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In this research work, MXene with a chemical formula of Ti3C2 is used for the first time with silicone oil to improve thermo-physical properties of MXene based silicone oil. This paper focuses on preparation, characterization, thermal properties, thermal stability and performance investigation of new class of silicone oil nanofluids induced with MXene in three different concentrations for a Concentrated Solar Photovoltaic Thermal (CPVT) collector.The thermal conductivity of the silicone oil-based MXene nanofluids is measured using a Transient Hot Bridge (THB) 500. Viscosity is measured using a Rheometer at various temperatures including 25, 50, 75, 100, and 125 °C. Perkin Elmer Lambda 750 is used to measure optical absorbance. The highest thermal conductivity enhancement is found to be 64% for 0.1 wt.% concentration of silicone oil-MXene nanofluid compared to pure silicone oil at 150 °C. The viscosity of MXene with silicone oil nanofluids is found to be independent of addition of MXene nanoparticles in the silicone oil base fluid. Viscosity is reduced by 37% when temperature is raised from 25 ºC to 50 ºC for different concentrations of MXene with silicone oil . Silicone oil-based MXene nanofluid with 0.1 wt.% concentration is thermally stable up to ~ 380 °C. Introducing more MXene nanoparticles into silicone oil improves electrical efficiency of PV module due to better cooling of MXene based nanofluids. Higher solar concentration is resulted in higher average temperature of the PV module. This consequently raises thermal energy gain which is useful for different applications.

Solar thermal collectors have been recognized as promising devices for solar energy harvesting. The absorbing properties of the working fluid are crucial because they can significantly influence the efficiency of the solar thermal collectors. The performance of photovoltaic-thermal (PV/T) systems can be optimized by applying nanofluids as working fluids. MXene is a newly developed 2-D nanomaterial that has proven excellent potential in electrical applications with a lack of research in the thermal and optical applications. The present work extensively studied the optical potential of the water/MXene nanofluids with respect to the variation of MXene concentrations (0.0005-0.05 wt. %) and types of surfactant (CTAB or SDBS) used in a hybrid PV/T system. The relationship between the investigated parameters was evaluated through an experimental correlation. The evaluation of the nanofluids in term of the transmittance was conducted through the Rayleigh method. The MXene concentrations and the types of the surfactant play predominant role in the transmittance, absorbance and dispersion stability of the water/MXene nanofluids.

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The present work investigates the effect of the nanoparticles concentration on the optical and stability performance of a water-based nanofluid in solar photovoltaic/thermal (PV/T) systems experimentally and numerically. A novel nanofluid is formulated with the inclusion of the reduced graphene oxide decorated with silver (rGO-Ag) nanoparticles in water. Five different concentrations of nanoparticles in the range from 0.0005 to 0.05 wt% is suspended in water to prepare the samples. Optical properties are measured using UV-Vis. The UV-Vis absorption analysis reveals that all samples show consistent optical absorption coefficient (α) at higher value (more than 3 cm −1) in the range of 1.5 to 4 eV. The application of optical filtration (OF) using water/rGO-Ag nanofluid in hybrid PV/T system presented more solar energy absorption through the OF. The hybrid system shows better performance at concentrations less than 0.0235 wt% compared to the PV system without integration with optical filtration. The hybrid solar PV/T system with OF using water/rGO-Ag nanofluid is able to produce thermal energy with efficiencies between 24% and 30%.

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In this research work, novel hybrid Graphene-Silver (Gr-Ag) nanomaterial has been used for first time with paraffin wax as a phase change material (PCM) to improve its thermo-physical properties. Thermal and electrical energy efficiencies of the novel synthesized nanocomposite (PCM/Graphene-Silver) has been investigated in solar thermal collector systems (CPV/T). This paper focuses on preparation, characterization, thermo-physical properties and energy efficiency in concentrated photovoltaic/thermal (CPV/T) system of new class of nanocomposites induced with hybrid Gr-Ag nanomaterial in three different concentrations. The specific heat capacity (cp) of hybrid PCM/Graphene-Silver nanocomposite increased by introducing hybrid Gr-Ag nanomaterial. Electrical and thermal energy performance of the hybrid PCM/Graphene-Silver is investigated in a CPV/T system using Matlab 2017b program. The improvement of cp is found to be ~40% with 0.3 mass% of hybrid Gr-Ag nanomaterial loaded in PCM. The highest thermal conductivity increment is found to be ~11% at 0.3 mass% concentration of hybrid Gr-Ag nanomaterial in PCM. The endothermic enthalpy value of the hybrid PCM/Graphene-Silver nanocomposite is found to be ~75.6 J g-1 at 0.1 mass% loading concentration of hybrid Gr-Ag nanomaterial. Melting point of hybrid PCM/Graphene-Silver nanocomposite with loading concentration of 0.3 mass% is measured to be 73.2 °C. The highest thermal efficiency using the hybrid Graphene-silver nanoparticles reached the value of 39.62% which represents 4.16% increment in comparison with the pure PCM. The equivalent electrical efficiency is improved by 2.8% at the loading concentration of 0.3 mass% of the hybrid Gr-Ag nanomaterial. These new class of nanocomposites represented the capability of enhancement in the performance of the CPV/T system consisting of lower PV temperatures, higher temperature gains across the cooling fluid and higher electrical and thermal efficiencies.