Numerical Study of Nanofluid Flow and Heat Transfer Characteristics in Linear Parabolic Trough Solar Collector

In the present study, the performance of nanofluid flow in a Linear Parabolic Trough Solar Collector was simulated and studied. The flow is considered three-dimensional, turbulent and incompressible. Flow modeling is a combination of Monte Carlo Ray Tracing (MCRT) and numerical simulation which was implemented by Soltrace and Ansys Fluent software, respectively. The radiative flux reflected from reflector on the absorber tube was calculated by Soltrace software and introduced to Ansys Fluent by UDF code. Thermophysical properties including density, specific heat, thermal conductivity and viscosity were considered as a function of temperature. It was observed that in Reynolds 1000 number and in two volume fractions of 2 and 5 percent, the enhancement of heat transfer coefficients were respectively 3 and 11 percent for Al2O3, 7 and 15 percent for copper powder (Cu), and 7 and 42 percent for silver powder (Ag). In Reynolds number 15,000, increases of 8 and 33 for Al2O3, 9 and 29% for copper powder (Cu), and 8 and 25% for silver powder (Ag) were respectively observed. The results showed that at a constant Reynolds number, the heat transfer coefficient increased with increased nanofluid volume. It was also observed that the performance of silver powder (Ag) nanoparticles at low Reynolds numbers was better than other nanoparticles, but it decreased with increasing Reynolds number. Unlike silver powder (Ag), the performance of Al2O3 at low Reynolds number was insufficient, but improved with increasing Reynolds number.