CFD Based Analysis Heat Transfer and Friction Factor in Triangular Duct Solar Air Heater With Continuous Transverse Trapezoidal Ribs
Increasing the heat transfer of the solar air heater (SAH) can be done by adding artificial roughness to the absorber plate. This study conducted CFD modeling to analyze the addition of continuous transverse trapezoidal ribs on heat transfer and friction in the triangular duct solar air heater. The 3-D model was used as a computational domain in CFD to describe the shape of airflow and heat transfer that occurs in SAH. The relative pitch ratio used (P/e) ranges from 9-21, and the relative height ratio (e/D) ranges from 0.03-0.05. The turbulence model used in this study is k-ε RNG. Artificial trapezoidal ribs rougheness can increase turbulence and break up the laminar sub-layer near the absorber plate, thereby increasing heat transfer even though increased friction also occurs. The combination of P/e = 12 and e/D = 0.04 with Re = 9000 and P/e = 12 and e/D = 0.045 with Re = 6000 results in a greater Nusselt number and friction factor of 1.77 and 2.04 respectively compared to smooth surfaces.