NUMERICAL ANALYSIS OF THE EFFECTS OF STREAMLINING GEOMETRY AND A VECTOR WALL ON THE THERMAL AND FLUID FLOW IN A SRU THERMAL REACTOR

2016 ◽  
Vol 40 (5) ◽  
pp. 811-820 ◽  
Author(s):  
Chun-Lang Yeh
Keyword(s):  
Fluid Flow ◽  
Recirculation Zone ◽  
Skin Friction Coefficient ◽  
Peak Temperature ◽  
Thermal Reactor ◽  
Radius Of Curvature ◽  
Average Temperature ◽  
Compression Effect ◽  
High Temperature Operation ◽  
Optimal Radius

To resolve the abnormality of a SRU thermal reactor under high temperature operation and to improve the recovery of sulfur, the effects of streamlining geometry and a vector wall on the thermal and fluid flow in a SRU thermal reactor are investigated numerically. It is found that the compression effect caused by a streamlined zone 1 corner leads to an increase in the average temperature. However, the corner recirculation zone using a streamlined zone 1 corner becomes smaller and this yields a reduction in temperature. The combined effect of compression and a smaller corner recirculation zone leads to an optimal radius of curvature at the zone 1 corner. The lowest peak temperature is obtained using a radius of curvature 1m at the zone 1 corner. With larger radii of curvature at the zone 1 corner, the compression effect overwhelms the effect of a smaller corner recirculation zone and the peak temperature is higher. The specific arrangement of the vector wall holes results in a spiral motion behind the vector wall. The average temperature increases and becomes more uniform across a vector wall. The peak temperature and the exit sulfur concentration are higher using a vector wall. Finally, the skin friction coefficient increases abruptly across a vector wall but becomes lower downstream, compared with using a choke ring. The results of this paper are helpful in improving the performance and safety of a SRU thermal reactor.

EFFECTS OF CHOKE RING DIMENSION ON THERMAL AND FLUID FLOW IN A SRU THERMAL REACTOR

2016 ◽  
Vol 40 (4) ◽  
pp. 511-520 ◽  
Author(s):  
Chun-Lang Yeh
Keyword(s):  
Fluid Flow ◽  
Temperature Region ◽  
Oxygen Supply ◽  
Skin Friction Coefficient ◽  
Thermal Reactor ◽  
Sulfur Recovery ◽  
Sulfur Concentration ◽  
Average Temperature ◽  
The Rich ◽  
Lower Temperature

The effects of choke ring dimension on the thermal and fluid flow in a practical SRU (sulfur recovery unit) thermal reactor are investigated numerically. It is found that zone 1 is a higher temperature region. In contrast, zone 2 is a lower temperature region. The average temperature for the rich oxygen supply is higher than that of normal oxygen supply. Without a choke ring, the temperature difference between zone 1 and zone 2 is smaller and the temperature in zone 1 becomes lower while the temperature in zone 2 becomes higher. In addition, the average temperature in zone 1 and the sulfur concentration at exit are the lowest without a choke ring. The reactor with a choke ring height of 0.74 m has the lowest peak temperature and the largest sulfur concentration at exit. Finally, with a choke ring height of 1.11 m, the blockage effect of the choke ring leads to the largest peak skin friction coefficient.

THE EFFECTS OF INLET AIR QUANTITY AND INLET OXYGEN MOLE FRACTION ON THE COMBUSTION AND FLUID FLOW IN A SULFUR RECOVERY UNIT THERMAL REACTOR

2017 ◽  
Vol 41 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Chun-Lang Yeh
Keyword(s):  
Fluid Flow ◽  
High Temperature ◽  
Mole Fraction ◽  
Thermal Reactor ◽  
Sulfur Recovery ◽  
Economical Method ◽  
Sulfur Recovery Unit ◽  
Recovery Unit ◽  
Field Temperature ◽  
High Temperature Operation

Owing to the high temperature inside a sulfur recovery unit (SRU) thermal reactor, detailed experimental measurements are difficult. In the author’s previous studies, several methods have been assessed to resolve the abnormality of the SRU thermal reactor under high temperature operation. This paper presents a new easier and more economical method. The effects of inlet air quantity and inlet O2 mole fraction on the combustion and fluid flow in a SRU thermal reactor are investigated numerically. The flow field temperature, S2 recovery, H2S mole fraction, and SO2 emissions are analyzed. This paper provides a guideline for adjusting the inlet air quantity and the inlet O2 mole fraction to reduce the high temperature inside a thermal reactor and to ensure an acceptable sulfur recovery.

scholarly journals A novel formulation of 3D Jeffery fluid flow near an irregular permeable surface having chemical reactive species

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110136
Author(s):  
Mumtaz Khan ◽  
Amer Rasheed ◽  
Shafqat Ali ◽  
Qurat-ul-Ain Azim
Keyword(s):  
Fluid Flow ◽  
Variable Thickness ◽  
Mass Transfer Rate ◽  
Skin Friction Coefficient ◽  
Deborah Number ◽  
Pictorial Representation ◽  
Fluid Temperature ◽  
Flow Parameters ◽  
Opposite Behavior ◽  
Thickness Parameter

The main objective of this paper is to offer a comprehensive study regarding solar radiation and MHD effects on 3D boundary layer Jeffery fluid flow over a non-uniform stretched sheet along with variable thickness, porous medium and chemical reaction of first order are assumed. The system of equations representing temperature, velocity and concentration fields are converted into dimensionless form by introducing dimensionless variables. Thereafter, the aforesaid equations are solved with the help of BVP4C in MATLAB. The numerical results obtained through this scheme are more accurate when compared with those in the existing literature. In order to have a pictorial representation, the effects of material and flow parameters on velocity, temperature and concentration profiles are presented through graphs. Moreover, the numerical values of heat and mass transfer rate and skin friction coefficient are given in tabular form. It is evident from the acquired results, that the velocity offers two fold behavior for variable thickness parameter that is, n < 1 close and away from the non-uniform surface. It is also noted that the axial and transverse velocities show an increasing behavior for Deborah number while the fluid temperature and concentration shows opposite behavior at the same time.

Numerical Analysis on Flow Characteristics of Anti-Gravity Flow

2011 ◽  
Author(s):  
Yan Li ◽  
Shuchao Zhang ◽  
Ning Mei
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Flow Characteristics ◽  
Gravity Flow ◽  
Radius Of Curvature ◽  
Micro Channel ◽  
Subcooled Boiling ◽  
Evaporation Heat ◽  
Micro Channels

Fluid flow phenomena in micro channels received wide attention due to its high heat transfer coefficient. As a new technique in the field of micro channel phase-change heat transfer, anti-gravity flow can drive fluid flow by capillary force and create enhanced evaporation heat transfer conditions by promoting the formation of an extended meniscus in the three-phase contact-line region. Resulting from the circumferential discrepancy of degree of superheat, the radius of curvature of intrinsic meniscus decreases rapidly as liquid rising up, leading to the formation of capillary pressure gradient. With the increase of heat flux, subcooled boiling occurs and micro-bubble appears at the bottom of the fluted tube. Under the action of buoyancy and drag force, the bubble rises along the channel and at the same time grows continually for the presence of superheat until its break. This paper focuses on the numerical study of flow characteristics of anti-gravity flow in the micro channel and the influence of bubble under the subcooled boiling circumstance. The results shows that bubble plays a positive role in the formation of anti-gravity flow and the analytical expressions are presented for the rising velocity of liquid, the contact angle and the curvature of the intrinsic meniscus, which are all influenced by heat flux, superheat temperature and the geometric parameters of the channel.

Analysis on Relation between Mixing Ratio and Outlet Temperature and Velocity in a Cold-Hot-Water Mixer

2014 ◽  
Vol 13 (05n06) ◽  
pp. 1460005
Author(s):  
Leilei Wang
Keyword(s):  
Water Temperature ◽  
Recirculation Zone ◽  
Mass Conservation ◽  
Geometrical Model ◽  
Hot Water ◽  
Outlet Temperature ◽  
Mixing Ratio ◽  
Average Temperature ◽  
Nonlinear Relation ◽  
Fluent Software

To study the relation between cold-hot-water mixing ratio and outlet-water temperature of a mixer, the geometrical model of the mixer was built. On the basis of theoretical analysis, the outlet-water temperature with different mixing ratio of cold and hot water was simulated by FLUENT software. The results show that: flow field in mixer can be divided into recirculation zone and convection zone, in which there are different thermal resistances individually, and it result in the nonlinear relation in outlet average temperature and mixing ratio; there is a linear relation between outlet average velocity and mixing ratio, which accords to the mass conservation principle of non-compressible and continuous fluid flow.

Peak and Average Temperatures in Adiabatic Shear Band for Thermo-Viscoplastic Metal Materials

2007 ◽  
Vol 345-346 ◽  
pp. 133-136 ◽  
Author(s):  
X.B. Wang
Keyword(s):  
Strain Hardening ◽  
Peak Temperature ◽  
Strain Hardening Exponent ◽  
Flow Shear ◽  
Average Temperature ◽  
Softening Parameter ◽  
Static Yield ◽  
Flow Shear Stress ◽  
Microstructural Effect ◽  
Strain Rate Parameter

Gradient-dependent plasticity considering the microstructural effect is introduced into Johnson-Cook model to calculate the nonuniform temperature distribution in adiabatic shear band (ASB) and the evolutions of average and peak temperatures in ASB. Effects of initial static yield stress, strain-hardening coefficient, strain-hardening exponent, strain-rate parameter and thermal-softening parameter are numerically investigated. The calculated peak temperature in ASB considering both the plastic work and the microstructural effect is always greater than the average temperature calculated only using the plastic work. For much lower flow shear stress, the peak temperature approaches two times the average temperature. The occurrence of phase transformation in ASB is easier in metal material with higher initial static yield stress, strain-hardening coefficient, strain-rate parameter and thermal-softening parameter. At much lower flow shear stress or much higher average plastic shear strain, the phase transformation occurs more easily in material with a lower strain-hardening exponent. Traditional elastoplastic theory without the microstructural effect underestimates the peak temperature in ASB so that the experimentally observed phase transformations cannot be explained.

Flow and Heat Transfer Enhancement of Nanofluids in Microchannel With Blocks and Grooves

2013 ◽  
Author(s):  
Ping Li ◽  
Jianhui Chen ◽  
Huancheng Qu ◽  
Yonghui Xie ◽  
Di Zhang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Heat Transfer Enhancement ◽  
Energy Transport ◽  
Recirculation Zone ◽  
Volume Concentration ◽  
Flow Analysis ◽  
Transfer Enhancement ◽  
Flow And Heat Transfer

A code based on the lattice-Boltzmann method was programmed. At various Reynolds numbers, simulations of the Cu/water nanofluid flow structure and heat transfer performance in a two dimensional microchannel with blocks (Re = 10–100) and grooves (Re = 50–200) were conducted, and the factors affecting the flow and heat transfer were explored. The flow and heat transfer of nanofluids with nanoparticle volume concentration of 0.5%, 1.0%, 1.5% and 2.0% were simulated, obtaining the velocity and temperature distributions to compare with the results of base fluid. Flow analysis showed that recirculation zones formed behind the blocks and in the grooves when nanofluids flowed in the microchannel, and the size of recirculation zone increased with the increase of Reynolds number and nanoparticle volume concentration. The core of the recirculation zone in the groove gradually moved to the right wall as Reynolds number increased at the same nanoparticle volume concentration, and the direction of the main flow was getting horizontal. Heat transfer results indicated that the addition of nanoparticles could promote fluid flow and energy transport, so that the thermal boundary layer thickness decreased and the heat transfer was enhanced. The heat transfer enhancement increased with the increase of Reynolds number and nanoparticle volume concentration. It was also shown that the heat transfer enhancement by increasing the Reynolds number was limited. The results could give a fundamental understanding for designing highly efficient heat exchangers.

Free-Stream Turbulence Effects on Convex-Curved Turbulent Boundary Layers

1989 ◽  
Vol 111 (1) ◽  
pp. 66-72 ◽  
Author(s):  
S. M. You ◽  
T. W. Simon ◽  
J. Kim
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Turbulence Intensity ◽  
Free Stream ◽  
Skin Friction Coefficient ◽  
Radius Of Curvature ◽  
Free Stream Turbulence ◽  
Curvature Effects ◽  
Asymptotic Shape ◽  
Turbulence Effects

Free-stream turbulence intensity effects on a convex-curved turbulent boundary layer are investigated. An attached fully turbulent boundary layer is grown on a flat plate and is then introduced to a downstream section where the test wall is convexly curved, having a constant radius of curvature. Two cases, with free-stream turbulence intensities of 1.85 and 0.65 percent, are discussed. They were taken in the same facility and with the same strength of curvature, δ/R = 0.03−0.045. The two cases have similar flow conditions upon entry to the curve, thus separating the free-stream turbulence effects under study from other effects. The higher turbulence case displayed stronger curvature effects on the skin friction coefficient Cf, and on streamwise-normal and shear stress profiles, than observed in the lower turbulence case. Observations of this are: (1) As expected, the higher turbulence case has a higher Cf value ( ∼ 5 percent) upstream of the curve than does the lower turbulence case, but this difference diminishes by the end of the curve. (2) Streamwise turbulence intensity profiles, differing upstream of the curve for the two cases, are found to be similar near the end of the curve, thus indicating that the effect of curvature is dominating over the effect of free-stream turbulence intensity. Many effects of curvature observed in the lower turbulence intensity case, and reported previously, e.g., a dramatic response to the introduction of curvature and the rapid assumption of an asymptotic shape within the curve, are also seen in the higher turbulence case.

scholarly journals Non-similarity method for heat and mass transfer of MHD radiative flow over exponentially stretching sheet

2021 ◽  
pp. 309-309
Author(s):  
Muavia Mansoo ◽  
Yasir Nawa ◽  
Qazi ul-Hassan
Keyword(s):  
Mass Transfer ◽  
Fluid Flow ◽  
Heat And Mass Transfer ◽  
Stretching Sheet ◽  
Skin Friction Coefficient ◽  
Physical Parameters ◽  
Local Skin ◽  
Exponentially Stretching Sheet ◽  
Prandtl Numbers ◽  
Exponentially Stretching

In this paper a modification of existing mathematical model of MHD radiative incompressible fluid flow over exponentially stretching sheet is given by accumulating equation of mass transfer under an influence of chemical reaction. Using local non-similarity variables method, governing equations for heat and mass transfer of viscous fluid flow are efficiently remodeled into the system of dimensionless partial differential equations (PDEs), and later on the obtained system of dimensionless PDEs is tackled numerically using MATLbuilt in solver bvp4c. Graphs of temperature, velocity and concentration profiles are explained through variation of different values of physical parameters. Significant effects of several parameters, for example radiation and magnetic parameters, Eckert and Prandtl numbers on local skin-friction coefficient, local Nusselt and Sherwood numbers are computed in tabular form

scholarly journals SELECTION OF THE EXTERNAL WALL ROUNDING ANGLE OPTIMAL RADIUS

2021 ◽  
pp. 69-76
Author(s):  
Volodymyr Semko ◽  
Oleg Yurin ◽  
Natliia Mahas ◽  
Anastasiia Norka ◽  
Yevhen Pylypenko
Keyword(s):  
Heat Flow ◽  
Outer Surface ◽  
Internal Surface ◽  
Outer Wall ◽  
Mineral Wool ◽  
Temperature Fields ◽  
Radius Of Curvature ◽  
Outer Corner ◽  
Inner Surface ◽  
Optimal Radius

The article analyzes one of the ways to increase the heat-protective properties of thebuilding corner - rounding the outer surface of the outer wall the corner . The walls of houses nearthe outer corner, due to their configuration, have less heat-insulating properties than the walls inother areas. This is due to the fact that the area of heat flow perception on the inner surface of thewalls at an angle less than the area of heat transfer on the outer surface. Convective heat exchangenear the inner surface of the corner, due to the inhibition of air movement is less than in other areas,so the amount of heat coming from the indoor air to the wall surface is less. For climatic conditionsof Poltava region the research of temperature fields of calculated sections of the wall (withoutrounding of a corner, with rounding of a wall of various radius an external surface) with definitionof a heat stream size, the minimum temperature on an internal surface of a wall and the resulted heattransfer resistance is carried out. The dependences of the rounding radius of the wall outer surfaceon the heat flow passing through the design area of the wall outer corner, brick consumption withinthe design area, insulation consumption within the design area, the amount of room area reductiondue to rounding the wall for five design schemes. The analysis of dependences the constructed graphsshowed that the intensive reduction of the heat flux passing through the calculated section occurs ata radius of the wall outer surface rounding of 0.9 m and more; a slight decrease in the area of theroom due to the rounding of the wall occurs to a radius of curvature of 1.4 m; intensive reduction ofbrick volume within the calculated area occurs when the radius of curvature is more than 0.8 m,similarly to mineral wool up to 0.7 m. It is determined that the optimal radius of curvature of theouter wall is 0.8 m, it will increase the thermal properties of the angle and reduce the heat transfercoefficient by the transmission of the external enclosing structure of the building as a whole.

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