scholarly journals Numerical study on the influence of foamed copper on flow boiling characteristics

2021 ◽  
Vol 714 (2) ◽  
pp. 022066
Author(s):  
Yitao Shen
Keyword(s):  
Author(s):  
Abhijit Mukherjee ◽  
Satish G. Kandlikar

Flow boiling through microchannels is characterized by nucleation of vapor bubbles on the channel walls and their rapid growth as they fill the entire channel cross-section. In parallel microchannels connected through a common header, formation of vapor bubbles often results in flow maldistribution that leads to reversed flow in certain channels. The reversed flow is detrimental to the heat transfer and leads to early CHF condition. One way of eliminating the reversed flow is to incorporate flow restrictions at the channel inlet. In the present numerical study, a nucleating vapor bubble placed near the restricted end of a microchannel is numerically simulated. The complete Navier-Stokes equations along with continuity and energy equations are solved using the SIMPLER method. The liquid-vapor interface is captured using the level set technique. The results show that with no restriction the bubble moves towards the nearest channel outlet, whereas in the presence of a restriction, the bubble moves towards the distant but unrestricted end. It is proposed that channels with increasing cross-sectional area may be used to promote unidirectional growth of the vapor plugs and prevent reversed flow.


Author(s):  
Hayder I. Mohammed ◽  
Donald Giddings ◽  
Gavin S. Walker ◽  
Pouyan Talebizadehsardari ◽  
Jasim M. Mahdi

Author(s):  
Yang Luo ◽  
Jingzhi Zhang ◽  
Wei Li

Abstract The manifold microchannel (MMC) heat sink system has been widely used in high-heat-flux chip thermal management due to its high surface-to-volume ratio. Two-phase, three-dimensional numerical methods for subcooled flow boiling have been developed using a self-programming solver based on OpenFOAM. Four different types of manifold arrangements (Z-type, C-type, H-type and U-type) have been investigated at a fixed operational condition. The numerical results evaluate the effects of flow maldistribution caused by different manifold configurations. Before simulating the two-phase boiling flow in MIMC metamodels, single-phase liquid flow fields are performed at first to compare the flow maldistribution in microchannels. It can be concluded from the flow patterns that H-type and U-type manifolds provide a more even and a lower microchannel void fraction, which is conducive to improving the temperature uniformity and decreasing the effective thermal resistance. The simulation results also show that the wall temperature difference of H-type (0.471 K) is only about 10% of the Z-type (4.683 K). In addition, the U-type manifold configuration show the lowest average pressure drop at the inlet and outlet of the MIMC metamodel domain. However, H-type manifold also shows an impressive 59.9% decrease in pressure loss. Results indicate that both the H-type and the U-type manifolds for flow boiling in microchannels are recommended due to their better heat transfer performance and lower pressure drop when compared with Z-type and C-type.


2018 ◽  
Vol 31 (6) ◽  
pp. 513-530 ◽  
Author(s):  
Sajjad Ahangar Zonouzi ◽  
Habibollah Safarzadeh ◽  
Habib Aminfar ◽  
Mousa Mohammadpourfard

Author(s):  
Hee Joon Lee ◽  
Eric A. Browne ◽  
Yoav Peles ◽  
Michael K. Jensen

A numerical study of subcooled onset of nucleate boiling (ONB) in a micro-channel under pulsed heating using the volume of fluids (VOF) model was conducted. The ONB time was determined when the void fraction at the microheater surface starts to exist. A smooth thin Pt heater was located between the water in the channel and the solid material. The theoretical superheat for homogeneous nucleation did not predict the transient ONB results of convective flow of water. Once heat load increases at the heater, transient flow boiling starts to occur. From a parametric study, it was found that the time constant increases with large substrate thermal diffusivity, low Reynolds number, and large channel diameter.


2007 ◽  
Vol 129 (7) ◽  
pp. 864-876 ◽  
Author(s):  
Ding Li ◽  
Vijay K. Dhir

Three-dimensional numerical simulation of single bubble dynamics during nucleate flow boiling is performed in this work. The range of bulk liquid velocities investigated is from 0.076to0.23m∕s. The surface orientations at earth normal gravity are varied from an upward facing horizontal surface to vertical through 30, 45, and 60deg. The gravity levels on an upward facing horizontal surface are varied from 1.0ge to 0.0001ge. Continuity, momentum, and energy equations are solved by finite difference method and the level set method is used to capture the liquid-vapor interface. Heat transfer within the liquid micro layer is included in this model. The numerical results have been compared with data from experiments. The results show that the bulk flow velocity, heater surface orientation, and gravity levels influence the bubble dynamics.


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