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  • Open Access

    ARTICLE

    EXPERIMENTAL AND 3D-CFD STUDY ON OPTIMIZATION OF CONTROL VALVE DIAMETER FOR A CONVERGENT VORTEX TUBE

    Seyed Ehsan Rafiee*, M. M. Sadeghiazad

    Frontiers in Heat and Mass Transfer, Vol.7, pp. 1-15, 2016, DOI:10.5098/hmt.7.13

    Abstract The aim of this investigation is study on separation phenomenon inside a special vortex tube affected by structural and physical factors including; throttle diameter, nozzle number and injection pressure as well as the parametric optimization based on separation efficiency using experimental and 3D-CFD methods. The results show that convergent VT with Dth=5.5mm provides 30.01% and 20.04% higher cooling and heating effectiveness compared to basic model. As another result, the higher injection pressure, the higher cooling effectiveness. The cooling effectiveness improves (16.86%) with increase in slot number up to N=4, then decreases. The maximum disagreement between experimental and predicted values is… More >

  • Open Access

    ARTICLE

    NUMERICAL INVESTIGATIONS ON HEAT TRANSFER AND FLOW STRUCTURE IN A CIRCULAR TUBE WITH VARIOUS SHAPES OF WINGLET VORTEX GENERATORS

    Amnart Boonloia, Withada Jedsadaratanachaib,*

    Frontiers in Heat and Mass Transfer, Vol.7, pp. 1-16, 2016, DOI:10.5098/hmt.7.22

    Abstract The numerical investigations on flow structure, heat transfer characteristic and thermal performance in a circular tube heat exchanger with various shapes of winglet vortex generators are reported. The rectangular winglet vortex generators (RWVG), delta winglet vortex generators (DWVG) and curve winglet vortex generators (CWVG) are inserted in the middle of the test tube on both downstream and upstream arrangements. The effects of blockage ratios; BR = 0.1 – 0.3, with single pitch ratio (PR = 1) and flow attack angle (α = 30o) on thermal performance are studied for the Reynolds numbers; Re = 100 – 2000. The numerical results… More >

  • Open Access

    ARTICLE

    NUMERICAL STUDY OF FIN-TUBE TYPE HEAT EXCHANGER WITH DELTA WINGLETS

    Divyprakash C. Pal, Abhik Majumder*

    Frontiers in Heat and Mass Transfer, Vol.7, pp. 1-9, 2016, DOI:10.5098/hmt.7.1

    Abstract In this present work heat transfer characteristics, thermal performance and pressure drop are studied numerically for a finned-tube bank heat exchanger with Delta Winglet Vortex Generator (DWVG) on the fin at different angle of attack (α). The thermo-fluid is studied by varying α at 15o , 25o , 30o and 35o . The base length (lDW) of the winglet also varied from 20mm to 35mm. The heat transfer coefficient and pressure drop increased in all the cases with increase in Reynolds number. However, significant increase in heat transfer of about 23.92% was observed for α at 35o when compared with… More >

  • Open Access

    ARTICLE

    On the Effect of Mist Flow on the Heat Transfer Performances of a Three-CopperSphere Configuration

    Karema A. Hamad*, Yasser A. Mahmood

    FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.11, pp. 2863-2875, 2023, DOI:10.32604/fdmp.2023.029049

    Abstract The cooling of a (pebble bed) spent fuel in a high-temperature gas-cooled reactor (HTGR) is adversely affected by an increase in the temperature of the used gas (air). To investigate this problem, a configuration consisting of three copper spheres arranged in tandem subjected to a forced mist flow inside a cylindrical channel is considered. The heat transfer coefficients and related variations as a function of Reynolds number are investigated accordingly. The experimental results show that when compared to those with only airflow, the heat transfer coefficient of the spherical elements with mist flow (j = 112 kg/m2 hr, Re =… More >

  • Open Access

    ARTICLE

    NEW SIMILARITY SOLUTION OF MICROPOLAR FLUID FLOW PROBLEM OVER AN UHSPR IN THE PRESENCE OF QUARTIC KIND OF AUTOCATALYTIC CHEMICAL REACTION

    O. K. Koriko, I. L. Animasaun*

    Frontiers in Heat and Mass Transfer, Vol.8, pp. 1-13, 2017, DOI:10.5098/hmt.8.26

    Abstract The motion of air (i.e fluid) in which tiny particle rotates past a pointed surface of a rocket (as in space science), over a bonnet of a car and past a pointed surface of an aircraft is of important to experts in all these fields. Geometrically, all the domains of fluid flow in all these cases can be referred to as the upper horizontal surface of a paraboloid of revolution (uhspr). Meanwhile, the solution of the corresponding partial differential equation is an open question due to unavailability of suitable similarity variable to non-dimensionalize the angular momentum equation. This article unravels… More >

  • Open Access

    ARTICLE

    Higher Order OAM Mode Generation Using Wearable Antenna for 5G NR Bands

    Shehab Khan Noor1, Arif Mawardi Ismail1, Mohd Najib Mohd Yasin1,*, Mohamed Nasrun Osman1, Thennarasan Sabapathy1, Shakhirul Mat Salleh2, Ping Jack Soh3, Ali Hanafiah Rambe4, Nurulazlina Ramli5

    Computer Systems Science and Engineering, Vol.47, No.1, pp. 537-551, 2023, DOI:10.32604/csse.2023.037381

    Abstract This paper presents a flexible and wearable textile array antenna designed to generate Orbital Angular Momentum (OAM) waves with Mode +2 at 3.5 GHz (3.4 to 3.6 GHz) of the sub-6 GHz fifth-generation (5G) New Radio (NR) band. The proposed antenna is based on a uniform circular array of eight microstrip patch antennas on a felt textile substrate. In contrast to previous works involving the use of rigid substrates to generate OAM waves, this work explored the use of flexible substrates to generate OAM waves for the first time. Other than that, the proposed antenna was simulated, analyzed, fabricated, and… More >

  • Open Access

    ARTICLE

    THERMAL PERFORMANCE ASSESSMENT IN A CIRCULAR TUBE FITTED WITH VARIOUS SIZES OF MODIFIED V-BAFFLES: A NUMERICAL INVESTIGATION

    Amnart Boonloia, Withada Jedsadaratanachaib,*

    Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-16, 2021, DOI:10.5098/hmt.16.17

    Abstract This research reports numerical examinations on fluid flow, heat transfer behavior and thermal performance analysis in a circular tube equipped with modified V-baffles (CTMVB). The modified V-baffle (MVB) is a combination vortex generator between V-baffles/V-orifices which are placed on the tube wall and V-baffles which are inserted at the core of the tested tube. The MVB height is separated into two parts; b1 represents the MVB height on the tube wall, while b2 represents the MVB height at the core of the tested round tube. The MVB height to tube diameter ratios, b/D, are adjusted; b1/D = 0.05, 0.1, 0.15… More >

  • Open Access

    ARTICLE

    NUMERICAL SIMULATION OF STEADY FLOW OF VORTEX FLOWMETER

    Yan-Juan Zhaoa,*, Yu-Liang Zhangb,† , Chen-Liang Zhangb

    Frontiers in Heat and Mass Transfer, Vol.17, pp. 1-7, 2021, DOI:10.5098/hmt.17.3

    Abstract Vortex flowmeter adopts advanced micro processing technology, which has the advantages of strong function, wide flow range, simple operation and maintenance, convenient installation and use. It is widely used in petroleum, chemical industry, electric power, metallurgy, urban gas supply and other industries to measure various gas flows. In order to study the characteristics of the inner flow passage of the vortex flowmeter and reach the normal working standard of the vortex flowmeter, this paper uses CFX to calculate the turbulent kinetic energy, eddy viscosity and flow velocity of the inner flow passage of the vortex flowmeter and analyze their distribution,… More >

  • Open Access

    ARTICLE

    EFFECTS OF BLOCKAGE LOCATIONS FOR ENHANCED HEAT TRANSFER AND FLOW VISUALIZATION IN A TESTED DUCT WITH DUAL-INCLINED BAFFLES (DIB): A CFD ANALYSIS

    Amnart Boonloia, Withada Jedsadaratanachaib,*

    Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-15, 2022, DOI:10.5098/hmt.18.20

    Abstract Numerical analysis of fluid flow mechanism and heat transfer in a heat exchanger duct (HXD) with dual-inclined baffles (DIB) are reported. Three DIB types are examined: 1. “Type A” is located at the center of the HXD, 2. “Type B” is located on the upper-lower duct walls (as an orifice) and 3. “Type C” is a combination of the type A and B (as double orifices). The impacts of the ratio of DIB heights (b) to the square duct height (H; b/H) on increased heat transfer and friction loss are analyzed. Laminar flow (Re = 100 – 2000 based on… More >

  • Open Access

    ARTICLE

    THE EFFECTS OF WINGLET VORTEX GENERATOR POSITION IN RECTANGULAR-DUCT-TYPE SOLAR AIR HEATERS

    Boonchai Lertnuwat

    Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-9, 2022, DOI:10.5098/hmt.18.1

    Abstract The aim of this work is to numerically investigate the effect of mounting winglet vortex generators on different positions in rectangular-duct-type air heaters. The two investigated positions were the absorber plate and the insulation plate, opposite to the absorber plate. Four shapes of winglet vortex generator, i.e. perforated rectangular winglet vortex generators (P-RWVG), rectangular winglet vortex generators (RWVG), perforated trapezoidal winglet vortex generators (P-TWVG) and trapezoidal winglet vortex generators (TWVG), were used. Results showed that heat-transfer capability would be better if the winglet vortex generators were mounted on the opposite insulation plate in the cases of P-RWVG, RWVG and P-TWVG. More >

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