oa Assessment of thermal performances of nanofluids in industrial type heat exchangers

Application of nanotechnology in industrial applications is receiving increased attention this century. Nanotechnology could be used to improve performances of heat exchangers, which are widely used in industrial applications by augmenting heat transfer characteristics of working fluids. Nanofluids, which are engineered colloidal suspensions consisting of nano-sized particles (less than 100 nm) dispersed in a base fluid, have shown potential as industrial cooling fluids mainly due to enhanced heat transfer characteristics. The present work examines the heat transfer performances of different industrial type heat exchangers using nanofluids. Experiments are conducted to compare the overall heat transfer coefficient and pressure drops of water vs. nanofluids in shell and tubes, and plate type heat exchangers on a laboratory scale. SiO2-water nanofluids prepared by dispersing 20 nm diameter nanoparticles at three different particle mass concentrations of 2%, 4% and 6% are used as the working fluid. The nanofluid is maintained in the cold loop of the circuit to avoid direct particle deposition on heater surfaces, and tap water is circulated in the hot loop. The experimental results show a consistent increase in the total heat transfer coefficient of the heat exchanger for the nanofluid concentrations tested. However, the pressure drop in the nanofluids flowline is observed to have increased in comparison to that of the base fluid, which can limit the applicability of nanofluids in heat exchangers.