In this study of heat transfer rate in heat exchanger comprising of helical coils has been studied. It is found that there is fewer publications has been produced on heat exchanger with varying pitch is investigated using horizontal helically coiled tube and water based TiO2 as Nanofluid of volume fractions of 0% ,0.1% ,0.2% ,0.3% ,0.4% and 0.5% prepared by two step method. Heat transfer variable and friction factor studies were experimentally conducted for 3 different helical coil tubes of same diameter and pitch variations of 25 mm, 30 mm, and 35 mm with a curvature ratio  = 0.0667. The study is conducted under turbulent flow condition (Re = 7713–8153). The combined effects of nanofluids, pitcHE’s, flow rate on inner Nusselt number, Dean Number, inner heat transfer coefficient and friction factor are investigated. The finding shows that the use of TiO2 nanofluid with DI water increases the heat transfer rate with increase in nanofluids volume concentrations. The rate of heat transfer in helical tubes enhances for lowest pitch of P =20mm.With Increase in nanofluid volume fraction the Pressure drop increases and the rate of heat transfer coefficient increases with decreasing friction factor. The higHE’st rate of heat transfer coefficient of 7720 W/m2 K is observed for helical coil tube of pitch 25mm and for 0.5 % volume concentration of TiO2 nanofluid with Dean Number of 2464. The higHE’st Nusselt number of 138 also observed for 0.5% volume fraction of nanofluid with friction factor of 0.0362