Mixed Convection Jet Impingement Cooling of a Rectangular Solid Heat Source Immersed in a Porous Layer

Abstract

In the present article the jet impingement cooling of a heated solid rectangular block immersed in a fluid saturated porous media is considered for numerical investigation. The jet direction is considered to be perpendicular from the top to the solid rectangular block which is heated from below. Therefore, the jet flow and the buoyancy driven flow are in opposite directions. For a fixed jet width, the governing parameters in the present Darcy flow problem are: Rayleigh number (Ra), Péclet number (Pe), solid to porous thermal conductivity ratio (K r) and the dimensionless thickness (or height) of the solid wall (H). The results are presented in the mixed convection regime with wide ranges of the governing parameters with fixed jet width of 20% of the solid wall length. At low values of Pe (natural convection cases), it is found that the effect of Pe is negligible and the average Nusselt number (Nu) is increasing with the increase of either Rayleigh number or the thermal conductivity ratio or decreasing the thickness of the solid wall. At high values of Pe (forced convection cases), it is found that the effect of Ra is negligible and the Nu is increasing with increasing either Pe or the thermal conductivity ratio or decreasing the thickness of the solid wall. At moderated values of Pe (opposing mixed convection cases), it is observed that the values of average Nusselt number show minimum values for some values of Pe. The value of Pe at which minimum Nu occurs depends on Ra, thermal conductivity ratio and the thickness of the solid wall. At low values of either Ra or thermal conductivity ratio this case where Nu shows minimum value is not obvious. It is found that the thinner solid walls have higher values of the average Nusselt number with fixed other parameters. This due to the fact that thicker walls have higher thermal resistances to the heat dissipation from the isothermal surface with fixed other parameters.

Numerical Study of Jet Impingement on Heated Sink Covered by a Porous Layer

“…As a consequence, the computational findings show that for cooling purposes, the solid wall should be as thin as feasible and have a high thermal conductivity. The chilling rate is slower inside the opposing missing convection mode than the natural convection form (where the free convection is the main mechanism criteria) [22]. The metal foam porous media enhances heat transfer surface area making better heat transfer characteristics for higher porosity beside the turbulence generation [23].…”

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“…As a consequence, the computational findings show that for cooling purposes, the solid wall should be as thin as feasible and have a high thermal conductivity. The chilling rate is slower inside the opposing missing convection mode than the natural convection form (where the free convection is the main mechanism criteria) [22]. The metal foam porous media enhances heat transfer surface area making better heat transfer characteristics for higher porosity beside the turbulence generation [23].…”