Numerical Study on the Enhanced Thermal Performance of the Porous Media-Assisted Flat-Plate Solar Collector

Abstract

In this study, a novel flat-plate solar collector (FPSC) with inserted porous metal foam is designed. A numerical investigation of the thermal performance of FPSC is conducted. The effects of some factors, such as porous block shape (rectangular, trapezoidal, and triangular), number of inserted porous blocks, and permeability parameters, on the enhanced thermal performance of the FPSC channel are analyzed. Numerical results show that, among the three types of porous block shapes, FPSC inserted with rectangular porous blocks has the highest thermal performance. When the number of porous blocks inserted in the FPSC channel increases, the thermal performance is enhanced correspondingly. Furthermore, the permeability of porous blocks has a significant influence, showing that the thermal performance is the best at $Da={10}^{-2}$ . Overall, the overall Nusselt number can reach a maximum value of 6.01 under the condition of $Da={10}^{-2}$ , $N=6$ for the rectangular porous blocks. Interestingly, as the nondimensional pressure drop in the channel, the friction factor reaches a maximum value of 8.66 under such a condition of $Da={10}^{-5}$ , $N=4$ for the rectangular porous blocks. Considering the pressure drop due to the porous foam occupying in the FPSC channel, a comprehensive performance evaluation criterion (PEC) is used to assess the thermal performance of the FPSC. The results show that the maximum value of PEC is even up to 1.68 under the condition of $Da={10}^{-2}$ , $N=6$ for inserting the rectangular porous blocks.