In the present work, a computational study of mixed convection in air-filled vented cavities is presented. The experimental work is also introduced in this study in order to enrich the computational results. The parametric study of the enclosure is presented for different ranges of Reynolds numbers, Re=103-12270; Richardson numbers, Ri=0.1-25; and vent ratio, gamma=0.1-0.8, and the heat input provided to the right wall, Q=0.84-5.90 W. The continuity, momentum, and energy equations are discretized by the finite volume method and solved using SIMPLEC algorithm. In the present study, optimization of the cavity vent ratio, heat source size, and location found as a novelty in the present work is introduced based on the combined numerical and experimental investigation to achieve better cooling. Empirical correlations for Nusselt number and maximum right wall temperature are developed as functions of Re, Ri, and gamma.