Anexperimentalstudy is conducted to investigate the effects of inclination angle on the natural convec-29 tion of nanofluids inside a cubic cavity with the side size of 10 cm. One of the surfaces of the cavity is kept 30 in cold temperature and another one (opposite side) in hot temperature while the other four surfaces are 31 insulated. The mixtures of three different types of nanoparticles including Al2O3, TiO2, and CuO within 32 turbine oil (TO) are used as the heat transfer fluid. The heat transfer in the cavity is investigated in three 33 inclination angles with respect to the horizontal position including 0,45and 90where the weight frac-34 tions of nanoparticles are0.2%,0.5%, and 0.8%. The Nusselt number results are presented for the three 35 types of nanofluids, and different angles of inclination, Rayleigh number, and weight fraction of nanopar-36 ticles. The results reveal that the turbine oil has the highest Nusselt number in any inclination angle of 37 the cavity compared to the nanofluids. Also, it is found that at the inclination angle of 90, and the weight 38 fraction 0.2%, the application of TiO2particles results in the maximum Nusselt number while for weight 39 fraction of 0.8%, the maximum Nusselt number is associated with the CuO nanopowders

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