In this study we focus on the double diffusive convection generated in a horizontal bi-layered porous cavity. All porous layers-cavity may occupy different positions relative to the horizontal axis for inclination angle values0 degrees <= alpha <= 60 degrees. Each porous layer is considered homogeneous, isotropic and saturated with the same fluid. The vertical walls are subjected to of uniform conditions of temperature and concentration whereas the horizontal walls are assumed to be adiabatic and impermeable. The set of equations describing the double diffusive convection within the enclosure are solved numerically using the numerical control volume approach. A scale analysis for predicting mass transfer rate is represented for the case, where the two porous layers in the cavity are arranged vertically and for solute-driven flows (N >> 1). The numerical results are presented and analyzed in terms of streamlines, isotherms, iso-concentrations lines and for the average Nusselt and Sherwood numbers. (C) 2015 Elsevier Ltd. All rights reserved.