scholarly journals Heat and mass transfer in the grain under variable conditions

2021 ◽  
pp. 84-87
Author(s):  
Mikhail Gennadievich Zagoruiko ◽  
Roman Aleksandrovich Marin
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Water Vapor ◽  
Heat And Mass Transfer ◽  
Internal Heat ◽  
Initial Moment ◽  
Dense Layer ◽  
Drying Process ◽  
Grain Moisture ◽  
Grain Surface

The article describes the drying process in the formulation of the internal problem, the main equations of internal heat and mass transfer of potentials are considered. The process of removing moisture from the surface of the grain, which is determined by the transfer of moisture and the diffusion-convective transfer of heat and moisture through the boundary layer, is studied. The movement of heat in the boundary layer was determined by the molecular thermal conductivity. It is established that the speed of the drying process depends on the rate of removal of water vapor from the surface of the grain. It was found that the change in the quality of the seed material did not depend on the absolute removal of moisture. The first drying period is shown, when the temperature of the grain surface rises from the temperature of the adiabatic air saturation, when the drying agent at the boundary of the grain surface is saturated with water vapor, and the drying speed depends on the speed of their removal from the evaporation surface. At this point, the moisture evaporated, the vapors were removed by the drying agent. At the initial moment, the movement of the evaporation line did not occur, but then it was fixed inside the grain. In the course of research, the process of removing moisture from the seeds is fast, but it has little effect on their quality. The removal of grain moisture reached up to 3 % from the upper layers of the seeds, which did not affect their quality. An analytical expression is considered for calculating the heat transfer coefficient and the drying agent velocity, taking into account the allowed moisture content, as well as the heat flux density. The permissible speed of the drying agent in a dense layer of grain is determined, which depends on the height of the layer, the specific surface of the grain, its temperature and the proportion of heat supplied to heat the material. For drying conditions typical for grain dryers, the drying speed should not exceed 0.6 m/s.

Thermodynamic Theory of Convective Drying Process of Porous Media

2002 ◽  
Author(s):  
You-Rong Li ◽  
Dan-Ling Zeng
Keyword(s):  
Mass Transfer ◽  
Heat Source ◽  
Heat And Mass Transfer ◽  
Internal Heat ◽  
Internal Heat Source ◽  
Thermodynamic Theory ◽  
Convective Drying ◽  
Internal Mass ◽  
Drying Process ◽  
Mass Source

Based on non-equilibrium thermodynamic theory and combined with the conservation laws, a comprehensive theoretical model was established to describe heat and mass transfer during convective drying process, and numerical calculation was performed. The results show that: (a) the external convective heat and mass transfer may be treated as the conductive heat transfer with internal heat source and the molecular mass diffusion with internal mass source, respectively, and the ability of heat and mass transfer mainly depends on the strength of the heat source and mass source; the higher the temperature of the drying media, the lower the strength of the internal heat source, but the higher that of the internal mass sources; (b) the evaporation of internal water takes place inside the whole material, and the molecular mass diffusion of the internal vapor is in the direction of decreasing mass transfer potential, not along the decreasing partial pressure of vapor.

scholarly journals Thermal radiation and hall effect on MHD flow, heat and mass transfer over an inclined permeable stretching sheet

2011 ◽  
Vol 15 (suppl. 2) ◽  
pp. 195-204 ◽  
Author(s):  
Chandra Shit ◽  
Raju Haldar
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Thermal Radiation ◽  
Heat And Mass Transfer ◽  
Stretching Sheet ◽  
Variable Viscosity ◽  
Internal Heat ◽  
Mhd Flow ◽  
Fluid Viscosity ◽  
Linear Ordinary Differential Equations

Of concern in this paper is an investigation of the combined effects of thermal radiation and Hall current on momentum, heat and mass transfer in laminar boundary-layer flow over an inclined permeable stretching sheet with variable viscosity. The sheet is linearly stretched in the presence of an external magnetic field and the fluid motion is subjected to a uniform porous medium. The effect of internal heat generation/absorption is also taken into account. The fluid viscosity is assumed to vary as an inverse linear function of temperature. The boundary-layer equations that governing the flow problem have reduced to a system of non-linear ordinary differential equations with a suitable similarity transformation. Then the transformed equations are solved numerically by employing a finite difference scheme. Thus the results obtained are presented graphically for the various parameters of interest.

Numerical Simulation Analysis of Heat and Mass Transfer during Drying of Jujubes

2012 ◽  
Vol 468-471 ◽  
pp. 2323-2327
Author(s):  
Xiao Kang Yi ◽  
Wen Fu Wu ◽  
He Lei Cui ◽  
Jun Xing Li
Keyword(s):  
Numerical Simulation ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Simulation Analysis ◽  
Internal Heat ◽  
Simulation Software ◽  
Drying Process ◽  
Finite Volume Discretization ◽  
Transfer Equations ◽  
Labview Program

A finite volume discretization method for solving the heat and mass transfer equations of drying jujubes was developed in this paper. Combined with the Labview program, development of a numerical simulation software for internal heat and mass transfer during drying of jujubes, and simulation of the drying process on the jujubes using the software. The results showed that the simulation results and experimental data were consistent.

scholarly journals Modeling and simulation of heat and mass transfer in an Ethiopian fresh injera drying process

Heliyon ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. e06201
Author(s):  
Alamrew B. Solomon ◽  
Solomon W. Fanta ◽  
Mulugeta A. Delele ◽  
Maarten Vanierschot
Keyword(s):  
Mass Transfer ◽  
Modeling And Simulation ◽  
Heat And Mass Transfer ◽  
Drying Process

scholarly journals Impact of Binary Chemical Reaction and Activation Energy on Heat and Mass Transfer of Marangoni Driven Boundary Layer Flow of a Non-Newtonian Nanofluid

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 702
Author(s):  
Ramanahalli Jayadevamurthy Punith Gowda ◽  
Rangaswamy Naveen Kumar ◽  
Anigere Marikempaiah Jyothi ◽  
Ballajja Chandrappa Prasannakumara ◽  
Ioannis E. Sarris
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Boundary Layer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Velocity Gradient ◽  
Boundary Layer Flow ◽  
Biological Fluids ◽  
Porosity Parameter ◽  
Layer Flow

The flow and heat transfer of non-Newtonian nanofluids has an extensive range of applications in oceanography, the cooling of metallic plates, melt-spinning, the movement of biological fluids, heat exchangers technology, coating and suspensions. In view of these applications, we studied the steady Marangoni driven boundary layer flow, heat and mass transfer characteristics of a nanofluid. A non-Newtonian second-grade liquid model is used to deliberate the effect of activation energy on the chemically reactive non-Newtonian nanofluid. By applying suitable similarity transformations, the system of governing equations is transformed into a set of ordinary differential equations. These reduced equations are tackled numerically using the Runge–Kutta–Fehlberg fourth-fifth order (RKF-45) method. The velocity, concentration, thermal fields and rate of heat transfer are explored for the embedded non-dimensional parameters graphically. Our results revealed that the escalating values of the Marangoni number improve the velocity gradient and reduce the heat transfer. As the values of the porosity parameter increase, the velocity gradient is reduced and the heat transfer is improved. Finally, the Nusselt number is found to decline as the porosity parameter increases.

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