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  • Open Access

    ARTICLE

    Investigate the Impact of Dimple Size and Distribution on the Hydrothermal Performance of Dimpled Heat Exchanger Tubes

    Abeer H. Falih*, Basima Salman Khalaf, Basim Freegah

    Frontiers in Heat and Mass Transfer, Vol.22, No.2, pp. 597-613, 2024, DOI:10.32604/fhmt.2024.049812

    Abstract In this study, the primary objective was to enhance the hydrothermal performance of a dimpled tube by addressing areas with low heat transfer compared to other regions. To accomplish this, a comprehensive numerical investigation was conducted using ANSYS Fluent 2022 R1 software, focusing on different diameters of dimples along the pipe’s length and the distribution of dimples in both in-line and staggered arrangements. The simulations utilized the finite element method to address turbulent flow within the tube by solving partial differential equations, encompassing Re numbers spanning from 3000 to 8000. The study specifically examined single-phase flow conditions, with water utilized… More > Graphic Abstract

    Investigate the Impact of Dimple Size and Distribution on the Hydrothermal Performance of Dimpled Heat Exchanger Tubes

  • Open Access

    ARTICLE

    An Experimental and Numerical Thermal Flow Analysis in a Solar Air Collector with Different Delta Wing Height Ratios

    Ghobad Shafiei Sabet1,*, Ali Sari1, Ahmad Fakhari2,*, Nasrin Afsarimanesh3, Dominic Organ4, Seyed Mehran Hoseini1

    Frontiers in Heat and Mass Transfer, Vol.22, No.2, pp. 491-509, 2024, DOI:10.32604/fhmt.2024.048290

    Abstract This study conducts both numerical and empirical assessments of thermal transfer and fluid flow characteristics in a Solar Air Collector (SAC) using a Delta Wing Vortex Generator (DWVG), and the effects of different height ratios (R = 0.6, 0.8, 1, 1.2 and 1.4) in delta wing vortex generators, which were not considered in the earlier studies, are investigated. Energy and exergy analyses are performed to gain maximum efficiency. The Reynolds number based on the outlet velocity and hydraulic diameter falls between 4400 and 22000, corresponding to the volume flow rate of 5.21–26.07 m/h. It is observed that the delta wing… More >

  • Open Access

    ARTICLE

    Research on the Method of Heat Preservation and Heating for the Drilling System of Polar Offshore Drilling Platform

    Yingkai Dong1,2, Chaohe Chen2,*, Guangyan Jia2, Lidai Wang3, Jian Bai1

    Energy Engineering, Vol.121, No.5, pp. 1173-1193, 2024, DOI:10.32604/ee.2024.046432

    Abstract This study investigates the heat dissipation mechanism of the insulation layer and other plane insulation layers in the polar drilling rig system. Combining the basic theory of heat transfer with the environmental requirements of polar drilling operations and the characteristics of polar drilling processes, we analyze the factors that affect the insulation effect of the drilling rig system. These factors include the thermal conductivity of the insulation material, the thickness of the insulation layer, ambient temperature, and wind speed. We optimize the thermal insulation material of the polar drilling rig system using a steady-state method to measure solid thermal conductivity.… More >

  • Open Access

    ARTICLE

    A Coupled Thermomechanical Crack Propagation Behavior of Brittle Materials by Peridynamic Differential Operator

    Tianyi Li1,2, Xin Gu2, Qing Zhang2,*

    CMES-Computer Modeling in Engineering & Sciences, Vol.140, No.1, pp. 339-361, 2024, DOI:10.32604/cmes.2024.047566

    Abstract This study proposes a comprehensive, coupled thermomechanical model that replaces local spatial derivatives in classical differential thermomechanical equations with nonlocal integral forms derived from the peridynamic differential operator (PDDO), eliminating the need for calibration procedures. The model employs a multi-rate explicit time integration scheme to handle varying time scales in multi-physics systems. Through simulations conducted on granite and ceramic materials, this model demonstrates its effectiveness. It successfully simulates thermal damage behavior in granite arising from incompatible mineral expansion and accurately calculates thermal crack propagation in ceramic slabs during quenching. To account for material heterogeneity, the model utilizes the Shuffle algorithm… More >

  • Open Access

    ARTICLE

    Coupled Numerical Simulation of Electromagnetic and Flow Fields in a Magnetohydrodynamic Induction Pump

    He Wang1,*, Ying He2

    FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.4, pp. 889-899, 2024, DOI:10.32604/fdmp.2023.042728

    Abstract Magnetohydrodynamic (MHD) induction pumps are contactless pumps able to withstand harsh environments. The rate of fluid flow through the pump directly affects the efficiency and stability of the device. To explore the influence of induction pump settings on the related delivery speed, in this study, a numerical model for coupled electromagnetic and flow field effects is introduced and used to simulate liquid metal lithium flow in the induction pump. The effects of current intensity, frequency, coil turns and coil winding size on the velocity of the working fluid are analyzed. It is shown that the first three parameters have a… More >

  • Open Access

    ARTICLE

    NUMERICAL SIMULATION OF TURBULENT FLOW IN A RECTANGULAR CHANNEL WITH PERIODICALLY MOUNTED LONGITUDINAL VORTEX GENERATORS

    Pankaj Sahaa, Gautam Biswasa,b,*

    Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-5, 2011, DOI:10.5098/hmt.v2.3.3008

    Abstract Detailed flow structure in turbulent flows through a rectangular channel containing built-in winglet type vortex generators have been analyzed by means of solutions of the full Navier-Stokes equations using a Large-Eddy Simulation (LES) technique. The Reynolds number of investigation is 6000. The geometry of interest consists of a rectangular channel with a built-in winglet pair on the bottom wall with common-flow-down arrangement. The winglet pair induces streamwise longitudinal vortices behind it. The vortices swirl the flow around the axis parallel to the mainstream direction and disrupt the growth of thermal boundary layer entailing enhancement of heat transfer. The influence of… More >

  • Open Access

    ARTICLE

    BIO-HEAT TRANSFER SIMULATION OF SQUARE AND CIRCULAR ARRAY OF RETINAL LASER IRRADIATION

    Arunn Narasimhan*, Kaushal Kumar Jha

    Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-8, 2011, DOI:10.5098/hmt.v2.3.3005

    Abstract Pan Retinal photocoagulation (PRP), a retinal laser surgical process, is simulated using a three-dimensional bio-heat transfer numerical model. Spots of two different type of array, square array of 3 × 3 spots and a circular array of six spots surrounding a central spot, are sequentially irradiated. Pennes bio-heat transfer model is used as the governing equation. Finite volume method is applied to find the temperature distribution due to laser irradiation inside the human eye. Each spot is heated for 100 ms and subsequently cooled for 100 ms with an initial laser power of 0.2 W. Based on the outcome of… More >

  • Open Access

    ARTICLE

    NUMERICAL SIMULATION OF DROPLET IMPACT AND SOLIDIFICATION INCLUDING THERMAL SHRINKAGE IN A THERMAL SPRAY PROCESS

    Sina Alavi, Mohammad Passandideh-Fard*

    Frontiers in Heat and Mass Transfer, Vol.2, No.2, pp. 1-9, 2011, DOI:10.5098/hmt.v2.2.3007

    Abstract In this paper, a numerical study is performed to investigate the effects of thermal shrinkage on the deposition of molten particles on a substrate in a thermal spray process using the Volume-of-Fluid (VOF) method. Thermal shrinkage is a phenomenon caused by the variation of density during cooling and solidification of a molten metal. The Navier-Stokes equations along with the energy equation including phase change are solved using a 2D/axisymmetric mesh. The VOF method is used to track the free surface of molten particles, and an enthalpy-porosity formulation is used to model solidification. For the normal impact of tin particles in… More >

  • Open Access

    ARTICLE

    DOUBLE DIFFUSION EFFECTS ON CONVECTION IN FLOW ON VERTICAL PLATE IMBEDDED IN POROUS MEDIA

    Z. Aouachriaa,*, F. Rouichia, D. Haddadb

    Frontiers in Heat and Mass Transfer, Vol.3, No.2, pp. 1-6, 2012, DOI:10.5098/hmt.v3.2.3004

    Abstract Natural convection flow past a vertical porous plate in a porous medium is studied numerically, by taking into account the Dufour and Soret effects. The similarity equations of the problem considered are obtained by using usual similarity technique. This system of ordinary differential equations, which are solved numerically by using the Nachtsheim -Swigerst hooting iteration technique together with a sixth order Runge-Kutta integrations scheme. The results show that Soret and Dufour effects do not appreciably influence the velocity, temperature and concentration fields, but rather only tend to increase the mass and energy flux due to the added contributions. More >

  • Open Access

    ARTICLE

    DETERMINATION OF RADIATION HEAT TRANSFER COEFFICIENT OF STANDING HUMAN BODY MODEL BY NUMERICAL APPROACH

    Ahmad Najjaran1, Ali R. Tahavvor, Abdolkarim Najjaran, Mohammad A. Ahmadfard

    Frontiers in Heat and Mass Transfer, Vol.3, No.3, pp. 1-6, 2012, DOI:10.5098/hmt.v3.3.3007

    Abstract In this paper, external radiation heat transfer coefficient and flux of a standing human body model are calculated for different emissivity coefficients and various temperature differences. To do this, a standing human body sample is designed in such a way that hands and feet are totally open and stretched. Soles are in contact with the ground and so do not have heat transfer. The results are extracted by weighted average method. Despite the existence of the air around the body in reality, the convection heat transfer of human body with the surrounding air is neglected in order to prevent errors… More >

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