Sıvı soğutucu akışkanı içerisine nano boyuttaki metal partiküller karıştırılarak motor içerisindeki ısı iletimini arttırmak mümkündür. Bu çalışmada da bir taşıtın motor soğutma sistemindeki baz soğutucu akışkan içerisine %0,1 ve %0,2 oranlarında SiO2, TiO2, Al2O3 nanoakışkanları ilave edilerek 1000, 2000, 3000 ve 4000 dev/dk çalıştırılan motorun soğutma sistemindeki sıcaklık değişimleri incelenmiştir. Ayrıca bu devirlerdeki CO2, HC, CO, NOx ve O2 egzoz emisyonlarındaki değişimler de incelenmiştir. Baz akışkana eklenen nanoakışkanların oranları arttıkça ısı iletiminin arttığı, ancak 3000 ve 4000 dev/dk ısı iletimin düştüğü gözlemlenmiştir. Düşük sıcaklık değerleri için çalışılan tüm nanoakışkan karışımlarında görülen olumlu ısı iletim etkisi, motordaki devir artışıyla birlikte soğutucu sıcaklık değerlerinin yükselmesi durumunda görülmemiştir. Dolayısı ile nanoakışkan karışımlarının her koşulda ısı iletimini iyileştirmediği belirlenmiştir. Ayrıca partikül oranındaki artış ısı iletiminde olumlu etkiye sahip olduğunu göstermiştir. CO2, HC, CO ve O2 emisyonları için baz akışkana kıyasla egzoz emisyon değerlerinde belirgin farklılıklar oluşmamıştır. NOx emisyon değerlerinde ise farklı motor devirleri için sırası ile yaklaşık %28, %27, %25 ve %21 oranında düşüşler olduğu tespit edilmiştir. Sıcaklık ve emisyon ölçümlerinde genelde en iyi sonuçlar %0,2 SiO2 nanoakışkanında elde edilmiştir.

The topic of energy saving is a constant in everyday life, and it is widespread all over the world. Space heating using solar panels is the most used renewable source of energy, but the application of solar energy for cooling the fluids used for refrigeration is growing very fast. Among the techniques used for refrigeration, this work focused on Desiccant Cooling. In particular, with the use of dynamic simulation software, it was possible to study the heat supplied and the energy consumption of a Heating Ventilation Air Conditioning (HVAC) system of a university building and to compare consumption with those of a Desiccant Cooling system applied to the same building. Four different cases were simulated: two related to the HVAC system, one of which operates with water and glycol and the other one with nanofluid, and the other ones to the Desiccant Cooling system with both types of fluids mentioned above. Keeping the same energy demand of the building in all the simulations, it was found that in summer the Desiccant Cooling system had higher performance than the traditional HVAC system and that the use of the nanofluid in both types of conditioning systems further increased the performance of 21%. Simulations were carried out using TRNSYS software.

The development and implementation of transient heat transfer characteristics of nanofluids in energy management were studied. Ultrasonic-assisted SiO₂/water nanofluids with 0.1–1.5 wt. % were prepared using polyvinyl alcohol (PVA) surfactant. The stability of nanofluids was tested and confirmed using zeta potential and light absorbance measurement. Thermophysical properties of nanofluid were investigated at various weight concentrations from 0.1 to 1.5 wt. % in a temperature range of 25–70°C. Transient heat transfer characteristics of nanofluids were examined. Thermophysical properties were enhanced by adding nanoparticles to base fluid. A major enhancement in transient heat transfer characteristics was obtained by applying SiO₂/water nanofluids. The convective heat transfer coefficient (CHTC) was increased up to 2.37 times compared to water. The heat absorbance efficiency of the system is increased by a maximum of 24.54%. Finally, a new CHTC correlation has been proposed.

Solar energy is a major renewable energy resource used in power production, heating processes, and other applications such as domestic and industrial utilization. It is an abundant form of green energy. Different techniques have been made for energy conversion and one among them is solar photovoltaic/thermal (PV/T) system. Unfortunately, the greatest cause of concern is the rise in temperature of solar PV cells, which will have a negative effect on electrical performance. Thereby, eliminating excess heat on PV cells with heat transfer fluids to lower the temperature of the cells can improve electrical efficiency. A nanofluid is a promising heat transfer fluid to effectively enhance the system efficacy compared with conventional fluids. As the nanoparticle size is very small, the surface area of the nanoparticle is large so it enhances the heat transfer rate. Thereby, recently it has taken on a new dimension for research studies to enhance its thermal behavior for engineering application. This review paper discusses about the importance of nanofluid in solar PV/T system and advantages of employing nanofluid in PV/T system which has high thermo-physical properties. Nanoparticle and nanofluid preparation methods were presented. The thermo-physical properties like thermal conductivity, viscosity, density, and specific heat capacity were also discussed.

Insulation systems of electrical apparatus (fluid and solid) include transformer oil, insulating paper, glass, ceramic, mica and rubber. Normally, they are designed well to be stable at high temperatures and provide excellent electrical insulating properties in different operating loads. There is an increasing demand to modify the effectiveness and capabilities of these insulation systems to overcome various issues (e.g., overheating, overloading and short circuits). Moreover, they should match the new high voltage insulation requirements, safety, ultra-high voltage, and being environmentally friendly are some of them. Nanoparticles (NPs) are promising compensator materials that can be used to develop insulation systems with good thermophysical and dielectric properties. The results of many studies show marvelous enhancements in electrical and thermal properties. In this paper, the authors present a review that focuses on different NPs that are used in several aspects of insulation systems to improve the dielectric as well as the heat transfer properties of high voltage insulation applications. The review covers NPs types, the preparation methods, analysis approaches, different properties, performances and results, challenges, and the limitation of the use of NPs.

Nanofluids have great potential to improve the heat transfer properties of liquids, as demonstrated by recent studies. This paper presents a novel idea of utilizing nanofluid. It analyzes the performance of a HVAC (Heating Ventilation Air Conditioning) system using a high-performance heat transfer fluid (water-glycol nanofluid with nanoparticles of Al₂O₃), in the university campus of Lecce, Italy. The work describes the dynamic model of the building and its heating and cooling system, realized through the simulation software TRNSYS 17. The use of heat transfer fluid inseminated by nanoparticles in a real HVAC system is an innovative application that is difficult to find in the scientific literature so far. This work focuses on comparing the efficiency of the system working with a traditional water-glycol mixture with the same system that uses Al₂O₃-nanofluid. The results obtained by means of the dynamic simulations have confirmed what theoretically assumed, indicating the working conditions of the HVAC system that lead to lower operating costs and higher COP and EER, guaranteeing the optimal conditions of thermo-hygrometric comfort inside the building. Finally, the results showed that the use of a nanofluid based on water-glycol mixture and alumina increases the efficiency about 10% and at the same time reduces the electrical energy consumption of the HVAC system.