Energy, exergy, and environmental assessments of a direct absorption parabolic trough collector based on nanofluid volume absorption approach

The transient behavior of a direct absorption parabolic trough collector (DAPTC) is simulated numerically to assess its energy and exergy efficiencies as well as the environmental effects. In this regard, a one-dimensional code is developed in matrix laboratory (MATLAB) software based on introducing a new approach of fluid volume absorption. The energy, exergy, and environmental analyses of a DAPTC have been carried out. Different volumetric fractions of CuO nanoparticles (i.e., 0.01, 0.05, and 0.1%) were dispersed in the water to produce a nanofluid as a heat transfer fluid. Obtained results have a little aberration with available experimental data, which indicates that the proposed new approach of fluid volume absorption is reasonable for modeling. Generally, a DAPTC shows better thermal efficiency than an indirect absorption one. Also, adding more nanoparticles to the water and increasing the diameter of the absorber tube can increase the thermal and exergy efficiencies up to 61.3 and 31.5%, respectively. Conversely, increasing the flow rate of heat transfer fluid as well as its inlet temperature can reduce the thermal efficiency. Finally, an environmental study is conducted to evaluate the amount of water consumption and CO2 emission.