This study examined and described the optical and photovoltaic (PV) characterizations of the Fruit Areca catechu (pinang) as a new type of organic sensitizer. Recent reports stated that including chenodeoxycholic acid (CDCA) in the dye improves the performance of dye-sensitized solar cells (DSSCs). The effectiveness of PV dye was investigated by applying it in a DSSC. The absorption spectra indicated that natural dyes with CDCA has an excellent stabilizing ability. The Fourier-transform infrared spectra indicated the existence of carboxylic and hydroxyl functional groups in the naturally extracted dye. These functional groups were responsible for the rapid electron transfer and strong electronic linkages of interactions within the TiO2 surface. In this study, photoluminescence spectra analysis showed that by narrowing the bandgap, incorporating CDCA as a co-adsorbent in natural dye could generate a significant photocurrent. The overall power conversion efficiency was enhanced by 4.6%. Moreover, the cell efficiency reached up to 0.076% after adding 1.5 mM of CDCA without optimizing the sensitization time. Results demonstrated that the present study contributes toward the improvement of DSSC through efficient electron injection.
Abstract:The study was carried out to determine the effect of pulsating frequencies on the local and average heat transfer characteristic of a heated circular air jet. The velocity profile of a heated circular pulsating air jet was measured in the first part of the study. The same set-up was used to measure the heat flux of the pulsating jet impinging on a wall. The heat flux of the heated air jet impinging on the plate was measured using a heat flux microsensor at different radial positions. Measurement of the heat flux was used to calculate the average and local Nusselt Number for different pulsating frequencies and at different flow Reynolds Number. The pulsating frequencies were between 10-80 Hz and the Reynolds number used were 16 000, 23 300 and 32 000. Results obtained show that the local Nusselt number calculated were higher at all radial position away from the stagnation point. The pulsed jet Nusselt number was higher than the average steady jet Nusselt number for all values of frequencies due to the higher localised heat transfer. The higher Nusselt number obtained at localized radial positions can be due to the higher instantaneous velocity as was shown from the velocity profile plotted in the first part of the experiment. Enhanced turbulence intensity found was due to the pulsed jet.
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