Numerical investigation of the interaction between local flow structures and particulate fouling on structured heat transfer surfaces

Kasper, Robert; Deponte, Hannes; Michel, A.; Turnow, Johann; Augustin, Wolfgang; Scholl, Stephan; Kornev, Nikolaĭ

doi:10.1016/j.ijheatfluidflow.2018.03.002

Cited by 20 publications

(9 citation statements)

References 30 publications

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“…Spherical dimples are hypothesized to suppress the deposition of particles from a liquid stream or even to induce a permanent cleaning of the surface. In addition to the numerical studies by Kasper et al [19] and the experimental studies by Deponte et al [8], the self-cleaning effect can be observed in the present study with locally resolved fouling resistances. Furthermore, the PFQ method provides insights into the dimple itself.…”

Section: Evaluation Of the Pfq Methodssupporting

confidence: 74%

“…Dimpled surfaces provide a local pattern for the fouling deposit due to the self-cleaning effect described by Kasper et al [19]. Kasper et al observed a trail downstream from the dimple, with a decreased particle deposit on the surface inside the trail in comparison to the area upstream of the dimple (see Fig.…”

Section: Test Platesmentioning

confidence: 89%

“…The characteristic fouling pattern, observed in previous studies, is visible and quantifiable by the PFQ results. Figure 10 shows the results of the numerical investigation [19]. Viz, the trail downstream of the dimple is made visible with the numerical calculation, as well as with the PFQ method.…”

Section: Evaluation Of the Pfq Methodsmentioning

confidence: 97%

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Development of a quantification method for fouling deposits using phosphorescence

2021

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Particulate fouling on structured surfaces is typically quantified using the integral thermal or mass-based fouling resistance. The observed geometries may be structures that can improve the heat transfer in heat exchangers (e.g., dimples), cavities in components, or more complex geometries. However, due to limited accessibility or the requirement for a locally resolved measurement, the existing quantification methods may not be applicable to structured surfaces. For this reason, a new method is needed for the quantification for fouling deposits. In this study, dimpled surfaces were evaluated by measuring the integral thermal and mass-based fouling resistance and comparing it with the local fouling resistance inside and around the dimple. This comparison was carried out online with the Phosphorescent Fouling Quantification method developed for this purpose, using phosphorescent particles to quantify the deposited mass. The mass-based fouling resistance can be calculated using computer-aided image analysis. The measurements for the evaluation were conducted on dimpled surfaces, which produced a characteristic fouling pattern. With the new method a reduced surface coverage from up to 33.3 % was observed, which led to lower fouling resistances downstream of the dimple compared to a plain surface. These results confirm earlier numerical and experimental findings, suggesting an advantage of dimpled surfaces over other surface structures with respect to thermo-hydraulic efficiency as well as reduced fouling. Thus, the Phosphorescent Fouling Quantification method provides the possibility of calculating values for local fouling resistances on structured surfaces, as well as the possibility of optimizing surface structures to minimize fouling propensity.

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Section: Evaluation Of the Pfq Methodssupporting

confidence: 74%

Section: Test Platesmentioning

confidence: 89%

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Development of a quantification method for fouling deposits using phosphorescence

2021

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“…Xu et al [20] studied the submicron particle deposition on a semi-circular structured surface and suggested that the recirculation wake is the main mechanism for more particle deposition. Kasper et al [21,22] developed numerical models with the capability of studying particle deposition on structured surfaces from turbulent liquid flow, and the predicted particle deposition agrees with their experimental study. More computational studies for particle transport and deposition are given in the review paper by Guha [4].…”

Section: Introductionmentioning

confidence: 64%

Effect of Surface Topography on Particle Deposition from Liquid Suspensions in Channel Flow

Zaw¹,

Zhu²,

Ma³

2020

Fluids

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A Eulerian—Lagrangian model has been developed to simulate particle attachment to surfaces with arc-shaped ribs in a two-dimensional channel flow at low Reynolds numbers. Numerical simulation has been performed to improve the quantitative understanding of how rib geometries enhance shear rates and particle-surface interact for various particle sizes and flow velocities. The enhanced shear rate is attributed to the wavy flows that develop over the ribbed surface and the weak vortices that form between adjacent ribs. Varying pitch-to-height ratio can alter the amplitude of the wavy flow and the angle of attack of the fluid on the ribs. In the presence of these two competing factors, the rib geometry with a pitch-to-height ratio of two demonstrates the greatest shear rate and the lowest fraction of particle attachment. However, the ribbed surfaces have negligible effects on small particles at low velocities. A force analysis identifies a threshold shear rate to reduce particle attachment. The simulated particle distributions over the ribbed surfaces are highly non-uniform for larger particles at higher velocities. The understanding of the effect of surface topography on particle attachment will benefit the design of surface textures for mitigating particulate fouling in a wide range of applications.

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“…Действительное 1 обтекание глубоких сферических лунок без управления является нестационарным и имеет характер нерегулярных переходов между несимметричными метастабильными состояниями течения. Недавние LES-расчеты [6] явно указывают на то, что доминирующую часть времени при обтекании глубокой лунки занимают два состояния течения с наклонным одноядерным вихрем, который спонтанно изменяет свою ориентацию внутри углубления относительно направления внешнего потока. Этот нестационарный переключательный режим принципиально не может быть воспроизведен в рамках вычислительной технологии URANS.…”

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Метастабильные Отрывные Структуры При Турбулентном Обтекании Круглых И Овальных Лунок

Гувернюк¹,

Чулюнин²

2019

Письма В Журнал Технической Физики

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At present paper, mechanisms which determine turbulent separated flow structures inside oval-trench dimples are described. In cases of short trenches, includes the semi-spherical dimple, three regimes exist: symmetrical and two mono-core asymmetrical. It should be noted, asymmetrical regimes are metastable, while the symmetrical regime is unstable. Therefore, for short dimples, an actual flow pattern has an unsteady nature, which is characterized by switching between two mono-cores vortex structures. With an increase in the length of dimples, the symmetrical regime becomes a stable and an actual flow pattern has a quasi-steady character. Further increase of dimple's length produces more complex flow topology with persisting of the quasi-steady nature.

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Numerical investigation of the interaction between local flow structures and particulate fouling on structured heat transfer surfaces

Cited by 20 publications

References 30 publications

Development of a quantification method for fouling deposits using phosphorescence

Development of a quantification method for fouling deposits using phosphorescence

Effect of Surface Topography on Particle Deposition from Liquid Suspensions in Channel Flow

Метастабильные Отрывные Структуры При Турбулентном Обтекании Круглых И Овальных Лунок

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