A Study on Possible Fire Protection of the Green Facade Design with Water Wall System

Description

A water wall system (WWS) is an energy efficient green façade design. It can be further exploited as a structure to enhance fire safety. The water layer in the WWS can act as an effective heat absorbent in the case of a room fire due to the high thermal capacity of water. This results in a much lower temperature rise and a more uniform temperature distribution within the window panes. Incorporating a WWS can thus protect large glass façades in a fire, and that is what this proposed project aims to study. Water stored in the system can also be useful to fire suppression once the glass pane is broken during a fire. In this proposed study, a WWS containing two commonly used normal glass panes will be selected for in-depth exploration under post-flashover fire conditions. Physical scale models, an analytical study of heat transfer through glass façades and full-scale burning tests will be used. A hot smoke layer will be formed, simulating the early stage of a room fire. The upper part of the WWS will be exposed to a higher heat flux. A small WWS, 0.1 m × 0.1 m, will be constructed and tested under different radiative heat fluxes emitted by a conical heater in both horizontal and vertical directions. The surface temperatures will be measured under different distributions of heat fluxes to explore the heat removed by the water layer. Medium-scale experiments on the WWS, 1 m × 0.5 m in size, using typical glass panes will be carried out using a thermal radiator developed to emit higher heat fluxes at the upper levels of the glass panes. Changes to the surface temperatures of glass panes that are hotter at the top can then be studied. Burning tests on part of a real WWS will be conducted to study how the water layer protects the glass panes. A 2 m × 2.2 m room with a height of 1.5 m will be constructed and a 2 m × 1.5 m WWS will be built on one wall. The heat removal rate achieved by the water layer will be investigated. Mathematical models simulating heat transfer through glass panes and water layersduring fires will be developed based on a thermal network system. The predicted results will be compared with the experimental results to understand how the WWS protects glass panes.