Xiang Lin^1,*, Jian Fang¹, Ming Zhang¹, Kuang Yin¹, Yan Tian¹, Yingfei Guo², Qianggang Wang²

Energy Engineering, Vol.121, No.5, pp. 1127-1141, 2024, DOI:10.32604/ee.2024.046861

Abstract Efforts to protect electric power systems from faults have commonly relied on the use of ultra-high frequency (UHF) antennas for detecting partial discharge (PD) as a common precursor to faults. However, the effectiveness of existing UHF antennas suffers from a number of challenges such as limited bandwidth, relatively large physical size, and low detection sensitivity. The present study addresses these issues by proposing a compact microstrip patch antenna with fixed dimensions of 100 mm × 100 mm × 1.6 mm. The results of computations yield an optimized antenna design consisting of 2nd-order Hilbert fractal units positioned within a four-layer serpentine… More > Graphic Abstract

Qianqian Shao¹, Min Wang^2,*, Nuo Xu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.139, No.2, pp. 1337-1356, 2024, DOI:10.32604/cmes.2023.044313

Abstract To investigate the influences of co-flow and counter-flow modes of reactant flow arrangement on a proton exchange membrane fuel cell (PEMFC) during start-up, unsteady physical and mathematical models fully coupling the flow, heat, and electrochemical reactions in a PEMFC are established. The continuity equation and momentum equation are solved by handling pressure-velocity coupling using the SIMPLE algorithm. The electrochemical reaction rates in the catalyst layers (CLs) of the cathode and anode are calculated using the Butler-Volmer equation. The multiphase mixture model describes the multiphase transport process of gas mixtures and liquid water in the fuel cell. After validation, the influences… More >

Yu Huang¹, Beilei Liu¹, Dianlei Feng^2,*, Hao Shi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.139, No.2, pp. 1679-1699, 2024, DOI:10.32604/cmes.2023.044094

Abstract Rigid barrier deflectors can effectively prevent overspilling landslides, and can satisfy disaster prevention requirements. However, the mechanisms of interaction between natural granular flow and rigid barrier deflectors require further investigation. To date, few studies have investigated the impact of deflectors on controlling viscous debris flows for geological disaster prevention. To investigate the effect of rigid barrier deflectors on impact mechanisms, a numerical model using the smoothed particle hydrodynamics (SPH) method with the Herschel–Bulkley model is proposed to simulate the interaction between natural viscous flow and single/dual barriers with and without deflectors. This model was validated using laboratory flume test data… More > Graphic Abstract

Mainak Bhaumik¹, Anirban Sur^2,*, Kavita Dhanawade³

Frontiers in Heat and Mass Transfer, Vol.21, pp. 467-486, 2023, DOI:10.32604/fhmt.2023.044605

Abstract Pin fins are widely used in applications where effective heat transfer is crucial. Their compact design, high surface area, and efficient heat transfer characteristics make them a practical choice for many thermal management applications. But for a high heat transfer rate and lightweight application, aerofoil shape pin fins are a good option. This work focuses on an experimental model analysis of pin-fins with aerofoil shapes. The results were evaluated between perforation, no perforation, inline, and staggered fin configurations. Aluminum is used to make the pin fins array. The experiment is carried out inside a wind tunnel, and the heat supply… More >

Deng Lu¹, Xujun Lang¹, Bo Yang¹, Ziyang Li¹, Hang Geng^2,*

Energy Engineering, Vol.120, No.10, pp. 2287-2306, 2023, DOI:10.32604/ee.2023.029140

Abstract The four-circuit parallel line on the same tower effectively solves the problems faced by the line reconstruction and construction under the condition of the increasing shortage of transmission corridors. Optimizing the conductor and phase sequence arrangement of multiple transmission lines is conducive to improving electromagnetic and electrostatic coupling caused by electromagnetic problems. This paper uses the ATP-EMTP simulation software to build a 500 kV multi-circuit transmission line on the same tower. It stimulates the induced voltage and current values of different line lengths, tower spacing, vertical and horizontal spacing between different circuits, phase sequence arrangement, and nominal tower height. Moreover,… More >

Kaprawi Sahim^* , Dewi Puspitasari^†

Frontiers in Heat and Mass Transfer, Vol.8, pp. 1-6, 2017, DOI:10.5098/hmt.8.16

Abstract One row of heated elliptical cylinder with aspect ratio 0.6 and 0.8 are studied to know the forced heat transfer performance. The transversal distance between the cylinders are changed and the heat transfer is observed. Numerical observation of the study is done by using finite volume method to solve the momentum equations in two dimension domains. The pressure term instead of velocity is obtained by measurement in a subsonic wind tunnel and then it is injected into the momentum equation. The results of the hydrodynamic calculation are then injected into the energy equation which is solved by the over relaxation… More >

Ibtisam A. Hasan^*, Wafa Maki

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.10, pp. 2749-2759, 2023, DOI:10.32604/fdmp.2023.027260

Abstract This research tests the effect of introducing turbulators of a new type into a circular tube heat exchanger under a constant and uniform longitudinal heat flux condition. A 45 mm diameter copper tube with a length of 1,350 mm is utilized with a solid disk being inserted inside the tube, which consists of three sections, each one containing two slots. The slot is cut at a 45 degree angle toward the inner tube surface, which results in diverging the flow toward the inner hot tube surface in order to enhance the heat transfer process. Air is considered as the working fluid with… More >

O. M. Oyewola^a,b,* , O. S. Ismail^b , M. O. Olasindeb , O. O. Ajide^b

Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-8, 2022, DOI:10.5098/hmt.18.30

Abstract In this work, attempt is made to investigate the effect of cylindrical arrangement on the thermal and flow fields within the mixed convective regime for different values of Reynolds number within the study zone. Constructal design was used to design the flow geometric. Two-dimensional unsteady laminar flow equations with buoyancy force were solved numerically using finite element technique implemented on ANSYS FLUENT software. The study showed an optimised arrangement of 50% difference in coefficient of drag and 10% difference in Nusselt number within the geometrical arrangement variation. The effect of geometric arrangement is pronounced at low Ri than at high… More >

Mousa Aqeel Ali^*, Saad Najeeb Sheha^b

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-10, 2022, DOI:10.5098/hmt.19.39

Abstract In this study, the hydrothermal water flow characteristics using a dimpled inner tube heat exchanger are investigated experimentally and numerically. A numerical analysis has performed on two types of dimpled tubes (In-lined and staggered distributions) for two distribution angles 60o and 90o , and two dimple diameters(4 mm and 6 mm) with constant pitch ratio (X/d=8). In experimental part, a staggered arrangement dimpled inner tube distribution with angle 60o , dimple diameter of 6 mm and constant pitch ratio (X/d=8)is used as well as plain tube. The results illustrate that the heat transfer as Nusselt number for case of staggered… More >

Kamyar Mohammadpour, Ali Chitsazan, Eckehard Specht

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-5, 2022, DOI:10.5098/hmt.19.34

Abstract Understanding the flow pattern of the gas jets in packed beds can have considerable significance in improving reactor design and process optimization. This study researches the fuel diffusion in the radial direction and the flame length in a packed bed of a Parallel Flow Regenerative (PFR) Shaft kiln. This kiln is characterized that the fuel being injected vertically into the packed bed using a lot of lances in the cross-section while the combustion air is distributed continuously. The packed bed approximated as a porous media and the measured values match approximately with those calculated with the Porous Media Model (PMM).… More >