Performance analysis of nanofluid based direct absorption solar collector of different configurations: A two-phase CFD modeling

In comparison to other renewable sources of energy, solar energy is most promising, and it can be collected with the help of solar collectors. However, the efficiency associated with the solar energy harvesting process is low. The direct-absorption type of solar collectors has been used in many applications such as heating, drying, etc. The current article presents the three different novel designs for direct absorption solar collectors and the proposed designs are compared with the conventional solar collector. To improve the performance of the solar collector, the nanoparticles of Al2O3 are suspended in the base fluid, i.e. water. The numerical modeling of the proposed solar collector is done with the help of commercial Ansys Fluent software and the two-phase Eulerian-Eulerian model is used for simulating the problem. The flow of water and nanoparticles was modeled separately under steady-state conditions. In comparison to the conventional working medium, i.e. water, a significant improvement of 39% in the solar collector efficiency is noticed with the use of nanofluid. The peak efficiency obtained is 85% at a velocity of 0.08 ms−1 in the case of the circular-corrugated collector, which is approximately 5%, 11%, and 16% higher than the triangular-corrugated, trapezoidal-corrugated, and flat-plate collector, respectively. The deposition of nanoparticles at the inner surface of the solar collector is noticed with the change in the collector design.