scholarly journals Heat Transfer and Hydrodynamics in Stirred Tanks with Liquid-Solid Flow Studied by CFD–DEM Method

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 849
Author(s):  
Xiaotong Luo ◽  
Jiachuan Yu ◽  
Bo Wang ◽  
Jingtao Wang
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Multiphase Flow ◽  
Convective Heat ◽  
Particle Temperature ◽  
Coupling Model ◽  
Stirred Tank ◽  
Stirred Tanks ◽  
Particle Flows ◽  
Heat Transfers

The heat transfer and hydrodynamics of particle flows in stirred tanks are investigated numerically in this paper by using a coupled CFD–DEM method combined with a standard k-e turbulence model. Particle–fluid and particle–particle interactions, and heat transfer processes are considered in this model. The numerical method is validated by comparing the calculated results of our model to experimental results of the thermal convection of gas-particle flows in a fluidized bed published in the literature. This coupling model of computational fluid dynamics and discrete element (CFD–DEM) method, which could calculate the particle behaviors and individual particle temperature clearly, has been applied for the first time to the study of liquid-solid flows in stirred tanks with convective heat transfers. This paper reports the effect of particles on the temperature field in stirred tanks. The effects on the multiphase flow convective heat transfer of stirred tanks without and with baffles as well as various heights from the bottom are investigated. Temperature range of the multiphase flow is from 340K to 350K. The height of the blade is varied from about one-sixth to one-third of the overall height of the stirred tank. The numerical results show that decreasing the blade height and equipping baffles could enhance the heat transfer of the stirred tank. The calculated temperature field that takes into account the effects of particles are more instructive for the actual processes involving solid phases. This paper provides an effective method and is helpful for readers who have interests in the multiphase flows involving heat transfers in complex systems.

scholarly journals An Experimental and Numerical Study of Flow and Convective Heat Transfer in a Freely Falling Curtain of Particles

1988 ◽  
Vol 110 (2) ◽  
pp. 172-181 ◽  
Author(s):  
J. Hruby ◽  
R. Steeper ◽  
G. Evans ◽  
C. Crowe
Keyword(s):  
Heat Transfer ◽  
Drag Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Air Temperature ◽  
Particle Velocity ◽  
Particle Temperature ◽  
Spherical Particles ◽  
Particle Flows ◽  
Heated Particle

The flow characteristics and convective heat transfer in a freely falling curtain of spherical particles with an average diameter of 650 μm has been studied experimentally and numerically. Both heated and unheated particle flows have been considered. This work is part of a larger study to determine the feasibility of using particles to directly absorb the insolation in a solar central receiver for high temperature applications. The particles of interest are Norton Master Beads™ which are primarily aluminum oxide. Measurements have been made of particle velocity in heated and unheated particle flows, and particle temperature and air temperature in heated particle flows. Comparison of the measurements with calculations has been made for two particle mass flow rates at room temperature and at two initial elevated particle temperatures. Excellent agreement between numerical and experimental results is obtained for particle velocity in the unheated flow. For the heated particles, both data and predictions show the same trends with regard to particle velocity, particle temperature, and air temperature. However, the calculations of these quantities overpredict the data. The results suggest that the drag coefficient in flows where the particles are hot compared to the air is larger than predicted using conventional methods to account for nonisothermal effects. The prediction of particle temperature and air temperature attained with a drag coefficient that is larger than the standard drag coefficient agrees well with the data.

scholarly journals Development of unsteady boundary layers on the generatrices of a vertical silicon rod heated by electric current in the mode of conjugate radiation-convective heat transfer

2021 ◽  
Vol 2119 (1) ◽  
pp. 012163
Author(s):  
A. V. Mitina ◽  
V. S. Berdnikov ◽  
K. A. Mitin
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Convective Heat Transfer ◽  
Electric Current ◽  
Convective Heat ◽  
Longitudinal Direction ◽  
Longitudinal Distribution ◽  
Grashof Number ◽  
Inhomogeneous Temperature ◽  
Inhomogeneous Temperature Field

Abstract The nonstationary conjugate radiation-convective heat transfer of a single silicon rod heated by an electric current with the surrounding gas medium is studied numerically in the axisymmetric formulation by the finite element method. The calculations were carried out at the Prandtl number Pr = 0.68, and the range of the Grashof number, determined by the temperature difference and the radius of the rod 9 703 ≤ Gr ≤ 261 977. It is shown that after a short incubation period, a circulation flow is formed. As a result, a significantly inhomogeneous temperature field in the longitudinal direction is formed in a silicon rod heated by an electric current. As the Grashof number increases, the inhomogeneity of the longitudinal distribution of the temperature field increases.

Thermal Conductivity Test and Coupling Simulation of Heat-Transfer in Fracture Rock

2011 ◽  
Vol 382 ◽  
pp. 3-6
Author(s):  
Shu Guang Zhang ◽  
Yong Gang Yu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Finite Element ◽  
Temperature Field ◽  
Rock Mass ◽  
Fractured Rock ◽  
Coupling Model ◽  
Fluid Temperature ◽  
Fracture Rock ◽  
Fractured Rock Mass

In order to research thermal conductivity of fracture rock, fluid-heat coupling test and simulation are studied. Empirical equation of thermal conductivity is obtained and conductivity factor is ensured by test data. Based on the fluid-heat coupling model of heat-transfer, temperature field distribution of fracture rock is described. At the same time, the heat-transfer equation is discretized by using weighted residual Galerkin finite element. Combined with boundary condition and parameters, the temperature field in fractured rock mass is simulated by finite element method. The temperature of fractured rock mass under the action of the seepage is combined with the initial rock temperature, fluid temperature and the rate of the flow. Thermo-isoline is discontiguous at boundary of fracture, which shows that the seepage affects the distribution of temperature field. The change rate of temperture isoline is gradually reduced along the single fissure flow, therefore the rate of heat-transfer is decreased. The influence of fluid temperature to temperature distribution is small, but different fluid temperature obviously affects thermo-isoline.

Gas Solids Suspension Convective Heat Transfer at a Reynolds Number of 130,000

1968 ◽  
Vol 90 (4) ◽  
pp. 464-468 ◽  
Author(s):  
R. Briller ◽  
R. L. Peskin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Particle Temperature ◽  
Convective Heat Transfer Coefficient ◽  
Loading Ratio ◽  
High Reynolds

An experiment was performed to determine the convective heat-transfer coefficient to heated and cooled gas solids suspensions at a Reynolds number of 130,000. Measurements of the heat transfer were performed by traversing the stream at various locations along the pipe with specially designed probes which measured air and particle temperature locally. The results showed that for a high Reynolds number, the heat-transfer coefficient for the suspension appears to be equal to that of the pure gas at the same Reynolds number, and independent of solids loading ratio, heating or cooling, and particle size (between 0.0011 and 0.0058 in. dia).

scholarly journals Microscale flow and heat transfer between the rotor and the flank for rotary engine

2019 ◽  
pp. 330-330
Author(s):  
Zhaoju Qin
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Flow Field ◽  
Velocity Slip ◽  
Coupling Model ◽  
Rotary Engine ◽  
Flow And Heat Transfer ◽  
Microscale Flow ◽  
Commercial Code ◽  
Steady Laminar

This paper is to investigate microscale flow and transfer between the rotor and the flank for rotary engine. The rotor and flank is simplified to two disks in order to study flow field and temperature field conveniently. The paper takes analysis of steady laminar flow and heat transfer between two disks separated by a gas-filled gap due to machining tolerance. A 3-D multi-physical coupling model is used, involving velocity slip, temperature jump, rarefaction and dissipation. A solution based on commercial code COMSOL is derived and the results are used to illustrate the effects to velocity field, temperature distribution, disks' torque and Nusselt number based on the governing parameters. The paper also investigates the effects of different modified Knudsen number on flow field and temperature field.

scholarly journals Experimental tests for the occurence of convective heat transfer within the bed of rectangular steel profiles

2012 ◽  
Vol 33 (3) ◽  
pp. 84-95
Author(s):  
Rafał Wyczółkowski ◽  
Dorota Musiał
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Natural Convection ◽  
Heat Exchange ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Experimental Tests ◽  
Steel Sections

Abstract The paper describes tests intended to examine the occurrence of natural convection within the space occupied by 40×20 mm rectangular steel sections. Within these tests the bed of four layers of section was heated by the electric palate heater. Depending on the manner in which the heater was positioned, the tests were divided into two series. In the case of heating from above, the heat flowing through the bed is transferred only by conduction and radiation. When heating the bed from below, in addition to conduction and radiation, also a convective heat transfer will occur. Should this be the case, it will result in the intensification of the heat exchange. The results of measurements carried out have not demonstrated that the occurrence of any possible natural convection would influence the development of a temperature field in this type of charge.

Study of Heat Transfer Control with Magnetic Field Using Higher Order Finite Difference Scheme

2016 ◽  
Vol 8 (3) ◽  
pp. 449-463 ◽  
Author(s):  
R. Sivakumar ◽  
S. Vimala ◽  
S. Damodaran ◽  
T. V. S. Sekhar
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Nusselt Number ◽  
Temperature Field ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Experimental Studies ◽  
Higher Order ◽  
Polar Coordinates ◽  
Cylindrical Polar Coordinates

Abstract.The control of convective heat transfer from a heated circular cylinder immersed in an electrically conducting fluid is achieved using an externally imposed magnetic field. A Higher Order Compact Scheme (HOCS) is used to solve the governing energy equation in cylindrical polar coordinates. The HOCS gives fourth order accurate results for the temperature field. The behavior of local Nusselt number, mean Nusselt number and temperature field due to variation in the aligned magnetic field is evaluated for the parameters 5≤Re≤40, 0≤N≤20 and 0.065≤Pr≤7. It is found that the convective heat transfer is suppressed by increasing the strength of the imposed magnetic field until a critical value of N, the interaction parameter, beyond which the heat transfer increases with further increase in N. The results are found to be in good agreement with recent experimental studies.

scholarly journals Lattice Boltzmann simulation of convective heat transfer of non-Newtonian fluids in impeller stirred tank

2017 ◽  
Vol 46 ◽  
pp. 519-535 ◽  
Author(s):  
Chieh-Li Chen ◽  
Shing-Cheng Chang ◽  
Chih-Yung Chen
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Lattice Boltzmann ◽  
Newtonian Fluids ◽  
Stirred Tank ◽  
Lattice Boltzmann Simulation
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