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The purpose of this paper is to study flow over two heat generating porous blocks situated in a cavity, and examine the effects of porous blocks geometric orientations in the cavity (configurations) and the amount of heat generation in the blocks on entropy generation rate due to heat transfer and fluid flow.

Four configurations of blocks and three heat fluxes are accommodated in the simulations. The equilibrium flow equations are used to compute the flow field. Entropy generation in the flow system due to fluid friction and heat transfer is also computed. A control volume approach is used to discretize the governing equations of flow and heat transfer. In the simulations, flow Reynolds number is kept 100 at cavity inlet and blocks' porosity is set to 0.9726.

The volumetric entropy generation rate attains high values around the blocks and configuration 4 results in reasonably low values of entropy generation rate due to heat transfer and fluid flow.

The simulations are limited to low Reynolds numbers due to practical applications. However, at high Reynolds numbers, flow separation in the cavity results in complex flow structure, which is difficult to simulate.

The thermodynamic irreversibility of the thermal system in the cavity becomes low for certain configuration of blocks in the cavity. The power loss, in this case, becomes less.

The work introduces original findings for cooling applications. When porous blocks are used for electronic cooling, the blocks configurations are very important. This is clearly demonstrated in this study.

Porous medium has always been introduced as an environment for increasing heat transfer in cooling systems. However, increase in heat transfer and resolving pressure drop in the fluid flow have been focused on by researchers.The purpose of this paper is to study the effects of creating porous micro-channels inside porous macro-blocks to optimize system performance in channels.

To simulate flow field, a developed numerical code that solves Navier–Stokes equations by finite volume method and semi-implicit method for pressure linked equations (SIMPLE) algorithm will be used together with bi-disperse porous medium (BDPM) method. Working fluid is air with Pr = 0.7 in laminar state. Influence of permeability changes by creation of micro-channels containing porous medium in vertical, horizontal and cross-shape patterns will be investigated.

By creating porous micro-channels inside macro-blocks, not only does the heat transfer increase significantly but the pressure also drops remarkably. Increase in performance evaluation criteria (PEC) is more evident in lower Reynolds numbers that can increase the PEC to 75 per cent by creating cross-shape micro-channels. By changing the permeability of micro-channels, PEC will increase by reducing the pressure drop but it has minor changes in Nu.

The current work is applicable to optimizing system performance by decreasing the pressure drop and increasing the heat transfer.

The developed patterns are useful in increasing the system performance including the increase in heat transfer and decrease in pressure drop in systems such as air coolers required in electrical circuits.

Development and optimization of system performance by new patterns using BDPM in comparison to the previous patterns.

The purpose of this study was to analyze the heat transfer in a square porous cavity that has a solid block placed at its center. The prime focus of this study is to investigate the effect of size of the square solid block and other physical parameters on the heat transfer rate from the hot surface into the porous medium. The left vertical surface of cavity is maintained at a hot temperature and the right vertical surface at a cool temperature, T_c. The finite element method is used to simplify the governing equations and is solved iteratively. It is noted that the size of the solid block plays a vital role in dictating the heat transfer from the hot surface to porous medium.

The current work is based on finite element formulation of a square porous cavity that has a solid square block placed at its center. Governing equations were solved iteratively.

The size of the solid block has a pronounced effect on the heat transfer behavior inside the porous cavity.

This study highlights the heat transfer due to a conducting square solid block at mid of porous cavity.

The purpose of this study is to analyze a new idea for external flow over a cylinder to increase the heat transfer and reduce pressure drop. Using wedge-shaped porous media in the front and wake regions of the cylinder can improve its hydrodynamic, and the rotating flow in the wake region can enhance the heat transfer with increased porous–liquid contact. Permeability plays a vital role, as a high-permeable medium improves heat transfer, whereas a low-permeable region improves the hydrodynamic.

Therefore, in the current research, external forced convection of nanofluid laminar flow over a bundle of cylinders is simulated using a two-phase mixture model. Four cases with different porous blocks around the cylinder are assessed: rectangular porous; wedge shape in trailing edge (TEP); wedge shape in leading and trailing edges (LTEP); and no porous block case. Also, three different lengths of wedge-shaped regions are considered for TEP and LTEP cases.

Results are presented in terms of Nusselt (Nu), Euler (Eu) and the performance evaluation criterion (PEC) numbers for various Reynolds (Re) and Darcy (Da) numbers.

It was found that in most situations, LTEP case provides the highest Nu and PEC values. Also, optimal Re and porous medium length exist to maximize PEC, depending on the values of Da and nanofluid volume fraction.

This paper aims to numerically investigate the thermal performance evaluation of a microchannel with different porous media insert configurations.

Heat transfer and pressure drop of fluid flow through a three-dimensional (3D) microchannel with different partially and filled porous media insert configurations are investigated numerically. The number of divisions and positions of porous material inside the microchannel for 12 different arrangements are considered. A control volume method is used for single-phase laminar flow with the Darcy–Forchheimer model used for the porous media. The geometry of the problem consists of a microchannel with a rectangular cross-section of 0.4 mm × 0.2 mm and length 20 mm, with a stainless steel porous material insert with a porosity coefficient of ε = 0.32 and a Darcy number of Da = 2.7 × 10⁻⁴.

Numerical results show that when the transverse arrangement is used, as the number of partitions increases, the thermal performance is improved and the heat transfer increases up to 300% compared to that of the plain microchannel. Comparing the obtained results from the microchannels with transverse and longitudinal configurations, at low Reynolds numbers, the transverse arrangement of porous blocks and at high Reynold numbers, the longitudinal arrangement present the best thermal performance which is virtually four times higher compared to the obtained Nu numbers from the plain microchannel. The results show that as the volume of porous material is constant in the cases with various transverse porous blocks, the pressure drop is not changed in these cases. Also, the highest thermal performance ratio is when the porous material is placed along the walls in a longitudinal direction.

To the best knowledge of the authors, in the previous research, the effect of the arrangement and location of the porous medium in the transverse and longitudinal direction in the microchannel and their effect in different states on the behavior of flow and heat transfer has not been numerically investigated. In this study, the porous media configuration and its placement in a 3D microchannel were numerically studied. The effect of porous material layout and configurations in different longitudinal and transverse directions on the pressure drop, heat transfer and thermal performance in the 3D microchannel is investigated numerically.

The purpose of this paper is to improve the volume-averaged models for free convection flow in porous media.

A pore scale simulation is conducted against which an independent volume-averaged solver is fine-tuned.

Micro and macro scale results can merge if proper choice of local thermal non-equilibrium and thermal dispersion models are selected. This depends on the range of Ra values investigated.

This is the first time a work like this is published in the literature.

This study aims to enhance natural convection heat transfer for a porous thermal cavity. Multi-frequency sinusoidal heating is applied at the bottom of a porous square cavity, considering top wall adiabatic and cooling through the sidewalls. The different frequencies, amplitudes and phase angles of sinusoidal heating are investigated to understand their major impacts on the heat transfer characteristics.

The finite volume method is used to solve the governing equations in a two-dimensional cavity, considering incompressible laminar flow, Boussinesq approximation and Brinkman–Forchheimer–Darcy model. The mean-temperature constraint is applied for enhancement analysis.

The multi-frequency heating can markedly enhance natural convection heat transfer even in the presence of porous medium (enhancement up to ∼74 per cent). Only the positive phase angle offers heat transfer enhancement consistently in all frequencies (studied).

The present research idea can usefully be extended to other multi-physical areas (nanofluids, magneto-hydrodynamics, etc.).

The findings are useful for devices working on natural convection.

The enhancement using multi-frequency heating is estimated under different parametric conditions. The effect of different frequencies of sinusoidal heating, along with the uniform heating, is collectively discussed from the fundamental point of view using the average and local Nusselt number, thermal and hydrodynamic boundary layers and heatlines.

Better membrane oxygenators need to be developed to enable efficient gas exchange between venous blood and air.

Optimal design and analysis of such devices are achieved through mathematical modeling tools such as computational fluid dynamics (CFD). In this study, a control volume-based one-dimensional (1D) sub-channel analysis code is developed to analyze the gas exchange between the hollow fiber bundle and the venous blood. DIANA computer code, which is popular with the thermal hydraulic analysis of sub-channels in nuclear reactors, was suitably modified to solve the conservation equations for the blood oxygenators. The gas exchange between the tube-side fluid and the shell-side venous blood is modeled by solving mass, momentum and species conservation equations.

Simulations using sub-channel analysis are performed for the first time. As the DIANA-based approach is well known in rod bundle heat transfer, it is applied to membrane oxygenators. After detailed validations, the artificial membrane oxygenator is analyzed for different bundle sizes (L/W) and bundle porosity (epsilon) values, and oxygen saturation levels are predicted along the bundle. The present sub-channel analysis is found to be reasonably accurate and computationally efficient when compared to conventional CFD calculations.

This approach is promising and has far-reaching ramifications to connect and extend a well-known rod bundle heat transfer algorithm to a membrane oxygenator community. As a variety of devices need to be analyzed, simplified approaches will be attractive. Although the 1D nature of the simulations facilitates handling complexity, it cannot easily compete with expensive and detailed CFD calculations.

This work has high practical value and impacts the design community directly. Detailed numerical simulations can be validated and benchmarked for future membrane oxygenator designs.

Future membrane oxygenators can be designed and analyzed easily and efficiently.

The DIANA algorithm is popularly used in sub-channel analysis codes in rod bundle heat transfer. This efficient approach is being implemented into membrane oxygenator community for the first time.

The purpose of this paper is to investigate computationally the hydrothermal characteristics for forced convective laminar flow of water through a channel with a top wavy wall and a flat bottom wall having metallic porous blocks.

The governing equations are solved computationally using a finite element method–based numerical solver COMSOL Multiphysics® for the following range of parameters: 10 ≤ Reynolds number (Re) ≤ 500 and 10^–4 ≤ Darcy number (Da) ≤ 10^–1.

The presence of porous blocks significantly influences the heat transfer rate, and the value of local Nusselt number increases with the increase in Da. The value of the average Nusselt number decreases with Da for the top wall and the same is enhanced for the bottom wall of the wavy channel with porous blocks (WCPB). The value of the average Nusselt number for WCPB is significantly higher than that of the wavy channel without porous block (WCWPB), plane channel without porous block (PCWPB) and plane channel with the porous block (PCPB) at higher Re. For PCPB, the performance factor (PF) is always higher than that of WCWPB and WCPB for Da = 10^–4 and Da = 10^–3. Also, PF for WCPB is higher than that of WCWPB for higher Re except for Da = 10^–4. Further, the value of for WCPB is higher than that of PCPB at Da = 10^–2 and 10^–1 at Re = 500.

The current study is useful in designing efficient heat exchangers for process plants, solar collectors and aerospace applications.

The analysis of thermo-hydraulic characteristics for laminar flow through a channel with a top wavy wall and a flat bottom wall having metallic porous blocks have been analyzed for the first time. Further, a comparative assessment of the performance has been performed with a wavy channel without a porous block, a plane channel without a porous block and a plane channel with porous blocks.

The purpose of this paper is to study numerically the fluid flow and heat transfer in an inclined channel provided with heated porous blocks on its lower plate.

The Brinkman‐Forchheimer extended Darcy model with the Boussinesq approximation is adopted for the flow in the porous regions. The governing equations with the appropriate boundary conditions are solved by the control volume method. The effect of some pertinent parameters such as the buoyancy force intensity, the porous blocks shape and height, the porous medium permeability and the Reynolds number are analyzed for various inclination angles ranging from −90° to +90°.

The results reveal, essentially, that the inclination angle of the channel can alter substantially the fluid flow and heat transfer mechanisms, especially at high Richardson and Darcy numbers. In this case, the maximum and minimum global Nusselt numbers are reached for α=+90° and α=−90°, respectively.

The results obtained in this work are valid for an inclined channel with porous blocks attached on the heated parts of the lower plate, whereas the upper wall is thermally insulated.

The results obtained in this worky can be used in the thermal control of electronic components. The use of porous blocks mounted on the heat sources will increase the rate of heat removal in order to maintain the electronic components at an acceptable operating temperature.

The paper provides an interesting method to improve the cooling of electronic devices by use of a porous medium.