FPE MS Thesis Defense - Andrew Goetz, MS Student

Fire Protection Engineering Department

MS Thesis Defense - Andrew Goetz, MS Student

Flammable Vapor Cloud Development in Naturally Ventilated Enclosures from Liquid Spills 

Friday, April 17, 2026

9:00 am – 10:30 am

FPE Classroom/50 Prescott St

Zoom Link:  https://wpi.zoom.us/j/98662858741

Committee:

Ali Rangwala, PhD – Professor, WPI Fire Protection Engineering (Advisor) 

Stephen Kmiotek, PhD – Professor, WPI Chemical Engineering 

Kelly Thomas, PhD – Baker Engineering and Risk Consultants

Abstract

Flammable liquid spills in poorly ventilated enclosures present a deflagration hazard due to the generation and accumulation of vapors that often fall within the flammable range. For many common fuels, these vapors are denser than air, leading to preferential accumulation near the floor and persistent, stratified layers. This thesis investigates the development of such vapor clouds and evaluates the effectiveness of natural ventilation as a hazard mitigation strategy. Experiments were conducted in a small-scale enclosure using pentane and acetone as test fuels. Vapor concentrations were measured at multiple heights for a range of vent areas, vent locations, and spill sizes. A one-dimensional engineering model was developed incorporating evaporation, vertical transport, and hydrostatically driven ventilation. The model resolves vertical concentration gradients and captures the coupling between vapor generation and vent driven exchange, providing a practical tool for evaluating hazard mitigation across expected spill sizes and vent configurations. Results demonstrate that natural ventilation can reduce vapor accumulation, but its effectiveness depends strongly on vent placement relative to the dense vapor layer. Lower-level openings provide the greatest mitigation by limiting the vertical extent of the flammable region, highlighting the importance of aligning ventilation design with the buoyancy-driven behavior of dense vapors.