Spacesuit CO2 Scrubber: Sorbent Breakthrough Front

Astronaut & Bed Setup

Metabolic CO2 rate 1.0×

Purge gas flow rate 1.0×

Sorbent condition

Live Readouts

ADSORBING

Outlet CO2 pp

0.0 mmHg

Bed loading

Cycle time

0.0 s

Mass-transfer zone

segment 1

bed inletC(z) profileoutlet

How it works

A real portable life-support system pulls the astronaut's exhaled gas through a packed bed of CO2 sorbent (LiOH, metal-oxide, or amine granules). CO2 is removed as the gas percolates through, but not instantly — a moving mass-transfer zone (MTZ) separates saturated bed (upstream) from still-fresh bed (downstream). When that zone reaches the outlet, CO2 "breaks through" into the helmet air.

Each bed segment i tracks a gas-phase CO2 level C_i and a solid loading q_i, coupled by a Langmuir equilibrium and a linear-driving-force (LDF) rate law — the standard textbook model for fixed-bed adsorption:

q_eq(C) = q_max · b·C / (1 + b·C)      (Langmuir isotherm)
dq_i/dt = k_LDF · (q_eq(C_i) − q_i)     (LDF uptake rate)
dC_i/dt = u·(C_{i−1} − C_i) − β·dq_i/dt  (convection − uptake)

Metabolic CO2 rate sets the inlet partial pressure C₀, normalized so 1.0× ≈ the ~7.6 mmHg ppCO2 design limit NASA uses for nominal EVA workload.
Purge gas flow rate sets the convective velocity u — faster flow pushes the front through the bed quicker but gives each granule less time to reach equilibrium.
Sorbent condition scales q_max: an aged/degraded bed holds noticeably less CO2 before breakthrough.
Start Regeneration switches the inlet to vacuum (C₀ → 0) with a faster desorption rate constant, draining q_i back toward zero — modelling a vacuum-swing or thermal-swing regeneration cycle between EVAs.

Granule color in the 3D bed encodes local loading q_i/q_max (blue = fresh, orange = saturated), so the MTZ is visible as a moving color gradient sweeping from inlet to outlet.

Fresh sorbent (low q) Saturated sorbent (q ≈ q_max)

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