Fire Safety in the Low-Gravity Spacecraft Environment

Friedman, Robert

doi:10.4271/1999-01-1937

Cited by 29 publications

(26 citation statements)

References 45 publications

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“…It is important to note that reaching the necessary heats for combustion is much easier in microgravity. Overheated motors, bearings, wires and other components will remain hot longer due to a lack of convective heat transfer in microgravity (Friedman, 1999).…”

Section: Fire Modes In Microgravitymentioning

confidence: 99%

“…Typically microgravity fires burns slower as well; mainly because flames tend to be weaker without the aid of convection currents. New oxygen is not -swept‖ into the fire but needs to diffuse into the combustion area, which takes more time to accomplish (Friedman, 1999). Fires in space:…”

Section: Fire Science Overviewmentioning

confidence: 99%

“…As far back as the Mercury and Gemini missions, astronauts had at their disposal various methods by which to extinguish fires (Friedman, 1999). PFE technology used today onboard the ISS is outdated, expensive, and not conducive for investment by the commercial spaceflight industry.…”

Section: Introductionmentioning

confidence: 99%

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Fire in Orbit: Equipping the Commercial Spaceflight Industry for Fighting Fire in Micro-Gravity

Cybela

2015

Proc. Wisc. Space Conf.

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For several years, Orbital Technologies (ORBITEC) has had keen interest in the development of a portable fire suppression system intended for use in commercial spaceflight applications. With the aid of recent developments in fine water mist (FWM) atomization technologies, and partnerships with the University of Wisconsin â€“ Platteville, work is commencing to develop a portable fire extinguisher (PFE). The extinguisher will be capable of operation in both gravity and microgravity environments regardless of orientation, and eliminate the use of toxic carbon dioxide as a fluid suppressant. The extinguisher will take advantage of the unique physics of microgravity to better suppress fires compared to previously used equipment. The following report outlines baseline research into the historical precedence of spacecraft fires, and common modes of fire ignition in microgravity. From this information we investigate design considerations necessary for the construction of a prototype PFE, as well as the market value of such a device.

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Section: Fire Modes In Microgravitymentioning

confidence: 99%

Section: Fire Science Overviewmentioning

confidence: 99%

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Fire in Orbit: Equipping the Commercial Spaceflight Industry for Fighting Fire in Micro-Gravity

Cybela

2015

Proc. Wisc. Space Conf.

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“…Fig. 1: Upward flammability test [3]. Picture on the right shows a sample failing the test [4], by flame spread criteria (flame length exceeds 15cm).…”

Section: Introductionmentioning

confidence: 99%

“…The material is ignited at the base (the igniter design is discussed in NASA-NHB 8060. 1 (1981), and Friedman [3]), and the flame propagation is recorded on a video camera. The passing criteria for this test is for the flame to self extinguish before the propagation has reached 6 inches (~15 cm), with self-extinction defined as "burned less than 6 inches (~15 cm) when exposed to an ignition source."…”

Section: Introductionmentioning

confidence: 99%

Flame Spread Analysis Using a Variable B-Number

Rangwala¹

2008

Fire Saf. Sci.

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Flame spread over solid materials is commonly described in the literature by a two-dimensional reactive boundary layer solution first formulated by Emmons (1956). In the recent past, experimental measurements associated with material flammability testing (e.g. NASA-STD-6001) are compared with the Emmons solution, as modified by Pagni and Shih (1979), and found in disagreement. In the classical solution, the B-number (Spalding mass transfer number) appears as one of the boundary conditions, and has been traditionally assumed a constant for mathematical simplicity. However, experimental results show that the B-number is not a constant, but varies with time and space. A simple modification to the standard measurement procedure is described, which allows calculation of the B-number from the flame stand-off distance. Measurements of flame standoff distance are performed to determine the B-number as a function of time. The classical combustion problem is revisited to model flame spread over a combustible surface. An experimentally-obtained B-number is used to model flame propagation, showing good agreement with current and previous experimental data obtained from the literature. Implications to microgravity flame spread are discussed.

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PEM Fuel Cell Stack Cold Start Thermal Model

Sundaresan

Moore

2005

Fuel Cells

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For passenger fuel cell vehicles (FCVs), customers will expect to start the vehicle and drive almost immediately, implying a very short system warmup to full power. While hybridization strategies may fulfill this expectation, the extent of hybridization will be dictated by the time required for the fuel cell system to reach normal operating temperatures. Quick‐starting fuel cell systems are impeded by two problems: (i) the freezing of residual water or water generated by starting the stack at below freezing temperatures and (ii) temperature‐dependent fuel cell performance, improving as the temperature reaches the normal range. Cold start models exist in the literature; however, there does not appear to be a model that fully captures the thermal characteristics of the stack during sub‐freezing startup conditions. Existing models lack the following features: (i) modeling of stack internal heating methods (other than stack reactions) and their impact on the stack temperature distribution and (ii) modeling of endplate thermal mass effect on end cells and its impact on the stack temperature distribution. Unlike a lumped model, which may use a single temperature as an indicator of the stack's thermal condition, a model considering individual cell layers can reveal the effect of the endplate thermal mass on the end cells, and accommodate the evaluation of internal heating methods that may mitigate this effect. This paper presents and discusses results from simulations performed with a new, layered model.

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Fire Safety in the Low-Gravity Spacecraft Environment

Cited by 29 publications

References 45 publications

Fire in Orbit: Equipping the Commercial Spaceflight Industry for Fighting Fire in Micro-Gravity

Fire in Orbit: Equipping the Commercial Spaceflight Industry for Fighting Fire in Micro-Gravity

Flame Spread Analysis Using a Variable B-Number

PEM Fuel Cell Stack Cold Start Thermal Model

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