# Economizer (internal)

Source: economizer HX used inside screw-economizer circuits (`HeatExchanger<LmtdModel>` patterns)

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## EN

### Purpose & model

Internal heat exchanger that subcools liquid / evaporates injection gas for economized screw cycles. Often **not** a standalone CLI leaf — instantiated inside compressor economizer plumbing or macro components.

Model: LMTD or ε-NTU between liquid line and eco vapor.

### Residuals

Standard two-stream HX residuals of the inner model.

### Ports

Hot/cold legs as wired by the parent circuit.

### Note

For user-facing machines, configure economizer via **ScrewEconomizerCompressor** + circuit topology rather than a free-floating Economizer node unless the CLI arm exposes it.

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## FR

### But

Échangeur **économiseur** interne (sous-refroidissement / injection).

### Note

Souvent intégré au circuit vis, pas un composant CLI autonome.