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Journal of Engineering
Volume 2014 (2014), Article ID 920970, 9 pages
http://dx.doi.org/10.1155/2014/920970
Research Article

Effect of Twisted-Tape Turbulators and Nanofluid on Heat Transfer in a Double Pipe Heat Exchanger

1Department of Chemistry, Sciences Faculty, Islamic Azad University, Arak Branch, Arak, Iran
2Department of Chemical Engineering, Islamic Azad University, Mahshahr Branch, Mahshahr, Iran
3Department of Chemistry, Islamic Azad University, Saveh Branch, Saveh 39197-15179, Iran

Received 18 August 2014; Revised 30 October 2014; Accepted 30 October 2014; Published 19 November 2014

Academic Editor: Michael Fairweather

Copyright © 2014 Heydar Maddah et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Heat transfer and overall heat transfer in a double pipe heat exchanger fitted with twisted-tape elements and titanium dioxide nanofluid were studied experimentally. The inner and outer diameters of the inner tube were 8 and 16 mm, respectively, and cold and hot water were used as working fluids in shell side and tube side. The twisted tapes were made from aluminum sheet with tape thickness (d) of 1 mm, width (W) of 5 mm, and length of 120 cm. Titanium dioxide nanoparticles with a diameter of 30 nm and a volume concentration of 0.01% (v/v) were prepared. The effects of temperature, mass flow rate, and concentration of nanoparticles on the overall heat transfer coefficient, heat transfer changes in the turbulent flow regime , and counter current flow were investigated. When using twisted tape and nanofluid, heat transfer coefficient was about 10 to 25 percent higher than when they were not used. It was also observed that the heat transfer coefficient increases with operating temperature and mass flow rate. The experimental results also showed that 0.01% TiO2/water nanofluid with twisted tape has slightly higher friction factor and pressure drop when compared to 0.01% TiO2/water nanofluid without twisted tape. The empirical correlations proposed for friction factor are in good agreement with the experimental data.