A Review of Flow Boiling in Mini and Microchannel for Enhanced Geometries

Dalkılıç, Ahmet Selim

doi:10.18186/journal-of-thermal-engineering.411437

Cited by 18 publications

(2 citation statements)

References 173 publications

(173 reference statements)

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“…T-junction is used in many petroleums, chemical industries and heat transfer applications. A review on flow boiling for enhanced geometries in mini and macro-channel, as well as a comprehensive thermo-economic analysis on refrigeration cycle, were summarized in the literature (Dalkilic et al , 2017; Dalkılıç, 2018). High liquid carryovers in the mixture extracted by the T-junction branch arm can trigger severe production interruption.…”

Section: Introductionmentioning

confidence: 99%

Numerical evaluation of separation efficiency in the diverging T-junction for slug flow

Ejaz

Pao

Ali

2021

HFF

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Purpose Offshore industries encounter severe production downtime due to high liquid carryovers in the T-junction. The diameter ratio and flow regime can significantly affect the excess liquid carryovers. Unfortunately, regular and reduce T-junctions have low separation efficiencies. Ansys as a commercial computational fluid dynamics (CFD) software was used to model and numerically inspect a novel diverging T-junction design. The purpose of diverging T-junction is to merge the specific characteristics of regular and reduced T-junctions, ultimately increasing separation efficiency. The purpose of this study is to numerically compute the separation efficiency for five distinct diverging T-junctions for eight different velocity ratios. The results were compared to regular and converging T-junctions. Design/methodology/approach Air-water slug flow was simulated with the help of the volume of the fluid model, coupled with the K-epsilon turbulence model to track liquid-gas interfaces. Findings The results of this study indicated that T-junctions with upstream and downstream diameter ratio combinations of 0.8–1 and 0.5–1 achieved separation efficiency of 96% and 94.5%, respectively. These two diverging T-junctions had significantly higher separation efficiencies when compared to regular and converging T-junctions. Results also revealed that over-reduction of upstream and downstream diameter ratios below 0.5 and 1, respectively, lead to declination in separation efficiency. Research limitations/implications The present study is constrained for air and water as working fluids. Nevertheless, the results apply to other applications as well. Practical implications The proposed T-junction is intended to reduce excessive liquid carryovers and frequent plant shutdowns. Thus, lowering operational costs and enhancing separation efficiency. Social implications Higher separation efficiency achieved by using diverging T-junction enabled reduced production downtimes and resulted in lower maintenance costs. Originality/value A novel T-junction design was proposed in this study with a separation efficiency of higher than 90%. High separation efficiency eliminates loss of time during shutdowns and lowers maintenance costs. Furthermore, limitations of this study were also addressed as the lower upstream and downstream diameter ratio does not always enhance separation efficiency.

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Section: Introductionmentioning

confidence: 99%

Numerical evaluation of separation efficiency in the diverging T-junction for slug flow

Ejaz

Pao

Ali

2021

HFF

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“…In these studies, there is a focus on heat transfer in terms of theoretical, experimental and numerical modeling. In their studies, they investigated the phase change heat transfer mechanism in order to increase performance of the thermal devices such as heat exchangers, flat plate solar air collectors and other electronic devices, which play an important role in the industry today [21][22][23][24][25][26][27][28][29][30][31][32]. In this regard, they carried out comprehensive studies on laminar or turbulent flow-forced convection in mini and micro channels of various shapes, such as; vertical, horizontal or inclined.…”

Section: Introductionmentioning

confidence: 99%

Boiling heat transfer simulation in rectangular mili-channels

Koca

Khalaji

Sepahyar

2021

Journal of Thermal Engineering

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Due to the high heat transfer coefficient and compactness of a system, mili-channel-based cooling and heating techniques are greatly expected to be distributing high heat flux from the electronic devices. In terms of cooling performance, the two-phase evaporating flow of boiling flow in mini and mili-channels is more effective than the single-phase flow due to the inclusion of latent energy in the process. In this study, a numerical model was proposed to simulate the boiling heat transfer of multiphase flow in a channel using different boundary conditions in the channel surfaces. The fluid volume approach regulating the hydrodynamics of the two-phase flow was used. Source terms of the energy and mass transfer that were taken into account at the interface of liquid and vapor were included in the management equations for the conservation of energy and vapor quality. A 3D Ansys-Fluent © simulation model was developed and numerical simulations were conducted for four different boundary conditions. A mili-channel with a length of 140 mm was used. The liquid and gas phases that were used in the model were liquid water and vapor; the total mass flux at the inlet was varied at 118-126 kg/m 2 s. In order to realize thin film annular flow over the boiler surface, employed specific boundary conditions in the 3D simulation model were obtained by means of one dimensional Matlab © simulation code. By means of utilizing the evaluated numerical results, distribution of heat transfer coefficient, vapor quality and dimensionless temperature over the heat transfer surfaces were reported and compared to experimental results. Numerically evaluated results are in agreement with experimentally measured results. For the studies cases an average value of 23600 W/m 2 .K was obtained for the heat transfer coefficient.

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Effects of Key Parameters on Nanofluid Thermal Performance in Heat Exchangers

2023

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Nanofluids are utilized in cooling equipment such as heat exchangers and renewable energies such as solar cells as heat transfer fluid. The techniques for nanofluid stability enhancement and stability evaluations, such as zeta potential, electron microscopy, and photographic techniques for sedimentation, are reviewed as well as some recent achievements in nanofluid stabilization and research on the parameters affecting the thermal properties of nanofluids. Finally, the applications of nanofluids in cooling devices are described. Increased heat transfer, reduced heat transfer time and size of heat exchangers, and finally higher energy and heat efficiency could be the most significant achievements. The parameters affecting the thermal conductivity of nanofluids include concentration, temperature, particle fluid, type of base fluid, and nanoparticles.

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A Review of Flow Boiling in Mini and Microchannel for Enhanced Geometries

Cited by 18 publications

References 173 publications

Numerical evaluation of separation efficiency in the diverging T-junction for slug flow

Numerical evaluation of separation efficiency in the diverging T-junction for slug flow

Boiling heat transfer simulation in rectangular mili-channels

Effects of Key Parameters on Nanofluid Thermal Performance in Heat Exchangers

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