LH2PoolX

LH2PoolX calculates an evidence-qualified, quasi-steady liquid-hydrogen pool source term for a declared time window. It is an upstream input module for dispersion models, not a dispersion model and not a general jet-impact or pool-spreading solver.

What it calculates

For a specified release rate, storage pressure, elapsed time, substrate and ground-deposition fraction, LH2PoolX calculates:

1. isenthalpic flash fraction using CoolProp;
2. liquid mass reaching the ground;
3. heat-limited evaporation flux using a semi-infinite ground-conduction relation with an LH2 critical-heat-flux cap; and
4. the unconfined equilibrium pool area and evaporation rate.

deposition_fraction is deliberately explicit. The package does not predict impingement, splashing, droplet transport, drainage, barriers, or transient pool spreading. A confined result reports liquid accumulation and must not be used as a steady source without a separate inventory model.

Observed-footprint route

Some records constrain a ground footprint more reliably than they constrain the liquid fraction transferred from the release to the ground. In this case, evaluate_observed_footprint_source converts a declared circular-equivalent radius into a heat-limited evaporation source on the declared solid substrate:

from lh2poolx import evaluate_observed_footprint_source

lower = evaluate_observed_footprint_source(
    equivalent_radius_m=0.5, elapsed_s=300.0
)
upper = evaluate_observed_footprint_source(
    equivalent_radius_m=1.0, elapsed_s=300.0
)
print(lower.area_m2, lower.evaporation_rate_kg_s)
print(upper.area_m2, upper.evaporation_rate_kg_s)

This is a conditional source route, not an inverse impact model. It does not accept a release rate or deposition_fraction, and does not reconstruct pool growth, inventory, liquid deposition, splash/droplet transport, drainage or the footprint history. If a record gives an extent range, calculate both bounds and retain the resulting source range; do not select a midpoint or fit an unobserved deposition fraction.

For example, the FFI large-scale LH2 report describes vertical-release pools as remaining within roughly 0.5-1.0 m of the release point, while also noting that fog prevented a precise visual verification. That record can support a 0.5-1.0 m conditional radial-extent envelope, not a single observed pool area, evaporation history or deposition fraction. See the FFI report.

Install

pip install lh2poolx

Minimal use

from lh2poolx import LH2Release, evaluate_pool_source

release = LH2Release(rate_kg_s=0.1055, storage_pressure_barg=1.0)
source = evaluate_pool_source(release, elapsed_s=300.0)
print(source.area_m2, source.evaporation_rate_kg_s)

Evidence boundary

The concrete heat-transfer implementation is checked against the four published PRESLHY E3.4 Concrete02 mass-loss windows. That comparison is a restricted substrate-and-condition check, not validation for other substrates or for jet-to-ground deposition. Literature supports the physical form of the source chain; it does not turn unknown deposition into a fitted value.

License

MIT. Cite the accompanying software record when one is released, plus the underlying experimental and heat-transfer sources used in an analysis.