scholarly journals Comprehensive Studies of the Processes of the Molecular Transfer of the Momentum, Thermal Energy and Mass in the Nutrient Media of Biotechnological Industries

2022 ◽  
Vol 9 (1) ◽  
pp. 18
Author(s):  
Aleksandr G. Novoselov ◽  
Sergei A. Sorokin ◽  
Igor V. Baranov ◽  
Nikita V. Martyushev ◽  
Olga N. Rumiantceva ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Dynamic Viscosity ◽  
Empirical Equation ◽  
Molecular Diffusion ◽  
Transport Coefficients ◽  
Molecular Transport ◽  
Rolling Ball ◽  
Molecular Transfer ◽  
Exchange Processes ◽  
Different Temperatures

This article puts forward arguments in favor of the necessity of conducting complex measurements of molecular transport coefficients that quantitatively determine the coefficients of dynamic viscosity, thermal diffusivity and molecular diffusion. The rheological studies have been carried out on the viscometers of two types: those with a rolling ball (HÖPPLER® KF 3.2.), and those with a rotary one (Rheotest RN 4.1.). The thermophysical studies have been performed using the analyzer Hot Disk TPS 2500S. The measurements have been taken in the temperature range of 283 to 363 K. The concentration of dry substances has varied from 16.2 to 77.7% dry wt. An empirical equation for calculating the density of aqueous solutions of beet molasses has been obtained. The diagrams of the dependence of the dynamic viscosity on the shear rate in the range of 1 s−1 to 500 s−1 at different temperatures have been provided. The diagrams of the dependence of the coefficients of thermal conductivity and thermal diffusivity on the temperature and the concentration of dry substances have been presented, and empirical equations for their calculation have been obtained. The findings can be used for engineering calculations of hydrodynamic and heat-exchange processes in biotechnological equipment.

Study of Effect of Thermal Diffusivity on Ground Temperature for Malaysian Climate

2014 ◽  
Vol 554 ◽  
pp. 301-306 ◽  
Author(s):  
Taib Mohd Yusof ◽  
Shahrani Anuar ◽  
Hassan Ibrahim
Keyword(s):  
Thermal Diffusivity ◽  
Empirical Equation ◽  
Electricity Consumption ◽  
Ground Temperature ◽  
Passive Cooling ◽  
Ground Heat Exchanger ◽  
Application Analysis ◽  
Main Input ◽  
Local Weather ◽  
Temperature Amplitude

Ground has been proven that it is able to supply cooling and heating resulting in significant reduction of electricity consumption. This paper discusses potential of ground towards implementation of ground thermal storage by using ground heat exchanger (GHE) to supply passive cooling for any application. Analysis has been conducted based on empirical equation from conduction heat transfer for depth up to 6 m and thermal diffusivity from 0.04 to 0.1 m2/day. The main input parameters were obtained from local weather station for three consecutive years. The results showed that significant reduction of temperature occur at depth below than 2.0 m in which cooling can be supplied constantly throughout the year. Temperature amplitude also gets attenuated relatively with depth in which amplitude less than 1°C occur at depth more than 4 m for thermal diffusivity 0.04 m2/day. In addition, thermal diffusivity plays important role in determining ground temperature variation. It has been obtained that the temperature amplitude significantly increase when the thermal diffusivity increase. Therefore, this paper had suggested that the application of GHE should be placed in condition of thermal diffusivity 0.06 m2/day and below.

Measurement and Correlation for Solubility of Hexachlorobenzene in Different Solvents

2014 ◽  
Vol 614 ◽  
pp. 61-64
Author(s):  
Yan Fei Wang ◽  
Shi Jie Xu ◽  
Yu Xiang Zhu ◽  
Liang Zhu ◽  
Li Bin Yang ◽  
...  
Keyword(s):  
Empirical Equation ◽  
Solubility Data ◽  
Laser Method ◽  
Equilibrium Method ◽  
Different Temperatures ◽  
Benzene Toluene

The solubility of hexachlorobenzene in different solvents (hexachlorobutadiene, tetrachloroprene, benzene, toluene and chloroform) at different temperatures was measured by the dynamic laser method and equilibrium method. The measured solubility data were correlated with Apelblat empirical equation. The results show that the equation is suitable for description of the solubility data of hexachlorobenzene in the above solvents.

Turbulent Transport at High Reynolds Numbers in an Inertial Confinement Fusion Context

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
J. Melvin ◽  
P. Rao ◽  
R. Kaufman ◽  
H. Lim ◽  
Y. Yu ◽  
...  
Keyword(s):  
Inertial Confinement Fusion ◽  
Turbulent Transport ◽  
Transport Coefficients ◽  
Mesh Refinement ◽  
Molecular Transport ◽  
Inertial Confinement ◽  
Turbulent Regime ◽  
Turbulent Structures ◽  
Confinement Fusion ◽  
Object Of Study

Mix is a critical input to hydro simulations used in modeling chemical or nuclear reaction processes in fluids. It has been identified as a possible cause of performance degradation in inertial confinement fusion (ICF) targets. Mix contributes to numerical solution uncertainty through its dependence on turbulent transport coefficients, themselves uncertain and even controversial quantities. These coefficients are a central object of study in this paper, carried out in an Richtmyer–Meshkov unstable circular two-dimensional (2D) geometry suggested by an ICF design. We study a pre-turbulent regime and a fully developed regime. The former, at times between the first shock passage and reshock, is characterized by mixing in the form of interpenetrating but coherent fingers and the latter, at times after reshock, has fully developed turbulent structures. This paper focuses on the scaling of spatial averages of turbulence coefficients under mesh refinement and under variation of molecular viscosity [i.e., Reynolds number (Re)]. We find that the coefficients scale under mesh refinement with a power of spatial grid spacing derived from the Kolmogorov 2/3 law, especially after reshock. We document the dominance of turbulent over molecular transport and convergence of the turbulent transport coefficients in the infinite Re limit. The transport coefficients do not coincide for the pre- and post-reshock flow regimes, with significantly stronger transport coefficients after reshock.

Nonlinear transport coefficients and plane Couette flow of a viscous, heat-conducting gas between two plates at different temperatures

1987 ◽  
Vol 65 (9) ◽  
pp. 1090-1103 ◽  
Author(s):  
Byung Chan Eu ◽  
Roger E. Khayat ◽  
Gert D. Billing ◽  
Carl Nyeland
Keyword(s):  
Boltzmann Equation ◽  
Couette Flow ◽  
Transport Coefficients ◽  
Heat Conducting ◽  
Hydrodynamic Equations ◽  
Nonlinear Transport ◽  
Plane Couette Flow ◽  
The Boltzmann Equation ◽  
Viscous Heat ◽  
Different Temperatures

By using the example of plane Couette flow between two plates maintained at different temperatures, we present a method of calculating flow profiles for rarefied gases. In the method, generalized hydrodynamic equations are derived from the Boltzmann equation. They are then solved with boundary conditions calculated by taking into consideration the interfacial interaction between the surface and the gas molecule. The nonlinear transport coefficients employed in the generalized hydrodynamic equations are obtained from the Boltzmann equation by means of the modified-moment method. The profiles calculated are in agreement with the Liu–Lees theory as long as the boundary values are in agreement. It is found that the viscous-heating effect has a significant influence on the temperature and velocity profiles. The nonlinearity of transport coefficients also has significant effects on the profiles as the Knudsen and Mach numbers increase.

scholarly journals Multiple scale investigation of molecular diffusion inside functionalized porous hosts using a combination of magnetic resonance methods

2015 ◽  
Vol 17 (24) ◽  
pp. 15976-15988 ◽  
Author(s):  
Martin Wessig ◽  
Martin Spitzbarth ◽  
Malte Drescher ◽  
Rainer Winter ◽  
Sebastian Polarz
Keyword(s):  
Magnetic Resonance ◽  
Epr Spectroscopy ◽  
Molecular Diffusion ◽  
Spin Exchange ◽  
Multiple Scale ◽  
Exchange Processes ◽  
P Diffusion

Diffusion in organo-functionalized porous hosts could be tracked by evaluation of spin exchange processes using EPR spectroscopy.

scholarly journals Experimental Validation of Formula for Calculation Thermal Diffusivity in Superlattices Performed Using a Combination of Two Frequency-Domain Methods: Photothermal Infrared Radiometry and Thermoreflectance

2021 ◽  
Vol 11 (13) ◽  
pp. 6125
Author(s):  
Michał Pawlak ◽  
Timo Kruck ◽  
Nikolai Spitzer ◽  
Dariusz Dziczek ◽  
Arne Ludwig ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Diffusivity ◽  
Thermal Transport ◽  
Theoretical Formula ◽  
Elastic Continuum ◽  
Frequency Domain Methods ◽  
Different Temperatures ◽  
Infrared Radiometry

In this paper, we validate two theoretical formula used to characterize thermal transport of superlattices at different temperatures. These formulas are used to measure cross-plane thermal conductivity and thermal boundary resistance, when it is not possible to obtain heat capacity or thermal diffusivity and in-plane thermal conductivity. We find that the most common formula for calculating thermal diffusivity and heat capacity (and density) can be used in a temperature range of −50 °C to 50 °C. This confirms that the heat capacity in the very thin silicon membranes is the same as in bulk silicon, as was preliminary investigated using an elastic continuum model. Based on the obtained thermal parameters, we can fully characterize the sample using a new procedure for characterization of the in-plane and cross-plane thermal transport properties of thin-layer and superlattice semiconductor samples.

scholarly journals Resonance Generation of Short Internal Waves by the Barotropic Seiches in an Ice-Covered Shallow Lake

2020 ◽  
Vol 27 (4) ◽  
Author(s):  
S. Yu. Volkov ◽  
S. R. Bogdanov ◽  
R. E. Zdorovennov ◽  
N. I. Palshin ◽  
G. E. Zdorovennova ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Internal Waves ◽  
Shallow Lake ◽  
Molecular Diffusion ◽  
Bottom Topography ◽  
Internal Tides ◽  
Buoyancy Frequency ◽  
Effective Thermal Diffusivity ◽  
Transfer Processes ◽  
Temperature Pulsations

Purpose. The observation measurements testify the fact that heat and mass transfer processes in the shallow ice-covered lakes are not limited to the molecular diffusion only. In particular, the effective thermal diffusivity exceeds the molecular one by up to a few orders of magnitude. Now it is widely accepted that the transfer processes, in spite of their low intensity, are controlled by intermittent turbulence. At the same time, its nature and generation mechanism are still studied insufficiently. The paper represents one of such mechanisms associated with resonance generation of short internal waves by the barotropic seiches. Methods and Results. The temperature measurements in a shallow lake in winter were used as an experimental base. Having been analyzed, the temperature profiles’ dynamics observed during a few weeks after freezing revealed the anomalous values of thermal diffusivity. At that the temperature pulsations’ spectra clearly demonstrate the peak close to the main mode of barotropic seiches. Counter-phase oscillations at the different depths and pronounced heterogeneity of the amplitudes of temperature pulsations over depth indicate presence of internal waves. Based on these data, the mechanism of energy transfer from the barotropic seiches to the internal waves similar to the “tidal conversion” (the latter governs resonance generation of internal tides in the ocean), is proposed. The expressions for heat flux, energy dissipation rate and effective thermal diffusivity are derived. Conclusions. Internal waves can play an essential role in the processes of interior mixing and heat transfer in the ice-covered lakes. Though direct wind-induced turbulence production is inhibited, baric perturbations in the atmosphere can give rise to barotropic seiches, which play the role of an intermediate energy reservoir and can generate short resonant internal waves resulted from interaction with the undulate lake floor. The internal wave field parameters strongly depend on the barotropic seiche amplitudes, buoyancy frequency and the bottom topography features.

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