Browsing by Author "Padilla, Rosa"
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Item Battery Fire Risk Assessment(50th International Conference on Environmental Systems, 7/12/2021) Padilla, Rosa; Dietrich, Daniel; Pitz, William; Ruff, Gary; Urban, DavidLithium ion batteries (LIB) are crucial for future power systems and are being adapted across a span of applications in the ISS, planetary and earth science missions. Their prevalence requires the evaluation of their severe hazards in light of the unique spacecraft environment (reduced gravity, low pressure, high oxygen, limited egress opportunities, etc.). A LIB under an abuse condition can rupture and eject electrolyte vapor that can result in a flammable mixture of toxic gases that can subsequently ignite and burn. These hazards can pose an immediate risk to both the health of the crew, life support equipment and hardware. To evaluate the risks of a LIB fire in a spacecraft, this work will focus on quantifying the failure characteristics in LIB, such as, peak heat release, total energy release and combustion products. Heat release rates provides an estimate of fire growth and overall assessment of the risks to the crew and the vehicle. The peak heat release and total energy release from a single pouch cell and tablet fires are approximated using the t2 growth model and oxygen consumption calorimetry. Preliminary measurements show peak heat release rates between 2-15 kW and total energy levels between 218-290 kJ. This work has focused in quantifying the most energetic component of a LIB the electrolyte solvent, dimethyl carbonate mechanism (DMC). Flame temperatures reach above 1700 ? and major and minor gases were predicted, showing, a high level of CO2 and CO, in addition, other gases such as, acetylene (C2H2), ethylene (C2H4) and ethane (C2H6), will all be prevalent in a fire. Measurements of heat release rates and the gaseous species calculated will be used to estimate the impact that a fire has to the health of the crew member and the vehicle by calculating pressure rise and environmental temperatures.Item Characterization of Laptop Fires in Spacecraft(49th International Conference on Environmental Systems, 2019-07-07) Padilla, Rosa; Dietrich, Daniel; Lynch, Kelly; Juarez, Alfredo; Harper, Susana; Nagel, Christopher; Ruff, Gary; Urban, DavidAn accidental fire involving the Lithium-Ion (Li-ion) battery in a laptop computer is one of the most likely fire scenarios on-board a spacecraft. These fires can occur from a defect in the battery that worsens with time, over-charging the battery and leading to failure or accidental damage caused by thermal runaway. While this is a relatively likely fire scenario, very little is known about the how a laptop computer fire would impact a sealed spacecraft. The heat release would likely cause a pressure rise, possibly exceeding the pressure limit of the vehicle and causing a relief valve to open. The combustion products from the fire could pose a short-term and long-term health hazard to the crew and the fire itself could cause injury to the crew and damage to the spacecraft. Despite the hazard posed by a laptop fire, there is little quantitative data on the fire size, heat release and toxic product formation. This paper presents the results of initial attempts to quantify the fire resulting from a failed laptop battery tested at the NASA White Sands Test Facility (WSTF). The fire size and characteristics such as maximum heat release rate, total heat release, maximum temperatures and fire duration are determined. Using existing models and correlations for fires, the measured fire characteristics are extrapolated to laptop fires on a vehicle the approximate size of the Orion spacecraft.Item Hazardous Effects of Li-Ion Battery Based Fires(2020 International Conference on Environmental Systems, 2020-07-31) Padilla, Rosa; Alcantara, Ilse; Meyer, Marit; Juarez, Alfredo; Dietrich, Daniel; Urban, David; Ruff, Gary; Nagel, Christopher R.A potential thermal runaway (TR) failure from a computer with a lithium ion (Li-ion) battery is one of many energetic fuel sources present on-board a spacecraft vehicle that poses a fire safety concern. Tests were performed inside an 8 m$^{3}$ test chamber at White Sands Test Facility (WSTF) to emulate a spacecraft, addressing major aspects related to fire safety prevention, detection, suppression and post fire cleanup. A tablet was forced into TR by using a 60 W patch heater on a single pouch cell and comparisons with a higher energy unit laptop are presented as the worst-case representation of a fire. Initial venting of electrolyte is first observed on a failed pouch cell followed by an open fire. Pouch cell surface temperatures reach a maximum thermal runaway between 340-544 $^{\circ}$C across all units tested and during this event a large presence of toxic gases are released. Tablet fires with a maximum of two pouch cells that underwent TR reached a maximum of 14 kW aggressively and over 0.4 m in height. A large presence of carbon monoxide, CO and carbon dioxide, CO$_{2}$ was measured for higher energy fires and, prior to fire suppression. Levels of acrolein, C$_{3}$H$_{4}$O and CO are present above the maximum allowable concentrations levels inside a spacecraft vehicle. Additional gases, such as, measured benzene, C$_{6}$H$_{6}$, propylene, C$_{3}$H$_{6}$ and acrylonitrile are also present. This work provides insight in to the detection capability and required response times for triggering fire alarms aboard a vehicle. In addition, the data can be used to assess the capacity at which the life support systems capability to provide a hazard free environment.Item Supercritical Water Oxidation: A Promising Wastewater Treatment Technology(51st International Conference on Environmental Systems, 7/10/2022) Figueroa, Adrialis; Flynn, Michael; Padilla, Rosa; Gotti, Daniel; Hegde, Uday; Kojima, Jun; Hicks, MichaelSupercritical water oxidation (SCWO) is a water treatment technology that operates above the critical point of water. The main benefits of SCWO are its ability to completely oxidize organic compounds and mineralize/separate inorganic compounds from wastewater. This suggests SCWO technology can conceptually be applied as a single step water treatment system. Additionally, with proper design and operations it is capable of handling liquid waste streams with high solid loading, thus eliminating the need for extensive pretreatment of the waste stream. This paper provides a description of commercial, academic and NASA developed SCWO reactors. A trade study is presented that shows SCWO is competitive with the International Space Station (ISS) state-of-the-art water recovery systems in all categories except power. However, thermal and mechanical energy recovery approaches are discussed that could be used to reduce SCWO energy consumption to a level that is more competitive with the ISS state-of-the art.