Parametrization of the fire-smoke exhaust system for a large and high-rise atrium in Shanghai through salt-bath experiment

Present specifications in Building Codes in China lack design parameters for smoke exhaust for large and high-rise atrium in buildings. An investigation of natural smoke filling and parametrization of fire-smoke exhaust in an atrium building in Shanghai was conducted based on salt-bath experiment, due to dynamic analogy between thermal smoke movement in air and brine dispersion in water. To obtain a small, scaled-down version of an atrium with a high polyfoam fire up to 1 MW, the brine-bath experiment was conducted with calcium chloride for small strength fire in small-space rooms, to demonstrate the natural smoke filling within the atrium. The interface height and filling time derived was highly comparable to those obtained by empirical equations. The results of computational fluid dynamics simulations agreed well with the salt-bath experiments. The evacuation time was also calculated with a dimensionless interface height of 0.2 to determine whether there was sufficient time for occupants to escape. The smoke filling process under mechanical smoke exhaust was also investigated by experiments, to parametrize the fire smoke exhaust system in the atrium. The optimal smoke exhaust level, natural and mechanical make-up level were determined and were recommended as the design parameters for the construction of atrium in buildings.