vle-units

Dimensional analysis and unit conversion for vapor-liquid equilibrium (VLE) and thermodynamic calculations.

Works standalone. Designed as the unit layer for vle-thermo but useful in any Rust project that needs thermodynamic-flavored units (gauge pressure, °C / °F, kJ/kmol, barg, psig, mmHg, etc.).

Features

Compile-time typed quantities via uom — zero runtime cost, full dimension safety. Canonical quantity aliases match VLE conventions (VleTemperature, VlePressure, VleMolarEnergy, …).
Runtime unit registry — parse user-supplied strings like "25 degC", "3.5 barg", "1 atm" at the FFI boundary.
Gauge ↔ absolute conversion with a runtime-configurable atmospheric pressure (never hardcoded). Default: 101.325 kPa.
Extensible — define custom units and derived dimensions at runtime (TOML or direct API) without recompiling.

Install

[dependencies]
vle-units = "0.1"

Example

use vle_units::UnitRegistry;

let mut reg = UnitRegistry::with_vle_defaults();

// Parse user input in arbitrary units.
let t = reg.parse("25 degC")?;
let p = reg.parse("3.5 barg")?;

assert!((t.value_kelvin() - 298.15).abs() < 1e-9);
assert!((p.value_kpa()    - 451.325).abs() < 1e-9); // gauge + P_atm

// Configure atmospheric pressure for a different location / altitude.
reg.set_atmospheric_pressure(95.0)?;
# Ok::<(), vle_units::RegistryError>(())

Full API docs: https://docs.rs/vle-units.

Why a separate crate?

Thermodynamics code needs a few things that generic unit libraries don't handle cleanly:

Gauge pressure (barg, psig, kPag) where absolute = gauge + P_atm, and P_atm is a runtime parameter the operator can set.
Temperature differences vs. absolute temperatures (ΔT in K vs. T in °C — uom models these as distinct dimensions to prevent misuse).
Molar units (kJ/kmol, cm³/mol) that map to the canonical internal units used by cubic-EOS codebases going back to the 1980s.

See docs/en/units/dimensional-analysis.md for the full design rationale.

License