Here, the researchers carried out an experimental analysis of the effect of the TiO2 nanosolution concentration on the heat transfer of the twin jet impingement on an aluminum plate surface. We used three different heat transfer enhancement processes. We considered the TiO2 nanosolution coat, aluminum plate heat sink, and a twin jet impingement system. We also analyzed several other parameters like the nozzle spacing, nanosolution concentration, and the nozzle-to-plate distance and noted if these parameters could increase the heat transfer rate of the twin jet impingement system on a hot aluminum surface. The researchers prepared different nanosolutions, which consisted of varying concentrations, and coated them on the metal surface. Thereafter, we carried out an X-ray diffraction (XRD) and a Field Emission Scanning Electron Microscopy (FESEM) analysis for determining the structure and the homogeneous surface coating of the nanosolutions. This article also studied the different positions of the twin jets for determining the maximal Nusselt number (Nu). The researchers analyzed all the results and noted that the flow structure of the twin impingement jets at the interference zone was the major issue affecting the increase in the heat transfer rate. The combined influence of the spacing and nanoparticle concentration affected the flow structure, and therefore the heat transfer properties, wherein the Reynolds number (1% by volume concentration) maximally affected the Nusselt number. This improved the performance of various industrial and engineering applications. Hypothesis: Nusselt number was affected by the ratio of the nanoparticle size to the surface roughness. Heat transfer characteristics could be improved if the researchers selected an appropriate impingement system and selected the optimal levels of other factors. The surface coating with the TiO2 nanosolution also positively affected the heat transfer rate.
Summary
In this study, the chlorophyll and anthocyanin natural dyes were extracted from Cymbopogon schoenanthus leaves and Ixora coccinea flowers, respectively. Thereafter, these dyes were used as sensitizers in the TiO2‐based dye‐sensitized solar cells (DSSCs). Ten solvents were used for solubilizing the dyes. Amongst the 10 solvents, the ethanol showed the highest absorption spectra for the anthocyanin and chlorophyll molecules. Temperature significantly affected the yield of the natural dyes. It was seen that an optimal extraction temperature of 70°C and 80°C results to higher anthocyanin and chlorophyll yields, respectively. However, an extraction temperature above 70°C and 80°C has shown a sharply decrease in the anthocyanin and chlorophyll concentrations, respectively. Also, the solution of acidic extraction, especially with a pH value of 4, increased the dyes concentrations. As seen in the results, the chlorophyll‐sensitized DSSCs had 0.23% conversion efficiency (ƞ), short‐circuit current (Isc) of 0.9 mA/cm–2, open‐circuit voltage (Voc) of 0.51 V, and 49.13% fill factor (FF). Meanwhile, the anthocyanin‐sensitized DSSCs showed 0.16% ƞ, 0.4 mA/cm–2 Isc, 0.53 V Voc, and 75.93% FF.
This article presents a study which sought to enhance heat transfer by employing a twin jet impingement mechanism (TJIM) and investigating the impact of the distance between the nozzles and plate on the Nusselt number (Nu) and heat transfer coefficient. This investigation was additionally based on the measurements of the heat flux temperature micro foil sensor and IR thermal imaging. A computational study of the cooling heated plate, through simulating the electronic components by the TJIM, was investigated using the RNG k-ε turbulence model. The jet-plate position was changed at the different jet-to-plate distances S = 1, 6, and 11 cm, Reynolds number = 17,000. The main flow structure, the static pressure, local and average Nus and heat transfer coefficient, were also examined. The findings have yielded new information about TJIM, and represent a new contribution about the flow and heat transfer characteristics of TJIM, and means of improving the rate of heat transfer in the passive heat transfer technique. The results of the various positions of the TJIM determined that the first model is, in fact, the best model for the heat transfer coefficient and the highest Nu, when S = 1 cm and H = 1 cm. Furthermore, the irregular distribution of the local Nu and the local heat transfer coefficient (h) on the impinged surface are due to the increase or decrease in the turbulence of flow on the measured surface.
We present the observational evidence by Time History of Events and Macroscale Interactions during Substorms (THEMIS)-D spacecraft to demonstrate that magnetic flux rope can have a core field polarity opposite to the guide field during asymmetric reconnection with a high magnetic shear across the magnetopause. In the presented event, a bipolar reconnection outflow was observed at the magnetopause, across which the magnetic shear was~149°corresponding to a predicted guide field B G = À15.6 nT. The ratios for magnetic field strength and ion density between the magnetospheric and magnetosheath sides of the magnetopause were~1.6 and~0.15, respectively. During the event, the component of magnetic field along the M axis (the intermediate variance direction) remained negative and stable for most of the time, and its mean value agreed with the B G . Two magnetic flux ropes with a strong core field were identified, but one flux rope had a core field polarity against the guide field B G . Our finding differs from current theoretical simulations that the core field polarity of the flux ropes inherits from the guide field.
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