An entropy generation analysis for the Cu-water nanofluid flow through a wavy channel over heat exchanger plat is investigated. Entropy generation is expressed as a function of velocity and temperature. Governing equations, containing mass conservation, momentum and energy equations, are solved by a finite volume technique. All simulations are performed with Ansys-Fluent. The effects of physical parameters such as Reynolds number, dimensionless amplitude, nanoparticles volume fraction and wave number on the total, thermal, and viscous entropy generation rates and Bejan number are examined. The obtained results indicate that the thermal entropy generation is main term in most part of the channel, including near the wavy walls. Moreover, the rise in viscous entropy generation with Reynolds number increases with increasing dimensionless amplitude. (C) 2017 Elsevier Ltd. All rights reserved.