Objective: Experimental and numerical investigation has been performed in
this work to study the enhancement of heat transfer coefficient of TiO2/water nanofluid
in spiral fluted tube equipped with twisted tape.
Method: The performance of spiral fluted tube equipped with twisted tape heat exchanger
with and without nanofluid was investigated experimentally. The concentration
of nanofluid was varied from 0.08 to 0.3% while the twisted ratio (y/w) of twisted tape
was kept constant at 4.0. Steam was used as a heating source where constant wall temperature
condition (110 °C) was achieved. The experiments were performed in turbulent
regime (Reynolds number spanned 7000 ≤ Re ≤ 15000).
Results: Experimental results reveal that the use of spiral fluted tube equipped with
twisted tape without nanofluid leads to an increase in 37% to 43% in heat transfer coefficient
compared with smooth tube. The maximum increase in heat transfer coefficient
occurs with nanofluid at 0.3% concentration, which was about 28.0% to 32.0% higher
than the pure water in spiral fluted tube equipped with twisted tape. Empirical correlation
for the thermal process was developed and represented in terms of Nusselt number.
Numerical simulation has been carried out on present heat exchanger to analyze both
flow field and heat transfer using ANSYS FLUENT package 14. The comparison between
experimental and numerical results showed good agreement.
Keywords: Heat exchanger, spiral fluted tube, twisted tape, nanofluid, coefficient, surface vibration.
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