The thermal management of electronic devices has become a major problem in recent years. Therefore, there is a growing need for research on many new materials and innovative fluids due to the developing technology and increasing cooling need in electronic systems. In this paper, heat transfer from a plate fin and pin fin type heat sinks that were placed in a water block that are used in electronic systems was investigated. A base fluid (pure water) and 0.1% mass concentration Al₂O₃-H₂O nanofluid were used as cooling fluids. The experiments were carried out for volumetric flow rates varying between 100 and 800 mL/min and heat flux values of 454.54 W/m² and 1818.18 W/m². The results demonstrated that the Al₂O₃-H₂O nanofluid on the empty surface provided a maximum improvement of 10.5% in heat transfer compared to the base fluid. In the use of plate finned heat sink, the maximum amount of improvement in heat transfer compared to the empty surface was obtained approximately 64.25% for the base fluid and 82.8% for the nanofluid. A similar comparison was made for the pin-fin heat sink, a maximum thermal improvement of 56.4% in the base fluid and 70.27% in the use of nanofluid was determined.

With the developing technology, the dimensions of electronic systems are becoming smaller, and their performance and the amount of energy they need increases. This situation causes the electronic components to heat up more and the existing cooling systems to become inadequate. In this study, instead of the fins used in existing systems, 10 PPI and 40 PPI PHS were placed inside a water block, and the Al₂O₃-H₂O nanofluid at a mass fraction of 0.1% was used as the cooling fluid. Experiments were carried out under constant heat flux of 454.54 W/m² and 1818.18 W/m², with volumetric flow rates varying between 100 mL/min and 800 mL/min. The heat transfer results were compared with the results obtained from the base fluid and the empty surface. The results showed that the nanofluid reduced the surface temperatures compared to the base fluid. Especially when PHSs were used together with the nanofluid, a significant increase in heat transfer occurred compared to the empty surface. The highest heat transfer was observed when both the nanofluid and 40 PPI PHS were used together. In addition, the highest thermal performance value was determined as 1.25 times compared to the empty surface when the nanofluid and 10 PPI PHS were used together.

In this study microcapsules were prepared by in-situ polymerization route with melamine formaldehyde as a shell material and tung oil as core material. Melamine formaldehyde (MF), a thermosetting polymer, is one of the most widely used monomers in microencapsulation due to its superior mechanical strength and thermal stability. Tung oil contains unsaturated double bonds that can be oxidized to form a film in air. Tung oil is fast drying and biodegradable, besides it is low cost and does not pollute the environment. Most importantly, tung oil is a versatile substance in industry. Therefore, tung oil is a good choice as core material. The chemical structure of microcapsules were characterized by Fourier Transform Infrared (FTIR) spectroscopy. The surface morphology and particle size and distribution were evaluated by Scanning Electron Microscopy (SEM). The thermal behavior of microcapsules and tung oil were studied by thermogravimetric analysis (TGA). The results showed that the spherical microcapsules (particle size of mostly 4-5 μm) were produced with a filling content of 15.64 wt.%, and a yield of 49.78 wt.%. The microcapsules exhibit a good thermal stability

This study investigates the impact of core-shell based nanofluids on the thermal performance of a solar water heating system by studying the changes in the useful heat gain and collector efficiency. This work would be the first to report the use of core-shell nanoparticles in solar water heating systems. The core-shell structure allows for dual improvements in thermal conductivity and better nanofluid stability, even without a surfactant. Therefore, three novel nanofluids were prepared by adding 2 wt% TiO₂@SiO₂, Fe₃O₄@SiO₂, and ZnO@SiO₂ core-shell nanoparticles to pure water to be used in the experiments. The experimental thermal performances of the nanofluids were individually compared with pure water by the simultaneous operation of two identical systems. The results showed that the nanofluids with Fe₃O₄@SiO₂ and ZnO@SiO₂ particles had better performance than the base fluid. In particular, 16.65% and 5.40% increase in the useful energy gain and a 17.12% and 7.39% increase in the collector efficiency were observed with Fe₃O₄@SiO₂ and ZnO@SiO₂ core-shell based nanofluids, respectively. It is possible to conclude that, with their improved performance, the Fe₃O₄@SiO₂-based nanofluids have great potential to be used in solar hot water systems instead of water.