Poiseuille number reaches its maximum when Knudsen number is equal to zero, i.e. no slip condition, and then increasing the value of rarefaction reduces the value of Poiseuille number.
Mostrar mais

10 Ler mais

Mixed convection boundary layer flow over a moving vertical flat plate in an external fluid flow with viscous dissipation effect.

Mixed convection boundary layer flow over a moving vertical flat plate in an external fluid flow with viscous dissipation effect.

Mixed convection flows, or combined forced and free convec- tion flows, arise in many transport processes both naturally and in engineering applications. They play an important role, for example, in atmospheric boundary-layer flows, heat exchangers, solar collectors, nuclear reactors and in electronic equipment. Such processes occur when the effects of buoyancy forces in forced convection or the effects of forced flow in free convection become significant. The interaction of forced and free convection is especially pronounced in situations where the forced flow velocity is low and/or the temperature differences are large. This flow is also a relevant type of flow appearing in many industrial processes, such as manufacture and extraction of polymer and rubber sheets, paper production, wire drawing and glass-fiber production, melt spinning, continuous casting, etc. (Tadmor and Klein [1]). This flow has also many industrial applications such as heat treatment of material traveling between a feed roll and wind-up roll or conveyer belts, extrusion of steel, cooling of a large metallic plate in a bath, liquid films in condensation process and in aerodynam- ics, etc. As per standard texts books by Bejan [2], Kays and Crawford [3], Bergman et al. [4] and other literatures the free and mixed convection flow occur in atmospheric and oceanic circulation, electronic machinery, heated or cooled enclosures, electronic power supplies, etc. This topic has also many applications such as its influence on operating temperatures of power generating and electronic devices. In addition it should be mentioned that this type of flow plays a great role in thermal
Mostrar mais

6 Ler mais

Investigation of Three-Dimensional Axisymmetric Unsteady Stagnation-Point Flow and Heat Transfer Impinging on an Accelerated Flat Plate

Investigation of Three-Dimensional Axisymmetric Unsteady Stagnation-Point Flow and Heat Transfer Impinging on an Accelerated Flat Plate

General formulation and solution of Navier-Stokes and energy equations are sought in the study of three- dimensional axisymmetric unsteady stagnation-point flow and heat transfer impinging on a flat plate when the plate is moving with variable velocity and acceleration towards the main stream or away from it. As an application, among others, this accelerated plate can be assumed as a solidification front which is being formed with variable velocity. An external fluid, along z - direction, with strain rate a impinges on this flat plate and produces an unsteady three-dimensional axisymmetric flow in which the plate moves along z - direction with variable velocity and acceleration in general. A reduction of Navier-Stokes and energy equations is obtained by use of appropriate similarity transformations, for the first time. The obtained ordinary differential equations are solved by using finite-difference numerical techniques. Velocity and pressure profiles along with temperature profiles are presented for different examples of the plate velocity functions and selected Prandtl numbers. According to the results obtained, the velocity and thermal boundary layers feel the effect of variations of the plate velocity more than the plate acceleration. It means that the minimum boundary layer thickness happens at the maximum value of the plate velocity and acceleration effect plays a secondary role.
Mostrar mais

11 Ler mais

Heat Transfer in MHD Mixed Convection Flow of a Ferrofluid along a Vertical Channel.

Heat Transfer in MHD Mixed Convection Flow of a Ferrofluid along a Vertical Channel.

results for these two types of base fluids after using implicit finite-difference method with quasi-linearization technique as the solution to a resultant problem. By using ferrofluid, Shei- kholeslami and Ganji [16] investigated heat transfer with thermal radiation inside an enclosure of semi annulus in the presence of a magnetic source. Idress et al. [17] studied application of the optimal homotopy asymptotic method for the solution of the Korteweg-de Vries equation. Ellahi et al. [18] studied series solutions of non-Newtonian nanofluids with Reynolds' model and Vogel's model by means of the homotopy analysis method. Herisanu and Vasile [19] inves- tigated that optimal homotopy perturbation method for a non-conservative dynamical system of a rotating electrical machine. Several other studies were conducted in the last few years, on nanofluids by taking different types of convectional base fluids with different nanoparticles, see for example [20–29] and the related references therein.
Mostrar mais

14 Ler mais

Numerical simulation and analyses for sinter cooling process with convective and radiative heat transfer

Numerical simulation and analyses for sinter cooling process with convective and radiative heat transfer

A two-dimensional unsteady model for sinter cooling process is established based on the actual sinter cooling process in an annular cooler. The complex heat transfer process, including three modes of heat conduction inside the sinter ore particles, gas-solid convection and radiation in the trolley, is taken into account. The heat transfer ratio is proposed to explore the effect of heat radiation to the cooling process. With actual device and operating parameters, modeling verification and analyses of datum based on numerical simulation are conducted. The results are consistent with actual production datum when the heat transfer ratio e varies from 0 to 0.1. The pressure field, temperature distribution and the temperature characteristic of outlet gas are obtained by numerical simulation method. The effect of radiative heat transfer on the cooling process is analyzed. The results show that the heat transfer ratio e has no effect on the gas flow and pressure distribution of air. The increase of the ratio e can reinforce the heat transfer between the sinter and air, which will lead to bigger increase of temperature drop rate of the sinter. The solid and gas temperature distribution trends at different heat transfer ratios are similar. The results obtained herein may provide some guidelines for the research on the actual cooling process in an annular cooler.
Mostrar mais

14 Ler mais

J. Braz. Soc. Mech. Sci. & Eng.  vol.33 número especial 1

J. Braz. Soc. Mech. Sci. & Eng. vol.33 número especial 1

Figures 2(a) and 2(b) show the effect of heat flux on the heat transfer coefficient for different mass velocities. It is possible to verify the dependence of the heat transfer coefficients on the heat flux, mainly at the low quality region (quality less than 40%). The heat transfer coefficient increased with the heat flux increment. As previously pointed, several authors (Choi et al., 2007, and Lin et al., 2001) have associated this behavior with nucleate boiling in the initial part of boiling, mainly under high heat flux. This condition will tend to be suppressed at high vapor quality where the effect of heat flux on heat transfer coefficient becomes lower and the coefficient decreases, as can be observed in Figs. 2(a) and 2(b). Figure 2(a) also shows that for low mass velocity (G = 240 kg/sm 2 ) and low heat flux ( q  = 5 kW/m 2 ), the heat transfer coefficient hardly
Mostrar mais

7 Ler mais

HEAT TRANSFER COEFFICIENT AND FRICTION FACTOR CHARACTERISTICS OF A GRAVITY ASSISTED BAFFLED SHELL AND HEAT-PIPE HEAT EXCHANGER

HEAT TRANSFER COEFFICIENT AND FRICTION FACTOR CHARACTERISTICS OF A GRAVITY ASSISTED BAFFLED SHELL AND HEAT-PIPE HEAT EXCHANGER

The ability of the heat pipe to transfer thermal energy with negligible temperature drop has recently enabled it to become one of the most versatile devices in the field of heat recovery systems [1, 2]. In past few years considerable interest has been generated with regard to the heat pipe heat exchanger as a heat recovery system [3@5]. In a gravity assisted mode, the presence of a capillary structure is not obligatory as in purely a capillary drive heat pipe. Nevertheless, most gravity assisted heat pipes do have a capillary structure in order to protect the liquid against the shear stress exerted by counter flowing vapour [6, 7] and also to induce circumferential distribution of the working fluid within the evaporator section. In gravity assisted heat pipes, relatively high rates of heat transfer can be achieved even with working fluids having low surface tension [8, 9].
Mostrar mais

9 Ler mais

Show all 10000 documents...

temas relacionados