Improving heat transfer fluid using nanofluids has received a great deal attention attention in recent years. Nanofluids technology offer various heat transfer equipments with remarkable efficiency achievement as alternative nanotechnology-based coolants in many industrial applications. The thermal and transport properties of the working fluid must have a high boiling temperature, density, heat capacity, thermal conductivity, and low viscosity for the heat exchanger to operate well. In the early period of nanofluid preparation, researchers only focused on and used water-based nanofluids in their research work. Though, the combination of base fluid between water and ethylene glycol is started to attract many researchers to explore the potential of these mixture base fluids. Since water is not suitable to flow below the freezing point, so ethylene glycol can be used as it can flow at lower temperature as compared with water. This research aims to study the heat transfer characteristics of a double pipe heat exchanger (DPHE) with Titanium Dioxide (TiO2-Ethylene glycol (EG)/water nanofluid using the Computational Fluid Dynamic (CFD) simulation method. The EG/Water mixture variation was 20:80, 40:60 and 60:40 with a TiO2concentration of 0.01. Besides, the nanofluid flow was also varied by 0.0024; 0.0048; and 0.0072 kg/s. The results show that TiO2 nanofluid affected the heat transfer rate when the different fluid mixing ratio of EG/water was used. Overall heat transfer coefficient of nanofluid encounter an increase when using a lower concentration of Ethylene glycol, which is 20. In contrast, the performance of DPHE decreased with the increase in the mass flow rate of nanofluid and the effectiveness of 0.09 vol. nanoparticles is about 25 higher than that 0.01 vol. using (EG:Water 20:80 nanofluid) at the rate of mass flow of 0.0024 kg/s. According to the outcomes of the present study, the heat transfer capability of EG/water offer substantial benefits with the addition of TiO2nanoparticles under laminar conditions at low concentration of EG and higher concentration of TiO2 nanofluid. The significant findings suggested that (EG:Water 20:80) based nanofluid has a better potential for future applications in the double pipe heat exchangers. © 2023 Author(s).