Nanofluid migration within an absorber pipe of solar unit considering radiation mechanism

To intensify the efficiency, T-shaped fins were utilized inside the tube in current LFR unit. Various configurations of fins with same volume were employed. The carrier fluid is Al₂O₃-water and turbulent regime was considered. Incorporating DO model and solving pure radiation results in distribution of radiation flux around the tube which is employed as source term in energy equation. Convective transportation with ambient was considered in outer wall. Various inlet temperature and velocity for four cases were examined and outputs were shown in term of plots and contours. Thermal and energy efficiency, irreversibility component and Bejan number were main outputs of this paper. Outputs indicate that selecting Case A leads to obtain the maximum turbulent fluctuation and lowest temperature of outer wall. Replacing Case C instead of A makes temperature of surface to augment about 0.19% while pressure drop decreases about 23.72%. Rise of Re for Case A leads to decrease of Darcy factor about 26%. Highest Nu belongs to Case A and it increases about 79.82% with rise of Re. Lowest values of total irreversibility belongs to case A and growth of Re lead to reduce S_gen,h about 41.88%. Also, this case has minimum value of Be. The highest exergy and thermal efficiency belong to case A. Augment of T_in makes \(\eta_{th}\) to decline about 23.46% while \(\eta_{ex}\) augments.