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.
Highlights
Forced convection heat transfer and friction faclor ror nanonuid nows inside circu lar horizontal tube with and without inscTting hel ical tape, was ex.perimcnta lly studied
Elcclric healer was wrapped around the outer surrace oflhe tube to obtain a constant and unirorm heat nux at the tube wall
The tested lUbe fined wi th screw helical tape inserts 10 eva luate its .efrecls on heal transfer rale and rrieti on ractor with nanonuid as the working fluid compared with pure water
Summary
Forced convection heat transfer and friction faclor ror nanonuid nows inside circu lar horizontal tube with and without inscTting hel ical tape, was ex.perimcnta lly studied. An ex perimental lest loop equipped wilh the required measuring insuum ents was designed and constructed to assess the effects ofn ano·particles concentration, mass Oow rate, and applied heat nux on the convection heal lransfer process and pressure drop. The tested lUbe fined wi th screw helical tape inserts 10 eva luate its .efrecls on heal transfer rale and rrieti on ractor with nanonuid as the working fluid compared with pure water. Higher rales of heallransrer and pressure d rop arc obtained rrom the lube filled wi ln screw helical tape in sert compared 10 in a plainllube under similor cond itions. This improvement in the convec ti on hea t transfer coefficient characterized by a. Especially in high Peclet number may cause the change in structure and lead to augmented heat transfer due 10 the presence of nano-particles
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