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Mixed convection heat transfer of a nanofluid in a closed elbow-shaped cavity (CESC)

Authors: 

Dariush Ebrahimi, Shahrouz Yousefzadeh, Omid Ali Akbari, Farnaz Montazerifar, Seyed Alireza Rozati, Shima Nakhjavani, Mohammad Reza Safaei

Source title: 
Journal of Thermal Analysis and Calorimetry, 144: 2295-2316, 2021 (ISI)
Academic year of acceptance: 
2020-2021
Abstract: 

The current survey’s primary purpose is to conduct the computational modeling of laminar mixed convection heat transfer of nanofluids inside a CESC using a finite volume method. Water/Cu nanofluid at 0–6% volume fractions was selected as a working fluid. The investigation was done at Grashof numbers of 10,000 < Gr < 100,000 and Richardson numbers of 0.1, 1, and 10. All parameters of the hydrodynamic flow and mixed convection heat transfer are presented as Nusselt number, the coefficient of friction, dimensionless velocity in different sections of the cavity, and entropy generation and temperature contours. Results indicated that nanofluid with higher volume fraction causes heat transfer enhancement. Using nanofluid, applying the gravity domain and the existence of lid driven in studied geometry affect flow behavior. Solid nanoparticles’ existence causes better temperature distribution and better stimulation of buoyancy force, which can be considered another factor for improving buoyancy force. By increasing Grashof number, the circulation mechanism’s improvement is the most significant factor in reducing entropy generation in studied geometry. At the beginning of fluid collision with the surface, the highest temperature variation between the surface and the fluid occurred by considering the fluid temperature. Hence, at the bottom areas of the hot surface, entropy generation is always the least.