Experimental Investigation of the Effect of Iron Oxide Nanofluid (Fe3O4) and Secondary Flow Injection on the Thermal Performance in Horizontal Pipe

This study has experimentally investigated the effect of Fe3O4 and secondary flow injection on convection heat transfer and friction coefficient on a horizontal pipe. Secondary flow injected to main flow to make more turbulence to five different models. Water and Fe3O4 have been considered in5865 to 18800 Reynolds range and three0.01%,0.03% and0.06% volume concentrations. Length and diameter of test tube considered 65 cm and 1.7 cm, respectively, the diameter of secondary flow injection holes considered 3 mm and 4.5 mm, the ratio of volumetric flow rate to total flow considered 10% and 20% and distance between secondary flow injection holes considered 4 and 2. The results show that the increase of diameter of secondary flow injections holes, the ratio of secondary flow volumetric flow rate to total flow and the decrease of distance between secondary flow injection holes are effective on coefficient of utilization increase. The highest coefficient of utilization achieved   =20%,  =2 in each model using water fluid in d=4.5 state. In this state, the mean of coefficient of utilization achieved 1.256, 1.266, 1.31, 1.45 and 1.52 for first, second, third, fourth and fifth models in all Reynolds, respectably. The above state has the highest thermal performance in the fourth and fifth models. The mean of coefficient of utilization in all Reynolds increased 0.91%, 3.97% and 4.98% for the above state in the fourth model using Fe3O4 with three0.01%,0.03% and0.06% volume concentrations to water fluid, respectively. Similarly, this increase achieved 1.58%, 4.56% and 5.66% in the fifth model, respectively.