Spacecraft Trace Contaminant Control System

Cabin & Crew

Crew size 4

TCCS airflow rate 60 m³/hr

Catalytic oxidizer temp 375 °C

Live Readouts

Cabin VOC concentration0.00 mg/m³

Charcoal bed saturation0%

SMAC-eq. limit

0.35 mg/m³

Status

Oxidizer conversion efficiency η_ox

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How it works

A crewed cabin's trace contaminant control system (TCCS) pulls cabin air through a physical/chemisorbent charcoal bed (captures higher-molecular-weight VOCs and ammonia) then a high-temperature catalytic oxidizer (destroys light gases like CO, H₂ and CH₄ by burning them to CO₂ and H₂O). The cabin is a well-mixed lumped volume:

dC/dt = G/V − (Q/V)·C·ε(t)
ε(t)  = 1 − (1−η_ads)·(1−η_ox)   (two beds in series)

The charcoal bed loads like a Langmuir trap and its adsorption efficiency falls as it saturates:

η_ads(t) = η_max·(1 − M/M_cap)
dM/dt    = Q·C·η_max·(1 − M/M_cap)

The catalytic oxidizer's conversion follows Arrhenius kinetics — hotter runs faster, but more airflow means less time in the bed to react:

k(T) = A·exp(−Ea / (R·T))     [T in kelvin]
τ    = V_ox / Q               (residence time)
η_ox = 1 − exp(−k(T)·τ)

Crew size — scales the VOC generation rate G (off-gassing + metabolic trace gases).
Airflow Q — more flow dilutes the cabin faster but shortens oxidizer residence time τ, so conversion efficiency drops even as more air is processed.
Oxidizer temperature — raises the Arrhenius rate constant k(T), pushing η_ox toward 1.
Regenerate bed — desorbs the charcoal canister to vacuum, resetting loaded mass M to zero, exactly like the periodic thermal-vacuum regeneration cycle used on real ECLSS charcoal beds.

Real-world relevance: this is the same two-stage architecture (sorbent bed + catalytic oxidizer) NASA's TCCS uses on the ISS to keep formaldehyde, ammonia and other off-gassed trace contaminants below Spacecraft Maximum Allowable Concentration (SMAC) limits.

Trace contaminant Adsorbed on charcoal Oxidized (CO₂ + H₂O)

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