Nanofluid Heat Transfer in Tubes with Twisted Tapes

Experimental Study on Heat Transfer of TiO2 Nanofluid Flow in a Circular Tube with Twisted Tape inserts

Amir Houshmand

The purpose of this study is to experimentally investigate heat transfer enhancement using nanofluid with TiO2 nanoparticles inside the tube with twisted tape inserts. To achive this, an experimental apparatus is designed and manufactured to study the effects of different parameters such as mass flow rate, concentration of nanoparticles in suspension and with varying pitch distance of the twisted tapes. The results of the enhanced heat transfer and pressure drops will be presented. This study evaluates the performance of water / TiO2 nanofluid for enhancing convective heat transfer in a heat exchanger tube with twisted tape inserts. Factors considered include the twist ratio, mass flow rate and the volumetric concentration of nano-particles. Experiments were conducted in a tube with constant wall temperature. The nano-particle volume concentration varies within the range of 0 < PHI< 0.5%, and the twsted tape inserts utilize twist ratio of 0 < H/D < 15. The Reynolds number variation is within the range of 3000 < Re < 22000  . The measured results revealed that the addition of nano-particles as well as twisted tape inserts enhanced the convective heat transfer for all test cases. Combining the positive effects of both nanofluid and the twisted tape, the convective heat transfer was significantly increased up to 103.45% for the test case with volumetric concentration of 0.5% nanofluid and twist ratio of H/D=5. However, the addition of nanoparticles to the base fluid has marginally increased the pressure drop coefficient. Appropriate correlations are introduced for the characteristic of the combined TiO2 / water nanofluid and twisted tape inserts in circular tubes.

Keywords: Experimental Heat transfer, TiO2/ Water Nanofluid, Twisted tape, Convection, Constant wall temperature