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Natural Convection Flows and Associated Heat Transfer Processes in Room Fires.


pdf icon Natural Convection Flows and Associated Heat Transfer Processes in Room Fires. (210154 K)
Sargent, W. S.

NBS GCR 83-447; 525 p. October 1983.

Sponsor:

National Bureau of Standards, Gaithersburg, MD

Available from:

National Technical Information Service
Order number: PB84-171172

Keywords:

compartment fires; convective flow; doors; heat transfer; room fires; windows

Abstract:

This report presents the results of experimental investigations of natural convection flows and associated heat transfer processes produced by small fires in rooms with a single door or window opening. Calculation procedures have been developed to model the major aspects of these flows. Two distinct sets of experiments were undertaken. First, in a roughly 1/4 scale facility, a slightly dense solution of brine was allowed to flow into a tank of fresh water. The resulting density difference produced a flow which simulated a very small fire in a room with adiabatic walls. Second, in an approximately 1/2 scale test room, a nearly stoichiometric mixture of air and natural gas was burned at flow level to model moderate strength fires. In this later facility, we directly measured the heat conducted through the walls, in addition to determining the gas temperature and composition throughout the room. The computed results both for the average floor and ceiling zone gas temperatures and for the convective heat transfer in the ceiling jet agreed reasonably well with our experimental data. This agreement suggests that our computational procedures can be applied to answer practical questions, such as whether the convective heat flux from a given fire in a real room would be sufficient to trigger sprinklers or other detection systems in a given amount of time.