Experimental and Numerical Investigation of Gypsum Calcination under Fire Exposure (Thesis)

• NCJ Number: 309925
• Date Published: 2021
• Author(s): Ethan Andrew Fowlie
• Length: 38 pages
• Grant Number(s): 2020-R2-CX-0050
• Agencies: NIJ-Sponsored
• Publication Type: Thesis/Dissertation; Research (Applied/Empirical)

Annotation

In this thesis, the researcher analyzes the calcination of gypsum exposed to fire.

Abstract

This study analyzes the calcination of gypsum in two phases. Phase 1 explores the impact of the position of the fire on the depth of calcination, and Phase 2 compares experimental results of gypsum calcination to the results predicted by the numerical model. The history of incident heat flux and the surface temperature of a gypsum board exposed to a constant heat release rate fire have been predicted using Fire Dynamics Simulator (FDS) for different distances from the burner. The predicted histories of heat flux and surface temperature from FDS have been used as boundary conditions to predict the depth of calcination of the gypsum board using a validated in-house one-dimensional unsteady computational model that solves the mass, species, momentum, and energy conservation equations assuming local thermodynamic equilibrium. Controlled laboratory-scale experiments are conducted with gypsum wallboard exposed to a uniform heat flux. The effects of heat flux and the duration of exposure on the depth of calcination are quantified. The same constant heat flux is used as an input into the numerical model to predict the depth of calcination of the gypsum board. The internal temperature profile and calcination from the experiments is compared to the temperature profile and dehydration predicted by the model. Gypsum wallboard undergoes calcination when exposed to heat. Quantitative analysis of the depth of calcination caused by a fire is of great use in fire investigations. The rate and the depth of calcination through the board are dictated by the heat and mass transfer through it.