Authors: Shahzada Zaman Shuja; Bekir Sami Yilbas; Mahmoud Kassas
Addresses: Mechanical Engineering Department, KFUPM, Dhahran 31261, Saudi Arabia ' Mechanical Engineering Department, KFUPM, Dhahran 31261, Saudi Arabia ' Electrical Engineering Department, KFUPM, Dhahran 31261, Saudi Arabia
Abstract: Flow over porous structures finds applications in heat transferring devices due to attainment of high heat transfer rates. Thermodynamic irreversibility can be used as a measure of quality of the porous body in the thermal system. In the present study, flow over a porous block situated in a square open-ends cavity and rate of entropy generation due to heat transfer and fluid friction are considered. The effects of the block aspect ratio and porosity on volumetric entropy generation rate are examined numerically. In the simulations, four aspect ratios and three porosities of the block are accommodated. The total area of the block is kept constant for all the aspect ratios considered in the simulations. A uniform heat generation (105 W/m²) is considered in the block resembling the heat generating device, such as encapsulated electronic device, and air is used as working fluid in the cavity. It is found that volumetric entropy generation rate in the cavity reduces with increasing aspect ratio and porosity of the block. Entropy generation rate due to heat transfer is considerably higher than its counter part due to fluid friction because of low Reynolds number flow at cavity inlet and small natural convection current generated in the cavity.
Keywords: cavities; porous blocks; fluid flow; aspect ratios; entropy generation; heat transfer; fluid friction; simulation.
Progress in Computational Fluid Dynamics, An International Journal, 2015 Vol.15 No.1, pp.16 - 24
Received: 08 May 2021
Accepted: 12 May 2021
Published online: 04 Feb 2015 *