Measurement of Local Mass Transfer Distribution in a Large Diameter S-Bend at High Reynolds Number

2014 ◽  
Author(s):  
D. Wang ◽  
D. Ewing ◽  
T. Le ◽  
C. Y. Ching
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Mass Transfer Rate ◽  
Large Diameter ◽  
High Mass ◽  
Flow Loop ◽  
Local Mass ◽  
Common Coordinate System ◽  
Local Mass Transfer ◽  
High Reynolds

The local mass transfer in a 203mm diameter back to back bend arranged in a S-configuration was measured at a Reynolds number of 300,000. A dissolving wall method using gypsum dissolution to water at 40°C was used, with a Schmidt number of 660. The experiment was performed in a flow loop by flowing water through the test section. The topography of the unworn and the worn inner surface was quantified using nondestructive X-ray Computed Tomography (CT) scans. The two scanned surfaces were aligned to a common coordinate system using commercial software and in-house routines. The local mass transfer rate was obtained from the local change in radius over the flow time. Two regions of high mass transfer were present: (i) along the intrados of the first bend near the inlet and (ii) at the exit of the extrados of the first bend that extends to the intrados of the second bend. The latter was the region of highest mass transfer in the S-bend.

Measurement of Local Mass Transfer and the Resulting Roughness in a Large Diameter S-Bend at High Reynolds Number

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
D. Wang ◽  
D. Ewing ◽  
T. Le ◽  
C. Y. Ching
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Mass Transfer Rate ◽  
Large Diameter ◽  
Reynolds Numbers ◽  
High Mass ◽  
Local Mass ◽  
Roughness Elements ◽  
Local Mass Transfer ◽  
High Reynolds

The local mass transfer and the resulting roughness in a 203 mm diameter back-to-back bend arranged in an S-configuration were measured at a Reynolds number of 300,000. A dissolving wall method using gypsum dissolution to water at 40 °C was used, with a Schmidt number of 660. The topography of the unworn and worn inner surface was quantified using nondestructive X-ray computed tomography (CT) scans. The local mass transfer rate was obtained from the local change in radius over the flow time. Two regions of high mass transfer were present: (i) along the intrados of the first bend near the inlet and (ii) at the exit of the extrados of the first bend that extends to the intrados of the second bend. The latter was the region of highest mass transfer, and the scaling of the maximum Sherwood number with Reynolds number followed that developed for lower Reynolds numbers. The relative roughness distribution in the bend corresponded to the mass transfer distribution, with higher roughness in the higher mass transfer regions. The spacing of the roughness elements in the upstream pipe and in the two regions of high mass transfer was approximately the same; however, the spacing-to-height ratio was very different with values of 20, 10, and 6, respectively.

The Effect of Naturally Developing Roughness on the Mass Transfer in Pipes Under Different Reynolds Numbers

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
D. Wang ◽  
D. Ewing ◽  
C. Y. Ching
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Initial Period ◽  
Reynolds Numbers ◽  
Multiple Time ◽  
Transfer Enhancement ◽  
Flow Loop ◽  
Local Mass ◽  
Mass Transfer Enhancement ◽  
Local Mass Transfer

The local mass transfer over dissolving surfaces was measured at pipe Reynolds number of 50,000, 100,000, and 200,000. Tests were run at multiple time periods for each Reynolds number using 203 mm diameter test sections that had gypsum linings dissolving to water in a closed flow loop at a Schmidt number of 1200. The local mass transfer was calculated from the decrease in thickness of the gypsum lining that was measured using X-ray-computed tomography (CT) scans. The range of Sherwood numbers for the developing roughness in the pipe was in good agreement with the previous studies. The mass transfer enhancement (Sh/Shs) was dependent on both the height (ep−v) and spacing (λstr) of the roughness scallops. For the developing roughness, two periods of mass transfer were present: (i) an initial period of rapid increase in enhancement when the density of scallops increases till the surface is spatially saturated with the scallops and (ii) a slower period of increase in enhancement beyond this point, where the streamwise spacing is approximately constant, and the roughness height grows more rapidly. The mass transfer enhancement was found to correlate well with the parameter (ep−v/λstr)0.2, with a weak dependence on Reynolds number.

scholarly journals Simultaneous measurements of thickness and local mass transfer rate on falling liquid films.

1979 ◽  
Vol 12 (6) ◽  
pp. 483-485
Author(s):  
RYUZO ITO ◽  
KAORU TOMURA ◽  
MASAO YAMAMOTO ◽  
YUKIE OKADA ◽  
NOBUHIRO TSUBOI ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Liquid Films ◽  
Local Mass ◽  
Simultaneous Measurements ◽  
Local Mass Transfer ◽  
Falling Liquid Films

Effect of Flow Angle-of-Attack on the Local Heat/Mass Transfer From a Wall-Mounted Cube

1994 ◽  
Vol 116 (3) ◽  
pp. 552-560 ◽  
Author(s):  
V. Natarajan ◽  
M. K. Chyu
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Angle Of Attack ◽  
Convective Transport ◽  
Stream Velocity ◽  
Flow Angle ◽  
Local Study ◽  
Local Mass ◽  
Local Mass Transfer

An experimental study of the local mass transfer over the entire surface of a wall-mounted cube is performed with a particular emphasis on the effects of flow angles-of-attack (0 deg ≤ α ≤ 45 deg). Invoking an analogy between heat transfer and mass transfer, the presently obtained mass transfer results can be transformed into their heat transfer counterparts. Reynolds number based on the cube height and mean free-stream velocity varies between 3.1 × 104 and 1.1 × 105. To substantiate the mass transfer results, streakline patterns are visualized on the cube surfaces as well as the endwall using the oil-graphite technique. Significantly different flow regimes and local mass transfer characteristics are identified as the angle-of-attack varies. The overall convective transport is dominated by three-dimensional flow separation that includes multiple horseshoe vortex systems and an arch-shaped vortex wrapping around the rear portion of the cube. In addition to the local study, power correlations between the surface-resolved mass transfer Sherwood number and the Reynolds number are presented for all α values studied. Mass transfer averaged over the entire cube is compared with that of its two-dimensional counterpart with crossflow around a tall prism.

Experimental Investigations of Couette-Taylor-Poiseuille Flows Using the Electro-Diffusional Technique

2016 ◽  
Author(s):  
Emna Berrich ◽  
Fethi Aloui ◽  
Jack Legrand
Keyword(s):  
Mass Transfer ◽  
Shear Rate ◽  
Mass Transfer Rate ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Wall Shear Rate ◽  
Experimental Investigations ◽  
Local Mass ◽  
Local Mass Transfer ◽  
Wall Shear

Couette-Taylor-Poiseuille flow CTPF consists on the superposition of Couette-Taylor flow to an axial flow. The CTPF flow hydrodynamics studies remain rather qualitative or numerical or are restricted to relatively low Taylor and/or axial Reynolds numbers. For more comprehensive and control of CTPF, especially for relatively high Taylor numbers and high axial Reynolds numbers, we investigated experimentally CTF with and without an axial flow, using the electro-diffusion ED method. This technique requires the use of Electro-Diffusion ED probe which allows the determination of the local mass transfer rate from the Limiting Diffusion current measurement delivered by the ED probe while it is polarized by a polarization voltage. From the local mass transfer (the Sherwood number), we determined the wall shear rate using different approaches. The results illustrate that low axial flow can generate a stabilizing effect on the CT flow. The time-evolutions of the local mass transfer and the wall shear rate are periodic. These evolutions characterize the waviness or the stretching of the vortices. However, Taylor Wavy Vortex Flow TWVF is destabilized under the effect of relatively important axial flow. The time-evolutions of wall shear rate are no longer periodic. Indeed, Taylor vortices are overlapped or completely destructed.

Effects of Surface Roughness and Bend Geometry on Mass Transfer in an S-Shaped Back to Back Bend at Reynolds Number of 200,000

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
D. Wang ◽  
D. Ewing ◽  
C. Y. Ching
Keyword(s):  
Mass Transfer ◽  
Surface Roughness ◽  
Reynolds Number ◽  
Local Development ◽  
High Mass ◽  
Transfer Enhancement ◽  
Flow Loop ◽  
Geometry Effect ◽  
Mass Transfer Enhancement ◽  
Spacing Ratio

Experiments were performed to investigate the local development of roughness and its effect on mass transfer in an S-shaped bend at Reynolds number of 200,000. The tests were performed over four consecutive time periods using a 203-mm-diameter test section with a dissolving gypsum lining to water in a closed flow loop at a Schmidt number of 1200. The surface roughness and the mass transfer over the test periods were measured using X-ray computed tomography (CT) scans of the surface. Two regions of high mass transfer are found: along the intrados of the first and second bends. The surface roughness in these two regions, characterized by the height-to-spacing ratio, grows more rapidly than in the upstream pipe. There is an increase in the mass transfer with time, which corresponds well with the local increase in the height-to-spacing ratio of the roughness. The two regions of high mass transfer enhancement in the bend can be attributed to both a roughness effect and a flow effect due to the bend geometry. The geometry effect was determined by normalizing the local mass transfer with that in a straight pipe with equivalent surface roughness. The mass transfer enhancement due to the geometry effect was found to be relatively constant for the two high mass transfer regions, with a value of approximately 1.5.

scholarly journals Mass transfer control of a backward-facing step flow by local forcing-effect of Reynolds number

2011 ◽  
Vol 15 (2) ◽  
pp. 367-378 ◽  
Author(s):  
Zouhaier Mehrez ◽  
Mourad Bouterra ◽  
Cafsi El ◽  
Ali Belghith ◽  
Quere Le
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Reynolds Numbers ◽  
Backward Facing Step ◽  
Local Mass ◽  
Eddy Simulation ◽  
Local Forcing ◽  
Large Eddy ◽  
Local Mass Transfer ◽  
Oscillating Jet

The control of fluid mechanics and mass transfer in separated and reattaching flow over a backward-facing step by a local forcing, is studied using Large Eddy Simulation (LES). To control the flow, the local forcing is realized by a sinusoidal oscillating jet at the step edge. The Reynolds number is varied in the range 10000 ? Re ? 50000 and the Schmidt number is fixed at 1. The found results show that the flow structure is modified and the local mass transfer is enhanced by the applied forcing. The observed changes depend on the Reynolds number and vary with the frequency and amplitude of the local forcing. For the all Reynolds numbers, the largest recirculation zone size reduction is obtained at the optimum forcing frequency St = 0.25. At this frequency the local mass transfer enhancement attains the maximum.

Local Mass Transfer From Rotating Wedge-Shaped Blades

1977 ◽  
Vol 99 (4) ◽  
pp. 634-640 ◽  
Author(s):  
H. Koyama ◽  
A. Nakayama ◽  
K. Sato ◽  
T. Shimizu
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Pressure Gradient ◽  
Sherwood Number ◽  
Negative Pressure ◽  
Local Mass ◽  
Contour Lines ◽  
Local Mass Transfer ◽  
Theoretical Considerations ◽  
Local Sherwood Number

The purpose of this investigation is to determine the mass transfer from rotating wedge-shaped blades in an air environment. Through theoretical considerations, effect of negative pressure gradient has been emphasized wherever possible. The experimental results are correlated with local Sherwood number and Reynolds number. Furthermore, a new method has been proposed to judge the flow type by reading directly the slope of contour lines of equal sublimation drawn on the surface.

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