The present paper is a numerical study on heat transfer and pressure drop of a nanofluid including water as base fluid with Al2O3 nanoparticles inside a square channel having an inner cylinder, with and without fin under constant heat flux condition using two-phase Euler–Lagrange approach. Numerical investigation has been carried out for various combinations of base fluid, nanoparticle size and concentration through a straight cylinder. Simulation has been performed in a laminar flow regime using finite volume method. Besides, the thermal boundary condition of constant uniform heat flux on the channel wall was applied. The results show that the increase in Reynolds number and nanoparticle volume concentration have considerable effects on heat transfer coefficient enhancement. The heat transfer coefficient decreases when nanoparticles diameter increases. The passive way used in this study, leads to higher pressure drops. For all fluids under consideration, pressure drop escalates with Reynolds number. Adding nanoparticles to the base fluid leads to rise in pressure drop, and this effect is more intensive for higher concentrations.
