The Visualisation of Mass Transfer Rate Around a Sphere

1964 ◽  
Vol 68 (638) ◽  
pp. 137-139 ◽  
Author(s):  
K. Lee ◽  
H. Barrow ◽  
D. J. Ryley
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Large Scale ◽  
Mass Transfer Rate ◽  
Droplet Surface ◽  
Scale Model ◽  
Flow Visualisation ◽  
Local Mass ◽  
Large Scale Model ◽  
Local Mass Transfer

The purpose of this note is to report the results of an experimental investigation which was conducted to permit the local mass transfer rate around a sphere to be visualised. The present problem of mass transfer from a sphere had its origin in a study of the evaporation of a water droplet in a superheated steam atmosphere. Because of the small physical size of the droplet and the difficulty of measuring local mass transfer rates from the droplet surface, it was necessary to employ a large scale model to study local transfer rate around a sphere. It was considered that flow visualisation would afford at least a qualitative result of local mass transfer rate. In fluid mechanics studies, the flow visualisation techniques are well known. Such methods include the use of smoke filaments, tufts, or chemical coatings and so forth to provide information about the state of boundary layer over a solid surface, fluid particle paths and state of flow.

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

Large-scale energetic coherent structures and their effects on wall mass transfer rate behind orifice in round pipe

2021 ◽  
Vol 927 ◽  
Author(s):  
F. Shan ◽  
S.Y. Qin ◽  
Y. Xiao ◽  
A. Watanabe ◽  
M. Kano ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Flow Field ◽  
Coherent Structures ◽  
Transfer Rate ◽  
Large Scale ◽  
Mass Transfer Rate ◽  
Low Frequency ◽  
Stochastic Estimation ◽  
Transfer Rates ◽  
Wall Mass

This paper first uses a low-speed stereoscopic particle image velocimetry (SPIV) system to measure the convergent statistical quantities of the flow field and then simultaneously measure the time-resolved flow field and the wall mass transfer rate by a high-speed SPIV system and an electrochemical system, respectively. We measure the flow field and wall mass transfer rate under upstream pipe Reynolds numbers between 25 000 and 55 000 at three specific locations behind the orifice plate. Moreover, we apply proper orthogonal decomposition (POD), stochastic estimation and spectral analysis to study the properties of the flow field and the wall mass transfer rate. More importantly, we investigate the large-scale coherent structures’ effects on the wall mass transfer rate. The collapse of the wall mass transfer rates’ spectra by the corresponding time scales at the three specific positions of orifice flow suggest that the physics of low-frequency wall mass transfer rates are probably the same, although the flow fields away from the wall are quite different. Furthermore, the spectra of the velocity reconstructed by the most energetic eigenmodes agree well with the wall mass transfer rate in the low-frequency region, suggesting that the first several energetic eigenmodes capture the flow dynamics relevant to the low-frequency variation of the wall mass transfer. Stochastic estimation results of the velocity field associated with large wall mass transfer rate at all three specific locations further reveal that the most energetic coherent structures are correlated with the wall mass transfer rate.

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.

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.

Study on self-purification capacity for organic pollutants in stagnant water

2002 ◽  
Vol 46 (9) ◽  
pp. 137-146 ◽  
Author(s):  
M. Saito ◽  
Y. Magara ◽  
Wisjnuprapto
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Large Scale ◽  
Oxygen Supply ◽  
Mass Transfer Rate ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Polluted Water ◽  
Small Water

Polluted water is abandoned or stored untreated in many places. Especially, small water bodies such as ditches, ponds, wastewater tanks, etc. have not yet well been considered. The self-purification stabilizes the wastewater, but oxygen supply limits the biodegradation process. In the natural environment, approximately 3 g oxygen can be dissolved per m2 per day if the water is completely deprived from dissolved oxygen; this is the magnitude of self-purification capacity. To improve the quality of polluted water with higher oxygen demand than natural reaeration capacity, enhanced aeration is required. The laboratory experiment disclosed that water trickling onto the water surface or shallow stirring of water less than 10 mm in depth increased the mass transfer rate significantly. At the same time, the methods were found more efficient than bubbling aeration of large-scale treatment plant in terms of energy input against oxygen supply. Though it is an efficient method, elaborate application will be necessary since the mass transfer rate is not as high as bubbling aeration.

Determining and Modeling Mass-Transfer Rate Limitations in Heterogeneous Aquifers

1992 ◽  
Vol 26 (1-2) ◽  
pp. 71-77 ◽  
Author(s):  
T. C. Harmon ◽  
P. V. Roberts
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Large Scale ◽  
Mass Transfer Rate ◽  
Pilot Scale ◽  
Transport Models ◽  
Heterogeneous Aquifers ◽  
Aquifer Systems ◽  
Volatile Organic Chemicals ◽  
Rate Limiting

This work focuses on assessing mass-transfer rate limitations on the transport of aqueous phase volatile organic chemicals (VOCs) in real aquifer systems. The rate limiting mechanism is considered as diffusion through immobile regions of a porous medium, i.e., through intra-particle, intra-aggregate, intra-layer pores, or through a series of such zones. Sorption/desorption studies are reviewed for two experimental aquifers: the large-scale, relatively homogeneous Borden site, and the pilot-scale, relatively heterogeneous Moffett site. The flame-sealed ampule method, with accompanying intermittent purge, is discussed with respect to supplying diffusion rate parameters for homogeneous and heterogeneous solute transport models.

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