Effect of Magnetic Field on the Laminar Heat Transfer Performance of Hybrid Nanofluid in a Lid Driven Cavity Over Solid Block

Author(s):  
Rajesh Nimmagadda ◽  
Durga Prakash Matta ◽  
Rony Reuven ◽  
Lazarus Godson Asirvatham ◽  
Somchai Wongwises ◽  
...  

Abstract A 2D numerical investigation has been carried out to obtain the heat transfer performance of hybrid (Al2O3 + Ag) nanofluid in a lid driven cavity over solid block under the influence of uniform as well as non-uniform magnetic field. The geometrical domain consists of a cavity containing nanofluid that is driven by means of lid moving in one direction. This circulating nanofluid will extract enormous amount of heat from the solid block underneath the cavity resulting in conjugate heat transfer. A homogenous solver based on the finite volume method with conjugate heat transfer was developed and adopted in the existing study. The heat efficient hybrid nanofluid (HyNF) pair (2.4 vol.% Ag + 0.6 vol.% Al2O3) obtained by Nimmagadda and Venkatasubbaiah [1] is used in the present investigation. Moreover, efficient non-uniform sinusoidal magnetic field identified by Nimmagadda et al. [2] is also implemented and compared with uniform magnetic field. Furthermore, the magnetic field is applied over the geometrical domain along the two axial directions separately and the effective heat transfer performance is obtained. The significant impact of extensive parameters like Reynolds number, nanoparticle type, nanoparticle concentration, magnetic field type, magnetic field location and the strength of the magnetic field on heat transfer performance are systematically analyzed and presented.

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Naveen Janjanam ◽  
Rajesh Nimmagadda ◽  
Lazarus Godson Asirvatham ◽  
R. Harish ◽  
Somchai Wongwises

AbstractTwo-dimensional conjugate heat transfer performance of stepped lid-driven cavity was numerically investigated in the present study under forced and mixed convection in laminar regime. Pure water and Aluminium oxide (Al2O3)/water nanofluid with three different nanoparticle volume concentrations were considered. All the numerical simulations were performed in ANSYS FLUENT using homogeneous heat transfer model for Reynolds number, Re = 100 to 500 and Grashof number, Gr = 5000, 13,000 and 20,000. Effective thermal conductivity of the Al2O3/water nanofluid was evaluated by considering the Brownian motion of nanoparticles which results in 20.56% higher value for 3 vol.% Al2O3/water nanofluid in comparison with the lowest thermal conductivity value obtained in the present study. A solid region made up of silicon is present underneath the fluid region of the cavity in three geometrical configurations (forward step, backward step and no step) which results in conjugate heat transfer. For higher Re values (Re = 500), no much difference in the average Nusselt number (Nuavg) is observed between forced and mixed convection. Whereas, for Re = 100 and Gr = 20,000, Nuavg value of mixed convection is 24% higher than that of forced convection. Out of all the three configurations, at Re = 100, forward step with mixed convection results in higher heat transfer performance as the obtained interface temperature is lower than all other cases. Moreover, at Re = 500, 3 vol.% Al2O3/water nanofluid enhances the heat transfer performance by 23.63% in comparison with pure water for mixed convection with Gr = 20,000 in forward step.


Author(s):  
J. Lee ◽  
T. Nomura ◽  
E. M. Dede

This paper introduces topology design optimization for a magnetically controlled convective heat transfer cooling system. It is well known that a stationary magnetic field subjected to a temperature gradient generates fluid motion in a magnetic fluid (e.g. ferrofluid). This physical phenomenon may be exploited to drive convective motion in the cooling system to maximize the heat transfer performance. Here, the magnetic field source layout of the system is designed to enhance the heat transfer performance. More specifically, the distribution and magnetization direction of the permanent magnet (PM) field source is optimized to minimize the maximum temperature of a closed loop heat transfer system. The design optimization is performed using a gradient-based topology optimization method with a fully coupled non-linear analysis for magnetic-thermal-fluid systems. Interestingly, magnet designs similar to Halbach arrays are obtained as the optimal PM layout. The magnetic field distribution generated by the designed layout affects the body force that the fluid is subjected to and results in unique fluid flow patterns for maximum cooling performance of the system. Thus, this paper will provide an explanation of the design optimization procedure and provide the design result.


2021 ◽  
Vol 11 (10) ◽  
pp. 4683
Author(s):  
Areum Lee ◽  
Chinnasamy Veerakumar ◽  
Honghyun Cho

This paper discusses the forced convective heat transfer characteristics of water–ethylene glycol (EG)-based Fe3O4 nanofluid and Fe3O4–MWCNT hybrid nanofluid under the effect of a magnetic field. The results indicated that the convective heat transfer coefficient of magnetic nanofluids increased with an increase in the strength of the magnetic field. When the magnetic field strength was varied from 0 to 750 G, the maximum convective heat transfer coefficients were observed for the 0.2 wt% Fe3O4 and 0.1 wt% Fe3O4–MWNCT nanofluids, and the improvements were approximately 2.78% and 3.23%, respectively. The average pressure drops for 0.2 wt% Fe3O4 and 0.2 wt% Fe3O4–MWNCT nanofluids increased by about 4.73% and 5.23%, respectively. Owing to the extensive aggregation of nanoparticles by the external magnetic field, the heat transfer coefficient of the 0.1 wt% Fe3O4–MWNCT hybrid nanofluid was 5% higher than that of the 0.2 wt% Fe3O4 nanofluid. Therefore, the convective heat transfer can be enhanced by the dispersion stability of the nanoparticles and optimization of the magnetic field strength.


2014 ◽  
Vol 6 ◽  
pp. 147059 ◽  
Author(s):  
Behrouz Takabi ◽  
Saeed Salehi

This paper numerically examines laminar natural convection in a sinusoidal corrugated enclosure with a discrete heat source on the bottom wall, filled by pure water, Al2O3/water nanofluid, and Al2O3-Cu/water hybrid nanofluid which is a new advanced nanofluid with two kinds of nanoparticle materials. The effects of Rayleigh number (103≤Ra≤106) and water, nanofluid, and hybrid nanofluid (in volume concentration of 0% ≤ ϕ ≤ 2%) as the working fluid on temperature fields and heat transfer performance of the enclosure are investigated. The finite volume discretization method is employed to solve the set of governing equations. The results indicate that for all Rayleigh numbers been studied, employing hybrid nanofluid improves the heat transfer rate compared to nanofluid and water, which results in a better cooling performance of the enclosure and lower temperature of the heated surface. The rate of this enhancement is considerably more at higher values of Ra and volume concentrations. Furthermore, by applying the modeling results, two correlations are developed to estimate the average Nusselt number. The results reveal that the modeling data are in very good agreement with the predicted data. The maximum error for nanofluid and hybrid nanofluid was around 11% and 12%, respectively.


Author(s):  
Bharath R Bharadwaj ◽  
K Sanketh Mogeraya ◽  
D M Manjunath ◽  
Babu Rao Ponangi ◽  
K S Rajendra Prasad ◽  
...  

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