scholarly journals Heat Transfer of Nanomaterial over an Infinite Disk with Marangoni Convection: A Modified Fourier’s Heat Flux Model for Solar Thermal System Applications

2021 ◽  
Vol 11 (24) ◽  
pp. 11609
Author(s):  
Mahanthesh Basavarajappa ◽  
Giulio Lorenzini ◽  
Srikantha Narasimhamurthy ◽  
Ashwag Albakri ◽  
Taseer Muhammad
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Thermal Energy ◽  
Fossil Fuels ◽  
Marangoni Convection ◽  
Solar Thermal ◽  
Solar Collectors ◽  
Thermal Systems ◽  
Flux Model ◽  
Heat Flux Model

The demand for energy due to the population boom, together with the harmful consequences of fossil fuels, makes it essential to explore renewable thermal energy. Solar Thermal Systems (STS’s) are important alternatives to conventional fossil fuels, owing to their ability to convert solar thermal energy into heat and electricity. However, improving the efficiency of solar thermal systems is the biggest challenge for researchers. Nanomaterial is an effective technique for improving the efficiency of STS’s by using nanomaterials as working fluids. Therefore, the present theoretical study aims to explore the thermal energy characteristics of the flow of nanomaterials generated by the surface gradient (Marangoni convection) on a disk surface subjected to two different thermal energy modulations. Instead of the conventional Fourier heat flux law to examine heat transfer characteristics, the Cattaneo–Christov heat flux (Fourier’s heat flux model) law is accounted for. The inhomogeneous nanomaterial model is used in mathematical modeling. The exponential form of thermal energy modulations is incorporated. The finite-difference technique along with Richardson extrapolation is used to treat the governing problem. The effects of the key parameters on flow distributions were analyzed in detail. Numerical calculations were performed to obtain correlations giving the reduced Nusselt number and the reduced Sherwood number in terms of relevant key parameters. The heat transfer rate of solar collectors increases due to the Marangoni convection. The thermophoresis phenomenon and chaotic movement of nanoparticles in a working fluid of solar collectors enhance the temperature distribution of the system. Furthermore, the thermal field is enhanced due to the thermal energy modulations. The results find applications in solar thermal exchanger manufacturing processes.

Direct Numerical Simulation of Turbulent Channel Flow With Heat Transfer for Low Prandtl and High Reynolds and Comparison With Algebraic Heat Flux Model

2015 ◽  
Author(s):  
Haomin Yuan ◽  
Elia Merzari
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Flux ◽  
Reynolds Number ◽  
Prandtl Number ◽  
Direct Numerical Simulation ◽  
Liquid Metals ◽  
Turbulent Channel Flow ◽  
Flux Model ◽  
Heat Flux Model

The flow characteristic of fluid at low Prandtl number is of continued interest in the nuclear industry because liquid metals are to be used in the next-generation nuclear power reactors. In this work we performed direct numerical simulation (DNS) for turbulent channel flow with fluid of low Prandtl number. The Prandtl number was set to 0.025, which is representative of the behavior of liquid metals. Constant heat flux was imposed on the walls to study heat transfer behavior, with different boundary conditions for temperature fluctuation. The bulk Reynolds number was set as high as 50,000, with a corresponding friction Reynolds number of 1,200, which is closer to the situation in a reactor or a heat exchanger than used in normally available databases. Budgets for turbulent variables were computed and compared with predictions from several RANS turbulence models. In particular, the Algebraic Heat Flux Model (AHFM) has been the focus of this comparison with DNS data. The comparisons highlight some shortcomings of AHFM along with potential improvements.

Free convective heat transfer in Jeffrey fluid with suspended nanoparticles and Cattaneo–Christov heat flux

2020 ◽  
Vol 234 (3-4) ◽  
pp. 99-114
Author(s):  
B Vasu ◽  
Atul Kumar Ray ◽  
Rama SR Gorla
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Temperature ◽  
Vertical Wall ◽  
Physical Parameters ◽  
Local Similarity ◽  
Species Concentration ◽  
Flux Model ◽  
Jeffrey Nanofluid ◽  
Heat Flux Model

Free convection flow of Jeffrey nanofluid past a vertical plate with sinusoidal variations of surface temperature and species concentration is presented. The study of heat transfer and nanofluid transport has been done by employing Cattaneo–Christov heat flux model and Buongiorno model, respectively. Equations governing the flow are non-dimensionalized using appropriate transformations. Furthermore, the method of local similarity and local non-similarity is used to reduce the equations into non-linear coupled system of equations which are then solved by homotopy analysis method. The obtained results are validated by comparing with the existing results available in the literature. The numerical results are found to be in good agreement. The effects of varying the physical parameters such as Deborah Number, Prandtl number, Schmidt number, thermophoresis parameter, Brownian motion parameter and buoyancy ratio parameter are obtained and presented graphically. The effect of sinusoidal variation of surface temperature and species concentration on the skin friction coefficient, Nusselt number and Sherwood number is also shown. Velocity for Jeffrey nanofluid is more than the Newtonian nanofluid while temperature and nanoparticle concentration for Jeffrey nanofluid is less than the Newtonian nanofluid. Raising value of thermal relaxation times leads to an increase in the heat transfer coefficient. It is observed that temperature of Cattaneo–Christov heat flux model is less than that in classical Fourier’s model away from the vertical wall. These types of boundary layer flow problems are found in vertical film solar energy collector, grain storage, transportation and power generation, thermal insulation, gas production, petroleum resources, geothermal reservoirs.

Heat Transfer Enhancement Feature of the Non-Fourier Cattaneo-Christov Heat Flux Model

2021 ◽  
Author(s):  
Mustafa Türkyilmazoglu
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Enhancement ◽  
Transfer Rate ◽  
Transfer Enhancement ◽  
Numerical Studies ◽  
Flux Model ◽  
Heat Flux Model ◽  
Present Effort ◽  
Enhancement Property

Abstract Cattaneo-Christov heat flux model was proposed to remedy the weakness of the traditional Fourier heat flux model in order to maintain the finite travel time of heat. The literature is replete with numerical studies to understand the heat transfer enhancement property. The present effort is to provide a mathematical rigor and to analytically demonstrate why the new model should act towards cooling and thus, in the way of enhancing the heat transfer rate from the surfaces. The derived and presented formulae here prove this assertion through comparison with a few selected examples from the open literature.

Analysis of radiative nonlinear heat transfer in a convective flow of dusty fluid by capitalizing a non-Fourier heat flux model

2021 ◽  
pp. 095440892110411
Author(s):  
G. Sowmya ◽  
B. Saleh ◽  
R. J. Punith Gowda ◽  
R. Naveen Kumar ◽  
R. S. Varun Kumar ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Velocity Slip ◽  
Slip Parameter ◽  
Dusty Fluid ◽  
Thermal Fields ◽  
Curvature Parameter ◽  
Flux Model ◽  
The Impact ◽  
Heat Flux Model

The study is concerned with the heat transfer in a slip flow of a dusty fluid with the impact of a magnetic field and nonlinear thermal radiation. Furthermore, for the heat transfer process the Cattaneo–Christov heat flux model is used. Suitable similarity transformations are used to transform the governing equations. Later, shooting method and the Runge-Kutta Fehlberg's fourth fifth order (RKF-45) process are utilized to solve these reduced system of nonlinear ordinary differential equations. Impact of numerous involved parameters on the flow, thermal fields of both dust and fluid phase, skin friction and rate of heat transfer are visually plotted through graphs and discussed quantitatively. The significant outcomes drawn from the current study are that, the rise in value of the velocity slip parameter decreases the velocity profile but improves the thermal profile of both the phases. The growing values of curvature parameter intensify the flow and the thermal fields of both phases. The cumulative values of magnetic parameter and dust particle mass concentration parameter declines the velocity and thermal gradients of both phases. The thermal relaxation time parameter decays the temperature profile. The heat transfer rate is strengthened with the growing values of the curvature parameter, the velocity slip parameter, and radiation parameter.

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