International Journal of Nano Dimension (Int. J. Nano Dimens.) Effect of nonionic surfactant additives on the performance of nanofluid in the heat exchanger Volume 8 (2017) Issue 1, March 2017 2024 02 28 Effect of nonionic surfactant additives on the performance of nanofluid in the heat exchanger 10.22034/ijnd.2017.24373 EN Gajanan P Lakhawat Department of Chemical Engineering, Priyadarshini Institute of Engineering and Technology, Nagpur-440 019 (M.S.), India Rajendra P Ugwekar Department of Chemical Engineering, Laxminarayan Institute of Technology, Nagpur-440 033 (M.S.), India Sanvidhan G Suke Department of Biotechnology, Priyadarshini Institute of Engineering and Technology, Nagpur-440 019 (M.S.), India Vivek M Nanoti Department of Physics, Priyadarshini Institute of Engineering and Technology, Nagpur-440 019 (M.S.), India Journal Article 2024 02 28 A nanofluid is mixture of nano sized particles and a base fluid. This paper investigates by using laboratory based double pipe heat exchanger model, the performance of nanofluid containing about 48.46nm  particle size nanoparticles (ZnO) without or with addition of nonionic surfactant Rokanol K7 (500ppm) into the base fluid double distilled water to prepared three different concentrations 1.0%, 2% and 3% (v/v) of ZnO-water or ZnO-RK7. Effects of temperature and concentration of nanoparticles on viscosity and heat transfer coefficient in heat exchanger are investigated. The experimental results shows that the viscosity of nanofluids increased with increasing concentration of fluid whereas decreased with increasing temperature from 20 to 60ºC. However, it has been also observed that heat transfer coefficient increases with the operating temperature and concentration of nanoparticles. The conclusion derived for the study is that overall heat transfer coefficient enhanced with increasing concentration upto 3% of ZnO-RK7 as compared to without surfactant nanofluids.