Results from On-Board CSA-CP and CDM Sensor Readings During the Burning and Suppression of Solids II (BASS-II) Experiment in the Microgravity Science Glovebox (MSG)
Olson, Sandra L., Ferkul, Paul V., Bhattacharjee, Subrata, Miller, Fletcher J., Fernandez-Pello, Carlos, Link, Shmuel, T'ien, James S., Wichman, Indrek
For the first time on ISS, BASS-II utilized MSG working volume dilution with gaseous nitrogen (N2). We developed a perfectly stirred reactor model to determine the N2 flow time and flow rate to obtain the desired reduced oxygen concentration in the working volume for each test. We calibrated the model with CSA-CP oxygen readings offset using the Mass Constituents Analyzer reading of the ISS ambient atmosphere data for that day. This worked out extremely well for operations, and added a new vital variable, ambient oxygen level, to our test matrices. The main variables tested in BASS-II were ambient oxygen concentration, ventilation flow velocity, and fuel type, thickness, and geometry. BASS-II also utilized the on-board CSA-CP for oxygen and carbon monoxide readings, and the CDM for carbon dioxide readings before and after each test. Readings from these sensors allow us to evaluate the completeness of the combustion. The oxygen and carbon dioxide readings before and after each test were analyzed and compared very well to stoichiometric ratios for a one step gas-phase reaction. The CO versus CO2 followed a linear trend for some datasets, but not for all the different geometries of fuel and flow tested. Lastly, we calculated the heat release rates during each test from the oxygen consumption and burn times, using the constant 13.1 kJ of heat released per gram of oxygen consumed. The results showed that the majority of the tests had heat release rates well below 100 Watts.
Test conditions.
Extracted from the paper by AI · “Verified” means a person checked it
| Fuel | O₂ | Pressure | Airflow | Sensors | Source | AI conf. | Status |
|---|---|---|---|---|---|---|---|
| PMMA (polymethylmethacrylate) Rods (6.35 to 12.7 mm), slabs (0.125 to 5 mm), or section of a 4 cm diameter sphere |
~21% to ~14% | — | Forced flow (opposed or concurrent) | CSA-CP (O2, CO), CDM (CO2), MCA (Major Constituents Analyzer), Thermopile detector, Still camera, Video camera | p. 1 | 95% | Pending |
| Cotton-fiberglass fabric Flat samples (1 cm or 2 cm wide) |
~21% to ~14% | — | Forced flow (opposed or concurrent) | CSA-CP (O2, CO), CDM (CO2), MCA (Major Constituents Analyzer), Thermopile detector, Still camera, Video camera | p. 3 | 90% | Pending |
Findings.
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01
BASS-II utilized MSG working volume dilution with gaseous nitrogen to achieve reduced oxygen concentrations.
Prevention · p. 1 · AI confidence 95% · Reported · Pending
“For the first time on ISS, BASS - II utilized MSG working volume dilution with gaseous nitrogen (N 2 ).”
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02
A perfectly stirred reactor model was developed to determine nitrogen flow time and rate for desired oxygen concentrations.
Other · p. 1 · AI confidence 95% · Reported · Pending
“We developed a perfectly stirred reactor model to determine the N 2 flow time and flow rate to obtain the desired reduced oxygen concentr ation in the working vol ume for each test.”
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03
Oxygen and carbon dioxide readings before and after tests compared well to stoichiometric ratios for a one-step gas-phase reaction.
Detection · p. 1 · AI confidence 95% · Reported · Pending
“The oxygen and carbon dioxide readings before and after each test were analyzed and compared very well to stoichiometric ratios for a one step gas - phase reaction.”
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04
CO versus CO2 readings followed a linear trend for some datasets but not for all fuel geometries and flow conditions.
Detection · p. 1 · AI confidence 95% · Reported · Pending
“The CO versus CO 2 followed a linear trend for some datasets, but not for all the different geometries of fuel and flow tested.”
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05
Heat release rates were calculated from oxygen consumption and burn times using 13.1 kJ of heat released per gram of oxygen consumed.
Detection · p. 1 · AI confidence 95% · Reported · Pending
“W e calculated the heat release r ates during each test from the oxygen consumption and burn times , using the constant 13.1 kJ of heat released per gram of oxygen consumed .”
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06
The global equivalence ratio for the tests is estimated to be fuel rich, averaging 1.3.
Other · p. 1 · AI confidence 95% · Reported · Pending
“Lastly, the global equivalence ratio for the tests is estimated to be fuel rich: 1.3 on average using mass loss and oxygen consumption data.”
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07
The CSA-CP oxygen sensor resolution is 0.1% O2.
Detection · p. 4 · AI confidence 95% · Reported · Pending
“The re solution of the oxygen sensor in the CSA - CP was 0.1% O 2 .”
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08
The CSA-CP CO sensor has a range of 0-1000 ppm and a resolution of 1 ppm.
Detection · p. 4 · AI confidence 95% · Reported · Pending
“The CO sensor in the CSA - CP is z ero calibrated every 60 days, with a range of 0 - 1000 ppm and a resolution of 1 ppm .”
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09
The MSG working volume is 0.25 m^3.
Other · p. 2 · AI confidence 95% · Reported · Pending
“V = volume of MSG working volume , 0.25 m 3”
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10
The maximum flow rate of gaseous N2 is 0.0005 m^3/min.
Other · p. 2 · AI confidence 95% · Reported · Pending
“r = fl ow rate of gaseous N 2 , 0.0005 m 3 /min maximum, adjustable”