Liqun Zhou^1,*, Weilin Yang¹, Chaojie Li², Shi Lin³

Frontiers in Heat and Mass Transfer, Vol.22, No.1, pp. 157-173, 2024, DOI:10.32604/fhmt.2023.045135

Abstract The power density of electronic components grows continuously, and the subsequent heat accumulation and temperature increase inevitably affect electronic equipment’s stability, reliability and service life. Therefore, achieving efficient cooling in limited space has become a key problem in updating electronic devices with high performance and high integration. Two-phase immersion is a novel cooling method. The computational fluid dynamics (CFD) method is used to investigate the cooling performance of two-phase immersion cooling on high-power electronics. The two-dimensional CFD model is utilized by the volume of fluid (VOF) method and Reynolds Stress Model. Lee’s model was employed to calculate the phase change… More > Graphic Abstract

Chen Fang^*, Milnes David, Anita Rogacs, Kenneth Goodson

Frontiers in Heat and Mass Transfer, Vol.1, No.1, pp. 1-11, 2010, DOI:10.5098/hmt.v1.1.3002

Abstract Vapor-venting microchannel heat exchangers are promising because they address the problems of high pressure drop, flow instability, and local dryout that are common in conventional two-phase microchannel heat sinks. We present a 3D numerical simulation of the vapor-venting process in a rectangular microchannel bounded on one side by a hydrophobic porous membrane for phase-separation. The simulation is based on the volume of fluid (VOF) method together with models for interphase mass transfer and capillary force. Simulation shows the vapor-venting mechanism can effectively mitigate the vapor accumulation issue, reduce the pressure drop, and suppress the local dry-out in the microchannel. Pressure… More >

Zheng Miao^a, Ya-Ling He^a,*, Tian-Shou Zhao^b, Wen-Quan Tao^a

Frontiers in Heat and Mass Transfer, Vol.2, No.1, pp. 1-10, 2011, DOI:10.5098/hmt.v2.1.3001

Abstract A non-isothermal two-phase mass transport model is developed in this paper to investigate the heat generation and transport phenomena in a direct methanol fuel cell with anisotropic gas diffusion layers (GDLs). Thermal contact resistances at the GDL/CL (catalyst layer) and GDL/Rib interfaces, and the deformation of GDLs are considered together with the inherent anisotropy of the GDL. Latent heat effects due to condensation/evaporation of water and methanol between liquid and gas phases are also taken into account. Formulation of the two-phase mass transport across the membrane electrode assembly (MEA) is mainly based on the classical multiphase flow theory in the… More >

Sira Saisorn^a,b, Somchai Wongwises^b,c,∗

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-7, 2012, DOI:10.5098/hmt.v3.1.3007

Abstract Two-phase pressure drop during flow boiling has been studied for several decades. Obviously, the publications available on micro-channels are relatively small compared with those for ordinarily sized channels. Although the use of micro-channels yields several advantages, the pressure drop taking p lace in these extremely small channels is higher than that in the ordinarily sized channels because of the increased wall friction. The knowledge of the two-phase pressure drop characteristics in addition to heat transfer phenomena is essential to the design and evaluation of the micro-systems. In this paper, recent research on the flow boiling pressure drop in micro-scale channels… More >

Amit Agrawal^a,*, V.S. Duryodhan^a, S. G. Singh^b

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-7, 2012, DOI:10.5098/hmt.v3.1.3005

Abstract An experimental study of flow boiling through diverging microchannels has been carried out in this work, with the aim of exploring reduction in flow instabilities during boiling in diverging microchannels. Effect of mass flux, heat flux and divergence angle on two phase pressure drop has been studied using deionized water as the working fluid. The experiments are carried out on three test sections with divergence angle of 4, 8 and 12 deg with nearly constant hydraulic diameter (146, 154 and 157 µm respectively), for inlet mass flux and heat flux range of 117 - 1197 kg/m² -s and 2.5 to… More >

Etienne Costa-Patry^a, Jonathan Olivier^b, John R. Thome^a,∗

Frontiers in Heat and Mass Transfer, Vol.3, No.1, pp. 1-14, 2012, DOI:10.5098/hmt.v3.1.3002

Abstract This article presents new experimental results for two-phase flow boiling of R-134a, R-1234ze(E) and R-245fa in a micro-evaporator. The test section was made of copper and composed of 52 microchannels 163μm wide and 1560μm high with the channels separated by 178μm wide fins. The channels were 13.2mm long. There were 35 local heaters and temperature measurements arranged in a 5×7 array as a pseudo-CPU. The total pressure drops of the test section were below 20kPa in all cases. The wall heat transfer coefficients were generally above 10’000W/m²K and a function of the heat flux, vapor quality and mass flux. A… More >

Yongwei Duan, Zhaopeng Zhu, Hui He^*, Gaoliang Xuan, Xuemeng Yu

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.2, pp. 349-364, 2024, DOI:10.32604/fdmp.2023.042659

Abstract The gas-water two-phase flow occurring as a result of fracturing fluid flowback phenomena is known to impact significantly the productivity of shale gas well. In this work, this two-phase flow has been simulated in the framework of a hybrid approach partially relying on the embedded discrete fracture model (EDFM). This model assumes the region outside the stimulated reservoir volume (SRV) as a single-medium while the SRV region itself is described using a double-medium strategy which can account for the fluid exchange between the matrix and the micro-fractures. The shale gas adsorption, desorption, diffusion, gas slippage effect, fracture stress sensitivity, and… More >

Jingjing Gao, Xingkai Zhang^*

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.1, pp. 109-127, 2024, DOI:10.32604/fdmp.2023.030106

Abstract A new approach and a new related distribution system are proposed to address the issue of uneven steam injection caused by the different suction capacities of the used wells during the application of steam “stimulation” methods for enhanced oil recovery. The new distribution system consists of a swirler, spiral dividing baffles, and critical flow nozzles. Numerical simulations are used to analyze the flow-field and degree of steam homogeneity obtained with such an approach. The results indicate that a higher inlet pressure leads to better results. Additionally, the internal flow field becomes more stable, and the deviation from an even distribution… More >

Yun Whan Na^* , J. N. Chung^†

Frontiers in Heat and Mass Transfer, Vol.11, pp. 1-14, 2018, DOI:10.5098/hmt.11.36

Abstract Flow instabilities of convective two-phase boiling in a trapezoidal microchannel were investigated. using a three-dimensional numerical model. Parameters such as wall temperature and inlet pressure that characterize the instability phenomena of flow boiling with periodic flow patterns were studied at different channel wall heat fluxes and flow mass fluxes. Results were obtained for various wall heat flux levels and mass flow rates. The numerical results showed that large amplitude and short period oscillations for wall temperature and inlet pressure fluctuations are major characteristics of flow instability. The wall temperature fluctuations are mainly initiated by the transition from bubbly to slug… More >

Amer A. Abdulrahman¹, Bashar J. Kadhim¹, Zainab Y. Shnain¹, Hassan Sh. Majidi², Asawer A. Alwaiti^1,*, Farooq Al-Sheikh¹, Adnan A. AbdulRazak¹, Mohammed Shorbaz¹, Mazin J. Shibeeb³

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.10, pp. 2579-2595, 2023, DOI:10.32604/fdmp.2023.027454

Abstract The well-known frictional effect related to liquid-liquid two-phase flow in pipelines can be reduced using drag-reducing additives. In this study, such an effect has been investigated experimentally using a mixture of oil and water. Moreover, numerical simulations have been carried out using the COMSOL simulation software. The measurements were taken in a horizontal pipe with the length and diameter equal to 3 and 0.125 m, respectively. Moreover, Polyethylene oxide with 150 ppm was exploited to reduce the drag effect while considering different water-to-oil fractions (0.3, 0.4, 0.5, and 0.7) and a constant total flow velocity of 2.3 m/s. As made… More >