scholarly journals INCREASING ENERGY EFFICIENCY OF CONTACT DEVICES OF THE DISTILLATION AND RECTIFICATION PLANTS AND DEGREE OF BIOETHANOL PURIFICATION

2018 ◽  
Vol 40 (3) ◽  
pp. 27-31
Author(s):  
Yu.V. Bulii ◽  
O. M. Obodovych
Keyword(s):  
Energy Efficiency ◽  
Cross Section ◽  
Residence Time ◽  
Fluid Motion ◽  
Fluid Retention ◽  
Driving Mechanism ◽  
Absolute Alcohol ◽  
Heating Steam ◽  
Contact Devices ◽  
Fusel Oils

The aim of the work was a study the energy efficiency of the heads and fusels concentrating column and beer still, the degree of purification of ethanol in the process of the separation of light fraction and the efficiency of the process of а beer distillation by increasing residence time of the liquid on the trays for contact with the vapor. The technology of rectification with controlled cycles of fluid retention on the stages of the contact and its overflow without mixing to the adjacent trays is proposed. For implementing the method the experimental column was equipped with scaly trays with coaxial arrangement of scales, which excluded the linearity of the fluid motion. The overflow holes of each tray is alternately opened and closed by movable valves associated with the driving mechanism in accordance with the controller program. Change the cross-section of the trays at 45-50 % resulted in an immediate reduction of rate of vapor and provided the spilled liquid through the overflow hole and the gap of scales. Due to this time the overflow was reduced from 5 to 2 seconds. It was studied that the increasing of the residence time of the beer on the trays to 12 seconds can increase the concentration of alcohol in beer distillate by 28 % in comparison with the standard columns. The coaxial arrangement of scales eliminates the possibility of formation of stagnant zones and burning of suspended particles of a beer. Specific consumption of heating steam to the process distillation not exceed 16 kg/dl of absolute alcohol of a beer. In the process of the separation of light fractions with the fluid retention on trays to 20 seсonds a degree of extraction of aldehydes, higher alcohols of fusel oils and methyl alcohol grew on average by 30 %, the multiplicity of concentration of light and intermediate impurities increased by 32 %. The consumption of heating steam for the distillation process was reduced to 14 kg/dl of absolute alcohol. To increase the efficiency of contact devices, it is advisable to prolong the residence time of the liquid on the trays until close to the equilibrium state of phases, and to provide overflow of liquid without mixing to the adjacent trays, to use trays with full compensation of co-current and alternating cross-section.

scholarly journals SIMULATION OF GAS DYNAMICS IN PLASMA REACTOR FOR CARBON DIOXIDE CONVERSION

2021 ◽  
pp. 131-135
Author(s):  
P.P. Platonov ◽  
S.V. Dudin ◽  
V.A. Lisovskiy
Keyword(s):  
Carbon Dioxide ◽  
Energy Efficiency ◽  
Residence Time ◽  
Plasma Reactor ◽  
Gas Injection ◽  
Navier Stokes ◽  
Carbon Dioxide Conversion ◽  
Navier Stokes Equation ◽  
Hydrodynamic Approximation ◽  
Gas Conversion

Numerical simulation of a bulk-type plasma reactor for carbon dioxide conversion with distributed gas injection and pumping has been performed in hydrodynamic approximation by solution of Navier-Stokes equation using the mathematical package COMSOL. It is shown that the geometry of gas injection and pumping, which determines the trajectories of the particles and their residence time in reactor, can significantly affect the energy efficiency of the conversion. Different particles on their way from inlet to pumping hole move along different trajectories and spend different times inside the reactor. If the residence time of the gas in the reactor is less than optimal, the gas conversion will be incomplete. If this time is more than optimal, then an excessive amount of energy will be applied to the already converted gas. It is shown that the reactor height affects significantly the energy efficiency of plasma conversion of carbon dioxide.

Extension of the Wall-Driven Enclosure Flow Problem to Toroidally Shaped Geometries of Square Cross-Section

1996 ◽  
Vol 118 (4) ◽  
pp. 779-786 ◽  
Author(s):  
L. M. Phinney ◽  
J. A. C. Humphrey
Keyword(s):  
Cross Section ◽  
Fluid Motion ◽  
Radius Of Curvature ◽  
Two Dimensional ◽  
Coordinate Direction ◽  
Concave Wall ◽  
Center Vortex ◽  
Convex Wall ◽  
Two Dimensional Flow ◽  
Moving Fluid

The two-dimensional wall-driven flow in an enclosure has been a numerical paradigm of long-standing interest and value to the fluid mechanics community. In this paradigm the enclosure is infinitely long in the x-coordinate direction and of square cross-section (d × d) in the y-z plane. Fluid motion is induced in all y-z planes by a wall (here the top wall) sliding normal to the x-coordinate direction. This classical numerical paradigm can be extended by taking a length L of the geometry in the x-coordinate direction and joining the resulting end faces at x = 0 and x = L to form a toroid of square cross-section (d × d) and radius of curvature Rc. In the curved geometry, axisymmetric fluid motion (now in the r-z planes) is induced by sliding the top flat wall of the toroid with an imposed radial velocity, ulid, generally directed from the convex wall towards the concave wall of the toroid. Numerical calculations of this flow configuration are performed for values of the Reynolds number (Re = ulidd/ν) equal to 2400, 3200, and 4000 and for values of the curvature ratio (δ = d/Rc) ranging from 5.0 · 10−6 to 1.0. For δ ≤ 0.05 the steady two-dimensional flow pattern typical of the classical (straight) enclosure is faithfully reproduced. This consists of a large primary vortex occupying most of the enclosure and three much smaller secondary eddies located in the two lower corners and the upper upstream (convex wall) corner of the enclosure. As δ increases for a fixed value of Re, a critical value, δcr, is found above which the primary center vortex spontaneously migrates to and concentrates in the upper downstream (concave wall) corner. While the sense of rotation originally present in this vortex is preserved, that of the slower moving fluid below it and now occupying the bulk of the enclosure cross-section is reversed. The relation marking the transition between these two stable steady flow patterns is predicted to be δcr1/4 = 3.58 Re-1/5 (δ ± 0.005).

Steady Flow in Tubes of Slowly Varying Cross Section

1978 ◽  
Vol 45 (3) ◽  
pp. 475-480 ◽  
Author(s):  
D. A. MacDonald
Keyword(s):  
Shear Stress ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Cross Section ◽  
Tube Wall ◽  
Fluid Motion ◽  
Pressure Rise ◽  
Wall Profile ◽  
Actual Shape ◽  
Viscous Fluid Motion

This paper studies steady incompressible viscous fluid motion in axisymmetric tubes of slowly varying cross section. Theory, which is independent of the actual shape of tube wall profile, is developed and a number of illustrative examples are studied. Results which portray the behavior of pressure drop (pressure rise, in some cases) and wall shear stress are presented.

Rate of Decay of a Passive Scalar in a Micro-Mixer and the Frequency of the Advecting Velocity Fields

2009 ◽  
Author(s):  
J. Rafael Pacheco ◽  
KangPing Chen ◽  
Arturo Pacheco-Vega
Keyword(s):  
Electric Fields ◽  
Fluid Motion ◽  
Passive Scalar ◽  
Driving Mechanism ◽  
Main Stream ◽  
Cross Sectional ◽  
Periodic Flows ◽  
Mixing Dynamics ◽  
Micro Mixer ◽  
Random Flows

In the current work, the mixing of a diffusive passive-scalar, e.g., thermal energy or species concentration, driven by electro-osmotic fluid motion being induced by an applied potential across a micro-channel is studied numerically. Secondary time-dependent periodic or random electric fields, orthogonal to the main stream, are applied to generate cross-sectional mixing. This investigation focuses on the mixing dynamics and its dependence on the frequency (period) of the driving mechanism. For periodic flows, the probability density function (PDF) of the scaled passive scalar (i.e., concentration), settles into a self-similar curve showing spatially repeating patterns. In contrast, for random flows there is a lack of self-similarity in the PDF for the interval of time considered in this investigation. The present study confirms an exponential decay of the variance of the concentration for the periodic and random flows.

Underpressured and Overpressured Tight Gas Sands: II. Spatially and Temporally Varying Conditions

2005 ◽  
Vol 23 (3) ◽  
pp. 169-180 ◽  
Author(s):  
Ian Lerche
Keyword(s):  
Steady State ◽  
Cross Section ◽  
Fluid Motion ◽  
Gas Pressure ◽  
Tight Gas ◽  
Physical Conditions ◽  
Variation Of Parameters ◽  
Sand Aquifer ◽  
Tight Gas Sands ◽  
Response Equation

This paper investigates the behavior of gas in tight sand aquifers when the shape of the aquifer, its cross-section, permeability, and temperature can all vary along the length of the aquifer. The basic response equation is steady state input of gas under pressure at the lower end of the aquifer and uses Darcy's law for fluid motion in association with buoyancy drive on the gas to determine the gas pressure variations along the aquifer as the lower end aquifer conditions are changed. Both overpressured and underpressured situations can arise, and are sensitive to the variation of parameters describing both the geometry and the physical conditions in the aquifer. Several illustrations are given to show how simple changes can cause different pressure conditions along the aquifer, making it difficult ahead of drilling to know which conditions prevail in a given tight gas sand aquifer.

scholarly journals The Boundary Conditions Governing Fluid Motions in Porous Media

1957 ◽  
Vol 10 (4) ◽  
pp. 587
Author(s):  
JR Philip
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Cross Section ◽  
Potential Distribution ◽  
Fluid Motion ◽  
Axial Flow ◽  
Stream Surface ◽  
Stated Condition ◽  
Equipotential Surfaces ◽  
Navier Equation

Further work has shown that the second of conditions (2.4) of a recent paper (Philip 1957?), supposed to govern the potential distribution during fluid motion in a porous medium, holds only for the case of linear axial flow in tubes of general cross section. The stated condition implied that the equipotential surfaces intersected the fluid-solid interface (a stream surface) normally. This may be approximately true for all media, but it can be shown by reference to the "complete" Stokes-Navier equation ((1.9) of Philip 1957) to be not exact in general. It follows that equation (2.8) and the thermal analogy (Section III) presented in that paper hold exactly for axial flow in tubes of general cross section, but are merely approximations when applied to more general media. Exact analysis for the general medium promises to be complicated and will not be pursued here.

Test Results for Sawtooth-Pattern Damper Seals: Leakage and Rotordynamic Coefficients

1987 ◽  
Vol 109 (1) ◽  
pp. 124-128 ◽  
Author(s):  
D. Childs ◽  
F. Garcia
Keyword(s):  
Cross Section ◽  
Fluid Motion ◽  
Transverse Force ◽  
Round Hole ◽  
Test Results ◽  
Damping Force ◽  
Force Coefficients ◽  
Rotordynamic Coefficients ◽  
Shaft Rotation

Test results consisting of direct and transverse force coefficients are presented for eleven, sawtooth-pattern, damper-seal configurations. The designation “damper” seal refers to a seal which uses a deliberately roughened stator and smooth rotor, as suggested by von Pragenau [1], to increase the net seal damping force. The designation “sawtooth-pattern” refers to a stator-roughness pattern whose cross section normal to the axis of the seal resembles saw teeth with the teeth direction opposing fluid motion in the direction of shaft rotation. The sawtooth pattern yields axial grooves in the stator which are interrupted by spacer elements which act as flow constrictions or “dams.” Sawtooth-pattern seals had more damping than smooth seals but less than the round-hole-pattern seals tested previously. Stiffness of sawtooth and round-hole-pattern seals were comparable. Leakage of maximum-damping configurations was greater for sawtooth-pattern than for round-hole-pattern seals; both types of seals leaked substantially less than did smooth seals. If damping is sacrificed, sawtooth-pattern seals can be designed to leak less than round-hole-pattern seals.

scholarly journals Evolution of Flow and Streaming in Exponential Variable Cross-Section Resonators

2020 ◽  
Vol 10 (5) ◽  
pp. 1694
Author(s):  
Heying Feng ◽  
Yehui Peng ◽  
Guangfu Bin ◽  
Yiping Shen
Keyword(s):  
Cross Section ◽  
Flow Direction ◽  
Kinetic Scheme ◽  
Variable Cross Section ◽  
Maximum Efficiency ◽  
Driving Mechanism ◽  
Variable Cross ◽  
Velocity Amplitude ◽  
Non Linear ◽  
Exponential Variable

A gas-kinetic scheme (GKS) based on an unstructured grid is applied to simulate the evolution of the fluid motions in exponential variable cross-section resonators. The effects of the acoustic field intensity on the oscillatory pressure, velocity, temperature, and flow streaming structure were investigated numerically, and the model was validated. The results demonstrate that the geometry and driving strength are the main factors affecting the final performance of the system. For the quasi-linear and moderate non-linear cases in optimum exponential tube, the periodic generation, evolution, and shedding of vortices in flow fields are associated with the storage and release of energy, which is the transmission mode of the third type of direct current (DC) flow, and its driving mechanism is attributed to the asymmetrical pressure and temperature. Meanwhile, some new physical characteristics were also discovered for the highly non-linear case, e.g., the disorder and unsteadiness of the flow direction accomplished with turbulent flow streaming structures. The secondary flow is manifested as multiscale, irregular and unsteady vortices throughout the tube. The smallest increment of pressure and velocity amplitude occurs concurrently with the biggest increment of temperature amplitude. These evidences suggest that there is an optimal driving strength, even for a good configuration tube, with which the maximum efficiency can be obtained.

Laboratory Simulation of a Factory Extrusion Process by the Die Swell Tester

1981 ◽  
Vol 54 (2) ◽  
pp. 439-448 ◽  
Author(s):  
Noboru Tokita
Keyword(s):  
Theoretical Analysis ◽  
Correlation Coefficient ◽  
Cross Section ◽  
Residence Time ◽  
Extrusion Process ◽  
Laboratory Simulation ◽  
Die Swell ◽  
Operation Temperature ◽  
D Values

Abstract The simulation principle (scaling) of the tire tubing process was studied by the “Die Swell Tester”. It was found that once the following three conditions were established, the die swells (ratio of extrudate to die cross section) of factory tubed extrudate were identical to lab scale DS results: namely, (1) same operation temperature, (2) same residence time in die, and (3) same ratio of die length to die diameter (L/D). In order to obtain the same L/D values between the complicated die shape of a factory tuber and the circular die of the DST, it is shown that the hydraulic radii (area/perimeters) must be kept the same. The correlation coefficient between factory extrudate properties and DST values was 99.6%. On the contrary, the Mooney torque ML1 + 4 values did not correlate with the die swell properties of the factory extrudates. Cold shrinkage of cut lengths of factory extrudates was simulated by the use of an extension control attachment to the DST. The theoretical analysis of potential recovery was established using die swell values and the stretch ratios. A good correlation between potential recovery (or total stretch) and cold shrinkage was obtained in both factory and laboratory samples.

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