an experimental investigation of heat transfer of fe2o3/water nanofluid in a double pipe heat exchanger

one way to increase the heat transfer is to use perforated twisted tapes with different hole diameters, which largely improve heat transfer with an increase in the heat transfer area at the constant volume and more mixed flow. in the previous studies, the effect of nanofluids with perforated twisted tapes is less studied. in this work, the performance of water / iron oxide nanofluid in a double pipe heat exchanger with perforated twisted tapes is investigated under turbulent flow regime. reynolds number considered is in the range between 2500 to 20500. iron oxide nanoparticles with diameter of 15 nm are used as nanofluid with the concentration range from 0.12 to 0.2% by volume. the results showed that the addition of nanoparticles increases the heat transfer and the nusselt number. also, reducing the twist ratio (h/d=2.5) of perforated twisted tape and using the nanofluid with concentration of 0.2%v/v increase this value by 130%.