In this study, developing laminar forced convection of Al2O3/water nanofluid flow inside a trapezoidal microchannel has been investigated. The numerical simulation is conducted using two different methods which consider the effect of non-uniform nanoparticle distribution: Buongiorno's Two-component non-homogeneous model, and Eulerian-Lagrangian two-phase method. The results are compared to experimental data and also single-phase and dispersion methods. It is shown that the Eulerian-Lagrangian method predicts microchannel Nusselt number more accurately than Buongiorno's model. Particle distribution is not uniform in the cross section of microchannel, and with increasing Reynolds number this nonuniformity is more. Moreover, the effect of different forces on heat transfer is discussed. It is found that the influence of Saffman's lift force is negligible while Brownian and thermophoretic forces affect the heat transfer coefficient slightly. Furthermore, it is shown that the use of experimental correlation for nanoparticle Nusselt number makes the numerical results more accurate, so it is important to take into account the scale effects and use the suitable correlations. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.