A Thin Skin Calorimeter (TSC) for quantifying irradiation during large-scale fire testing

This paper details a novel method for quantifying irradiation (incident radiant heat flux) at the exposed surface of solid elements during large-scale fire testing. Within the scope of the work presented herein, a type of Thin Skin Calorimeter (TSC) was developed intending for a practical, low cost device enabling the cost-effective mass production required for characterising the thermal boundary conditions during multiple large-scale fire tests. The technical description of the TSC design and a formulation of the proposed calibration technique are presented. This methodology allows for the quantification of irradiation by means of an a posteriori analysis based on a temperature measurement from the TSC, a temperature measurement of the gas-phase in the vicinity of the TSC and a correction factor defined during a pre-test calibration process. The proposed calibration methodology is designed to account for uncertainties inherent to the simplicity of the irradiation measurement technique, therefore not requiring precise information regarding material thermal and optical properties. This methodology is designed and presented so as to enable adaption of the technique to meet the specific requirements of other experimental setups. This is conveyed by means of an example detailing the design and calibration of a device designed for a series of large-scale experiments as part of the 'Real Fires for the Safe Design of Tall Buildings' project.