Solar thermal energy performance on mono/trihybrid nanofluid flow through the evacuated thermal collector tube.

Solar thermal energy is a versatile and sustainable form of energy. It has vast applications and can be used to reduce fossil fuel consumption. The sun's heat harnesses this renewable energy; therefore, the energy transmission rate plays a significant role here. This article gives the idea of a new geometric design of solar thermal collector tubes for multiple uses and materials to be used on the tube's outer layer to maximize heat absorption. For this purpose, we investigated velocity, temperature, and heat transfer rates due to different nanoparticle (Cu/Al 2 O 3 /GO) combinations. We assumed the flow of Newtonian/non-Newtonian nanofluids flowing through the coaxial region of the cylindrical shape solar tubes. Here, water and seawater are considered for the Newtonian case, and sodium alginate is regarded for the non-Newtonian case. The governing equations of the flow are converted into ODEs with the help of similarity variables and solved numerically using the Keller box method. The MATLAB code for the Keller box method has been developed to plot graphical results. The primary outcomes are exhibited through graphs and tables. It is perceived that the temperature and heat transfer rates in Newtonian and non-Newtonian fluids are enhanced due to the trihybrid (Cu + Al 2 O 3 +GO) combination. This work can be utilized in an evacuated solar thermal system and gives the idea to develop a sustainable solar thermal system for multipurpose usage. • A sustainable solar thermal system model for multipurpose usage. • Simultaneous outcomes for Newtonian and non-Newtonian cases. • Al 2 O 3 +GO nanomaterial combination enhances the sun's heat absorption rate. • The heat absorption rate of evacuated solar heater tubes can be improved with a Cu + Al 2 O 3 +GO + sea water combination. [ABSTRACT FROM AUTHOR]