Determination of the optimum frequency of gas velocity fluctuations in motion and heat exchange of particles

2010 ◽  
Vol 83 (1) ◽  
pp. 141-145 ◽  
Author(s):  
P. V. Akulich
Keyword(s):  
Heat Exchange ◽  
Gas Velocity ◽  
Optimum Frequency ◽  
Velocity Fluctuations

scholarly journals Investigation of dynamics of roll forming processes

2018 ◽  
Vol 224 ◽  
pp. 01134 ◽  
Author(s):  
Leonid A. Kondratenko ◽  
Lubov I. Mironova
Keyword(s):  
Heat Exchange ◽  
Service Life ◽  
Dynamic Process ◽  
Theoretical Aspect ◽  
Complex Interaction ◽  
Roll Forming ◽  
Structural Elements ◽  
Velocity Fluctuations

This article contains the analysis of tube expander dynamics in complex interaction of structural elements of heat-exchange tubes attachment assembly in the process of roll-forming operation, description of dynamic process theoretical aspect. It is shown that torque variations lead to velocity fluctuations and influence the service life of operative parts of tube expander and quality of tube attachment assemblies.

Determination of the characteristics of nonsteady heat exchange in one disperse reactive system

1978 ◽  
Vol 35 (6) ◽  
pp. 1429-1435
Author(s):  
A. M. Grishin ◽  
G. S. Loskutov ◽  
T. S. Sandrykina
Keyword(s):  
Heat Exchange ◽  
Reactive System ◽  
Nonsteady Heat

Mass Transfer Studies in a Novel Perforated Plate Bubble Column

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
S. Dhanasekaran ◽  
T. Karunanithi
Keyword(s):  
Mass Transfer ◽  
Liquid Velocity ◽  
Bubble Column ◽  
Perforated Plate ◽  
Gas Velocity ◽  
Plate Spacing ◽  
Mass Transfer Studies ◽  
Superficial Gas Velocity ◽  
Superficial Liquid Velocity

This investigation reports the experimental and theoretical results carried out to evaluate the volumetric mass transfer coefficient (kLa) in a novel hybrid rotating and reciprocating perforated plate bubble column. Countercurrent condition is performed. kLa is studied by the absorption of oxygen from air into deoxygenated water at room temperature (27 ± 1°C). Effects of agitation level, superficial gas velocity, superficial liquid velocity and plate spacing on kLa were analyzed and found to be significant. With an increase in agitation level at a constant superficial gas and liquid velocities, the breakage process of gas bubbles starts to be more pronounced and intensive oxygen mass transfer occurs. Hence, kLa increases sharply. kLa increases with an increase in superficial gas velocity, due to higher gas holdup and the enhanced breakup of bubbles. Similarly, kLa increases with an increase in superficial liquid velocity and the effect is found to be significant. When plate spacing is decreased (by increasing the number of plates), it is observed that the kLa increases at higher superficial gas velocity and agitation level. Correlation is developed for the determination of kLa and found to concur with experimental results. This correlation can be used for the determination of kLa for this hybrid column with 95% accuracy within the range of variables investigated in this present study.

Bubble Diameter and Effective Interfacial Area in a Novel Hybrid Rotating and Reciprocating Perforated Plate Bubble Column

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Dhanasekaran S ◽  
Karunanithi T
Keyword(s):  
Liquid Velocity ◽  
Bubble Column ◽  
Bubble Diameter ◽  
Perforated Plate ◽  
Interfacial Area ◽  
Gas Velocity ◽  
The Mean ◽  
Superficial Gas Velocity ◽  
Plate Column

This investigation reports on the experimental and theoretical investigation carried out to evaluate the bubble diameter and effective interfacial area in a novel Hybrid Rotating and Reciprocating Perforated Plate Bubble Column. Air-water system is used in this investigation. Countercurrent mode is employed. The effects of agitation level, superficial gas velocity and superficial liquid velocity on the bubble size distribution are studied. The mean bubble diameter is predicted using photographic technique. A simple correlation is developed for the determination of mean bubble diameter. It is found that the mean bubble diameter values for hybrid column are 1.8 to 2.5 times smaller when compared with conventional reciprocating plate column. The interfacial area is calculated based on the experimental results of the gas holdup and bubble diameter. Effects of agitation level, superficial gas velocity, superficial liquid velocity and plate free area on the interfacial area have been investigated. Correlations are developed for the determination of interfacial area for both mixer-settler and emulsion regions. It could be noted that the interfacial area for the hybrid column is 3 to 6 times higher in both mixer-settler region and emulsion region than that of conventional reciprocating plate column which is quite large.

scholarly journals Determination of Heat Exchange Law Using Mean Isotherm

2020 ◽  
Vol Volume 14 ◽  
Keyword(s):  
Temperature Field ◽  
Heat Exchange ◽  
Heat Flow ◽  
Heat Exchange Coefficient ◽  
Main Attention ◽  
One Dimensional ◽  
Mean Temperature ◽  
Inverse Heat Transfer ◽  
Transfer Problems

Determination of heat exchange between a solid and the environment is a significant inverse thermal physical problem. This heat exchange law irrespective of its nature can be defined easier if mean temperature of such solid is known. When mean temperature of the solid and speed of its change are known, it becomes possible to determine heat flow on the boundary of the solid. In its turn, when heat flow on the boundary, temperature on the boundary and ambient temperature are defined, heat exchange coefficient can be established. Therefore, the main attention is paid to a manner how mean temperature of a solid can be determined in the article. Examining inverse heat transfer problems, input data consist of measurements taken in temperature field as simple as possible mathematically in laboratory conditions. Hence, a symmetrical one-dimensional temperature field is discussed in the article

Numerical Modeling of Heat and Mass Transport with Inner Heat Exchange in Unsaturated Porous Media

2020 ◽  
Vol 27 ◽  
pp. 166-176
Author(s):  
Jozef Kačur ◽  
Patrik Mihala
Keyword(s):  
Mathematical Model ◽  
Porous Media ◽  
Heat Exchange ◽  
Inverse Problems ◽  
Water Transport ◽  
Heat Conductivity ◽  
Unsaturated Porous Media ◽  
Heat Transmission ◽  
Matrix Heat

We are focused to the numerical modelling of heat, contaminant and water transport in unsaturated porous media in 3D. The heat exchange between water and porous media matrix is taken into the account. The determination of heat energy transmission coefficient and matrix heat conductivity is solved by means of inverse problem methods. The mathematical model represents the conservation of heat, contaminant and water mass balance. It is expressed by coupled non-linear system of parabolic-elliptic equations. Mathematical model for water transport in unsaturated porous media is represented by Richard's type equation. Heat transport by water includes water flux, molecular diffusion and dispersion. A successful experiment scenario is suggested to determine the required parameters including heat transmission and matrix heat conductivity coefficients. Additionally we investigate contaminant transport with heat transmission and contaminant adsorption. The obtained experiments support our method suitable for solution of direct and inverse problems. This problem we have discussed previously in 1D model, but preferential streamlines in 1D thin tubes shadow accurate results in determination of required parameters. In our presented setting we consider a cylindrical sample which is suitable in laboratory experiments for inverse problems.

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