Experimental investigation on the thermal performance of compact heat exchanger and the rheological properties of low concentration mono and hybrid nanofluids containing Al2O3 and CuO nanoparticles
“…Fattahi [20] investigated the performance of a hybrid nanofluid in a solar collector and concluded that up to 23% improvement in the heat transfer was possible by employing the nanofluid. Asokan et al [21] investigated the effect of using nanofluids containing CuO, Al 2 O 3 and their hybrid particles in a compact heat exchanger. They found that applying the hybrid nanofluids caused better enhancement in the performance compared with the mono nanofluids.…”
Thermal performance of energy conversion systems is one of the most important goals to improve the system’s efficiency. Such thermal performance is strongly dependent on the thermophysical features of the applied fluids used in energy conversion systems. Thermal conductivity, specific heat in addition to dynamic viscosity are the properties that dramatically affect heat transfer characteristics. These features of hybrid nanofluids, as promising heat transfer fluids, are influenced by different constituents, including volume fraction, size of solid parts and temperature. In this article, the mentioned features of the nanofluids with hybrid nanostructures and the proposed models for these properties are reviewed. It is concluded that the increase in the volume fraction of solids causes improvement in thermal conductivity and dynamic viscosity, while the trend of variations in the specific heat depends on the base fluid. In addition, the increase in temperature increases the thermal conductivity while it decreases the dynamic viscosity. Moreover, as stated by the reviewed works, different approaches have applicability for modeling these properties with high accuracy, while intelligent algorithms, including artificial neural networks, are able to reach a higher precision compared with the correlations. In addition to the used method, some other factors, such as the model architecture, influence the reliability and exactness of the proposed models.
“…Fattahi [20] investigated the performance of a hybrid nanofluid in a solar collector and concluded that up to 23% improvement in the heat transfer was possible by employing the nanofluid. Asokan et al [21] investigated the effect of using nanofluids containing CuO, Al 2 O 3 and their hybrid particles in a compact heat exchanger. They found that applying the hybrid nanofluids caused better enhancement in the performance compared with the mono nanofluids.…”
Thermal performance of energy conversion systems is one of the most important goals to improve the system’s efficiency. Such thermal performance is strongly dependent on the thermophysical features of the applied fluids used in energy conversion systems. Thermal conductivity, specific heat in addition to dynamic viscosity are the properties that dramatically affect heat transfer characteristics. These features of hybrid nanofluids, as promising heat transfer fluids, are influenced by different constituents, including volume fraction, size of solid parts and temperature. In this article, the mentioned features of the nanofluids with hybrid nanostructures and the proposed models for these properties are reviewed. It is concluded that the increase in the volume fraction of solids causes improvement in thermal conductivity and dynamic viscosity, while the trend of variations in the specific heat depends on the base fluid. In addition, the increase in temperature increases the thermal conductivity while it decreases the dynamic viscosity. Moreover, as stated by the reviewed works, different approaches have applicability for modeling these properties with high accuracy, while intelligent algorithms, including artificial neural networks, are able to reach a higher precision compared with the correlations. In addition to the used method, some other factors, such as the model architecture, influence the reliability and exactness of the proposed models.
“…Thus, high μ (specific heat capacity) sample transfers more heat than a sample with low μ (specific heat capacity). Similarly, Asokan et al 76 discovered that as the volumetric concentration of nanoparticles increases, the specific heat capacity of Al 2 O 3 –CuO hybrid nanofluids decreases.Figure 7.Specific heat as a function of temperature (a) Al 2 O 3 : ZnO, (b) Al 2 O 3 :2ZnO, and (C) 2Al 2 O 3 : ZnO. 75 Figure 8.Specific heat as a function of volume concentration (a) at 25°C and (b) at 65°C.…”
Section: Analysis Of Significant Properties To Enhance Thermal and El...mentioning
confidence: 86%
“…Thus, high μ (specific heat capacity) sample transfers more heat than a sample with low μ (specific heat capacity). Similarly, Asokan et al 76 discovered that as the volumetric concentration of nanoparticles increases, the specific heat capacity of Al 2 O 3 -CuO hybrid nanofluids decreases.…”
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.
“…Furthermore, the specific heat capacity (SHC) of nanofluids (which determines the heat storage capacity of fluids) is an ongoing study concerning the heat storage capacity of hybrid nanofluids. A study by Neeshoun et al [51], which investigated the performance of a hybrid Al 2 O 3 -CuO on a compact heat exchanger, reported that the hybrid nanofluid showed a lower SHC as compared to the mono nanofluids (Al 2 O 3 , and CuO), except at higher volume concentrations of 0.06%. Their study conclusively stated that upon the result of the SHC, hybrid nanofluids would gain and lose heat more rapidly, and therefore would be a better choice for heat transfer purposes.…”
The amelioration of photovoltaic (PV) and photovoltaic/thermal (PV/T) systems have garnered increased research interest lately, more so due to the discovery of the thermal property augmentation of nanofluids. The overarching goal of this study is to conduct a comparative analysis of mono, hybrid, and ternary hybrid nanofluids utilized as fluids for heat transfer applications and particularly as cooling mediums in PV/T applications. Al2O3, ZnO, Al2O3-ZnO, and Al2O3-ZnO-Fe3O4 nanofluids are synthesized at 1% volume concentration using the two-step method. The zeta potential tests carried out showed that the fluids have high stability. The numerical model developed in this study was validated using real data culled from Cyprus International University. The findings in this study showed that the Al2O3-ZnO-Fe3O4 ternary hybrid nanofluid and ZnO mono nanofluid were more efficient heat transfer fluids for the PV/T system. The optimum relative electrical PV/T efficiency against that of the PV is 8.13% while the electrical and thermal enhancement recorded in this study was 1.79% and 19.06%, respectively, measured for the ternary hybrid nanofluid based PV/T system. This present study shows that despite the limitation of pumping power and pressure drop associated with nanofluid in thermal systems, the close performance evaluation criterion values as compared with water is positive for practical utilization of nanofluid in PV/T systems.
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