controlled environment systems research facility hypobaric chambers for biological life support...

Controlled Environment Systems Research Facility

Hypobaric Chambers for Biological Life Support Research

Michael Stasiak, Cara Ann Wehkamp, Jamie Lawson, and Michael Dixon

Controlled Environment Systems Research Facility Department of Environmental Biology

University of Guelph


Bioregenerative Life Support Systems

Edible Biomass Production Carbon Dioxide Absorption Oxygen Generation Water Recycling Waste Degradation

CO2O2

Edible Biomass

Processed Waste

Gray H2O

Pure H2O

Inedible Biomass


Plant Growth Structure on Mars

Two options exist:

Earth atmospheric pressure- heavy and opaque

Reduced atmospheric pressure- light-weight and transparent material


Benefits of Low Atmospheric Pressure

Need to minimize the pressure differential between the growth structure and the Martian atmosphere

- simplifies the engineering requirements of the structure

- decreases atmospheric leakage

- reduces the amount of supplemental gas required for startup

- ability to modify plant growth rates

Martian Atmosphere (0.6 kPa)

10 kPa

Plant Growth Structure

100 kPa


Mars is the best candidate for human exploration

Low pressure conditions may be advantageous to Martian habitation

Further investigation is required for the development of an atmospheric composition that allows for reduced pressure plant growth without compromising the plant production yields required for human life support

Summary


Chamber design Data acquisition and control Temperature and humidity Pressure Carbon dioxide and oxygen Lighting Nutrient delivery

Hypobaric chambers: design and function


Five full canopy plant growth chambers 1.0 x 1.8 x 2.5 m (WHD) 4500 litre volume Growing area of 1.5 m2

Highly closed systems with low leakage Internal surfaces 316 stainless steel 20.5 mm laminate glass roof panels Viton sealing rings on doors and glass Fully automated Capable of maintaining low pressures

Hypobaric chamber design


Co

nd

en

se

r

He

ate

r

Blower

InternalReservoir

DO

OR

Lighting System Canopy

2.5 m

1.8 m

External Hydroponics Reservoir

Blower

Co

olin

g C

oil

1.5 m

Vacuum

Nitrogen

CO2

Oxygen

GasSampling


Data acquisition and control

Argus Control Systems Inc. Distributed real-time control Stand-alone microcontroller (Motorola 68HC811) on

each chamber Proprietary RS 485 communications network Each hypobaric chamber operates independently All sensor readings sampled once per second Experimental data recorded once per minute (higher

speeds available) Operator interface provided through a PC-based

system access and management program (Argus for Windows)

PC component is not used for real time control - failure of the PC has no consequence on system control


Temperature and humidity

Variable speed blower Blower speed control coupled to pressure Chilled water (4°C) and hot water (55°C)

heat exchange coils Cold exchange coil controlled to achieve

required VPD setpoint Hot exchange coil used to reheat cooled

air to regulate final temperature setpoint Two Honeywell 4139 T/RH sensors Four Argus TN2 temperature sensors (2

soil, 2 heat exchange) Tipping bucket for evapotranspiration

measurement


17

18

19

20

21

22

23

24

25

0 2 4 6 8 10 12 14 16 18

ambient

66 kPa

33 kPa

Temperature: Radish

Days after closure

Tem

pera

ture

(°C

)


7

8

9

10

11

12

0 2 4 6 8 10 12 14 16 18

ambient

66 kPa

33 kPa

Vapour pressure deficit: Radish

Days after closure

VP

D (

mb)


50

55

60

65

70

75

80

0 2 4 6 8 10 12 14 16 18

ambient

66 kPa

33 kPa

Relative humidity: Radish

Days after closure

%R

H


0

2

4

6

8

10

12

0 6 12 18 24

ambient

66 kPa

33 kPa

Evapotranspiration: Radish 18 DAP

Hours

H2O

Acc

umul

atio

n (li

tres

)


Pressure

Vacuum pump: Busch Vacuum Pressure sensors: Pribusin Inc Control Valve: Swagelok Control range +/- 0.1 kPa Pressure control ambient to 0.01 kPa Systems not designed for pressurization Leakage rate less than 1% per day


64.0

64.5

65.0

65.5

66.0

66.5

67.0

0 6 12 18 24

32.0

32.5

33.0

33.5

34.0

0 6 12 18 24

66 kPa

33 kPa

Hours

kPa

System leakage


9.0

9.5

10.0

10.5

11.0

0 6 12 18 24

4.0

4.5

5.0

5.5

6.0

0 6 12 18 24

10 kPa

5 kPa

Hours

kPa

System leakage


20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

ambient

66 kPa

33 kPa

Pressure: RadishkP

a

Days after closure


Carbon dioxide and oxygen

CO2/O2 analyzer: California Analytical Instruments Inc. Model 200

NDIR CO2 and paramagnetic O2 sensors

One analyzer per chamber

CO2: 0 – 6000 µmol mol-1 (+/- 15 from set point)

O2: 0 -100%


Cold trapHypobaricChamber

CO2/O2 Analyzer

CO2

NC1

Cold trapNV2

Pump

O2

NC2

N2

NC3

Condensate return

NV1

CO2/O2 sampling system based on repressurization of hypobaric chamber air

Chamber air continuously removed by a vacuum pump (KNF Neuberger Inc)

Air is repressurized in a sampling loop controlled by a non-bleed precision pressure regulator (Parker) and needle valve (HAM-LET)

Pressure gauge (Noshok) used to monitor and manually set the sampling stream to 0.2 psi

Pressure regulator/gauge


1100

1200

1300

1400

1500

1600

1700

0 6 12 18 24

0

100

200

300

400

500

600

700

800

900

ambient

66 kPa

33 kPa

Carbon dioxide: Radish 18 DAP

Hours

µm

ol m

ol-1

mm

ol accumulated


20.0

20.5

21.0

21.5

22.0

22.5

23.0

23.5

24.0

0 6 12 18 24

ambient

66 kPa

33 kPa

Oxygen: Radish 18 DAP

Hours

Per

cent

oxy

gen


Lighting

six 1000 watt HPS lamps (P.L. Light Systems) per chamber

Maximum irradiation intensity at highest bench level approximately 1500 μmol m-2 s-1 PAR

Externally mounted lighting canopy cooled with chilled water heat exchanger coupled to a blower

Two LiCor PAR sensors continuously monitor irradiation

lighting schedule automated and under control of the Argus Control System.


ExternalReservoir Internal Reservoir

Nu

trie

nt

A

FM

Legend:• Electrical Conductivity (EC)• Temperature (T)• Flow Meter (FM)• Normally Closed Valve (NC)• Tipping Bucket (TB)• Gravity Return (GR)• Proportional Valve (PV)

Nu

trie

nt

B

FM

AC

ID

FM

BA

SE

FM

Chamber interiorPressure compensation

GR

NC1 NC2 NC3 NC4

TB

PV1

EC2 T2

EC1 T1

Pump

pH1 pH2

Condenser

NFT design 400 litre temperature controlled external stainless steel reservoir Circulation pump (International Pump Technology Inc.) provides

sufficient pressure for chamber delivery from ambient to 2 kPa Gravity return of water Electrical conductivity (2 - Argus Control Systems, Inc) pH sensors (2 - Honeywell Inc.) currently non-functional – pH is

manually adjusted daily Gravity feed of acid, base, and nutrient solutions

Nutrient delivery


0.8

0.9

1

1.1

1.2

1.3

1.4

0 5 10 15 20

ambient

66 kPa

33 kPa

Days after planting

Ele

ctric

al c

ondu

ctiv

ity (

mS

)EC: Radish


Nutrient delivery

Removable tray system Pump truck to move crop to harvest lab Quick-connect couplings for water delivery Gravity return to external tank


Acknowledgements

controlled environment systems research facility hypobaric chambers for biological life support...

Documents

closed systems

control argus control

kpa slide

system control slide

function slide

reduced pressure plant

kpa plant growth structure

canopy plant growth