Twine Models

Domain-specific models and model-building tools for Twine.

What this crate provides

twine-models offers opinionated Model implementations for engineering domains, along with the supporting utilities needed to build and compose them.

It is organized into two top-level modules:

• models — ready-to-use Model implementations
• support — utilities used by models, also available for downstream use

See the crate docs for details on each module.

Models

Thermal

Heat exchangers (models::thermal::hx)

• Recuperator — a discretized counter-flow heat exchanger that solves for outlet conditions given a UA value and inlet streams

Tanks (models::thermal::tank)

• StratifiedTank — a multi-node stratified thermal storage tank with configurable ports, auxiliary heat, conductive losses, and buoyancy-driven mixing

Feature flags

Feature	What it enables	Default
coolprop-dylib	CoolProp model via prebuilt shared library	no
coolprop-static	CoolProp model compiled from source (cmake + vendored)	no

The two CoolProp features are mutually exclusive.

coolprop-dylib

Links against prebuilt shared libraries from platform-specific coolprop-sys-* crates. Fast builds, good for local development. Works from crates.io.

twine-models = { version = "0.2", features = ["coolprop-dylib"] }

coolprop-static

Compiles CoolProp from source as a static library via cmake. Slower first build (cached after), but self-contained. Works for native, Python wheels, and WASM (wasm32-unknown-emscripten).

Requires a git clone with submodules — the CoolProp source tree (~240MB) exceeds crates.io's package size limit, so this feature is not available from a crates.io install.

git clone --recurse-submodules https://github.com/isentropic-dev/twine-models

COOLPROP_SOURCE_DIR

If you have a local CoolProp checkout (e.g., when installing from crates.io), set COOLPROP_SOURCE_DIR to point build.rs at it instead of the vendored submodule:

COOLPROP_SOURCE_DIR=/path/to/CoolProp cargo build --features coolprop-static

For WASM builds, the Emscripten SDK must be installed with em-config on PATH:

brew install emscripten        # macOS
rustup target add wasm32-unknown-emscripten
cargo test --target wasm32-unknown-emscripten --features coolprop-static --tests

Examples

Stratified tank simulation

Simulates five days of residential hot water tank operation with a thermostat-controlled heating element, a daily draw schedule, and an interactive time-series plot.

cargo run --example stratified_tank --release

Utility code (support)

Modules in support are public because they're useful, but their APIs are not yet stable — breaking changes may occur. The lifecycle for utility code is:

1. Model-specific — starts private inside a model's core module
2. Domain-specific — moves to a domain support module when useful across models in a domain
3. Crate-level — moves to support when useful across domains
4. Standalone — may become its own crate if broadly useful and stable

Twine ecosystem

Crate	Description
twine-core	Model trait and core abstractions
twine-solvers	ODE solvers (Euler, etc.)
twine-observers	Observer utilities (plotting, logging)