Dynamics of pressure drop oscillations during flow boiling inside minichannel

Grzybowski, Hubert; Mosdorf, Romuald

doi:10.1016/j.icheatmasstransfer.2018.03.025

Cited by 35 publications

(15 citation statements)

References 23 publications

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“…300 s) oscillations associated with the presence of compressible volumes in the tested system were observed. This observation was confirmed by other researchers [4,5]. Additionally, short-period density wave oscillations were superimposed on long-period pressure drop oscillations.…”

Section: Methodssupporting

confidence: 88%

“…Figure 6a,b shows the pressure drop oscillations of two neighboring minichannels. Figure 6c presents the results of the image analysis indicating the function SL (Equations (5) and (6)).…”

Section: Resultsmentioning

confidence: 99%

“…This occurs when instability of one type causes an oscillation that is overlapped by another oscillation caused by a different instability. Due to such a phenomenon, different types of flows were observed [5]. In the literature, instabilities were specified not only as flow instabilities but also as parallel channel instabilities.…”

Section: Introductionmentioning

confidence: 99%

“…The challenge considering the identification and description of boiling synchronization in a flow includes choosing an appropriate method for the stated task. Already, numerous approaches have been taken in order to analyze two-phase flow, such as nonlinear analysis [5,8,9], Eulerian space-time correlations [10], modeling [11,12], and image analysis [10,13,14]. The method mentioned last is based on processing frames registered by, for example, a high-speed camera, which presents a real-time image of the observed flow.…”

Section: Introductionmentioning

confidence: 99%

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Boiling Synchronization in Two Parallel Minichannels—Image Analysis

et al. 2020

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In this paper, the boiling synchronization of two-phase flow patterns in two parallel minichannels of 1 mm in diameter with connected compressible volumes was analyzed. The analysis was performed using images recorded with a high-speed camera. The degree of synchronization between channels was evaluated by assessing the presence of liquid flow in the small part of the minichannels. It can be concluded that boiling is synchronized when small bubble flow or wavy annular flow occur in neighboring channels. The occurrence of slug flow in one channel causes the boiling in neighboring channels to become unsynchronized. The result of the image analysis shows that the correlation coefficient based on the evaluation of the presence of liquid flow in the small part of the minichannels over a long enough time period allows for the detection of boiling synchronization.

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Section: Methodssupporting

confidence: 88%

“…Figure 6a,b shows the pressure drop oscillations of two neighboring minichannels. Figure 6c presents the results of the image analysis indicating the function SL (Equations (5) and (6)).…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Boiling Synchronization in Two Parallel Minichannels—Image Analysis

et al. 2020

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“…Moreover, the gas-liquid transition boundary for slug-wave and boiling wave flow was defined. Liu et al [21] used a combination of Lyapunov stability theory and numerical analysis to investigate dynamic features of excursive instability for forced two-phase boiling flow in a horizontal channel.In the previous paper [22], we used the combination of the windowed recurrence quantification analysis (RQA) and principal component analysis (PCA) to identify the occurrence of a dominant sequence of flow patterns. On the basis, conducted analysis to map of the dynamical properties of two-phase flow patterns was constructed.…”

mentioning

confidence: 99%

Boiling Flow Pattern Identification Using a Self-Organizing Map

Zaborowska¹,

Grzybowski²,

Mosdorf³

2020

Applied Sciences

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In the paper, a self-organizing map combined with the recurrence quantification analysis was used to identify flow boiling patterns in a circular horizontal minichannel with an inner diameter of 1 mm. The dynamics of the pressure drop during density-wave oscillations in a single pressure drop oscillations cycle were considered. It has been shown that the proposed algorithm allows us to distinguish five types of non-stationary two-phase flow patterns, such as bubble flow, confined bubble flow, wavy annular flow, liquid flow, and slug flow. The flow pattern identification was confirmed by images obtained using a high-speed camera. Taking into consideration the oscillations between identified two-phase flow patterns, the four boiling regimes during a single cycle of the long-period pressure drop oscillations are classified. The obtained results show that the proposed combination of recurrence quantification analysis (RQA) and a self-organizing map (SOM) in the paper can be used to analyze changes in flow patterns in non-stationary boiling. It seems that the use of more complex algorithms of neural networks and their learning process can lead to the automation of the process of identifying boiling regimes in minichannel heat exchangers.

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Image Analysis of Flow Maldistribution during Boiling in Parallel Minichannels

et al. 2021

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The boiling flow of distilled water with reverse flow in three parallel, rectangular, horizontal minichannels was investigated. The analyzed data was in the form of a set of video frames. An image analysis and statistical analysis of changes of pixel brightness in minichannels was conducted. A self-organizing process was identified for short slug flow in neighboring minichannels. The identified synchronization process was accompanied by the increase in standard deviation of pixel brightness changes. The process of synchronization was observed for short slugs, but not for long slugs. It can be concluded that the synchronization of heat and mass transfer in minichannels can be achieved when the character of two-phase flow patterns in each channel is not fully blocking the flow.

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Dynamics of pressure drop oscillations during flow boiling inside minichannel

Cited by 35 publications

References 23 publications

Boiling Synchronization in Two Parallel Minichannels—Image Analysis

Boiling Synchronization in Two Parallel Minichannels—Image Analysis

Boiling Flow Pattern Identification Using a Self-Organizing Map

Image Analysis of Flow Maldistribution during Boiling in Parallel Minichannels

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