Investigation of Heat Transfer and Entropy Generation in a Parabolic Trough Collector Receiver using Square Porous Media and Nanofluids

The main problem with parabolic trough collector receivers is the focus of solar radiation on one side of the tube, resulting in a non-symmetric heat flux distribution on the absorber. This condition leads to non-uniform temperature, deterioration of the absorber tube, and a decline in efficiency. To improve the performance of PTC systems, it is crucial to enhance heat transfer and achieve temperature uniformity in the absorber tube. The objective of the numerical investigation is to examine a two-dimensional absorber tube that includes seven copper matrices of square porous media and investigate their combined effects on heat transfer and temperature uniformity. The basis fluid in this numerical simulation is Syltherm 800, which is used under laminar flow conditions to examine the effects of four physical parameters: variations in the Reynolds number (300, 500, 1000, and 1500), porosity levels (91% and 95%), types of nanoparticles (Al₂O₃, CuO, and Cu), and nanoparticle volume fractions (1%, 2%, and 3%). The results signify that the presence of nanofluids maximizes the enhancement of heat transfer, especially at a 3% concentration of Cu/Syltherm 800 nanofluids in a smooth tube. The novel configuration significantly enhances heat transfer, offers a more homogeneous temperature, and reduces thermal energy losses by minimizing entropy generation, which makes the system more sustainable for long-term thermal applications. Reducing porosity from 95% to 91% in novel configurations improved heat transfer and thermal homogeneity but increased the coefficient of friction.