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Capture uncommitted solver robustness work (regularization, domain errors, linear solver lifecycle, tube DP/MSH), web workbench updates, and synced BMAD skills across IDE agent folders before starting BPHX pressure-drop. Co-authored-by: Cursor <cursoragent@cursor.com>
120 lines
3.7 KiB
Markdown
120 lines
3.7 KiB
Markdown
# BphxEvaporator / BphxCondenser (Brazed Plate HX)
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Config types: `"BphxEvaporator"`, `"BphxCondenser"`
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Source: `crates/components/src/heat_exchanger/bphx_evaporator.rs`, `bphx_condenser.rs`, shared geometry/correlation helpers
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---
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## EN
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### Purpose & model
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Brazed-plate HX with **geometry + two-phase correlation → h → UA estimate**, then runtime solve on an **inner ε-NTU** residual model.
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#### Correlations (selectable)
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Default **Longo 2004**. Also **Shah 1979**, **Shah 2021**.
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Full registry (also Kandlikar, Gungor–Winterton, Gnielinski, Dittus–Boelter, Ko 2021, Friedel ΔP): see [correlations-and-maps.md](./correlations-and-maps.md).
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Equivalent Reynolds construction (schematic):
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```
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Re_l = G · d_h / μ_l
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Re_eq = Re_l · (1 − x + x · √(ρ_l / ρ_v))
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```
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Longo-style Nu (illustrative forms used in the implementation path):
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```
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Evaporation: Nu ~ f(Re_eq, Pr_l) (e.g. 0.05 · Re_eq^0.8 · Pr_l^0.33)
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Condensation: Nu ~ f(Re_eq, Pr_l, ρ*) (e.g. 1.875 · Re_eq^0.35 · Pr_l^0.33 · …)
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h = Nu · k_l / d_h
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UA_est = h · A · z_ua
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```
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Pressure drop (schematic):
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```
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ΔP = z_dp · 2 · f · L · G² / (ρ · d_h)
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```
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**Important:** the **Newton system residuals** for the component are the **inner ε-NTU** residual set (`n_equations` of the inner model, typically 2 for the base HX path). The correlation updates **UA** (when `update_ua_from_htc` / geometry path is engaged); it is **not** a full multi-zone moving-boundary residual stack.
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### Modes / targets
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| Type | Mode | Notes |
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|------|------|--------|
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| `BphxEvaporator` | **DX only** | Outlet is superheated vapor. `target_superheat_k` (default 5 K) is diagnostic/target storage — not a flooded shell model. For flooded shell-and-tube use `FloodedEvaporator`. |
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| `BphxCondenser` | Subcooling target | `target_subcooling_k` (default 3 K) |
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### Ports
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4-port Modelica-style naming in the system graph when wired:
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| Port | Role |
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|------|------|
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| `inlet` / `outlet` | Refrigerant |
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| `secondary_inlet` / `secondary_outlet` | Secondary fluid |
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Geometry fields: plate length/width, thickness, chevron, channel spacing, optional `dh_m` / `area_m2` overrides.
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### Calibration
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| Key | Meaning | Default |
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|-----|---------|---------|
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| `z_ua` / `Z_UA` | UA scale | **1.0** |
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| `z_dp` / `Z_dpc` | ΔP scale | **1.0** |
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| `ua` explicit | sets `z_ua = ua / UA_nom` | – |
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Legacy `f_ua` / `f_dp` accepted in JSON.
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### JSON parameters (main)
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| Key | Meaning | Default |
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|-----|---------|---------|
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| `n_plates` | plate count | 20 |
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| `plate_length_m` / `plate_width_m` | geometry | – |
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| `chevron_angle_deg` | chevron | 60 |
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| `correlation` | Longo2004 / Shah1979 / Shah2021 | Longo2004 |
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| `target_superheat_k` | DX target (evap) | 5 K |
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| `target_subcooling_k` | SC target (cond) | 3 K |
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| `refrigerant` / `secondary_fluid` | fluids | – |
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| `z_ua`, `z_dp` | calib | 1.0 |
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### DoF / system usage
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Prefer live secondary wiring for closed loops. Pair `z_ua` free + measured SST/SDT for inverse calibration (same Fixed/Free discipline as other HX).
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---
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## FR
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### But & modèle
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Échangeurs **à plaques brasées** : géométrie + **corrélation biphasique** (Longo 2004 / Shah) → coefficient h → UA, puis solveur sur modèle **ε-NTU interne**.
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Formes types :
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```
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Re_eq = Re_l · (1 − x + x · √(ρ_l/ρ_v))
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Nu = f(Re_eq, Pr, …) # Longo / Shah selon `correlation`
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h = Nu · k / d_h
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UA = h · A · z_ua
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```
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Le **Newton** ne résout pas la corrélation plaque par plaque : il résout le **HX ε-NTU** ; la corrélation **calibre/estime UA**.
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### Modes
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- **BphxEvaporator** : DX uniquement (pas un flooded shell).
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- **BphxCondenser** : cible de sous-refroidissement.
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### Calibration
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`z_ua = 1`, `z_dp = 1` par défaut. Alias BOLT `Z_UA`, `Z_dpc`.
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### Ports / JSON
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Voir tableaux EN.
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