Home / Journals / FHMT / Vol.2, No.3, 2011
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  • Open AccessOpen Access

    ARTICLE

    RECENT ADVANCES IN UNDERSTANDING OF MASS TRANSFER PHENOMENA IN DIRECT METHANOL FUEL CELLS OPERATING WITH CONCENTRATED FUEL

    Q.X. Wua, Y.L. Heb, T.S. Zhaoa,b,*
    Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-14, 2011, DOI:10.5098/hmt.v2.3.2001
    Abstract Running direct methanol fuel cells (DMFC) with concentrated fuel is desirable to maximize the specific energy of the fuel cell system and to improve the performance by mitigating the water flooding problem associated with diluted methanol operation. This article provides a comprehensive review of recent advances in understanding mass transport phenomena in DMFCs operating with concentrated fuel. The review starts with elaborating the key issues of mass transport of reactants and products associated with highly-concentrated methanol operation, followed by summarizing and discussing past experimental and numerical investigations into the effects of the membrane electrode assembly (MEA) design, flow field structure… More >

  • Open AccessOpen Access

    ARTICLE

    FLOW SEPARATION IN FALLING LIQUID FILMS

    Georg F. Dietze, Reinhold Kneer
    Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-14, 2011, DOI:10.5098/hmt.v2.3.3001
    Abstract Despite the use of liquid films in a wide variety of technical applications involving heat and mass transfer (e.g. nuclear reactors, cooling towers and gas turbines), where they often play an important role, the underlying momentum and heat transport processes within these thin liquid layers remain to be fully elucidated. In particular, this applies to the influence that surface waves, developing due to the film’s natural instability, exert on the mentioned processes. In this context, it has been suggested by several experimental and numerical observations that momentum and heat transfer in the capillary wave region (which precedes large surface waves)… More >

  • Open AccessOpen Access

    ARTICLE

    NUMERICAL INVESTIGATION OF NON-NEWTONIAN FLOW AND HEAT TRANSFER IN TUBES OF HEAT EXCHANGERS WITH RECIPROCATING INSERT DEVICES*

    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 law model with temperature dependent… More >

  • Open AccessOpen Access

    ARTICLE

    THERMOHYDRAULIC CHARACTERISTICS OF A SINGLE-PHASE MICROCHANNEL HEAT SINK COATED WITH COPPER NANOWIRES

    M. Yakut Alia,*, Fanghao Yanga, Ruixian Fanga, Chen Lia, Jamil Khana,†
    Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-11, 2011, DOI:10.5098/hmt.v2.3.3003
    Abstract This study experimentally investigates single phase heat transfer and pressure drop characteristics of a shallow rectangular microchannel heat sink whose surface is enhanced with copper nanowires (CuNWs). The hydraulic diameter of the channel is 672 μm and the bottom wall is coated with Cu nanowires (CuNWs) of 200 nm in diameter and 50 μm in length. CuNWs are grown on the Cu heat sink by electrochemical synthesis technique which is inexpensive and readily scalable. The heat transfer and pressure drop results of CuNWs enhanced heat sink are compared with that of bare copper surface heat sink using deionized (DI) water… More >

  • Open AccessOpen Access

    ARTICLE

    MECHANISMS AND APPLICATIONS OF CATALYTIC COMBUSTION OF NATURAL GAS*

    Shihong Zhang#, Ning Li, Zhihua Wang
    Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-5, 2011, DOI:10.5098/hmt.v2.3.3004
    Abstract This article discussed the thermal efficiency, stability and pollutant emissions characteristics of the combustion of lean natural gas-air mixtures in Pd metal based honeycomb monoliths by means of experiments on a practical burner V. The chemistry at work in the monoliths was then investigated by the stagnation point flow reactor( SPFR), a fundamental experimental reactor. It was found that catalytic combustion inhibited the extent of gas-phase oxidation and increased the surface temperature of homogeneous ignition. According to the applications of catalytic combustion in the condenser boiler, the data of catalytic combustion condenser boiler V were measured at atmospheric temperature and… More >

  • Open AccessOpen 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 AccessOpen Access

    ARTICLE

    ON UNCERTAINTY AND LOCAL SENSITIVITY ANALYSIS FOR STEADY-STATE CONJUGATE HEAT TRANSFER PROBLEMS PART 1: EMISSIVITY, FLUID TEMPERATURE, AND CONDUCTANCE

    Christian Rauch*
    Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-8, 2011, DOI:10.5098/hmt.v2.3.3006
    Abstract In recent years, significant effort has been placed into developing automated multi-physics simulation. The exchange of boundary conditions has lead to more realistic as well as more complex simulations with usually slower convergence rate when the coupling is being performed between two different codes. In this paper the equations of local sensitivities for element centered steady-state combined convection, conduction, and thermal radiation problems are being derived. A numerical analysis on the stability of the solution matrix is being conducted. Partial uncertainties and the relative importance of the heat transfer modes are investigated by their uncertainty factors and conclusions are being… More >

  • Open AccessOpen Access

    ARTICLE

    LAMINAR FORCED CONVECTION HEAT AND MASS TRANSFER IN A VENTURI TUBE WITH WETTED WALLS

    S.W. Igoa,*, D.J. Bathiébob, K. Palma, K. N’wuitchac, B. Zeghmatid, X. Chesneaud
    Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-7, 2011, DOI:10.5098/hmt.v2.3.3007
    Abstract A combined heat and mass transfer in laminar forced convection flow in a rectangular venturi tube have been numerically simulated. A transformation has been used to transform the irregular profile of the venturi walls into a straight line. Transfers equations are solved using finite volume method, Gauss and Thomas algorithms. The influences of venturi effect, inlet Reynolds number and venturi diameter ratio on the heat and mass transfer are discussed in detail. Results presented as pressure gradient, Nusselt and Sherwood numbers profiles, velocity patterns and isotherms show that the throat play an important role on the heat an mass transfer… More >

  • Open AccessOpen 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 >

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