3D numerical study using three novel windbreak walls in natural draft dry cooling towers for performance enhancement under various crosswind conditions. (1st October 2021) - Shirazi, Mehran
Graphical abstract: Highlights: NDDCTs are investigated by CFD methods in various crosswind conditions. Three novel windbreak walls are introduced to enhance the efficiency of NDDCTs. The problem of occupied space inside NDDCTs is solved because of novel windbreakers. The thermal performance of all models is improved and the best model is chosen. Abstract: Because of Natural draft dry cooling towers' (NDDCTs) extreme vulnerability to crosswind, performance enhancement of these towers is essential. Various strategies have been introduced to improve the efficiency of NDDCTs. One of the best techniques is using internal windbreak walls. Internal windbreakers' most significant problem is that they occupy much space inside the tower and block the major part of paths and openings through which air can pass. In this study, by introducing three novel internal windbreak walls named Sugarloaf-type, Swirl-type, and Impeller-type that take up less of the tower's interior portion, an attempt has been made to solve previous studies' problems. Navier-Stokes and energy equations are solved for a 3D, incompressible, and steady flow using CFD methods to investigate the flow field inside and around the tower. Temperature distribution, velocity vectors, streamlines, and thermal performance are obtained for all the models at various crosswind velocities and directions. Results show that not only did the suggested windbreakers solve the problem of occupied space, but also, they are capable of competing against the former designs under windy conditions. The asymmetric models, which are the Swirl-type and the Impeller-type, are studied in other directions, and the angle of 60° is determined to be the best direction of crosswind. Altogether, the Sugarloaf-type, symmetry windbreaker is chosen as the best model due to its independence in different crosswind directions and high-performance enhancement. The efficiency of the mentioned NDDCT is improved by 7.5% at a crosswind velocity of 10 m/s.