Fire Protection Engineering Theses and Dissertations
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- ItemDEVELOPMENT OF A COUPLED FDS MODELING AND VIDEO ANALYSIS APPROACH TO ESTIMATE THE BURNING CHARACTERISTICS OF A THIN-WALLED HUMANITARIAN SHELTER(2022) Tan, Genevieve Claire; Milke, James A.; Trouve, Arnaud; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Large fires in humanitarian settlements lead to enormous losses in material, time, and resources that organizations allocate toward supporting refugee camps and displaced persons. In the absence of full-scale shelter fire experiments in humanitarian settlements, a combination of video analysis and fire modeling can be used to estimate burning characteristics of the shelter fire. A MATLAB-based image binarization method is developed to measure the flame height and structure loss over the course of fire development in footage from a shelter burn test conducted in Cox’s Bazar, Bangladesh. The conditions of the shelter fire are recreated in Fire Dynamics Simulator (FDS). Diagnostics in the FDS models provide estimates for the flame height, heat release rate, heat flux, and radiant integrated intensity in and around the shelter. The FDS models exhibit a 10-25 second delay in matching key events in the fire development timeline of the original shelter fire. Otherwise, measurements from the FDS simulations show good agreement to measurements from image processing. Based on results from image processing and FDS models, the steady burning HRR is approximately 900 kW for a shelter fire with a flame height range of approximately 4.1-4.5 m.
- ItemA REDESIGN OF THE EXHAUST AND GAS SAMPLING SYSTEM OF THE FIRE PROPAGATION APPARATUS(2022) Roy, Shuvam; Stoliarov, Stanislav; Raffan-Montoya, Fernando; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Standard bench scale fire apparatuses are useful tools to perform repeatable and reproducible firetests that acquire key fire properties, such as heat release rate and time to ignition, for materials in a cost-effective manner. The Fire Propagation Apparatus (FPA) is one of the only standard bench scale apparatuses that has the ability to acquire these key fire properties in a controlled environment setting. However, the design of the apparatus is quite complex. In this work, the exhaust and gas sampling system designs were redesigned and constructed to increase modularity and manufacturability, adapt to the University of Maryland’s Department of Fire Protection Engineering laboratory settings, and provide greater ease for the end user operations. After the construction of the FPA systems, tests were conducted to verify the accuracy of the measurement devices. Equations for the calculation of heat release rate from FPA sensor data were derived and used for a series of combustion experiments. These equations were compared to the ones provided in the standard to gain insight on their systematic differences.
- ItemSPHERICAL GAS-FUELED COOL DIFFUSION FLAMES(2022) Kim, Minhyeng; Sunderland, Peter B.; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)An improved understanding of cool diffusion flames could lead to improved engines. These flames are investigated here using a spherical porous burner with gaseous fuels in the microgravity environment of the International Space Station. Normal and inverse flames burning ethane, propane, and n-butane were explored with various fuel and oxygen concentrations, pressures, and flow rates. The diagnostics included an intensified video camera, radiometers, thin-filament pyrometry, and thermocouples. Spherical cool diffusion flames, transitioned from hot flames, burning gases were observed for the first time. However, these cool flames were not readily produced and were only obtained for normal n-butane flames at 2 bar with an ambient oxygen mole fraction of 0.39. The sizes of hot and cool diffusion flames were investigated with the intensified camera images. The hot flames that spawned the cool flames were 2.6 times as large. An analytical model is presented that combines previous models for steady droplet burning and the partial-burning regime for cool diffusion flames. The results identify the importance of burner temperature on the behavior of these cool flames. They also indicate that the observed cool flames reside in rich regions near a mixture fraction of 0.53.
- ItemDEVELOPMENT AND IMPROVEMENTS OF THE CONTROLLED ATMOSPHERE PYROLYSIS APPARATUS(2022) Bellamy, Grayson; Stoliarov, Stanislav I; McKinnon, Mark B; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Previously developed, the Controlled Atmosphere Pyrolysis Apparatus (CAPA) was designed to address the needs of a well-characterized gasification apparatus from which material properties could be derived. Although the data from CAPA has been well-validated through modeling and other various means, only a single functional and published version of the apparatus exists which hinders widespread acceptance. Additional concerns and questions about the design remain which warrants further improvement and investigation. In this work, elements of CAPA are revisited, redesigned, and improved to provide a more defined environment for bench-scale material evaluation. Existing geometrical constraints were maintained to allow for a direct comparison to previous work and confirm previous characterizations. In pursuit of these goals, several improvements were made. Implementation of an integrally water-cooled chamber was accomplished through additive manufacturing, allowing chamber temperatures to remain steady throughout the duration of a test, reducing additional radiant heat flux to the sample. Measurement resolution was increased with an upgraded thermal imaging camera, mass balance, and data acquisition system. Full analysis of the gas temperatures, chamber temperatures, oxygen concentration, and overall thermal environment was performed to replicate previous results and provide quantitative information for use in a pyrolysis modeling. Characterization experiments confirmed that heat flux profiles and gas temperatures are within the experimental uncertainty of both apparatuses. Chamber temperatures were reduced, providing for more clear boundary conditions and simplified modeling. Experimental results of this improved version of CAPA were compared against previous experiments conducted on poly(methyl methacrylate) (PMMA) and oriented strand board (OSB). Mass loss rate and surface temperature data were comparable indicating the apparatus performs as intended. Several problems and concerns were identified in this process for further study. This work provides further confirmation of the usefulness and accuracy of CAPA for use in analyzing the thermal decomposition of materials.
- ItemFirefighter Portable Radio Carrying Methods: Pocket or Strap?(2022) Brondum, Nicholas Joseph; Milke, James A; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Firefighters rely on their portable radios daily for communication. This project examines firefighter portable radios and their carrying methods. Carrying methods such as radio pockets sewn into turnout gear and radio straps are examined with respect to carrying utility, thermal protection, and decontamination ability. Information was gleaned from several firefighter line of duty death and “near miss” reports, personal interviews, empirical testing, computational fire modeling, and previous studies. Tests were conducted with radios carried in radio straps both above and below the turnout coat, as well as in the radio pocket. Radios were exposed to a radiant heat flux determined from computational fire modeling via a radiant panel until the test radio was either unable to transmit or receive messages from another radio. From this analysis, it is determined that wearing a portable radio in a radio strap under a turnout coat is the most efficient and safest way to carry a radio.