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This paper proposes a solar collector that utilizes supercritical CO2 as the working fluid to detect implicit water heating and boost the collector's heating rate efficiency. Solar water heating system efficiency, cost, and environmental friendliness all depend on the working fluid used. CO2 is a possible natural refrigerant replacement. Even a little increase in temperature or pressure may have a big impact on the density of CO2 at the critical point. Because of this, solar heating can readily generate a spontaneous convection flow of supercritical carbon dioxide. The most basic collector characteristics, such as CO2 pressure and temperature, were determined by building and testing an experimental setup using a CO2-based solar collector. Due to solar radiation, liquid, gas, or supercritical CO2 pressures and temperatures change throughout the test. There was a 50% time average collector efficiency (ηcol) and a 30% heat recovery efficiency (ηRE). Solar thermal collectors based on supercritical CO2 have now been shown in this paper. Since the results show that even though the solar energy is low, the CO2 temperature, pressure, and supercritical stress remain constant, this is distinct from conventional liquid-based solar collectors. [ABSTRACT FROM AUTHOR]

This paper proposes a solar collector that utilizes supercritical CO2 as the working fluid to detect implicit water heating and boost the collector's heating rate efficiency. Solar water heating system efficiency, cost, and environmental friendliness all depend on the working fluid used. CO2 is a possible natural refrigerant replacement. Even a little increase in temperature or pressure may have a big impact on the density of CO2 at the critical point. Because of this, solar heating can readily generate a spontaneous convection flow of supercritical carbon dioxide. The most basic collector characteristics, such as CO2 pressure and temperature, were determined by building and testing an experimental setup using a CO2-based solar collector. Due to solar radiation, liquid, gas, or supercritical CO2 pressures and temperatures change throughout the test. There was a 50% time average collector efficiency (ηcol) and a 30% heat recovery efficiency (ηRE). Solar thermal collectors based on supercritical CO2 have now been shown in this paper. Since the results show that even though the solar energy is low, the CO2 temperature, pressure, and supercritical stress remain constant, this is distinct from conventional liquid-based solar collectors. [ABSTRACT FROM AUTHOR]

This paper presents an effort to estimate the impact of dust accumulation on exterior building roof absorptivity and total radiative heat gain. A new model is introduced to calculate a building solar absorptivity as a function of dust accumulation rate. Hourly dust deposition is modeled using the Non-hydrostatic Multi-scale Model (NMMB) to predict monthly averaged dust accumulation over time. The correlation sensitivities to its input parameters and the impact of dust accumulation on building annual loads are also studied. Results show that dust accumulation increases the roof solar absorptivity from its initial value up to dust absorptivity based on the site climatic condition and roof characteristics. The predicted monthly averaged accumulated dust for all studied sites varies between 1.3 and 73.8 g/m 2 /month. The new model has resulted in an annual cooling space increase of 44.7–181.1 kWh/m 2 /year, for the selected hot-dry sites with moderate to extreme dust storm conditions. Heating reductions were found to be 0.5–13.1 kWh/m 2 /year which are not significant in comparison to the increase in annual cooling load. The results of this work were attempted to improve the predictive capability of current building simulation models. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sensible and Latent energy storage capabilities of Ionic liquids are assessed. • Nanoparticles dispersed Ionic Liquids significantly improves absorption capabilities and molar extinction coefficient. • Effects of variation in cation chain length and anion on thermophysical and optical properties are discussed. • Future challenges on the formulation of Ionanofluid are discussed. Ionic liquids are liquid salts that are composed entirely of ions having melting points lower than 100 °C. Ionic Liquid possesses some salient properties like low melting point, negligible vapor pressure, and elevated thermal stability, making them a potential candidate as a working fluid for solar energy systems. Ionanofluid is formulated by incorporating nanomaterials in Ionic Liquid, which tunes the Ionic Liquid's thermophysical, optical, and energy storage properties and allows them more reliable as a medium for energy storage and heat transfer fluids for solar systems. This current review deals with the applicability of Ionic liquids, Ionanofluids in solar systems together with the role of some advanced nanomaterials to meet the permissible properties. Energy storage capability (sensible and latent), optical properties (absorbance, transmittance, molar extinction coefficient), together with thermal stability, thermal conductivity, and viscosity are assessed. The effects of anion/cation variations on these properties are discussed. The applications of Ionic Liquids and Ionanofluids in different solar systems have been critically reviewed together with recent advances of nanoparticles in the solar energy system. Outstanding sensible energy storage properties of Ionanofluids together with improved thermophysical properties are the significant findings of this present review. Finally, the existing challenges that require to be overcome for the successful implementation in the real case are also brought to light. [ABSTRACT FROM AUTHOR]