Characterization of heat transfer and artificial neural networks prediction on overall performance index of a channel installed with arc-shaped baffle turbulators

Influences of baffle pitch ratio (p/w) and attached angle of arc-shaped baffles (AB) on the overall performance index (OPI) of a channel installed with AB have been carefully studied. In addition, an artificial neural network (ANN) model for predicting the OPI of the channel was reported. The arc-shaped baffle (AB) showed a significant effect on the augmented heat transfer and friction loss penalty as compared to a smooth channel. As the attached arc shaped angle (θ) increased, both Nusselt number and friction factor intensified. The Nusselt number values at θ = 90° were higher than those at θ = 20°, 40°, 60°, and 80° by up to 5.8%, 3.9%, 2.3% and 2.5%, respectively. The Nusselt number increased when the p/w was raised from 4.0 to 8.0 while the opposite trend was observed when the p/w was raised from 8.0 to 12.0. The maximum OPI of 1.43 was achieved by using the baffles with θ = 90° and pitch ratio of 8.0 at Re = 4000. For the development of ANN models for predicting the OPI, it was found that the best predictive performance was (R2) of 0.99843407 for ANN model of 3-50-50-1 with Tanh-Tanh activation function at epoch of 1200

Graphene on Metal Grids as the Transparent Conductive Material for Dye Sensitized Solar Cell

Metal grids covered by graphene were used as transparent conductive electrodes in dye sensitized solar cells. The efficiency of dye sensitized solar cells with graphene-on-Pt grids was 0.4%. Compared to the control group, in which the platinum grids were used as a transparent conductive layer, the efficiency of dye sensitized solar cells with graphene was more than 2 times better. To our knowledge, it is the most efficient dye sensitized solar cell to use a graphene-based transparent conductive electrode without a conductive oxide support such as fluorine-doped tin oxide or indium-doped tin oxide. The dye sensitized solar cell prepared by 150 °C as the low temperature processes, which are essential for fabricating flexible dye sensitized solar cells, was fabricated using a hybrid graphene on Ni grids transparent conductive electrode, and it exhibited an efficiency of 0.25%. The mechanical properties of the flexible hybrid transparent electrode are better than the oxide-based transparent conductive electrode in both bending and stretching tests. Therefore, the long-term stability of the flexible dye sensitized solar cells could be enhanced by using this new transparent conductive layer