Analysis Of Evaluation Indexes Of Subway Ventilation And Smoke Control System

This thesis introduced the status quo, existent problems and tasks which still need to be studied in the domestic and international research on subway ventilation and exhaust system, briefly introduced the evaluation indexes of subway ventilation and smoke control system. According to this, this thesis adopted three methods which include theoretical analysis, numerical simulation and experimental tests, by combining them together to study evaluation indexes of subway ventilation and smoke control system.Through theoretical analysis, the ventilation system evaluation indexes about thermal comfort, ventilation efficiency, contaminant removal effectivency and the smoke control system evaluation indexes of dilute coefficient, exhaust efficiency, smoke layer height, visibility were summarized, designed and constructed a certain percentage of the reduced scale subway station model.The interior of reduced scale subway station model has been chosen as research object, studing the field simulation on the normal ventilation and fire conditions in the subway station, and calculating the relevant evaluation indexes. Researched the change of temperature, velocity and distribution of pollutant concentration in the project of air-condition and ventilation conditions, and used the evaluation indicators to evaluate the effectiveness of central control. Fire was represented as a source of heat and mass. Special emphasis was placed on the evolution of smoke propagation under smoke control in the fire condition. Different from other study on this issue, we solved the concentration field of carbon monoxide, which is more poisonous in combustion products of fire. Combining it with the velocity and temperature as the indexes to analyse the efficiency of different smoke control schemes and evaluate the performance of safety system so as to find out the effective smoke control scheme, which either confined the smoke to a small region or evacuate it from the station. These data will play a guiding role for ventilation and smoke control system. Reliable CFD results can play a good role in the project application. However, because of the complication of this issue and the limitation of the computational fluid dynamics; some hypotheses are inevitable during computing. So it has to be validated before applying the information to the full-scale subway station. For this case-fire in subway station, field test is almost impossible, then, the reduced-scale model is the remedy. Scale model experiment was used to compare with the computational results, which proved the feasibility and accuracy of using simulation methods.