Wenting Ding

Smoke Movement Characteristics and Fire Safety in Subway Stations

Experimental and numerical studies on smoke movement and control in subway stations are presented. The experiments were conducted in three actual stations in service using small methanol pool fires as the fuel to generate data basis to validate and tune numerical models for subway station fires and furthermore to examine the performance of smoke control systems. A control volume smoke movement model has been applied to the stations. The model was first tuned to reproduce the test results for the simplest condition for each station, and was then applied and compared with test results for other test conditions. The model was finally applied to predict smoke movement in the subway stations of more plausible fires. The effective design and functional operation of fire safety measures in subway systems are discussed. Primarily, importance of restriction of heat release rate through either the control of combustibility of lining materials or installation of sprinkler system is pointed out. And it is clarified that arrangement of alternative evacuation routes on either ends of the platform, and appropriate operation of shutters in stairways between the platform and the concourse ensure safe evacuation.

Smoke Control using a Double-skin Facade

Double-skin facades have been increasingly used as they open up new possibilities for clients and planners seeking creative new designs that are intelligently adapted to environmental conditions. Among them natural ventilation is commonly carried out in a building with double-skin facades. However double-skin facade construction is still not covered by statutory building regulations. Virtually no information exists on the behavior of this kind of facade in case of a fire. Usually for a building with a multistory double-skin facade, smoke of a fire room escaping through the inner facade into the intermediate space between the two skins may accumulate and spread horizontally and/or vertically to other rooms that have openings connected to the intermediate space for the purpose of natural ventilation. However if smoke pressure in the intermediate space can be kept lower than that of the room, smoke spread through the openings will be prevented. Considering similarity of smoke movement and stack natural ventilation, in this paper a double-skin facade used for natural ventilation is also considered for smoke control. As the results, it is proved that smoke spread can be prevented with suitable opening arrangements. Therefore natural ventilation and smoke control can be realized through one system. Reduced scale model experiments and computational fluid dynamics (CFD) analysis are carried out in this research.

Model Experiment and CFD Analysis on a Solar Assisted Ventilation System

abstract A prototype atrium building is suggested with a large solar chimney on top of the atrium, which is expected to promote natural smoke exhaust and accumulate smoke at a event of a fire and promote natural ventilation when outdoor climate is desirable. In this paper natural ventilation efficiency is evaluated. The solar chimney is similar to conventional chimneys except the south-facing wall is replaced by a glazing. Solar radiation transmits the glass and thermal energy is stored in the other three walls. Air in the chimney is heated and by stack effect natural ventilation is realized. Experiment is conducted on a 1/25 scale model to evaluate the efficiency of this solar assisted natural ventilation system. Several area conditions of inlet and outlet are chosen while other conditions keep the same. CFD simulation is simultaneously done. According to results of model experiment and simulation, natural ventilation promoted by the solar chimney is quite sufficient to meet the demands of atrium ventilation. As to the office rooms, if area is properly set, fresh air requirement can be satisfied only by natural ventilation. In the case of this study, when inlet area changes to 24m2, necessary ventilation rate can be obtained.