WSEAS Transactions on
Heat and Mass Transfer
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Print ISSN: 1790-5044
E-ISSN: 2224-3461
Volume 8, 2013
Issue 1, Volume 8, January 2013
Title of the Paper: Starting Effects on the Performance of a Reciprocating Piston Pump Driven by a Wind Machine
Authors: Mahmoud Mohamed El-Ghobashy El-Hagar
Abstract: The torque applied by a reciprocating pump on a wind machine axis is a fluctuating torque. The energy furnished by the pump on the wind machine axis is absorbed mainly in raising the water and the piston when the latter moves up. This has a direct adverse effect on the starting speed. The lower the maximum torque to be overcome, the easier will the wind machine start. If the necessary torque is high, a faster wind speed is required to start the wind machine. The operating time of the machine is consequently reduced. It is therefore desirable to reduce the starting torque, and hence to make the starting easier. This paper presents a theoretical study to reduce the starting torque of a non-conventional reciprocating piston pump using new methods, for example, changing the wind machine parameters, such as the aerodynamics configuration of the rotor and blade elements, or by studying the effect of wind speed velocity on the starting torque. Also by controlling the stroke volume of the pump or by controlling the flow rate of the piston pump. The last two methods are the best to control, smooth and reduce the starting torque of the pump by drilling a very small hole in the piston. The effect of this hole is that at very low speed (at starting) all water that could be pumped is leaked through the hole. This is the main important of the hole which made the pressure on the piston is very low and as a result the starting torque is low. The quantity of water leaking through the hole is small compared to the normal output of the pump. Finally the comparison between normal and leakhole piston pump and the effect of this leakhole on the Cavitation phenomena are studied.
Keywords: Wind machine, Starting torque, Normal piston pump, Leakhole piston pump, Performance, Characteristics
Title of the Paper: Similarity Methods in the Analysis for Laminar Forced Convection on a Horizontal Plate
Authors: Adnan K. Al-Salihi, A. H. Hasmani, M. G. Timol
Abstract: Heat conduction across a collection of square modules forming a large plane wall is a one–dimensional problem, whereas heat conduction across a collection of scalloped modules forming a large corrugated wall is a two–dimensional problem. In this work, the two dimensional heat conduction equation for three different scalloped modules derived from a basic square module is solved numerically with the Finite Element Method using COMSOL Multiphysics. When the temperature fields in the three modules are post-processed, the conduction shape factors S to be used in the algebraic equation can be easily determined. The heat conductive increments provided by the derived scalloped modules are qualitatively compared with the square module, subsequently accounting for beneficial mass reductions
Keywords: Large plane wall, Stackable square modules, Large corrugated wall, Stackable scalloped modules, Incremental heat conduction, Mass reduction
Title of the Paper: Premixed Charge Compression Ignition in a Direct Injection Diesel Engine using Computational Fluid Dynamics
Authors: R. Manimaran, R. Thundil Karuppa Raj, K. Senthil Kumar
Abstract: In this research work, numerical studies are carried out for different injection timings to arrive at premixed charge compression ignition in a direct injection Diesel engine. Various models and submodels accounting for turbulence, combustion and emission formation, droplet spray, wall impingement and collision are considered. The flame propagation phase is modeled by solving the transport equation for flame surface density equation in extended coherent flame model for 3 zones. A sector model of the engine cylinder is taken to avoid expensive computational resources. Standard k- model is used for modeling the turbulent flow in the cylinder. The species equation is discretised by monotone advection and reconstruction schemes. PISO algorithm is employed for solving the Navier-Stokes equations. The CFD code is validated against experimental data and further investigations are performed on various injection timings from 6 deg before TDC to 30 deg before TDC. From the studies, it is found that oxides of nitrogen increases and soot decreases as injection is advanced.
Keywords: 4-stroke constant speed diesel engine, Direct injection, Premixed Charge Compression Ignition (PCCI), Computational Fluid Dynamics (CFD), Extended Coherent Flame Model, Combustion, Emissions
Issue 2, Volume 8, April 2013
Title of the Paper: One-Dimensional Fractional Quasi-Static Thermoelasticity Problem for a Half-Space
Authors: L. A. Fil’Shtinskii, T. A. Kirichok, D. V. Kushnir
Abstract: This paper is devoted to the analytical solution of the space-time fractional heat conduction equation and associated thermoelasticity problem for a half-space in one-dimensional case. Finite Riesz fractional derivative and Caputo derivative are considered. Laplace transform with respect to time and sin-Fourier transform with respect to spatial coordinate are used. Numerical results are also presented.
Keywords: Fractional heat conduction equation, Caputo derivative, Riesz derivative, Laplace transform, Fourier transform, generalized Mittag-Leffler function, rapidly heated boundary, quasi-static thermoelasticity problem
Title of the Paper: Thermochemical Non-Equilibrium Reentry Flows in Two-Dimensions: Eleven Species Model – Part I
Authors: Edisson Sávio De Góes Maciel, Amilcar Porto Pimenta
Abstract: This work describes the thermochemical non-equilibrium simulations of reactive flow in twodimensions. The Van Leer and Liou and Steffen Jr. schemes, in their first- and second-order versions, are implemented to accomplish the numerical simulations. The Euler and Navier-Stokes equations, on a finite volume context and employing structured and unstructured spatial discretizations, are applied to solve the “hot gas” hypersonic flows around a blunt body, around a double ellipse, and around a reentry capsule in twodimensions. The second-order version of the Van Leer and Liou and Steffen Jr. schemes are obtained from a “MUSCL” extrapolation procedure in a context of structured spatial discretization. In the unstructured context, only first-order solutions are presented. The convergence process is accelerated to the steady state condition through a spatially variable time step procedure, which has proved effective gains in terms of computational acceleration (Maciel). The reactive simulations involve a Earth atmosphere chemical model of eleven species: N, O, N2, O2, NO, N+, O+, 2 N , 2 O , NO+ and e-, based on the works of Dunn and Kang and of Park. Thirtytwo, to the former, and fourth-three, to the latter, chemical reactions, involving dissociation, recombination and ionization, are simulated by the proposed models. The Arrhenius formula is employed to determine the reaction rates and the law of mass action is used to determine the source terms of each gas species equation. The results have indicated the Van Leer scheme as the most accurate one, both inviscid and viscous cases.
Keywords: Thermochemical non-equilibrium, Earth reentry, Eleven species model, Hypersonic “hot gas” flow, Finite volume, Euler and Navier-Stokes equations, Two-dimensions
Title of the Paper: Influence of Rheological Behavior of Nanofluid on Heat Transfer
Authors: Adnan Rajkotwala, Jyotirmay Banerjee
Abstract: The influence of rheological behavior of nanofluid on heat transfer is established. A comparative analysis is presented for heat transfer behavior of Newtonian and non-Newtonian model of nanofluid for natural convection. Ostwald–de Waele model for non-Newtonian fluid is used for calculating the shear stresses from the velocity gradients. Brinkmann model is used for incorporating the influence of volume fraction on viscosity for Newtonian model. The numerical analysis is presented for Rayleigh number (Ra) in the range of 104 to 106 and nanoparticle volume fraction (ϕ) in the range of 0.05% to 5%. For non-Newtonian model, a reduction in the average Nusselt number is observed with increase in volume fraction (ϕ) for a particular Rayleigh number. On the other hand, augmentation of Nusselt number is observed for Newtonian model. It is also observed that heat transfer rate increases with the increase in Rayleigh number for both the cases, though the augmentation in case of Newtonian model is more compared to Non-Newtonian model.
Keywords: Nanofluid, natural convection, non-Newtonian fluid, Brownian motion
Issue 3, Volume 8, July 2013
Title of the Paper: The Characteristics of Cooling on Heat Sink Using a Cross Flow Synthetic Jet Actuated by Variation of Wave Function
Authors: Harinaldi, Arief Randy, Aldy Andika, Damora Rhakasywi
Abstract: Synthetic jet which is based on zero netto mass input but non-zero momentum is a new approach utilized for cooling system. The synthetic air jet was generated by vibrating membranes which pushed out the air from the cavity through the exit nozzles with oscillatory motion. This research investigated the forced cooling characterization of a cross flow synthetic jet using double membrane actuator with two different variations of sinusoidal and square wave and was conducted in computational as well as experimental stage. Computational stage was conducted by a commercial CFD software of Fluent® with a turbulence model k- ω SST with meshing elements quad type pave, while in the experimental work the function generators was used to drive the membranes with the variation of sinusoidal and square wave in three oscillation frequencies i.e 80 Hz, 120 Hz, and 160 Hz at fixed amplitude of 0.002 m/s. The experimental results show significant effect of the reduction of the confinement effect phenomena by using the cross flow synthetic jet. The best heat transfer rate, hence the optimum cooling effect was obtained at a lower oscillation frequency; in this study at sinusoidal 120 Hz – sinusoidal 120 Hz.
Keywords: Cross Flow Synthetic Jet, Double Membranes, Confinement Effect, Heat Transfer Rate, K - ω SST
Title of the Paper: Thermochemical Non-Equilibrium Reentry Flows in Two-Dimensions: Eleven Species Model – Part II
Authors: Edisson Sávio De Góes Maciel, Amilcar Porto Pimenta
Abstract: This work describes the thermochemical non-equilibrium simulations of reactive flow in two-dimensions. The Van Leer and Liou and Steffen Jr. schemes, in their first- and second-order versions, are implemented to accomplish the numerical simulations. The Euler and Navier-Stokes equations, on a finite volume context and employing structured and unstructured spatial discretizations, are applied to solve the “hot gas” hypersonic flows around a blunt body, around a double ellipse, and around a reentry capsule in two-dimensions. The second-order version of the Van Leer and Liou and Steffen Jr. schemes are obtained from a “MUSCL” extrapolation procedure in a context of structured spatial discretization. In the unstructured context, only first-order solutions are presented. The convergence process is accelerated to the steady state condition through a spatially variable time step procedure, which has proved effective gains in terms of computational acceleration (Maciel). The reactive simulations involve a Earth atmosphere chemical model of eleven species: N, O, N2, O2, NO, N+, O+, , , NO+ and e-, based on the works of Dunn and Kang and of Park. Thirty-two, to the former, and fourth-three, to the latter, chemical reactions, involving dissociation, recombination and ionization, are simulated by the proposed models. The Arrhenius formula is employed to determine the reaction rates and the law of mass action is used to determine the source terms of each gas species equation. The results have indicated the Van Leer scheme as the most accurate one, both inviscid and viscous cases. This work is the second part of this study and only the solutions of the structured blunt body problem are presented.
Keywords: Thermochemical non-equilibrium, Earth reentry, Eleven species model, Hypersonic “hot gas” flow, Finite volume, Euler and Navier-Stokes equations, Two-dimensions
Title of the Paper: Soret and Dufour Effects on Natural Convection Heat and Mass Transfer Flow past a Horizontal Surface in a Porous Medium with Variable Viscosity
Authors: M. B. K. Moorthy, T. Kannan, K. Senthilvadivu
Abstract: The heat and mass transfer characteristics of natural convection about a horizontal surface embedded in a saturated porous medium subject to variable viscosity are numerically analyzed, by taking into account the diffusion-thermo (Dufour) and thermal-diffusion (Soret) effects. The governing equations of continuity, momentum, energy and concentration are transformed into non- linear ordinary differential equations, using similarity transformations and then solved by using Runge-Kutta-Gill method along with shooting technique. The governing parameters of the problem are variable viscosity (θc), buoyancy ratio (N), Lewis number (Le), Prandtl number (Pr), Dufour number, Soret number and Schmidt number. The velocity, temperature and concentration distributions are presented graphically. The Nusselt number and Sherwood number are also derived and discussed numerically.
Keywords: Heat and Mass transfer, Natural convection, Variable viscosity, Dufour and Soret effects
Issue 4, Volume 8, October 2013
Title of the Paper: The Numerical Simulation of Double-Diffusive Laminar Mixed Convection Flow in a Lid-Driven Porous Cavity
Authors: Shashak Misra, A. Satheesh, C. G. Mohan, P. Padmanathan
Abstract: This paper presents the numerical investigation of double-diffusive mixed convective flow in an impermeable enclosed cavity. The uniform temperature and concentration is imposed along the vertical walls and the horizontal walls are considered as insulation. The flow behavior is analyzed when the top wall moves left side at a constant velocity (Uo) and the other walls kept remains stationary. Transport equations are solved using finite volume technique. The pressure and velocity terms are coupled by SIMPLE algorithm. The third order deferred Quadratic Upwind Interpolation for Convection Kinematics (QUICK) scheme and second order central difference scheme are applied at the inner and boarder nodal points, respectively. The present numerical simulation is compared with the reported literature and found that are in good agreement. The heat and mass transfer results are presented in the form of iso-temperature and concentration. The Lewis number (Le) and aspect ratio are varied over a wide range to analyse non-dimensional horizontal (U) and vertical velocities (V), stream line contours, temperature and concentration gradients. The present analysis is carried out at constant Prandtl (Pr=0.7), Richardson (Ri=1.0), Darcy (Da=1.0) and Reynolds (Re=100) numbers. Results show that the fluid flow and heat transfer increase with the increase in Lewis Number and low aspect ratio. The local and average Nusselt and Sherwood numbers are also presented for the different Aspect ratio and Lewis number.
Keywords: Double-diffusive, mixed convection, numerical study, aspect ratio, Lewis number
Title of the Paper: The Effect of MHD on Laminar Mixed Convection of Newtonian Fluid between Vertical Parallel Plates Channel
Authors: Rasul Alizadeh, Alireza Darvish Behanbar
Abstract: This paper presents the numerical investigation of double-diffusive mixed convective flow in an impermeable enclosed cavity. The uniform temperature and concentration is imposed along the vertical walls and the horizontal walls are considered as insulation. The flow behavior is analyzed when the top wall moves left side at a constant velocity (Uo) and the other walls kept remains stationary. Transport equations are solved using finite volume technique. The pressure and velocity terms are coupled by SIMPLE algorithm. The third order deferred Quadratic Upwind Interpolation for Convection Kinematics (QUICK) scheme and second order central difference scheme are applied at the inner and boarder nodal points, respectively. The present numerical simulation is compared with the reported literature and found that are in good agreement. The heat and mass transfer results are presented in the form of iso-temperature and concentration. The Lewis number (Le) and aspect ratio are varied over a wide range to analyse non-dimensional horizontal (U) and vertical velocities (V), stream line contours, temperature and concentration gradients. The present analysis is carried out at constant Prandtl (Pr=0.7), Richardson (Ri=1.0), Darcy (Da=1.0) and Reynolds (Re=100) numbers. Results show that the fluid flow and heat transfer increase with the increase in Lewis Number and low aspect ratio. The local and average Nusselt and Sherwood numbers are also presented for the different Aspect ratio and Lewis number.
Keywords: MHD, Mixed convection, Non-Newtonian fluid, Parallel-plates channel
Title of the Paper: Visco-Elastic MHD Boundary Layer Flow with Heat and Mass Transfer over a Continuously Moving Inclined Surface in Presence of Energy Dissipation
Authors: Rita Choudhury, Paban Dhar, Debasish Dey
Abstract: The problem of two-dimensional free convective boundary layer flow of a visco-elastic fluid over a continuously moving inclined surface has been investigated in presence of transverse magnetic field and energy dissipation. Effects of heat and mass transfer are also analyzed in this paper. Heat is supplied from the plate to the fluid at a uniform rate. The suction at the plate is assumed to be constant and the plate is assumed to move continuously with a uniform velocity U in the upward direction. The visco-elastic fluid flow is characterized by Walters liquid (model B′). A uniform magnetic field of strength B0 is applied in the direction perpendicular to the plate. Highly non-linear momentum boundary layer equation, thermal boundary layer equation and concentration equation are converted into non dimensional form and then solved analytically by using regular perturbation technique. The analytical expressions for velocity profile, temperature field, concentration field, shearing stress, rate of heat transfer and rate of mass transfer at the surface have been obtained. The effects of Grashof number (Gr), Hartmann number (M), Prandtl number (Pr) and Schmidt number (Sc) on velocity profiles and shearing stress at the surface have been illustrated graphically for various values of visco-elastic parameter in combination with other flow parameters.
Keywords: Visco-elastic, Walters liquid (model B/), MHD, heat and mass transfer, regular perturbation technique, Prandtl number, Schmidt number