To broaden safe operation range of the indirect dry cooling system with internal annular windbreak cloth in extremely cold days

摘要

As for the natural draft dry cooling tower, air leakage is inevitable in practical running, even though all louvers in front of the air-cooled heat exchanger closed entirely. To reduce the adverse effects of air leakage on safe operation of the indirect dry cooling system in extremely cold days, a novel annular windbreak cloth is proposed to be arranged on the horizontal cross section of the tower at air inlet height. By numerical simulation, flow fields in and around the tower are presented, and cooling water temperature drop is exported as well, under different sizes of the annular windbreak cloth. By the analysis of flow fields, it was found that the gradual increasing resistance caused by the windbreak cloth and the external airflow intrusion appearing at the top of the tower as ventilation area reduces to a critical value, would greatly reduce thermal performance of the tower. Then, coupling the tower with the condenser, ranges of ambient temperature are determined for safe operation of the indirect dry cooling system.