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Superspreading and Drying of Trisiloxane-Laden Quantum Dot Nanofluids on Hydrophobic Surfaces
摘要： Nano?uids hold promise for a wide range of areas of industry. However, understanding the wetting behavior and deposition formation in the course of drying and spreading of nano?uids, particularly containing surfactants, is still poor. In this paper, the evaporation dynamics of quantum dot-based nano?uids and evaporation-driven self-assembly in nanocolloidal suspensions on hexamethyldisilazane-, polystyrene-, and polypropylene-coated hydrophobic surfaces have been studied experimentally. Moreover, for the very ?rst time, we make a step toward understanding the wetting dynamics of superspreader surfactant-laden nano?uids. It was revealed that drying of surfactant-free quantum dot nano?uids in contrast to pure liquids undergoes not three but four evaporation modes including last additional pinning mode when the contact angle decreases while the triple contact line is pinned by the nanocrystals. In contrast to previous studies, it was found out that addition of nanoparticles to aqueous surfactant solutions leads to deterioration of the spreading rate and to formation of a double co?ee ring. For all surfaces examined, superspreading in the presence and absence of quantum dot nanoparticles takes place. Despite the formation of co?ee rings on all substrates, they have di?erent morphologies. In particular, the knot-like structures are incorporated into the ring on hexamethyldisilazane- and polystyrene-coated surfaces.
关键词： Self-assembly,Superspreading,Quantum dots,Wetting dynamics,Evaporation,Nano?uids
更新于2025-09-23 15:19:57
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Performance analysis for hybrid PV/T system using low concentration MWCNT (water-based) nanofluid
摘要： This paper presents experimental work on utilising Nano?uid as a working agent for Photovoltaic Thermal Systems (PV/T). PV/T systems are one kind of hybrid systems in energy utilisation. They convert the incident solar radiation into two energy types; electricity and heat. In this research, experimental outdoor tests were directed to assess the execution of PV/T system that utilises water-based Multi Walls Carbon Nano Tubes “MWCNT” as a heat storage/heat absorption agent. The e?ect of varying Nano?uid volume concentration ratio was studied within the range (0%:0.3%) while ?xing the circulation rate at 1.2 l/min. By analysing the experimental results, it can be noted that adding Nano Particles to the base ?uid caused the thermal properties to have a signi?cant increment leading the PV/T system to have a better thermal and electrical e?ciency. The best system e?ciencies were obtained at 0.075% V of MWCNTs – water based Nano?uid. At this concentration, a temperature reduction of 12 °C for the PV panel was attained at maximum incident radiation leading to an overall system e?ciency of 83.26%. Also, an average temperature reduction of 10.3 °C was achieved over the daytime leading to an overall e?ciency of 61.23%.
关键词： Nano?uids,MWCNT,Solar energy,Hybrid PV/T,Photovoltaic
更新于2025-09-19 17:15:36
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Efficiency Improvement of a Photovoltaic Thermal (PVT) System Using Nanofluids
摘要： Many studies and considerable international e?orts have gone into reducing greenhouse gas emissions. This study was carried out to improve the e?ciency of ?at-plate photovoltaic thermal (PVT) systems, which use solar energy to produce heat and electricity simultaneously. An e?ciency analysis was performed with various ?ow rates of water as the working ?uid. The ?ow rate, which a?ects the performance of the PVT system, showed the highest e?ciency at 3 L/min compared with 1, 2, and 4 L/min. Additionally, the e?ects of nano?uids (CuO/water, Al2O3/water) and water as working ?uids on the e?ciency of the PVT system were investigated. The results showed that the thermal and electrical e?ciencies of the PVT system using CuO/water as a nano?uid were increased by 21.30% and 0.07% compared to the water-based system, respectively. However, the increase in electrical e?ciency was not signi?cant because this increase may be due to measurement errors. The PVT system using Al2O3/water as a nano?uid improved the thermal e?ciency by 15.14%, but there was no di?erence in the electrical e?ciency between water and Al2O3/water-based systems.
关键词： e?ciency,PVT system,?ow rate,nano?uids
更新于2025-09-19 17:13:59
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Concentration dependent thermo-optic properties of yellow emissive ZnO quantum dots
摘要： This paper study the thermal properties of ZnO quantum dots (QDs) synthesized by sol-gel method. The structural and morphological properties were investigated using x-ray diffraction technique (XRD) and transmission electron microscopy (TEM). Thermal properties of ZnO QDs were measured using dual beam mode matched thermal lens technique. The results reveal that the thermal diffusivity of the nano?uid depends on the concentration of ZnO QDs. There is an optimum concentration of ZnO QDs, above which thermal diffusivity increases more than that of the base ?uid whereas thermal diffusivity decreases below the optimum concentration. This variation in thermal diffusivity of ZnO QDs nano?uid is explained using absorption and emission spectra.
关键词： optical properties,ZnO QDs,thermal properties,nano?uids
更新于2025-09-11 14:15:04