Researchers Conduct Experiments Measuring Gravimetric Soot Mass and Soot Particle Size
Earlier this summer, UL Research Institutes' Fire Safety Research Institute conducted experiments to better understand gravimetric soot mass and soot particle size. Following initial data analysis from the first phase of experiments conducted in 2024, ULRI’s Fire Safety Research Institute has begun the second phase of experiments in May at ULRI’s Fire Safety Research Institute’s large-scale research facility in Delaware County, Pennsylvania, and will wrap up later this fall.
Using Soot Data in the Fire Dynamics Simulator
The Fire Dynamics Simulator (FDS) is a widely used computer fire modeling system developed by the National Institute of Standards and Technology (NIST). It predicts variables in the fire environment, such as smoke concentration, temperature, flame position, and heat release rate. Through the Fire Modeling Development and Validation research project, ULRI’s Fire Safety Research Institute contributes to FDS’s ongoing development through software development and both bench- and large-scale experiments.
This series of experiments aims to improve the predictions of visibility made by FDS. Visibility is a key quantity in performance-based fire protection design due to its impact on egress times. The experiments are designed to collect a comprehensive set of soot-related data to support both model validation and improvements to user inputs for performance-based design. The experiments are designed to yield data on the relationship between soot mass and visibility, the relationship between soot size distribution and visibility, and deposition rates at prototypical scales. To achieve this, ULRI’s Fire Safety Research Institute researchers designed a set of small-scale (hood) and full-scale experiments to collect measurements of gas temperature, gas concentration, laser obscuration, gravimetric soot mass, gravimetric soot particle size, and gravimetric surface deposition.
Hood testing took place under a small hood with oxygen consumption calorimetry. These tests were used to develop model inputs for the soot production in the propylene fire.
At-scale testing took place in a standalone compartment with both closed and open-door tests. Gravimetric soot mass and soot particle size were measured by pulling gas from the compartment through filters, and the surface deposition was measured through filter paper attached to the wall, ceiling, and floor.
“Visibility during egress, fire patterns seen post-fire, and radiation from flames and hot layers are all tied to the behavior and properties of soot in a fire; however, there are few large-scale experiments where data for soot are collected beyond a simple obscuration measurement. This poses challenges for model validation and user guidance for model inputs.”
Principal Research Engineer
UL Research Institutes | Fire Safety Research Institute
Following data analysis, findings from this experiment phase will contribute to the continued development of the Fire Dynamics Simulator.
