Yasushi Koito^1,*, Akira Fukushima²

Frontiers in Heat and Mass Transfer, Vol.22, No.3, pp. 869-887, 2024, DOI:10.32604/fhmt.2024.050910

Abstract Thermal and fluid-flow characteristics were numerically analyzed for ultra-thin heat pipes. Many studies have been conducted for ultra-thin heat pipes with a centered wick structure, but this study focused on separated wick structures to increase the evaporation/condensation surface areas within the heat pipe and to reduce the concentration of heat flux within the wick structure. A mathematical heat-pipe model was made in the three-dimensional coordinate system, and the model consisted of three regions: a vapor channel, liquid-wick, and container wall regions. The conservation equations for mass, momentum, and energy were solved numerically with boundary conditions… More >

Ivan Sboev^1,*, Tatyana Lyubimova^2,3, Konstantin Rybkin³, Michael Kuchinskiy^2,3

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.6, pp. 1425-1439, 2024, DOI:10.32604/fdmp.2024.051341

Abstract The intensification of physicochemical processes in the sonochemical reactor chamber is widely used in problems of synthesis, extraction and separation. One of the most important mechanisms at play in such processes is the acoustic cavitation due to the non-uniform distribution of acoustic pressure in the chamber. Cavitation has a strong impact on the surface degradation mechanisms. In this work, a numerical calculation of the acoustic pressure distribution inside the reactor chamber was performed using COMSOL Multiphysics. The numerical results have revealed the dependence of the structure of the acoustic pressure field on the boundary conditions More > Graphic Abstract

Ali Shokor Golam^*

Frontiers in Heat and Mass Transfer, Vol.22, No.2, pp. 633-653, 2024, DOI:10.32604/fhmt.2024.050218

Abstract The thermal-hydraulic performance of plain tubes with and without wire coils in turbulent regimes is investigated experimentally and numerically. The effects of wire coil distribution (circular cross section) within the tube were explored experimentally, and water was employed as the working fluid. The numerical simulation was carried out using software programmer ANSYS Fluent 2019 R3 using the finite-volume approach. In the turbulent regime, six cross-sectioned wire coils were analyzed, including: circular, rectangular, hexagonal, square, star shape, and triangle. The utilization of a tube with a wire coil has been shown to increase heat transfer rate More >

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… More > Graphic Abstract

D. S. Martínez^†, J. P. Solano, J. Pérez, A. Viedma

Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-10, 2011, DOI:10.5098/hmt.v2.3.3002

Abstract Non-Newtonian flow and heat transfer in tubes of heat exchangers with reciprocating insert devices have been numerically investigated. The heat exchanger is mechanically assisted by a reciprocating cylinder, which moves the scraping rods inserted in the tubes. An array of semi-circular elements is mounted on each rod, with a pitch p=5D. These elements fit the internal diameter of the tubes. During the reciprocating motion, they scrape the inner tube wall, avoiding fouling. Additionally, the movement of the inserted device generates macroscopic displacements of the flow, which continuously mix core regions with peripheral flow. A power 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 More >

Frantisek Kavicka^a,*, Jana Dobrovska^b, Karel Stransky^a, Bohumil Sekanina^a, Josef Stetina^a

Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-9, 2012, DOI:10.5098/hmt.v3.2.3002

Abstract Corundo-baddeleyit material (CBM) – EUCOR – is a heat- and wear-resistant material even at extreme temperatures. This article introduces an original numerical model of solidification and cooling of this material in a non-metallic mold. The second, cooperating model of chemical heterogeneity and its application on EUCOR samples prove that the applied method of measuring the chemical heterogeneity provides the detailed quantitative information on the material structure and makes it possible to analyze the solidification process. The verification of both numerical models was conducted on a real cast 350 x 200 x 400 mm block. More >

Keyong Cheng^a,b,*, Chunzi Zhang^c, Wei Chen^a,b, Shiqiang Liang^a,†, Yongxian Guo^a,d, Xiulan Huai^a

Frontiers in Heat and Mass Transfer, Vol.3, No.3, pp. 1-6, 2012, DOI:10.5098/hmt.v3.3.3003

Abstract A film cooling method with chemical heat sink for gas turbine blades is proposed. In this method, an endothermic reaction of cooling stream occurs due to the heating from the mainstream, which leads to an improvement of film cooling effectiveness. The proposed method at different blowing ratios are computed and compared with the conventional one. The simulation result shows that due to the exsitence of the chemical heat sink the proposed method can enhance film cooling effectiveness not only in the streamwise direction, but also in the spanwise direction. More >

Di Peng^1,2, Guoqing Chen¹, Jiale Yan^1,*, Shiping Wang^2,*

CMES-Computer Modeling in Engineering & Sciences, Vol.139, No.3, pp. 2947-2964, 2024, DOI:10.32604/cmes.2024.047265

Abstract Cavitation is a prevalent phenomenon within the domain of ship and ocean engineering, predominantly occurring in the tail flow fields of high-speed rotating propellers and on the surfaces of high-speed underwater vehicles. The re-entrant jet and compression wave resulting from the collapse of cavity vapour are pivotal factors contributing to cavity instability. Concurrently, these phenomena significantly modulate the evolution of cavitation flow. In this paper, numerical investigations into cloud cavitation over a Clark-Y hydrofoil were conducted, utilizing the Large Eddy Simulation (LES) turbulence model and the Volume of Fluid (VOF) method within the OpenFOAM framework. More > Graphic Abstract

Bingzhu Wang^1,*, Xiangrui Ye^2,*

CMES-Computer Modeling in Engineering & Sciences, Vol.139, No.2, pp. 1401-1425, 2024, DOI:10.32604/cmes.2024.047364

Abstract A novel three-dimensional-fiber reinforced soft pneumatic actuator (3D-FRSPA) inspired by crab claw and human hand structure that can bend and deform independently in each segment is proposed. It has an omni-directional bending configuration, and the fibers twined symmetrically on both sides to improve the bending performance of FRSPA. In this paper, the static and kinematic analysis of 3D-FRSPA are carried out in detail. The effects of fiber, pneumatic chamber and segment length, and circular air chamber radius of 3D-FRSPA on the mechanical performance of the actuator are discussed, respectively. The soft mobile robot composed of More >