The Packed Bed Reactor Experiment: an overview of hardware ...
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Vent to Atmosphere FS32 57 l/h FS E2 H48 RV-2 50 psia E1 E1 E1 E1 140 140 E1 E1 RV-1 215 PSIA HV-2 Vent HV-1 R-1 GN2 Source 2400 PSIG 140 R = Regulator FS = Flow Switch QD-1 H-1 N.O. N.C. The Packed Bed Reactor Experiment: an overview of hardware and science Fig. 2: Left: Test section with glass beads showing key components (Engineering Model). Note the 5 pressure transducers; and one camera trained to the third sector of the column. The PBRE fits in the ISS Microgravity Science Glovebox. Right: Test section packed with Teflon beads. Life support systems in space depend on the ability to effectively recycle water from waste, air humidity and other water-producing systems. Subsystems and components critical to water treatment use packed-bed reactors for various stages of treatment. While design rules for gas-liquid flows through packed beds in normal gravity have been known for decades, they are lacking for other gravity environments. The Packed Bed Reactor Experiment (PBRE) focuses exclusively on the hydrodynamics of these flows, specifically, pressure drop, holdup and flow regime map correlations. Flow regime (implying phase distribution) and holdup correlations are a prerequisite to developing mass transfer correlations needed to model the reactor. The packed bed consists of a cylindrical test section 60 cm in length and 5 cm in diameter, filled with 3mm-diameter spherical beads. To examine the effect of wettability, two test sections will be tested, one with glass and the other with Teflon beads. The fluids are ISS-nitrogen and water. Water and gas exiting the test section flow into a centrifugal vortex phase separator. The water is recycled into the test section, while the gas is vented. Science Diagnostics: 5 absolute pressure transducers and two high-speed video cameras (up to 170 fps) along the test section. Video: Two high-speed video cameras (AVT GX1050) are trained at two 10-cm segments along the test section length. One segment is located at the column inlet and the other is 3/4 of the total column length downstream of the inlet. The field of view is 6X from 74.4 mm to 12.5 mm in the axial direction. The frame rate is variable with a maximum of 170 fps. The camera lenses are parfocal, so they maintain focus across zoom magnifications. Strobe lights are also used for illumination, with the camera shutter providing stopping action. Fig. 4: PBRE Operation Range: this plot of friction factor (f) vs. liquid Reynolds number (Re L ) shows the relevant regions of operation for several water purification concepts. The area in turquoise is the PBRE test range. Conditions below red-dashed line cannot be handled in the low-gravity aircraft due to limited 0-g time on aircraft. All purification concepts fall below the low-g aircraft range. Fig. 1: Flow Diagram of the PBRE flight hardware Test matrix philosophy: 1) Steady state: Identify flow regime boundaries in steady state. Increase gas flow rate for each fixed liquid flow rate. 2) Transients: increase, then decrease gas flow rate for each fixed liquid flow rate. Look for hysteresis in pressure drop and flow regime boundaries. Fig. 5: Low-gravity bubbly-to-pulse flow regime transition: Aircraft data showing a clear boundary between bubbly and pulse flows. Vertical axis: Suratman number (Su=d p σρ L /µ L 2 ); horizontal axis: gas over liquid Reynolds numbers. In normal gravity and for a given liquid flow rate, this transition occurs at higher gas flow rates. Supported by the Space Life & Physical Sciences Research and Applications Division of the Human Exploration and Operations Mission Directorate E. Ramé, 1 B. J. Motil, 2 V. Balakotaiah, 3 P. Salgi, 3 and N. Pham 2 1 USRA at NASA Glenn Research Center; 2 NASA Glenn Research Center, Cleveland, OH; 3 University of Houston, Houston, TX Flow Regimes Liquid always down Gas Gas Trickle Flow Only in G!!! Counter- or Co-flow Spray Flow 0-G or G Co-flow only Large Gas Inertia Pulse Flow 0-G or G Co-flow only Liquid-rich and gas- rich regions alternate Bubbly Flow Liquid continuous Counter or co-flow in G Co-flow only in 0-G Gas Liquid Gas Liquid Fluid Min. flow rate Max. flow rate Range Max. incr. Control Gas (kg/hr) 0 3 G<0.01 0.01<G<0.1 G>0.1 0.0005 0.01 0.1 ±0.0002 ±0.005 ±0.05 Liquid (l/hr) 0 150 L<20 L>20 1 5 ±0.5 ±1 Gas flow rates must be measured to 1% of actual flow rate for G>0.01 kg/hr; and to 2% of actual flow rate for G<0.01 kg/hr. Liquid flow rates must be measured to 1% of actual flow rate. (See Table 1.) Camera lens Strobe Pressure transducer 10 0 10 1 10 2 10 3 10 4 10 5 0.1 1 10 100 1000 Re LS / (1 - ) Initial porosity BWP Final porosity BWP VRA IVGEN & APCO (1ε) ACTEX Ion X-Ca+2 : Startup flow rates OGA Fig. 3: Flow regimes in normal and low gravity. Trickle flow: liquid flow rate is low enough that liquid never floods the column. Trickle flow can not develop in zero-gravity as it needs gravity for liquid to flow down. All other regimes can arise in any gravity level. Bubbly flow: liquid is continuous and gas is dispersed. Co-flow only in zero- gravity but either co-flow or counter-flow (where liquid flows down and gas rises by buoyancy for large enough bubbles) can develop in normal gravity. Pulse flow: most efficient for mass/heat transport in multiphase flows. For fixed liquid flow rate, bubbly-to-pulse transition occurs as gas flow rate is increased. Spray flow: only with high gas inertia. Not relevant in microgravity applications. f 10 1 10 2 10 3 10 4 10 5 10 6 0.01 0.1 1 10 100 Re GS /Re LS Su L Re GS /Re LS =700*Su L -2/3 Table 1: Flow rate requirements capabilities Lowest gas-liquid flow rates on aircraft Single-phase Ergun equation Bubbly Pulse
Transcript of The Packed Bed Reactor Experiment: an overview of hardware ...
OSG68E
S12
11M
FS15
00-
1
01/17/13NONE 31
-S1211MFS1500
SCHEMATICPBRE FLIGHT FLUID
Vent toAtmosphere
FS3257 l/hFS
E2
H48
RV-250 psia
E1
E1
E1
E1
140
135140
E1
E1
RV-1215 PSIA
HV-2Vent
HV-1R-1
GN2 Source 2400 PSIG
OSG68E
S12
11M
FS15
00-
1
01/17/13NONE 31
-S1211MFS1500
SCHEMATICPBRE FLIGHT FLUID
Vent toAtmosphere
FS32
FS
E2
H48
RV-250 psia
E1
E1
E1
E1
140
135140
E1
E1
RV-1215 PSIAR-1
HV-2Vent
GN2 Source 2400 PSIG
HV-1
140
R = RegulatorFS = Flow Switch
QD-1
H-1
N.O.
N.C.
The Packed Bed Reactor Experiment: an overview of hardware and science
Fig. 2: Left: Test section with glass beads showing key components (Engineering Model). Note the 5 pressure transducers; and one camera trained to the third sector of the column. The PBRE fits in the ISS Microgravity Science Glovebox. Right: Test section packed with Teflon beads.
Life support systems in space depend on the ability to effectively recycle water from waste, air humidity and other water-producing systems. Subsystems and components critical to water treatment use packed-bed reactors for various stages of treatment. While design rules for gas-liquid flows through packed beds in normal gravity have been known for decades, they are lacking for other gravity environments. The Packed Bed Reactor Experiment (PBRE) focuses exclusively on the hydrodynamics of these flows, specifically, pressure drop, holdup and flow regime map correlations. Flow regime (implying phase distribution) and holdup correlations are a prerequisite to developing mass transfer correlations needed to model the reactor. The packed bed consists of a cylindrical test section 60 cm in length and 5 cm in diameter, filled with 3mm-diameter spherical beads. To examine the effect of wettability, two test sections will be tested, one with glass and the other with Teflon beads. The fluids are ISS-nitrogen and water. Water and gas exiting the test section flow into a centrifugal vortex phase separator. The water is recycled into the test section, while the gas is vented. Science Diagnostics: 5 absolute pressure transducers and two high-speed video cameras (up to 170 fps) along the test section. Video: Two high-speed video cameras (AVT GX1050) are trained at two 10-cm segments along the test section length. One segment is located at the column inlet and the other is 3/4 of the total column length downstream of the inlet. The field of view is 6X from 74.4 mm to 12.5 mm in the axial direction. The frame rate is variable with a maximum of 170 fps. The camera lenses are parfocal, so they maintain focus across zoom magnifications. Strobe lights are also used for illumination, with the camera shutter providing stopping action.
Fig. 4: PBRE Operation Range: this plot of friction factor (f) vs. liquid Reynolds number (ReL) shows the relevant regions of operation for several water purification concepts. The area in turquoise is the PBRE test range. Conditions below red-dashed line cannot be handled in the low-gravity aircraft due to limited 0-g time on aircraft. All purification concepts fall below the low-g aircraft range.
Fig. 1: Flow Diagram of the PBRE flight hardware
Test matrix philosophy: 1) Steady state: Identify flow regime boundaries in steady state. Increase gas flow rate for each fixed liquid flow rate. 2) Transients: increase, then decrease gas flow rate for each fixed liquid flow rate. Look for hysteresis in pressure drop and flow regime boundaries.
Fig. 5: Low-gravity bubbly-to-pulse flow regime transition: Aircraft data showing a clear boundary between bubbly and pulse flows. Vertical axis: Suratman number (Su=dpσρL/µL
2); horizontal axis: gas over liquid Reynolds numbers. In normal gravity and for a given liquid flow rate, this transition occurs at higher gas flow rates.
Supported by the Space Life & Physical Sciences Research and Applications Division of the Human Exploration and Operations Mission Directorate
E. Ramé,1 B. J. Motil,2 V. Balakotaiah,3 P. Salgi,3 and N. Pham2 1USRA at NASA Glenn Research Center; 2NASA Glenn Research Center, Cleveland, OH; 3University of Houston, Houston, TX
Flow Regimes Liquid always
down Gas
Gas
Trickle Flow Only in G!!! Counter- or Co-flow
Spray Flow 0-G or G Co-flow only Large Gas Inertia
Pulse Flow 0-G or G Co-flow only Liquid-rich and gas-rich regions alternate
Bubbly Flow Liquid continuous Counter or co-flow in G Co-flow only in 0-G
Gas Liquid Gas Liquid
Fluid Min. flow rate
Max. flow rate Range Max.
incr. Control
Gas (kg/hr)
0
3
G<0.01 0.01<G<0.1 G>0.1
0.0005 0.01 0.1
±0.0002 ±0.005 ±0.05
Liquid (l/hr) 0 150
L<20 L>20
1 5
±0.5 ±1
Gas flow rates must be measured to 1% of actual flow rate for G>0.01 kg/hr; and to 2% of actual flow rate for G<0.01 kg/hr. Liquid flow rates must be measured to 1% of actual flow rate. (See Table 1.)
Camera lens
Strobe
Pressure transducer
100
101
102
103
104
105
f
0.1 1 10 100 1000ReLS / (1 - )
Single Phase Ergun Equation
BWP TEST MATRIX 2 inch diameterbased on 2 mm spheres
IncreasingGas Flow
IncreasingLiquid Flow
Lowest Gas/Liquid Flow Rates on Aircraft (water)
Effect of higher porosityInitial porosity BWP
Final porosity BWP
VRA
IVGEN & APCO
(1-‐ε)
ACTEX
Ion X-Ca+2
: Startup flow rates
OGA
Fig. 3: Flow regimes in normal and low gravity.
Trickle flow: liquid flow rate is low enough that liquid never floods the column. Trickle flow can not develop in zero-gravity as it needs gravity for liquid to flow down. All other regimes can arise in any gravity level. Bubbly flow: liquid is continuous and gas is dispersed. Co-flow only in zero-gravity but either co-flow or counter-flow (where liquid flows down and gas rises by buoyancy for large enough bubbles) can develop in normal gravity. Pulse flow: most efficient for mass/heat transport in multiphase flows. For fixed liquid flow rate, bubbly-to-pulse transition occurs as gas flow rate is increased. Spray flow: only with high gas inertia. Not relevant in microgravity applications.
f
101
102
103
104
105
106
Su L
0.01 0.1 1 10 100ReGS / ReLS
Bubbly FlowPulse Flow
ReG / ReL = 700 x SuL-2/3
ReGS/ReLS
Su L
ReGS/ReLS=700*SuL-2/3
Table 1: Flow rate requirements capabilities
Lowest gas-liquid flow rates on aircraft
Single-phase Ergun equation
Bubbly Pulse
