Heat transfer enhancement in T-Tube convertor concept using nanofluids

An experimental investigation was carried out to study the effect of γAl2O3-H2O nanofluid concentration (weight percent) and its Reynolds number (Re) on the local and average heat transfer coefficients (HTC) as well as on the surface temperature. In doing so, an experimental set up was built to investigate the impingement of nanofluid via a slot jet on the inside surface of a hot tube. Nanofluids with five different concentrations varying from 0.0073 to 0.0757 wt% were used, and at Reynolds numbers between 1259 and 2080, the inlet power as well as heat flux were respectively set at 300 W and 34.37 kW/m2. For both water and nanofluid, there is a decreasing trend of local HTCs with the impingement angle due to the boundary layer development beyond the stagnation point. The results showed that the heat transfer performance was improved with addition of nanoparticles up to concentration of 0.0597 wt% (in water). Highest percentage enhancement in local HTC for this concentration at the Re of 2080 was 57.10%. For nanofluid concentration of 0.0597 wt%, when compared with distilled water, highest HTC enhancement percentages was 44.86%, related to 0.0597 wt% nanofuid for the Reynolds number of 1908.