Convection Heat Transfer and Friction Factor of AL2O3/ Water Nanofluid Flows inside Circular Tube with Inserting Helical Tape.

Mostafa, Hesham; Saafan, Mohamed

doi:10.21608/bfemu.2020.130480

Convection Heat Transfer and Friction Factor of AL2O3/ Water Nanofluid Flows inside Circular Tube with Inserting Helical Tape.

Document Type : Research Studies

Authors

Hesham Mostafa ¹
Mohamed Saafan ²

¹ Assistant Professor., Mechanical Power Engineering Department., Faculty of Engineering., Higher Technology Institute., Tenth of Ramadan City., Egypt.

² Associate Professor., Mechanical Power Engineering Department., Faculty of Engineering., El-Mansoura University., Mansoura., Egypt.

10.21608/bfemu.2020.130480

Abstract

Forced convection heat transfer and friction factor for nanofluid flows inside circular horizontal tube with and without inserting helical tape, was experimentally studied. Electric heater was 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 (AI₂O₃) to water up 10, 2% by volume 10 obtain diffrerent concentrations of nanonfluids. An experimental test loop equipped with the required measuring instruments was designed and constructed to assess the effects of nano-particles concentration, mass flow rate, and applied heat flux on the convection heal transfer process and pressure drop. The tested tube fitted with screw helical tape inserts to evaluate its effects on heal transfer rate and friction factor with nanofluid as the working fluid compared with pure water. The measurements of temperature, now 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 was reduced by using nanofluid compared with pure water. Accordingly. the convection heal transfer coefficient;' increased when using nanofluid and increased also with increasing heat flux and mass now rate (Reynolds number). Higher rates of heat transfer and pressure drop are obtained from the tube fitted with screw helical tape insert compared to flow in a plain/tube under similar conditions. This improvement in the heat transfer coefficient characterized by a swirling flow as a result of the secondary flow of the fluid flow inside tube with helical tape.
The average value for the thermal-hydraulic performance(ŋ) for tube with inserting helical tape was 1.4 for water only , and 1.8 for nanofluid at concentration 0.8% comparison with the previous work gave good agreement.

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