Free convection heat transfer of Al2O3/water nanofluid in an inclined closed enclosure is investigated numerically considering radiation effects. A horizontal and constant magnetic field is applied to the chamber. The chamber also has an angle with the horizontal axis. A partition with constant thermal conductivity is positioned on the horizontal diameter of the enclosure and divides the fluid inside it into two parts. Parts of the left and lower walls of the chamber are kept at high temperature, and the right wall is kept at low temperature. The rest of the walls are also insulated. In the present work, in addition of investigation of the heat transfer rate (HTR), total entropy generation (TEG) and Bejan number (Be) are also evaluated. The results show that as the Hartmann number intensifies from 0 to 40, heat transfer and entropy generation decrease by 35% and 46%, respectively. An intensification of the Rayleigh number results in an intensification of the HTR by 39% and the entropy generation by 90%. The Bejan number decreases by augmenting the Rayleigh number and intensifies with the Hartmann number. The addition of radiation heat transfer results in an intensification of the entropy generation and a reduction in the Bejan number. The enclosure angle changes have different effects on the vortices formed at the top and bottom of the partition. As the hot wall length intensifies from 0.1 to 0.9, the Nusselt number and entropy generation become 3.77 and 2.8 times, respectively. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.