ABSTRACT
This paper communicates the enhancement of heat transfer, friction characteristics and thermal performance of micro finned tube fitted with Left/Right and regular insert tape inserts using CNT and CNT/Al2O3 nanofluid. Two different concentrations of nanoparticles were used in the present investigation. In contrast, the CNT/Al2O3 nanoparticles are mixed in a weight ratio (50:50) and sonicated for about 2 hours using a bath type sonicator. The prepared nanofluids are stable for almost 48 hours without any sedimentation. Results show that the increase in nanoparticle concentration in the base fluid increases the performance index under turbulence flow regime while the Reynolds number in the range of 2000< Re<5500. Similarly, the Nusselt number and friction increase by 250% and 400%, respectively, with the maximum concentration of nanoparticle and minimum twist ratio. Results also reveal that the use of alternate arrangement increases the turbulence for maximum friction gain and improvement in the convective heat transfer coefficient.
Nomenclature
Al2O3–Aluminium oxide
A–Area (m2)
avg–Average
CNT–Carbon nano tubes
d – Diameter (m)
μ–Dynamic Viscosity
f – Friction factor
Q – Heat flux (W/m2)
Al2O3/CNT-Hybrid Alumina – Carbo Nano Tubes Nanofluid
i – Inlet
Tw,in–Inlet fluid temperature
LR–Left Right
LRT – Left right tape
MWCNT – Multiwall Carbon Nano Tubes
Nu – Nusselt number
Nuplain–Nusselt number of plain tube
o – Outlet
Tw,out–Outlet fluid temperature
Pr – Prandtl number
Re – Reynolds number
Cpnf–Specific heat of nanofluid
Ts–Surface temperature
k – Thermal conductivity (W/mK)
Knf–Thermal conductivity of nanofluid
u – Velocity (m/s)
ϕ-Volume concentration
w – Water
Disclosure statement
No potential conflict of interest was reported by the authors.