scholarly journals Numerical Optimization of Heat Transfer from Multiple Jets Impinging on a Moving Curved Surface for Industrial Drying Machines

2021 ◽  
Vol 39 (1) ◽  
pp. 32-40
Author(s):  
Ali Chitsazan ◽  
Georg Klepp ◽  
Birgit Glasmacher
Keyword(s):  
Heat Transfer ◽  
Turbulence Model ◽  
Transfer Rate ◽  
Curved Surface ◽  
Surface Velocity ◽  
Design Parameters ◽  
Maximum Heat ◽  
Inlet Velocity ◽  
Surface Distance ◽  
Multiple Jets

Jet impingements enhance the heat and mass transfer rate in industrial drying machines. The designer should optimize the design parameters of industrial drying equipment to achieve maximum heat transfer rate. The heat transfer between multiple jets and a moving curved surface is more difficult to study due to the changing boundaries and the effect of surface curvature but is also very relevant in industrial drying applications. SST k-ω turbulence model is used to simulate a real geometry for industrial drying applications. The SST k-ω turbulence model succeeded with reasonable accuracy in reproducing the experimental results. The jet to surface distance, jet to jet spacing, jet inlet velocity, jet angle, and surface velocity are chosen as the design parameters. For the optimization of the impinging round jet, the average Nu number on the moving curved surface is set as the objective functions to be maximized. The SHERPA search algorithm is used to search for the optimal point from the weighted sum of all objectives method. One correlation is developed and validated for the average Nu number. It is found that the maximum average Nu number correlates with high values of jet inlet velocity (Vj), jet angle (θ) and jet to jet spacing (S/d) and low values of the jet to surface distance (H/d) and relative surface velocity (VR). The agreement in the prediction of the average Nu number between the numerical simulation and correlation is found to be reasonable and all the data points deviate from the correlation by less than 4%.

scholarly journals Numerical Optimization of Drying Energy Consumption from Multiple Jets Impinging on a Moving Curved Surface

2021 ◽  
Vol 39 (3) ◽  
pp. 755-762
Author(s):  
Ali Chitsazan ◽  
Georg Klepp ◽  
Birgit Glasmacher ◽  
Kamyar Mohammad Pour
Keyword(s):  
Energy Consumption ◽  
Turbulence Model ◽  
Search Algorithm ◽  
Specific Energy Consumption ◽  
Surface Velocity ◽  
Design Parameters ◽  
Optimal Point ◽  
Inlet Velocity ◽  
Surface Distance ◽  
Data Points

Due to the increasing energy cost, the efficiency of the industrial dryer as the energy-intensive processes should be improved. The designer should optimize the design parameters of industrial drying equipment to achieve the minimum drying energy consumption. SST k-ω turbulence model is used to simulate a real geometry for industrial drying applications. For the optimization of the impinging round jet, the specific drying energy consumption is set as the objective function to be minimized. The jet to surface distance, jet to jet spacing, jet inlet velocity, jet angle, and surface velocity are chosen as the design parameters. The SHERPA search algorithm is used to search for the optimal point from the weighted sum of all objectives method. One correlation is developed and validated for the specific drying energy consumption. It is found that the SST k-ω turbulence model succeeded with reasonable accuracy in reproducing the experimental results. The minimum specific energy consumption correlates with high values of the jet to jet spacing, jet angle, and surface velocity and low values of the nozzle to surface distance and jet inlet velocity. The agreement in the prediction of the specific drying energy consumption between the numerical simulation and correlation is found to be reasonable and all the data points deviate from the correlation by less than 7%.

scholarly journals Significance of Shape Factor in Heat Transfer Performance of Molybdenum-Disulfide Nanofluid in Multiple Flow Situations; A Comparative Fractional Study

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3711
Author(s):  
Asifa ◽  
Talha Anwar ◽  
Poom Kumam ◽  
Zahir Shah ◽  
Kanokwan Sitthithakerngkiet
Keyword(s):  
Heat Transfer ◽  
Skin Friction ◽  
Molybdenum Disulfide ◽  
Heat Transfer Rate ◽  
Shape Factor ◽  
Transfer Rate ◽  
Maximum Heat ◽  
Left Wall ◽  
Maximum Heat Transfer ◽  
Mos2 Nanoparticles

In this modern era, nanofluids are considered one of the advanced kinds of heat transferring fluids due to their enhanced thermal features. The present study is conducted to investigate that how the suspension of molybdenum-disulfide (MoS2) nanoparticles boosts the thermal performance of a Casson-type fluid. Sodium alginate (NaAlg) based nanofluid is contained inside a vertical channel of width d and it exhibits a flow due to the movement of the left wall. The walls are nested in a permeable medium, and a uniform magnetic field and radiation flux are also involved in determining flow patterns and thermal behavior of the nanofluid. Depending on velocity boundary conditions, the flow phenomenon is examined for three different situations. To evaluate the influence of shape factor, MoS2 nanoparticles of blade, cylinder, platelet, and brick shapes are considered. The mathematical modeling is performed in the form of non-integer order operators, and a double fractional analysis is carried out by separately solving Caputo-Fabrizio and Atangana-Baleanu operators based fractional models. The system of coupled PDEs is converted to ODEs by operating the Laplace transformation, and Zakian’s algorithm is applied to approximate the Laplace inversion numerically. The solutions of flow and energy equations are presented in terms of graphical illustrations and tables to discuss important physical aspects of the observed problem. Moreover, a detailed inspection on shear stress and Nusselt number is carried out to get a deep insight into skin friction and heat transfer mechanisms. It is analyzed that the suspension of MoS2 nanoparticles leads to ameliorating the heat transfer rate up to 9.5%. To serve the purpose of achieving maximum heat transfer rate and reduced skin friction, the Atangana-Baleanu operator based fractional model is more effective. Furthermore, it is perceived that velocity and energy functions of the nanofluid exhibit significant variations because of the different shapes of nanoparticles.

Prediction of Phase Segregation During Mold Filling of Semi-Solid Slurries

1999 ◽  
Author(s):  
Mahmut D. Mat ◽  
Olusegun J. Ilegbusi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Solid Fraction ◽  
Transfer Rate ◽  
Phase Segregation ◽  
Mold Filling ◽  
Semisolid Slurry ◽  
Processing Parameter ◽  
Inlet Velocity ◽  
Semi Solid

Abstract Phase segregation during the mold filling of semisolid slurry (Sn-15%Pb) is numerically investigated under non-isothermal conditions. The effects of operating parameters on the phase segregation including inlet velocity, initial solid fraction, heat transfer rate, mold geometry are considered. The semi-solid slurry is considered a non-Newtonian fluid below a critical solid fraction (fcr) and a viscoplastic medium saturated with liquid phase above the critical solid fraction. A group of particles are introduced at the mold inlet and phase segregation is studied by following the trajectories of these particles. The sharp property change at the slurry air interface is resolved with Van Leer numerical method. It is found that phase segregation is significantly affected by processing parameter. The segregation decreases with high inlet velocity, low heat transfer rate from the mold wall and cylindrical mold geometry.

Investigation of the effects of geometrical parameters, eccentricity and perforated fins on natural convection heat transfer in a finned horizontal annulus using three dimensional lattice Boltzmann flux solver

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mahyar Ashouri ◽  
Mohammad Mehdi Zarei ◽  
Ali Moosavi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Lattice Boltzmann ◽  
Transfer Rate ◽  
Three Dimensional ◽  
Maximum Heat ◽  
Content Type ◽  
Dimensional Lattice ◽  
Fin Spacing

Purpose The purpose of this paper is to investigate the effects of geometrical parameters, eccentricity and perforated fins on natural convection heat transfer in a finned horizontal annulus using three-dimensional lattice Boltzmann flux solver. Design/methodology/approach Three-dimensional lattice Boltzmann flux solver is used in the present study for simulating conjugate heat transfer within an annulus. D3Q15 and D3Q7 models are used to solve the fluid flow and temperature field, respectively. The finite volume method is used to discretize mass, momentum and energy equations. The Chapman–Enskog expansion analysis is used to establish the connection between the lattice Boltzmann equation local solution and macroscopic fluxes. To improve the accuracy of the lattice Boltzmann method for curved boundaries, lattice Boltzmann equation local solution at each cell interface is considered to be independent of each other. Findings It is found that the maximum heat transfer rate occurs at low fin spacing especially by increasing the fin height and decreasing the internal-cylindrical distance. The effect of inner cylinder eccentricity is not much considerable (up to 5.2% enhancement) while the impact of fin eccentricity is more remarkable. Negative fin eccentricity further enhances the heat transfer rate compared to a positive fin eccentricity and the maximum heat transfer enhancement of 91.7% is obtained. The influence of using perforated fins is more considerable at low fin spacing although some heat transfer enhancements are observed at higher fin spacing. Originality/value The originality of this paper is to study three-dimensional natural convection in a finned-horizontal annulus using three-dimensional lattice Boltzmann flux solver, as well as to apply symmetry and periodic boundary conditions and to analyze the effect of eccentric annular fins (for the first time for air) and perforated annular fins (for the first time so far) on the heat transfer rate.

scholarly journals Topology design of two-fluid heat exchange

2020 ◽  
Author(s):  
Hiroki Kobayashi ◽  
Kentaro Yaji ◽  
Shintaro Yamasaki ◽  
Kikuo Fujita
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Transfer Rate ◽  
Design Variable ◽  
Pressure Loss ◽  
Transfer Rate ◽  
Maximum Heat ◽  
Variable Field ◽  
Two Fluids ◽  
Two Fluid

Abstract Heat exchangers are devices that typically transfer heat between two fluids. The performance of a heat exchanger such as heat transfer rate and pressure loss strongly depends on the flow regime in the heat transfer system. In this paper, we present a density-based topology optimization method for a two-fluid heat exchange system, which achieves a maximum heat transfer rate under fixed pressure loss. We propose a representation model accounting for three states, i.e., two fluids and a solid wall between the two fluids, by using a single design variable field. The key aspect of the proposed model is that mixing of the two fluids can be essentially prevented. This is because the solid constantly exists between the two fluids due to the use of the single design variable field. We demonstrate the effectiveness of the proposed method through three-dimensional numerical examples in which an optimized design is compared with a simple reference design, and the effects of design conditions (i.e., Reynolds number, Prandtl number, design domain size, and flow arrangements) are investigated.

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