Climbing film, flooding and falling film behavior in upflow condensation in tubes

Park, Ilchung; Mudawar, Issam

doi:10.1016/j.ijheatmasstransfer.2013.05.065

Cited by 22 publications

(10 citation statements)

References 56 publications

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“…Many prior studies have investigated boiling through a variety of mechanisms, including capillary-driven devices [2][3][4], pool boiling thermosyphons [5][6][7], falling film [8,9], channel flow boiling [10,11], micro-channel boiling [12][13][14][15][16], jet impingement [17][18][19][20], and spray [21][22][23][24][25][26][27], as well as hybrid configurations [28][29][30][31] involving two or more of these schemes. Similarly, condensation has been investigated in several configurations, including falling film [32][33][34], flow through single circular mini-channels [35][36][37][38][39][40][41], and flow through parallel micro-channel arrays [42][43][44]. A common deficiency found across most studies on condensation, however, is lack of emphasis on transient flow behavior and analysis of potential instability modes brought on by the condensation process.…”

Section: Importance Of Flow Condensation Dynamic Behaviormentioning

confidence: 99%

“…Flow visualization images corresponding to vertical upflow orientation were not captured using CM-FV due to time constraints on testing, but to present representative behavior for similar operating conditions, Fig. 17 has been adapted from the work of Park and Mudawar [40]. Their work involved investigation of vertical upflow condensation using FC-72 as working fluid in a smooth circular tube with comparable hydraulic diameter and condensation length to that used in the present study.…”

Section: Relationship To Observed Interfacial Behaviormentioning

confidence: 99%

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Flow condensation pressure oscillations at different orientations

O’Neill

Mudawar

Hasan

et al. 2018

International Journal of Heat and Mass Transfer

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Investigation of two-phase flow dynamic behavior and instabilities has traditionally centered on phenomena present in boiling flows due to the safety critical nature of boiling in a variety of cooling applications. Analysis of pressure signals in condensing systems reveal the presence of relevant oscillatory phenomena during flow condensation as well, which may impact performance in applications concerned with precise system control. Towards this end, the present study presents results for oscillatory behavior observed in pressure measurements during flow condensation of FC-72 in a smooth circular tube in vertical upflow, vertical downflow, and horizontal flow orientations. Dynamic behavior observed within the test section is determined to be independent of other components within the flow loop, allowing it to be isolated and interpreted as resulting from physical aspects of two-phase flow with condensation. The presence of a peak oscillatory mode (one of significantly larger amplitude than any others present) is seen for 72% of vertical upflow test cases, 61% of vertical downflow, and 54% of horizontal flow. Relative intensities of this peak oscillatory mode are evaluated through calculation of Q Factor for the corresponding frequency response peak. Frequency and amplitude of peak oscillatory modes are also evaluated. Overall, vertical upflow is seen to exhibit the most significant oscillatory behavior, although in its maximum case amplitude is only seen to be 7.9% of time-averaged module inlet pressure, indicating there is little safety risk posed by oscillations under current operating conditions. Flow visualization image sequences for each orientation are also presented and used to draw parallels between physical characteristics of condensate film behavior under different operating conditions and trends in oscillatory behavior detected in pressure signals.

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Section: Importance Of Flow Condensation Dynamic Behaviormentioning

confidence: 99%

Section: Relationship To Observed Interfacial Behaviormentioning

confidence: 99%

Flow condensation pressure oscillations at different orientations

O’Neill

Mudawar

Hasan

et al. 2018

International Journal of Heat and Mass Transfer

Self Cite

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“…The second integration of eq. (7) with respect to the variable r allows us to recover unknown functions: (8) where D, E and F are integration constants. All integration constants have to be determined from the boundary conditions (5).…”

Section: Mathematical Model Of the Flowmentioning

confidence: 99%

“…The amplitude of the waves can grow rapidly under certain conditions, the surface becomes unstable. As a result, the channel can go into a flooding regime [8].…”

Section: Introductionmentioning

confidence: 99%

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Axisymmetric laminar flow of two-phase medium inside the system of two coaxial pipes

Кузменко¹,

Gourjii²

2018

energetika

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The problem of the axisymmetric laminar flow of a two-phase (liquid-gas) flow inside the infinite system of coaxial tubes with a circular cross-section located vertically is considered. Analysis of the analytical solution showed that increase in velocity of the gas flow leads to the appearance of the hold-up regime (then the velocity of media at the interface is zero) and flooding regime (when volume flow of liquid is zero). It is discovered that these regimes occur at lower values of the velocity of the gas flow for the heated medium in comparison with the cold medium.

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