scholarly journals Hydrodynamics of Liquid-Liquid Flows in Micro Channels and Its Influence on Transport Properties: A Review

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6066
Author(s):  
Arijit A. Ganguli ◽  
Aniruddha B. Pandit
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Transport Properties ◽  
Flow Patterns ◽  
Coupled Systems ◽  
Geometrical Parameters ◽  
Transfer Coefficients ◽  
Micro Channels ◽  
Liquid Flows ◽  
Regime Map

Hydrodynamics plays a major role in transport of heat and mass transfer in microchannels. This includes flow patterns and flow regimes in which the micro-channels are operated. The flow patterns have a major impact the transport properties. Another important aspect is the pressure drop in micro-channels. In the present review, the experimental and Computational Fluid Dynamics (CFD) studies covering all the above aspects have been covered. The effect of geometrical parameters like shape of channel, channel size, material of construction of channels; operating parameters like flow velocity, flow ratio and fluid properties have been presented and analyzed. Experimental and analytical work of different pressure drop models has also been presented. All the literature related to influence of flow patterns on transport properties like volumetric mass transfer coefficients (VMTC) and heat transfer coefficients (HTC) have been presented and analyzed. It is found that most works in Liquid-Liquid Extraction (LLE) systems have been carried out in slug flow and T-junctions. Models for coupled systems of flow and mass transfer have been presented and works carried out for different coupled systems have been listed. CFD simulations match experimental results within 20% deviations in quantitative and qualitative predictions of flow phenomena for most research articles referred in this review. There is a disparity in prediction of a generalized regime map and a generalized regime map for prediction of flow patterns for various systems would need the help of Artificial Intelligence.

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2003 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Micro Channels

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406 × 2.032 mm cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal that the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Annual flow is identified as the dominant flow pattern for conditions relevant to two-phase micro-channel heat sinks, and forms the basis for development of a theoretical model for both pressure drop and heat transfer in micro-channels. Features unique to two-phase micro-channel flow, such as laminar liquid and gas flows, smooth liquid-gas interface, and strong entrainment and deposition effects are incorporated into the model. The model shows good agreement with experimental data for water-cooled heat sinks.

Flow Boiling Heat Transfer, Pressure Drop, and Flow Pattern for CO2 in a 3.5mm Horizontal Smooth Tube

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Chang Yong Park ◽  
Pega Hrnjak
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Mass Flux ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Flow Patterns ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Flow Boiling Heat Transfer

Abstract C O 2 flow boiling heat transfer coefficients and pressure drop in a 3.5mm horizontal smooth tube are presented. Also, flow patterns were visualized and studied at adiabatic conditions in a 3mm glass tube located immediately after a heat transfer section. Heat was applied by a secondary fluid through two brass half cylinders to the test section tubes. This research was performed at evaporation temperatures of −15°C and −30°C, mass fluxes of 200kg∕m2s and 400kg∕m2s, and heat flux from 5kW∕m2 to 15kW∕m2 for vapor qualities ranging from 0.1 to 0.8. The CO2 heat transfer coefficients indicated the nucleate boiling dominant heat transfer characteristics such as the strong dependence on heat fluxes at a mass flux of 200kg∕m2s. However, enhanced convective boiling contribution was observed at 400kg∕m2s. Surface conditions for two different tubes were investigated with a profilometer, atomic force microscope, and scanning electron microscope images, and their possible effects on heat transfer are discussed. Pressure drop, measured at adiabatic conditions, increased with the increase of mass flux and quality, and with the decrease of evaporation temperature. The measured heat transfer coefficients and pressure drop were compared with general correlations. Some of these correlations showed relatively good agreements with measured values. Visualized flow patterns were compared with two flow pattern maps and the comparison showed that the flow pattern maps need improvement in the transition regions from intermittent to annular flow.

Analysis of Hydrodynamics and Mass Transfer of Gas-Liquid and Liquid-Liquid Taylor Flows in Microchannels

2019 ◽  
pp. 1-49
Author(s):  
Rufat Abiev
Keyword(s):  
Mass Transfer ◽  
Point Of View ◽  
Process Conditions ◽  
Two Phase ◽  
Physical Point ◽  
Micro Channels ◽  
Liquid Systems ◽  
Simplifying Assumptions ◽  
Liquid Flows ◽  
Solid Liquid

Analysis of hydrodynamics and mass transfer Taylor flows in micro channels of both gas-liquid and liquid-liquid systems on the basis of classical theoretical approach with some simplifying assumptions was performed. Results of theoretical analysis for description of hydrodynamic parameters and mass transfer characteristics were confirmed by comparison with the author's own and available in literature experimental data. It was shown that the main parameters of two-phase Taylor flows could be quite precisely described theoretically: mean bubble/droplet velocity, liquid film thickness, real gas holdup (which is always smaller than so-called dynamic holdup), pressure drop. Peculiarities of liquid-liquid flows compared to gas-liquid Taylor flows in capillaries are discussed. Wettability effect on hydrodynamics was examined. Tools of mass transfer intensification of gas-liquid and liquid-liquid Taylor flow in micro channels are analyzed. Three-layer model for heat and mass transfer has been proposed and implemented for the case of solid-liquid mass transfer for gas-liquid Taylor flows; optimal process conditions for this process are found theoretically and discussed from physical point of view.

Evaluation of Nusselt number and pressure drop in hexagonal and rectangular micro-channels in the presence of nano-fluids

2020 ◽  
Vol 234 (6) ◽  
pp. 665-672
Author(s):  
S Emami ◽  
MH Dibaei Bonab ◽  
M Mohammadiun ◽  
H Mohammadiun ◽  
M Sadi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Heat Sinks ◽  
Nano Particles ◽  
Geometrical Parameters ◽  
Micro Channels ◽  
Nano Fluids

Few papers investigated the effect of different nano-fluids and geometrical parameters of the micro channels on the performance of heat sinks. In this study, Nusselt number and pressure drop are investigated in differential geometry and Reynolds numbers. Then the effect of the micro-channel is studied for different heat flux. The results show that hexagonal micro-channels represents a better performance than the rectangular and the heat transfer of without using nano-particles in the hexagonal cross-section is about 9% higher than the rectangular cross-section and with the presence of nanoparticles (Al2O3 - CUO- TiO2, φ  =  4%), heat transfer is about 30 to 40% higher than the base liquid.

Enhancement of Inter-Phase Transport in Mini/Micro-Scale Applications Using Passive Mixing

2011 ◽  
Author(s):  
Adam A. Donaldson ◽  
Patrick Plouffe ◽  
Arturo Macchi
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Scale Up ◽  
Interfacial Area ◽  
Flow Patterns ◽  
High Mass ◽  
Two Phase ◽  
Initial Flow ◽  
Micro Scale ◽  
Passive Mixing

Structured mini/micro-scale reactors continue to receive attention from both industry and academia due to their low pressure drop, high mass transfer rates and ease of scale-up when compared to conventional reactor technology. Commonly considered for heat and mass transfer limited reactions such as hydrogenations, hydrodesulphurization, oxidations and Fischer-Tropsch synthesis, the performance of these systems is highly dependent on mixing and the interfacial area between phases. While existing literature describes the initial flow patterns generated by a broad range of two-phase contactors, few studies explore the dynamic impacts of downstream passive mixing elements. Experimental and computational methodologies for characterizing two-phase flow pattern transitions, pressure drop, mixing and mass transfer are discussed, with relevant examples for serpentine and venturi-based passive mixing designs. The efficacy of these two configurations are explored in the context of pressure drop, conditions leading to significant interface renewal, and design considerations for optimizing mass transfer. Challenges associate with the characterization of multiphase flow through these systems are highlighted, and strategies suggested for both experimental and computational analysis of dynamic flow patterns and fluid-fluid interactions.

Experiments on In-line Pin Fin Arrays and Performance Comparisons with Staggered Arrays

1980 ◽  
Vol 102 (1) ◽  
pp. 44-50 ◽  
Author(s):  
E. M. Sparrow ◽  
J. W. Ramsey ◽  
C. A. C. Altemani
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Pressure Drop ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Naphthalene Sublimation Technique ◽  
Line Array ◽  
Naphthalene Sublimation ◽  
And Performance ◽  
Pin Fin Arrays

Heat transfer and pressure drop experiments were performed for in-line pin fin arrays to obtain basic data to complement available information for staggered arrays. The experimental data were utilized as input to analyses aimed at establishing performance relationships between in-line and staggered arrays. In the experiments, mass transfer measurements via the naphthalene sublimation technique were employed to determine the row-by-row distribution of the heat (mass) transfer coefficient. Fully developed conditions prevailed for the fourth row and beyond. In general, the fully developed heat transfer coefficients for the in-line array are lower than those for the staggered array, but the pressure drop is also lower. The deviations between the two arrays increase with increasing fin height. With regard to performance, the in-line array transfers more heat than the staggered array under conditions of equal pumping power and equal heat transfer area. On the other hand, at a fixed heat load and fixed mass flow rate, the staggered array requires less heat transfer surface than the in-line array.

Transport Phenomena in Two-Phase Micro-Channel Heat Sinks

2002 ◽  
Author(s):  
Weilin Qu ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Hydrodynamic Instability ◽  
Transport Phenomena ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Micro Channel ◽  
Two Phase ◽  
Convective Boiling ◽  
Micro Channels

The design and reliable operation of a two-phase micro-channel heat sink require a fundamental understanding of the complex transport phenomena associated with convective boiling in small, parallel coolant passages. This understanding is the primary goal of this paper. This goal is realized by exploring the following aspects of boiling in micro-channels: hydrodynamic instability, two-phase flow patterns, pressure drop, and convective boiling heat transfer. High-speed photographic methods were used to determine dominant flow patterns and explore as well as characterize hydrodynamic instabilities. Two types of dynamic instability were identified, a severe pressure drop oscillation and a mild parallel channel instability, and a simple method is recommended to completely suppress the former. Predictions of three popular two-phase pressure drop models and correlations were compared to micro-channel water data, and only a separated flow (Lockhart-Martinelli) correlation based on the assumption of laminar flow in both phases gave acceptable predictions. Several popular heat transfer correlations were also examined and deemed unsuitable for micro-channel heat sinks because all these correlations are based on turbulent flow assumptions, and do not capture the unique features of micro-channel flow such as abrupt transition to slug flow, hydrodynamic instability, and high droplet entrainment in the annular regime. These findings point to the need for further study of boiling behavior and new predictive tools specifically tailored to micro-channel heat sinks.

Liquid-Liquid Two-Phase Flow Patterns and Mass Transfer Characteristics in a Circular Microchannel

2012 ◽  
Vol 482-484 ◽  
pp. 89-94
Author(s):  
Xu Bin Zhang ◽  
Dan Chen ◽  
Yan Wang ◽  
Wang Feng Cai
Keyword(s):  
Mass Transfer ◽  
Annular Flow ◽  
Flow Patterns ◽  
Immiscible Fluids ◽  
Viscous Force ◽  
Inertia Force ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Transfer Characteristics ◽  
Circular Microchannel

In this paper, flow patterns and mass transfer characteristics of two immiscible fluids in a T-junction circular microchannel were investigated. Four flow patterns, i.e. slug flow, irregular flow, parallel flow and annular flow, were captured by a CCD method, which were resulted from the competition among interfacial tension, viscous force and inertia force. Besides, the overall volumetric mass transfer coefficients ka for the four flow patterns was determined experimentally. The values of ka are in the range of 0.006~0.545s−1 and mainly dependent on the superficial velocity and the flow pattern regime.

Vortex Laden Flows in a Micro-Gap for Enhanced Direct Chip Cooling

2016 ◽  
Author(s):  
Amir Gorodetsky ◽  
Herman D. Haustein
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Pressure Drop ◽  
Vortex Shedding ◽  
Excitation Frequency ◽  
Flow Patterns ◽  
Flow Pulsation ◽  
Additional Advantage ◽  
Micro Channels ◽  
Wide Range

Heat dissipation in modern high-power electronics require high performance cooling, which traditional air-based systems cannot provide. Rather, novel systems using liquids, which have inherently better heat transfer characteristics, must be used. Therefore, these have recently been extensively examined. The present study aims to identify the liquid flow patterns which significantly increase heat transfer, examine them through simulation (transient 2D laminar DNS) and experimentally realize the most promising configuration. Any such flow patterns should target a major inhibitor of heat transfer, namely, the development of the thermal boundary layer. From the literature, it was seen that traveling vortices should meet this demand, due to generation of perpendicular unsteady or periodic flows, and consequently significant disruption of the boundary layer. Traditionally, micro-channels have been widely employed for micro-electronics cooling. However, the generation and persistence of the desired vortices over longer distances, as well as a desired lower pressure drop can be obtained in micro-gaps, which have inherently overall lower wall-fluid friction. The desired vortices can be further enhanced by active methods such as inlet flow pulsation. In the present study, based on numerical simulations (grid-independent and validated against an analytical solution) a suitable micro-gap geometrical configuration was chosen, while the flow rate (Re) and excitation frequency (Strouhal number around the well-known resonance, St = 0.3) with low amplitude, were examined over a wide range. Further examination led to the choice of two methods for vortex generation. The first is a use of bluff bodies as flow obstructers in the micro-gap, whereby vortex shedding (von Karman street) occurs already at low Reynolds numbers (Re>50). A preliminary experimental device was constructed with side and top view capabilities, for flow visualization, as well as the possibility of wall temperature measurement by IR thermography. Preliminary simulations and experiments showed that Vortex shedding onset was only mildly affected in the micro-scale (200 micron obstruction in 600 micron channel), while heat transfer was seen to increase three-fold over obstruction-free gap, with only mild pressure drop increase. The second method has additional advantage of imposed perpendicular flow. The model consists of a row of slot-jets in a micro-gap with cross-flow. Recent experimental and numerical studies employing a similar hybrid cooling scheme, showed significant heat flux dissipation (305 W/cm2). Here too, significant increase of the heat transfer was found, with additional increase associated with flow pulsation. In future experimental work, the intention is to include MEMS based actuators for individual control of the jets’ excitation ability and effective slot width.

scholarly journals Mathematical model of compact type evaporator

2018 ◽  
Vol 180 ◽  
pp. 02012
Author(s):  
Martin Borovička ◽  
Tomáš Hyhlík
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Ad Hoc ◽  
Data Transfer ◽  
Local Heat ◽  
Geometrical Parameters ◽  
Transfer Coefficients ◽  
Inlet Conditions ◽  
Transfer Problems

In this paper, development of the mathematical model for evaporator used in heat pump circuits is covered, with focus on air dehumidification application. Main target of this ad-hoc numerical model is to simulate heat and mass transfer in evaporator for prescribed inlet conditions and different geometrical parameters. Simplified 2D mathematical model is developed in MATLAB SW. Solvers for multiple heat and mass transfer problems - plate surface temperature, condensate film temperature, local heat and mass transfer coefficients, refrigerant temperature distribution, humid air enthalpy change are included as subprocedures of this model. An automatic procedure of data transfer is developed in order to use results of MATLAB model in more complex simulation within commercial CFD code. In the end, Proper Orthogonal Decomposition (POD) method is introduced and implemented into MATLAB model.

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