Present study has some consideration to simplify the analysis.
In particular, attention has been focused on a helical coil heat exchanger
subjected to a constant boundary heat flux. In this analysis,
it is assumed that the nanofluids flows through the coil tube is
fully developed both thermally and hydrodynamically, and also assumed
that the nanofluids flows through the tubes are incompressible
and turbulent flow regime. The thermophysical properties of
nanofluids are constant throughout the system. The design specifications
and geometrical dimensions of helically coiled-tube heat
exchanger are obtained from the literature [25].