Abstract
In current unsteady simulation, charging of paraffin in an enclosure which is equipped with spiral pipe was scrutinized. Not only in paraffin but also in water inside the pipe, nanoparticles were dispersed to boost the thermal treatment. Outputs were reported in various stages in forms of irreversibility components. Increasing inlet velocity leads to higher liquid fraction which means better performance. As time increases, inlet velocity has lower effect on melting process. Increasing pumping power is beneficial only when time is lower than 20 min. Frictional irreversibility increases with time at initial time, and then, it reduces.