A modified bubble dynamics model for predicting bubble departure diameter on micro-pin-finned surfaces under microgravity

Zhou, Jie; Zhang, Yonghai; Wei, Jinjia

doi:10.1016/j.applthermaleng.2017.12.113

Cited by 34 publications

(9 citation statements)

References 35 publications

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“…Coalescence events in microgravity may also cause lateral reversals of bubble motion, thus encouraging lateral detachment from microelectrodes 63 . The importance of bubble-bubble interaction for bubble detachment on a micro-pin-finned electrode was also discussed by Zhou et al (2018) in subcooled pool boiling experiments 66 .…”

Section: Electrode Wettability and Bubble Departurementioning

confidence: 99%

Electrolysis in reduced gravitational environments: current research perspectives and future applications

et al. 2022

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Electrochemical energy conversion technologies play a crucial role in space missions, for example, in the Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS). They are also vitally important for future long-term space travel for oxygen, fuel and chemical production, where a re-supply of resources from Earth is not possible. Here, we provide an overview of currently existing electrolytic energy conversion technologies for space applications such as proton exchange membrane (PEM) and alkaline electrolyzer systems. We discuss the governing interfacial processes in these devices influenced by reduced gravitation and provide an outlook on future applications of electrolysis systems in, e.g., in-situ resource utilization (ISRU) technologies. A perspective of computational modelling to predict the impact of the reduced gravitational environment on governing electrochemical processes is also discussed and experimental suggestions to better understand efficiency-impacting processes such as gas bubble formation and detachment in reduced gravitational environments are outlined.

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Section: Electrode Wettability and Bubble Departurementioning

confidence: 99%

Electrolysis in reduced gravitational environments: current research perspectives and future applications

et al. 2022

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“…This assumption, while not always clearly stated, seems to be at the basis of other force balance models appearing in the literature (e.g., see Refs. [5][6][7][8][9][10][11][12][13][14][15][16]). However, experimental investigations of quasi-static gas bubbles ejection from orifices (e.g.,…”

Section: Force Definition Modelmentioning

confidence: 99%

“…In summary, there is no shortage of such models in the literature (e.g., see also Refs. [9][10][11][12][13][14][15][16]).…”

Section: Introductionmentioning

confidence: 99%

The not-so-subtle flaws of the force balance approach to predict the departure of bubbles in boiling heat transfer

2021

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We present a critical evaluation of the force balance approach in predicting the departure of rapidly growing bubbles from a boiling surface. To this end, we conduct separate effect bubble growth experiments in a carefully controlled environment. We use high-speed video to quantify experimentally all the external forces acting on a growing bubble through the profile of the liquid-vapor interface. Our experimental data show that the momentum conservation equation is always rigorously satisfied, as it should, if the various forces are precisely quantified. However, based on our analysis and our observations, we come to the conclusion that force balance models cannot be either robust or accurate for the purpose to predict bubble departure. They are not robust because the rate of change of the bubble momentum, i.e., the key quantity that force balance models aim at evaluating as the sum of the external forces, is orders of magnitude smaller than each of the force terms in the momentum conservation equation throughout the entire bubble life cycle. Thus, the slightest error on one of the external forces leads to very different predictions for bubble departure. The approach is also not accurate because the analytical expressions used to estimate the external forces are riddled with questionable assumptions (e.g., on the bubble growth rate, added mass coefficient, contact line length, and contact angle) and uncertainties that are, once again, orders of magnitude larger than the rate of change of the bubble momentum itself.

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“…Cao et al 32 studied heat transfer through pool boiling of FC‐72 around a pin‐fin silicon surface and found the enhancement of heat transfer around the micro‐pin‐fin surface rather than the smooth surface. Zhou et al 33 developed a bubble dynamics model to anticipate the diameter of bubble departure on the micro‐pin‐fin surface under microgravity. In another experiment Zhang et al 34 experimentally analyzed the improvement of pool‐boiling heat transfer through micro‐pin–finned surfaces.…”

Section: Experimental Studiesmentioning

confidence: 99%

Improvement of heat transfer through fins: A brief review of recent developments

Maji¹,

Choubey

2020

Heat Trans

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Fins or extended surfaces are generally used in heat exchangers to enhance heat transfer between the main surface and ambient fluid. Various types of simple-shaped fins, namely, rectangular, square, annular, cylindrical, and tapered, have been used with different geometrical combinations. To satisfy industrial demand, different trials have also been carried out for designing optimized fins. The optimization of fins can be performed either by enhancing heat dissipation at an exact fin weight or by diminishing the weight of the fin by precise heat dissipation. Recently a notable amount of work on some typical fins, like, porous fins and perforated fins, has also been carried out. This paper presents a brief review on heat transfer enhancement using fins of different types considering variable thermophysical and geometric parameters, which will also be useful for future use of geometrical modifications of extended surfaces, based on the cost and availability of space.analytical approach, computational approach, experimental approach, perforated fin, porous fin | INTRODUCTIONAdvanced technologies need high-performance heat transfer equipment. Techniques for enhancing the heat transfer rate are classified into two categories: active and passive methods. In the design point of view, active methods are complex as they require some extraneous power input for necessary flow adjustments and to improve the heat transfer rate and thus applications are limited. On the other hand, passive methods require geometrical or surface adjustments to the flow passage by incorporating additional devices. Additionally, by interrupting or varying the existing flow behavior (except for extended surfaces); higher heat transfer coefficients are promoted through this method, which is also followed by an increase in the corresponding pressure drop. The amount of conduction, convection, and radiation of an object shows the amount of heat it transfers. The heat transfer rate is enhanced by increasing the temperature difference between the object and the environment or by enhancing the coefficient of convective heat transfer or by maximizing the surface area of the body. In some cases, it is not appropriate or cost effective to alter the first two options. Introducing a fin to a body, however, expands the surface area and sometimes this is a cost-effective solution for heat transfer problems. Extended surfaces or fins are illustrations of passive methods that are generally used in different industrial applications for the enhancement of heat transfer between the primary surface (heat sink) and the surrounding fluid. Currently reducing the cost and size of fins is the key target of the fin industry. This demand is generally met by the high-thermal-conductivity and costly metals used to fabricate finned surfaces. Many efforts have been made to construct optimized fins. (a) By changing the size and shape of the solid fin: Instead of a longitudinal rectangular solid fin, if the geometry of fin design is changed, the performance parameters and heat tr...

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A modified bubble dynamics model for predicting bubble departure diameter on micro-pin-finned surfaces under microgravity

Cited by 34 publications

References 35 publications

Electrolysis in reduced gravitational environments: current research perspectives and future applications

Electrolysis in reduced gravitational environments: current research perspectives and future applications

The not-so-subtle flaws of the force balance approach to predict the departure of bubbles in boiling heat transfer

Improvement of heat transfer through fins: A brief review of recent developments

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