Numerical simulation of flow patterns and the effect on heat flux during R32 condensation in microtube

Wu, Chunxu; Li, Junming

doi:10.1016/j.ijheatmasstransfer.2017.12.123

Cited by 29 publications

(6 citation statements)

References 22 publications

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“…It should be noted that the zero slopes of the wall pressure in the bubble region indicate that all pressure drops can be neglected in this region. Similar observations were reported in the literature [67][68][69] .…”

Section: Hydrodynamic Analysissupporting

confidence: 92%

Parametric study on hydrothermal properties of condensing flow in microtube heat exchangers using numerical and experimental approaches

Sadaghiani¹

2021

Preprint

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Microchannels have increasingly been used to miniaturize heat transfer equipment, improve energy efficiency, and minimize heat transfer fluid inventory. A fundamental understanding of condensation in microscale will yield far-reaching benefits for the different areas of industry. In this study, microtubes with inner diameters of 250, 500, 600, and 900 µm were used to investigate the effect of microtube diameter, inlet quality, and mass flux on the liquid/vapor interface near the wall boundaries in condensing flow. After validation with the experimental results, a transient numerical model (based on the volume of fluid approach) was developed to investigate the hydrothermal properties of condensing such as bubble dynamics, flow map transitions, transient interface shear force, and temperature on flow condensation performance in terms of heat transfer coefficient and pressure drop. The liquid film thickness, slug velocity, and location of transition from annular flow to slug flow inside the microtube were characterized for different microtubes, and the resultant alteration in condensation flow heat transfer and pressure drop is discussed in detail. The obtained results indicated that the interfacial characteristics of condensing flow in microtubes with hydraulic diameters lower than 500µm are majorly different from those with D>500µm.

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Section: Hydrodynamic Analysissupporting

confidence: 92%

Parametric study on hydrothermal properties of condensing flow in microtube heat exchangers using numerical and experimental approaches

Sadaghiani¹

2021

Preprint

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“…Wu and Li [59] proposed a transient numerical investigation for analysing condensation heat transfer and flow characteristics. Their research delved into simulating the condensation flow of R32 within a circular tube of 0.1 mm diameter.…”

Section: Numerical Studies Focused On Mini/microchannel Condensation ...mentioning

confidence: 99%

Condensation Flow of Refrigerants Inside Mini and Microchannels: A Review

Başaran,

Benim

2024

Applied Sciences

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Nowadays, the demand for obtaining high heat flux values in small volumes has increased with the development of technology. Condensing flow inside mini- and microchannels has been becoming a promising solution for refrigeration, HVAC, air-conditioning, heat pumps, heat pipes, and electronic cooling applications. In these applications, employing mini/microchannels in the condenser design results in the working fluid, generally refrigerant, undergoing a phase change inside the mini/microchannels. On the other hand, the reduction in the hydraulic diameter during condensation gives rise to different flow regimes and heat transfer mechanisms in the mini- and microchannels compared to the conventional channels. Therefore, the understanding of fluid flow and heat transfer characteristics during condensation of refrigerant inside mini- and microchannels has been gaining importance in terms of condenser design. This study presents a state-of-the-art review of condensation studies on refrigerants inside mini- and microchannels. The review includes experimental studies as well as correlation models, which are developed to predict condensation heat transfer coefficients and pressure drop. The refrigerant type, thermodynamical performance, and compatibility, as well as the environmental effects of refrigerant, play a decisive role in the design of refrigeration systems. Therefore, the environmental impacts of refrigerants and current regulations against them are also discussed in the present review.

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“…This small length also gives benefits to fewer computation resources. The surface tension force’s dominance over gravity at a small tube diameter is confirmed using the Bond number criterion [ 41 ]. The gravitational impact was therefore neglected, and the 2D calculation region is validated.…”

Section: Mathematical Modelingmentioning

confidence: 99%

Flow Boiling of Liquid n-Heptane in Microtube with Various Fuel Flow Rate: Experimental and Numerical Study

Rashid,

Ahmad,

Swati

et al. 2023

Micromachines

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The evaporation of liquid hydrocarbon n-heptane is discussed in detail with experimentation and numerical techniques. A maximum wall temperature of 1050 K was reported during an experimental process with a two-phase flow that was stable and had a prominent meniscus at a small fuel flow rate (FFR) ≤ 10 µL/min. At medium to high FFR (30–70 µL/min), the flow field was unstable, with nucleating bubbles and liquid droplets inside the microtube and the maximum temperature recorded was 850 K for 70 µL/min. For the numerical model, the temperature of the wall was used as a boundary condition. Using the numerical model, the evaporative flux at the meniscus, pressure drop, pressure oscillation, and heat transfer coefficient (HTC) were investigated. A single peak in HTC was obtained at a low fuel flow rate, while multiple peaks were obtained for high FFR. At low FFR, the pressure peak was observed to be 102.4 KPa, whereas at high FFR, the pressure peak increased to 105.5 KPa. This shows a 2% increase in pressure peak with an increase in FFR. Similarly, when the FFR increased from 5 µL/min to 70 µL/min, the pressure drop increased from 500 Pa to 2800 Pa. The high amplitude of pressure drops and a high peak of HTC were found, which depend on the mass flow rate. The coefficient of variation for pressure drop depends mainly on the fuel flow rate.

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Numerical simulation of flow patterns and the effect on heat flux during R32 condensation in microtube

Cited by 29 publications

References 22 publications

Parametric study on hydrothermal properties of condensing flow in microtube heat exchangers using numerical and experimental approaches

Parametric study on hydrothermal properties of condensing flow in microtube heat exchangers using numerical and experimental approaches

Condensation Flow of Refrigerants Inside Mini and Microchannels: A Review

Flow Boiling of Liquid n-Heptane in Microtube with Various Fuel Flow Rate: Experimental and Numerical Study

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