LAUSR

Abstract To investigate the efficiency of solar system not only in term of hydrothermal behavior but also in view of thermal efficiency, numerical modeling has been employed in this attempt. To evaluate the hydrothermal behavior, uniform radiation flux has been applied while for analyzing the thermal efficiency, space-dependent radiation flux in three time steps (9AM, 5PM, 9PM) has been considered. Al2O3 nano sized powders were mixed with H2O to create new operating fluid with greater thermal features. Install of helical tape makes the secondary flow to augment and more intense impingement to wall has been observed. Configurations of flow style with change of diameter ratio (D∗), revolution of tape (N) and Reynolds number (Re) were demonstrated in first step. Besides, influence of wind speed (uwind), time of the day and inlet temperature (Tin) on thermal efficiency ( η t h ) were illustrated in second step. As widths of tape and its revolution enhances, more intense impingement of nanoparticles to wall happens. When D∗ = 0.045, N = 7, values of velocity for highest mass flow rate is 4.63 times greater than that of Re = 4000. Velocity magnitude rises about 2.9% with augment of N when D∗ = 0.045, Re = 20,000. Velocity increases about 5.19% with utilize of greater width of tape when Re = 20,000, N = 7. As Re increases, friction factor declines about 37.31% while Nu rises by 294% when D∗ = 0.045, N = 4. Growth of N leads to augmentation of f and Nu about 8.1% and 3.05% when D∗ = 0.02, Re = 20,000. Maximum hydrothermal performance belongs to case with lowest Re and highest D∗ and N. Highest η t h was obtained when Tin = 283.15, uwind = 1 m/s and t = 1PM. Augment of Tin leads to 1.19% reduction in η t h when uwind = 1 m/s and t = 1PM.