Experimental study on parallel and counter flow configuration of a shell and helically coiled tube heat exchanger using Al2O3 / water nanofluid

In this work, heat transfer coefficients of shell and helically coiled tube heat exchanger using al2o3 / water nanofluid were studied. this study was done by changing the parallel flow configuration into counter flow configuration under laminar flow regime. the al2o3 / water nanofluid at 0.4% and 0.8% particle volume concentration were prepared by using two step method. the nanoparticles were characterized by x-ray diffraction (xrd) and scanning electron microscope (sem). it is found that the overall heat transfer coefficient of counter flow was 4-8% higher than that of parallel flow at 0.4% nanofluid. the overall heat transfer coefficient was found to be 5-9% higher than that of parallel flow at 0.8% nanofluid. it is studied that there is no considerable effect on heat transfer coefficient on changing flow configuration. this is because of helically coiled tube flow and shell flows are perpendicular direction both in parallel and counter flow configuration. it is also studied the thermal performance of 0.8% nanofluid is higher than 0.4% nanofluid.