Investigation Of Flow Characteristics Of Nanofluids In The Tube

With the rapid development of science and technology,the industrial development in the global has become increasingly prominent,but it also exposed the problems which are related to energy shortages.Nowadays,the requirement to the heat transfer load and heat transfer intensity of heat exchange system gradually increased,the traditional pure heat-transfer medium with low conductivity can't keep up with the needs in the development of industry and it is more important to study the new heat-transfer medium,which has higher thermal conductivity.To solve this problem,some scholars have proposed a new concept,which is named with nanofluids.It is formed by adding nanosized metal particles or non-metallic particles into the pure liquid medium in a certain way and proportion.It has a lot of advantages,such as higher thermal conductivity,good stability and small abrasion of equipment.Assume the nanofluids is homogeneous,single phase,incompressible,the numerical simulation of flow and heat transfer characteristics in pipe is investigated for the deionized water and different volume concentrations of Cu-water nanofluids respectively with the help of FLUENT software and the DPM?discrete phase model?model.Observing the temperature contours and particle concentration contours of nanofluids under the same Reynolds number and the same inlet velocity and making analysis to the numerical simulation results and the reasons for this phenomenon,which provides a new idea and new method for the further study of nanofluids.In this paper,“two-step method” was used for preparing the Al₂O₃-water nanofluids.Adding the dispersant and the prepared Al₂O₃ nanoparticles in advance to the deionized water firstly and then getting the nanofluids by the mixed solution with a magnetic stirrer.A set of experimental apparatus is designed and established for measuring the flow characteristics of nanofluids.The flow resistance coefficient at different flow velocity in the tube of Al₂O₃-water nanofluids with different particle mass fraction was measured and compared with the liquid water.The conclusions are as follows: Due to the micro motion of nano-particles added in the liquid,the flow uniformity was better and it reduced the resistance coefficient of liquid in the tube.At the same concentration of nanofluids,the pressure drop of nanofluids is proportional to the flow velocity.