Abstract <p>In this study, transfer of heat and flow peculiarities in triangular grooved finless, double and triple triangular grooved finned channels were searched numerically by comparing them with straight channels. Using the Ansys-Fluent computer program, numerical analysis was performed by solving the conservation equations under steady, two-dimensional and laminar flow conditions. To better direct the flow to the lower surfaces of corrugated channels with constant surface temperature, the fins were positioned between the grooves at the top surface of the duct at angles of 30°, 60°, and 90° (θ) with the horizontal and at different heights of 4, 8, and 12 mm (<i>z</i>). The outcomes of the work were examined as variations in the mean Nu number (Nu_{mcorrugated ch.}/Nu_{mstraight ch.}), mean surface temperature (<i>T</i>_{smcorrugated ch.}/<i>T</i>_{smstraight ch.}) and performance evaluation criteria (PEC), taking into account the effects of fin angles and heights. The study’s findings were checked against both the numerical outcomes and the analytical equation of the work in the literature giving the mean Nu number (Nu_m), and it was determined that the outcomes were quite compatible and consistent with each other. The outcomes depicted that for Re = 1200, θ = 90°, and <i>z</i> = 12 mm, the (Nu_{mcorrugated ch.}/Nu_{mstraight ch.}) ratio of TiO₂–water nanofluid in the triple triangular grooved finned channel is 4.28% higher than in the double triangular grooved finned channel. Furthermore, when the fin height of the triple triangular corrugated channel is reduced from 12 to 4 mm for the Re = 1200 and θ = 90°, the increase in the PEC value for the nanofluid reaches 6.02%.</p>