The Experimental Investigation of Steam Condensation With Non-Condensable Gas Under Natural Convection

2018 ◽  
Author(s):  
Xizhen Ma ◽  
Wen Fu ◽  
Haijun Jia ◽  
Peiyue Li ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
High Pressure ◽  
Natural Convection ◽  
Heat And Mass Transfer ◽  
Vertical Wall ◽  
Experimental System ◽  
Steam Condensation ◽  
Transfer Coefficients ◽  
Calculation Results

The non-condensable gas is used to keep the pressure stable in the steam-gas pressurizer. The processes of heat and mass transfer during steam condensation in the presence of non-condensable gas play an important role and the thermal hydraulic characteristics in the pressurizer is particularly complicated due to the non-condensable gas. The effects of non-condensable gas on the process of heat and mass transfer during steam condensation were experimental investigated. A steam condensation experimental system under high pressure and natural convection was built and nitrogen was chosen in the experiments. The steam and nitrogen were considered in thermal equilibrium and shared the same temperature in the vessel under natural convection. In the experiments, the factors, for instance, pressure, mass fraction of nitrogen, subcooling of wall and the distribution of nitrogen in the steam, had been taken into account. The rate of heat transfer of steam condensation on the vertical wall with nitrogen was obtained and the heat transfer coefficients were also calculated. The characteristics curve of heat and mass transfer during steam condensation with non-condensable gas under high pressure were obtained and an empirical correlation was introduced to calculated to heat transfer coefficient of steam condensation with nitrogen which the calculation results showed great agreement with the experimental data.

Natural Convection Heat and Mass Transfer in the Vertical Cylindrical Porous Channel Under the Effects of Time-Periodic Boundary Condition

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Hayder I. Mohammed ◽  
Donald Giddings
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Boundary Condition ◽  
Porous Medium ◽  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Heat And Mass Transfer ◽  
Vertical Wall

Abstract Heat and mass transfer are investigated numerically with steady-state laminar natural convection through a vertical cylindrical enclosure filled with a liquid-saturated porous medium. The vertical wall is under a constant magnetic field and various durations of periodic heating boundary condition; the top and bottom surfaces are kept at a constant cold temperature. Continuity, momentum, and energy equations are transformed to dimensionless equations. The finite difference approach with the line successive over-relaxation (LSOR) method is used to obtain the computational results. This study covers the heat transfer, the temperature distribution, and the velocity field in the domain under the variation of different parameters. The code used is validated by modifying it to analyze the Nusselt number in the existing experimental literature of Izadpanah et al. (1998, “Experimental and Theoretical Studies of Convective Heat Transfer in a Cylindrical Porous Medium,” Int. J. Heat Fluid Flow, 19(6), pp. 629–635). This work shows that Nusselt number decreases (with varying gradient) as the aspect ratio increases, and that it increases as the Rayleigh number increases. The centerline temperature has a proportional relationship with the heating amplitude and the heating period (as the system receives more heat) and is inversely proportional with Rayleigh number. Increasing the Rayleigh number causes increased convective velocity, which affects the position of the hot region, and causes a decrease in the temperature field. Increasing the aspect ratio results in a warm stream at the center of the cylinder, and when the time period of the heating increases, the circulation becomes faster and the intensity of the temperature contour layers decreases. In this work, a correlation for Nu as a function of the mentioned parameters is developed.

Heat Transfer on Nanofluid Flow With Homogeneous–Heterogeneous Reactions and Internal Heat Generation

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Raj Nandkeolyar ◽  
Peri K. Kameswaran ◽  
Sachin Shaw ◽  
Precious Sibanda
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Heat Generation ◽  
Internal Heat ◽  
Internal Heat Generation ◽  
Heterogeneous Reactions ◽  
Transfer Coefficients ◽  
Transfer Characteristics ◽  
Fluid Properties

We investigated heat and mass transfer on water based nanofluid due to the combined effects of homogeneous–heterogeneous reactions, an external magnetic field and internal heat generation. The flow is generated by the movement of a linearly stretched surface, and the nanofluid contains nanoparticles of copper and gold. Exact solutions of the transformed model equations were obtained in terms of hypergeometric functions. To gain more insights regarding subtle impact of fluid and material parameters on the heat and mass transfer characteristics, and the fluid properties, the equations were further solved numerically using the matlab bvp4c solver. The similarities and differences in the behavior, including the heat and mass transfer characteristics, of the copper–water and gold–water nanofluids with respect to changes in the flow parameters were investigated. Finally, we obtained the numerical values of the skin friction and heat transfer coefficients.

Numerical Simulation of Heat and Mass Transfer Enhancement in Absorption Process With Double-Side Film-Inversion

2008 ◽  
Author(s):  
Ya-Ping Chen ◽  
Chen-Jie Shi ◽  
Ming-Heng Shi ◽  
Chen-Min Ling
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Vertical Plane ◽  
Mathematic Model ◽  
Absorption Process ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Plane Plate ◽  
Before And After ◽  
Calculation Results

Film-inversion is an effective way recently developed to enhance heat and mass transfer in absorbers. However, only one-side of round or rectangular tube i.e. half of the total heat transfer area is used to form film-inverting configuration in the published literature. The paper presents a double-side film-inverting scheme, which consists of two plate bundles and a set of comb shaped conjunction guiders between them for leading solution film from both-sides of each couple of the upper plate bundle to the opposite sides of the bottom ones. A two-scale crosswise corrugation plate bundle, which has vertical large corrugations and horizontal small ones, is suggested instead of the plane plate bundle. The horizontal small corrugation can make the film turbulent and film distribution uniform before and after inversion with surface tension effect, thus increasing the heat and mass transfer coefficients of the absorption process. A mathematic model for heat and mass transfer in absorption process with aqueous Li-Br solution falling film-inverting on two sequential vertical plane plates was established and solved numerically. The distributions of dimensionless velocity, temperature and concentration of liquid film profile before and after film-inverting were obtained. The influence of the number of inversion on heat and mass transfer characteristics was analyzed. The calculation results show that the heat and mass transfer coefficients of the once-film-inverting scheme have about 58% and 73% increment respectively over these of the none film-inverting scheme.

Heat and Mass Transfer With Liquid Evaporation Into a Turbulent Air Stream

1986 ◽  
Vol 108 (1) ◽  
pp. 4-8 ◽  
Author(s):  
T. Kumada ◽  
T. Hirota ◽  
N. Tamura ◽  
R. Ishiguro
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Turbulent Heat ◽  
Transfer Coefficients ◽  
Enhancement Of Heat Transfer ◽  
Heat Transfer Coefficients ◽  
Air Stream ◽  
Liquid Evaporation ◽  
Experimental Errors

Some of the previously reported heat transfer coefficients with evaporation are fairly large as compared with those of a dry body under similar hydrodynamic conditions. In order to clarify this curious enhancement of heat transfer, a method of error evaluation was developed and applied to correct the experimental errors in the recently reported results. An experimental study was also made on turbulent heat and mass transfer of air flowing over a water surface. The present and the previously reported experimental results revealed that the heat transfer coefficient with evaporation agrees with that of a dry body without evaporation, within experimental error, if the erroneous heat inputs into the liquid are properly corrected according to the proposed method.

scholarly journals Heat and mass transfer in the process of heat treatment and drying of natural leather with the convective method of energy supply

2021 ◽  
Vol 66 (1) ◽  
pp. 84-92
Author(s):  
A. O. Ol’shanskii ◽  
A. M. Gusarov ◽  
S. V. Zhernosek
Keyword(s):  
Heat Transfer ◽  
Heat Treatment ◽  
Mass Transfer ◽  
Heat Conduction ◽  
Differential Equations ◽  
Heat And Mass Transfer ◽  
Analytical Solutions ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Unsteady Heat Conduction

In the work, the authors investigated the possibility of using the results of analytical solutions of the linear differential equations of unsteady heat conduction with constant heat transfer coefficients to calculate the temperature of the material during heat treatment of leathers. Heat treatment of natural leathers as heat-sensitive materials is carried out under mild temperature conditions and high air moisture contents, the temperature does not undergo significant changes, and the heat transfer coefficients change almost linearly. When using analytical solutions, the authors made the assumptions that for small temperature gradients over the cross section of a thin body, the thermal transfer of matter can be neglected and for values of the heat and mass transfer Biot criteria less than unity, the main factor, limiting heat and mass transfer, is the interaction of the evaporation surface of the body with the environment; so, in solving the differential heat equation we can restrict ourselves to one first member of an infinite series. In this case, a piecewise stepwise approximation of all thermophysical characteristics with constant values of these coefficients at the calculated time intervals was applied, which made it possible to take into account the change in the transfer coefficients throughout the entire heat treatment process. Processing of experimental data showed that in low-intensity processes with reliable values of the transfer coefficients, it is possible to use the results of solutions of differential equations of unsteady heat conduction in heat transfer calculations. The results of the study of heat transfer during drying of leather confirm the laws of temperature change established experimentally. Together with experimental studies of drying processes, analytical studies are of great practical importance in the development of new methods for calculating heat and mass transfer in wet bodies.

A Study of Enhanced Heat and Mass Transfer From Variable Height Fin Array Undergoing Natural Convection

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Debayan Dasgupta ◽  
Kankan Kishore Pathak ◽  
Asis Giri
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Natural Convection ◽  
Heat And Mass Transfer ◽  
Latent Heat ◽  
Numerical Study ◽  
Boussinesq Approximation ◽  
Heat Transfer Analysis ◽  
Simpler Algorithm ◽  
Fin Spacing

Abstract A numerical study is performed on simultaneous heat and mass transfer from a shrouded vertical nonisothermal variable height fin array, representing dehumidification process under natural convection. Fluid properties are treated as uniform, and the fluid is assigned to comply with Boussinesq approximation to include the effect of density variation with temperature and concentration. Semi-implicit method for the pressure linked equations revised (SIMPLER) algorithm is adopted to resolve pressure and velocity coupling. A detailed parametric investigation of fin spacing, variable fin height, and fin tip to shroud clearance for a range of thermal and mass Grashof number is undertaken. Results indicate that in case of smaller fin spacing, involving fin length of 0.3 m, coefficients of sensible and latent heat transfer increase with the decreasing variable height (H1*) of fin and become maximum at H1*=0.5, for all thermal and mass Grashof numbers considered presently. Further, total heat transfer analysis on a particular base length due to sensible heat shows a maximum of 24.4% enhancement, whereas same due to the latent heat shows a maximum of 25.8% enhancement, depending on the values of clearance. Induced velocities also increase with the decreasing variable height of fin (H1*), which influences the heat and mass transport. The output parameters of this analysis, like induced velocities and overall Nusselt numbers due to the sensible and latent heat, are correlated with the governing parameters. The correlation coefficients are found to be in a range from 0.97 to 0.99.

Nanofluid Heat and Mass Transfer in a Deformable and Peristaltic Pump

2019 ◽  
Vol 8 (8) ◽  
pp. 1632-1639
Author(s):  
Aamir Ali ◽  
Y. Ali ◽  
D.N. Khan Marwat ◽  
M. Awais
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Surface Deformation ◽  
Wave Number ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Flow And Heat Transfer ◽  
Diffusion Parameters ◽  
Peristaltic Movement

Flow heat and mass transfer in a deformable channel of peristaltically moving walls is investigated in this paper. Moreover, the channel is filled with nanofluids. The purpose of this study is to examine the combined effects of surface deformation and peristaltic movement of the walls on the nanofluid flow in a channel. We have considered the effects of nanofluid in the peristaltically deformable porous channel whose walls are contracting or expanding in the normal direction. Nanofluids have been used to enhance the thermo-physical properties of fluids such as thermal diffusivity, thermal conductivity and convective heat transfer coefficients on flow and heat transfer. The analytic solution of the problem have been presented. We have analyzed the effects of different involved parameters such as Reynolds number, surface deformation parameter, Prandtl number, wave number, Brownian and thermophoretic diffusion parameters and Schmidt number on the velocity profile, the temperature profile, pressure distribution and the concentration profile with the help of graphs. The results are shown graphically and discussed physically. It is observed that the deformation increases the axial velocity and temperature of the fluid.

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