Developing convective flow in a square channel partially filled with a high porosity metal foam and rotating in a parallel-mode

Abstract

The development of three-dimensional heat transfer and fluid flow in a square channel rotating in a parallel-mode has been investigated numerically. The duct is partially occupied by a foam material of high porosity ε≥0.89 and subjected to a uniform wall heat flux. In regards to the influence of rotation, both the centrifugal buoyancy and Coriolis forces are considered in the current study. The generalised model is used to mathematically simulate the momentum equations employing the Boussinesq approximation for the density variation. Moreover, thermal dispersion has been taken into account with considering that fluid and solid phases are in a local thermal non-equilibrium. The governing equations are discretised according to the finite volume method with employing a hybrid differencing scheme. Computations are performed for a wide range of parameters including the hollow ratio (0≤S≤1), foam porosity (0.89≤ε≤0.97), pore density (5PPI≤ω≤40PPI), solid to fluid thermal conductivity ratio (250≤κ≤4000), Reynolds number (250≤Re≤2000), and rotation number (0≤Ro≤1), while the values of characteristic temperature difference and Prandtl numbers are maintained constant at ΔTc=1000°C and Pr=0.7, respectively. Results reveal that flow resistance and heat transport are augmented with either decreasing the hollow ratio and foam porosity or increasing Reynolds and rotation numbers, while two contradictory trends are found for the impact of increasing pore density on heat transfer; either enhancing or suppressing depending on the size of hollow zone. In addition, both rotation and thermal dispersion have dominant roles in enhancing heat transfer at the higher levels of porosity or the lower values of conductivity ratios. However, these roles are reduced gradually with decreasing the foam porosity or increasing thermal conductivity ratio, but do not completely vanish. Eventually, the worth of using high porosity fibrous media in enhancing the heat transported through rotating channels has been inspected. An overall enhancement parameter is compared for the current study with a previous work regarding turbulent flow in a rotating clear channel, where it has been confirmed that the current proposal is practically justified and efficient. 06-05-2015Ahmed Alhusseny A5, George Begg Building, Sackville Street Manchester, M60 1QD (+44) 7876340153 ahmed.alhusseny@postgrad.manchester.ac.uk International Journal of Heat and Mass TransferThe current research presents a numerical simulation of the three-dimensional fluid flow and heat transfer in a square channel rotating around a parallel axis. The duct is partially occupied by metal foam of high porosity (ε≥ 0.89) and subjected to a uniform wall heat flux. Both the centrifugal buoyancy effect and Coriolis forces are considered regarding to the rotation effect in the current study.The generalised model is used to mathematically simulate the momentum equations employing the Boussinesq approximation for the density variation. Moreover, thermal dispersion has been taken into account w...

Rotating metal foam structures for performance enhancement of double-pipe heat exchangers

“…To this end, boundary conditions proposed by Ochoa-Tapia and Whitaker [32] for the fluid-solid interface are used with taking the thermal dispersion into account as detailed in Eqs. (11.a-e) mentioned previously by Alhusseny et al [19]. …”

“…Also, their open-cell structure makes them less resistant to the fluids flowing through them, and hence, pressure drop across them is much less than it in the case of flow via packed beds or granular porous media. Therefore and due to their ability to meet the highly thermal demands with no excessive loss in pressure, open-cell metal foams have been utilised in heat exchangers [14], [15] besides internal cooling of both turbine blades [16] and the rotor windings of high-capacity electrical generators [17], [18], and [19]. Thus, it is not surprising to use them recently in double-pipe heat exchangers [20] and [21], where a substantial enhancement in the heat transfer performance has been acquired.…”

“…Therefore, channels partially filled with permeable materials have been proposed as an alternative to avoid unnecessary pressure drop while keeping the heat transfer at as high rates as possible. For example, and in order to improve the overall enhancement achieved, the effect of utilising rotating cooling channels partially filled with open-cell metal foams was numerically investigated by Alhusseny et al [19].…”

High-Porosity Metal Foams: Potentials, Applications, and Formulations

“…Similarly, they have been proposed as an effective way to enhance the heat dissipated from heavy-duty electrical generators through filling their rotating cooling passages either fully or partially with open-cell metal foams [23][24][25]. The value of the this proposal was inspected by introducing an enhancement factor as the ratio of heat transported to the pumping power required, that is, Nu Re p in Àp e ðÞ =ρu 2 in , and comparing it with the corresponding values from a previous work regarding turbulent flow in a rotating clear channel [26], as shown in Figure 4 [25], where it was confirmed that the proposed enhancement is practically justified and efficient.…”

Unlocking the Thermal Efficiency of Irregular Open-Cell Metal Foams: A Computational Exploration of Flow Dynamics and Heat Transfer Phenomena

“…Alhusseny et al [39] analyzed the distribution of the flow resistance and heat transfer coefficient in square channels partially filled with a metal foam for different filling rates, ε values, pore densities, and Re values (250~2000). Heat transfer was found to increase significantly as the filling rate and foam ε decreased or as Re increased.…”