الفهرس 
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Abstract
Forced convection heat transfer and friction factor for nanofluid flows inside circular horizontal tube with and without inserting solid and perforated tape, is experimentally studied. Electric heater is wrapped around the outer surface of the tube to obtain a constant and uniform heat flux at the tube wall. Experiments are conducted with adding nano-particles (Al2O3) to water up to 2% by volume to obtain different concentrations of nanofluids. An experimental test loop equipped with the required measuring instruments is designed and constructed to assess the effects of nano-particles concentration, mass flow rate, and applied heat flux on the convection heat transfer process and pressure DROP. The tested tube fitted with solid and perforated tape inserts to evaluate its effects on heat transfer rate and friction factor with nanofluid as the working fluid compared with pure water. The measurements of temperature, flow rate, applied volt and pressure DROP are recorded and manipulated to calculate the convection heat transfer coefficient and friction factor. The obtained experimental results show that, wall temperature is reduced by using nanofluid compared with pure water. Accordingly, the convection heat transfer coefficient increased when using nanofluid and increased also with increasing heat flux and mass flow rate (Reynolds number). Higher rates of heat transfer and pressure DROP are obtained from the tube fitted with solid tape insert compared to flow in a plain tube under similar conditions. This improvement in the convection heat transfer coefficient is characterized by a swirling flow as a result of the secondary flow when the fluid flows inside the tube with helical tape. The average value for the thermal–hydraulic performance () for tube with inserted helical tape was 1.4 for pure water, while it is 1.8 for nanofluid at concentration 0.8%. The heat transfer coefficient decrease for increasing the number of holes in tapes. The decrease of heat transfer coefficient can be explained by minimization of the swirling flow as a result of the secondary flows of the fluid. This compared with the previous work is in good agreement.