Experimental investigation of photo-thermal analysis of blended nanoparticles (Al2O3/Co3O4) for direct absorption solar thermal collector

Abstract

The demand of non-renewable energy resources is increasing due to increase of population. Due to the dependency on these resources the environment is degrading. In order to mitigate the effects on the environment, the usage of renewable energy resources is highly encouraged. Solar energy is the renewable energy, which is freely and widely available on the earth's surface. In recent time, the heat transfer fluids suspended with nanoparticles have shown that nanofluids have an immense potential to harness the solar energy. In the present experimental study, the photo-thermal analysis has been conducted with both surface absorption-based system (SAS) as well as blended nanofluid absorption-based system (BNAS). In the blended nanofluid absorption system (BNAS), the mixture of aluminum oxide (Al2O3) and cobalt oxide (Co3O4) nanoparticles has been used. The effectiveness of both systems has been evaluated and compared under identical working conditions. The experimental results with BNAS reveal that the performance of BNAS depends on the mass fraction of the nanoparticles in the base fluid. It is found that combination of 40 mg/L Al2O3 þ 40 mg/L Co3O4 is an optimum mass fraction of the nanoparticles in the base fluid at which the average temperature rise (19.4 C) of the fluid above the ambient temperature is maximum compared to other values of mass fractions. Furthermore, on comparing the effectiveness of BNAS with SAS the results show that the temperature rise with BNAS (at an optimum mass fraction) is 5.4 C more than SAS under similar working conditions.