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

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 (Re ≥ 2300), 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% TiO 2 /water nanofluid with twisted tape has slightly higher friction factor and pressure drop when compared to 0.01% TiO 2 /water nanofluid without twisted tape. The empirical correlations proposed for friction factor are in good agreement with the experimental data.

Investigation of heat transfer performance and friction factor of a counter-flow double-pipe heat exchanger using nitrogen-doped, graphene-based nanofluids

“…Recent efforts have tried to enhance heat transfer performance of heat exchangers. The applied methods mostly comprise creation of turbulent flow [2] and use of fins, twisters, and baffles [3][4][5]. An obstacle to heat transfer improvement of heat exchangers is the limited thermal properties of conventional coolants.…”

Applications of Compound Nanotechnology and Twisted Inserts for Enhanced Heat Transfer

“…By combining the nanofluid enhancement with inserts, [14] found that using Al 2 O 3 nanoparticles with distilled water and full-length twisted tape gave a superior performance with a noticeable increment in friction loses than plain tube. Reference [15], achieved 20 and 2.5% increase in overall heat transfer coefficient and friction factor, respectively, by using nanofluid with single twisted tape insert in double pipe heat exchanger than that without insert. Reference [16] presented an experimental analysis of the turbulent flow in tube fitted with (single, dual, triple, and quadruple) twisted tapes and nanofluid under turbulent flow conditions.…”

A survey on experimental and numerical studies of convection heat transfer of nanofluids inside closed conduits

“…39,40 In recent years, efforts have been made to enhance heat transfer performance of heat exchangers. The applied methods mostly include creation of turbulent flow, 41,42 use of fins, twisters, and baffles. [43][44][45] An obstacle in heat transfer improvement of heat exchangers is the limited thermal properties of conventional coolants.…”