A brief evaluation of heat transfer through helical coil heat exchangers is present in this study. Improvement in heat transfer owed to helical coils has been stated by many scholars. Heat exchanger are significant engineering system with extensive variety of application including HVAC, power plants,heat recovery system, chemical processing, refrigeration and air conditioning system, food industries, nuclear reactors etc. Functioning towards the energy saving and to make short design for mechanical and chemical plans and plants, heat transfer plays a very important role in design of heat exchangers. We can improve the heat transfer rate by modifying the design by providing the helical tubes in place of straight tubes, and by using nano-fluids.Laterauthenticating the procedure of CFD analysis of a heat exchanger, the effect of seeing the actual fluidproperties in its place of a constant value is established. Heat transfer characteristics inside a helical coil for various types ofnano-fluids, they are. Zinc Oxide (ZnO), Silicon dioxide (SiO2) and Magnesium Oxide (MgO) using oil as a base fluid are compared.