An Investigation of Natural Convection Heat Transfer in A Cubic Enclosure with Oriented Partial Partitions at Different Angles

Abstract

Natural convection heat transfer in an enclosure provided with inclined partitions to the two adiabatic sides, heated from the bottom with uniform heat flux and cooled from the top at constant temperature is studied experimentally and numerically in this work. The inclined partitions is well covered with an insulated material, so that, it can be assumed as parts of the adiabatic walls that places on. The governing parameter, Rayleigh number, is fixed in this work within 2.6x10¹¹, so that the effect of inclination angles of the two side’s partitions can be investigated. The inclination angles of the two baffles range as (0^o ≤ and ≥ 150^o). In numerical solution the effect of turbulence is modelled using (k-ε) model. Some applications need to use the enclosed fluid layers as insulation, so that one purpose of this work deals with improve the insulating properties of fluid layers. The experimental and numerical works are done in 36 runs, grouped into 6 collections. Each collection with 6 runs done under a fixed inclination angle of one baffle and change the second baffle inclination angle to investigate the enclosure flow field and heat transfer. The result shows that a multi cells forms when the two baffles aboard to each other’s, which is a reason to make a separation between a cold, and hot circulation cells that forms in the enclosure and act as insulator. It is also conclude that for all cases, the long insulated baffle of any inclination angle causes a reduction to the heat exchange inside the enclosure due to the damping cause to the flow field. The less average Nusselt number occurs when the two angles are equals, and the worst case is (θ=β=90^o).