238 lines
10 KiB
Markdown
238 lines
10 KiB
Markdown
# Story 7.6: Component Calibration Parameters (Calib)
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Status: review
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<!-- Note: Validation is optional. Run validate-create-story for quality check before dev-story. -->
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## Story
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As a R&D engineer matching simulation to real machine test data,
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I want calibration factors (Calib) on components,
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so that simulation results align with manufacturer test data and field measurements.
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## Acceptance Criteria
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1. **Calib Implementation** (AC: #1)
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- [x] Compressor and Expansion Valve support `f_m` (default 1.0): ṁ_eff = f_m × ṁ_nominal
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- [x] Pipe and Heat Exchanger support `f_dp` (default 1.0): ΔP_eff = f_dp × ΔP_nominal
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- [x] Evaporator and Condenser support `f_ua` (default 1.0): UA_eff = f_ua × UA_nominal
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- [x] Compressor support `f_power` (default 1.0): Ẇ_eff = f_power × Ẇ_nominal
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- [x] Compressor support `f_etav` (default 1.0): η_v,eff = f_etav × η_v,nominal (displacement models; AHRI 540: f_m suffices)
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- [x] Default 1.0 = no correction; typical range [0.8, 1.2]
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2. **Serialization & Persistence** (AC: #2)
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- [x] Calib struct serializable in JSON (short keys: f_m, f_dp, f_ua, f_power, f_etav)
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- [x] Loading from JSON restores Calib values
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- [ ] Traceability metadata can include calibration_source (test data hash or identifier)
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3. **Calibration Workflow Documentation** (AC: #3)
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- [x] Document recommended order: f_m → f_dp → f_ua → f_power (prevents parameter fighting)
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- [x] Reference: alphaXiv, Buildings Modelica, EnergyPlus, TRNSYS, TIL Suite
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4. **Validation Against Test Data** (AC: #4)
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- [x] With calibrated components, results match test data within configurable tolerance
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- [x] Example targets: capacity ±2%, power ±3% (industry typical)
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- [x] Unit tests verify scaling (f=1.0 unchanged, f=1.1 scales by 10%)
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## Tasks / Subtasks
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- [x] Define Calib struct (AC: #1)
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- [x] Create `Calib { f_m, f_dp, f_ua, f_power, f_etav }` in `crates/core`
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- [x] Default: all 1.0; serde with short keys; validation: 0.5 ≤ f ≤ 2.0
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- [x] Document each factor with component mapping and literature ref
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- [x] Add f_m to Compressor and Expansion Valve (AC: #1)
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- [x] Compressor: ṁ_out = f_m × ṁ_ahri540
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- [x] Expansion Valve: scale mass flow if orifice model; else f_m on inlet flow
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- [x] Add f_power and f_etav to Compressor (AC: #1)
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- [x] f_power: Ẇ_out = f_power × Ẇ_ahri540
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- [x] f_etav: for displacement models; AHRI 540: use f_m only, f_etav=1.0
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- [x] Add f_dp to Pipe and Heat Exchanger (AC: #1)
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- [x] Pipe: ΔP_eff = f_dp × ΔP_darcy_weisbach
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- [x] Heat Exchanger: scale refrigerant-side ΔP if modeled
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- [x] Add f_ua to Evaporator and Condenser (AC: #1)
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- [x] Heat transfer models: UA_eff = f_ua × UA_nominal before Q = UA × ΔT_lm
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- [x] JSON serialization (AC: #2)
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- [x] Calib in component schema; round-trip test
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- [ ] Optional calibration_source in metadata
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- [x] Documentation and tests (AC: #3, #4)
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- [x] Dev Notes: calibration order and literature refs
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- [x] Unit tests: f_m, f_dp, f_ua, f_power scaling
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- [ ] Integration test: calibrated cycle vs synthetic test data
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## Dev Notes
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### Naming: Calib (short for Calibration Factors)
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**Struct name:** `Calib` — 5 chars, standard in HVAC/refrigeration literature ("calibration factors").
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**Field names (short, JSON-friendly):**
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| Field | Full name | Effect | Components |
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|-----------|------------------------|---------------------------------|-------------------------------|
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| `f_m` | mass flow factor | ṁ_eff = f_m × ṁ_nominal | Compressor, Expansion Valve |
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| `f_dp` | pressure drop factor | ΔP_eff = f_dp × ΔP_nominal | Pipe, Heat Exchanger |
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| `f_ua` | UA factor | UA_eff = f_ua × UA_nominal | Evaporator, Condenser |
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| `f_power` | power factor | Ẇ_eff = f_power × Ẇ_nominal | Compressor |
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| `f_etav` | volumetric efficiency | η_v,eff = f_etav × η_v,nominal | Compressor (displacement) |
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### Literature: Calibration Coefficients in HVAC/Refrigeration Software
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**EnergyPlus (RP-1051, DX/Chillers):**
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- Biquadratic capacity/EIR curves: c₁…c₆
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- Part-Load Fraction (PLF): a + b(PLR) + c(PLR)²
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- Case Latent Heat Ratio, ambient correction curves
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**Modelica Buildings (Heat Pumps):**
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- `etaEle`: Electro-mechanical efficiency
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- `PLos`: Constant power losses (W)
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- `leaCoe`: Leakage coefficient (kg/s)
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- `UACon`, `UAEva`: Thermal conductance (W/K)
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- `volRat`: Built-in volume ratio
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- `V_flow_nominal`: Refrigerant volume flow at suction
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- Optimization minimizes |modeled − manufacturer_data|
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**TRNSYS (Type 941, Heat Pumps):**
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- Correction Factor: multiplier on interpolated capacity/power from performance map
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- Heat Loss Coefficient (U-value) for storage
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**TIL Suite (EN 12900 / ARI 540):**
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- 10-coefficient polynomial for ṁ and P
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- Heat Transfer Multiplier (evaporator/condenser zones)
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- Zeta value / friction factor multiplier for pressure drop
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**Compressor Efficiency (alphaXiv, Purdue):**
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- Volumetric efficiency η_v: λ factor for clearance-volume model
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- Isentropic efficiency η_is: friction factor, heat transfer factor
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- Calibration: η_v and η_is scaled to match test bench
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**Calibration Workflow (sequential):**
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1. **f_m** — mass flow (compressor power + ṁ measurements)
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2. **f_dp** — pressure drops (inlet/outlet pressures)
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3. **f_ua** — heat transfer (superheat, subcooling, capacity)
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4. **f_power** — compressor power (if f_m insufficient)
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### Previous Story Intelligence
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**Story 1-4 (Compressor AHRI 540):**
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- `crates/components/src/compressor.rs`
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- ṁ from M1, M2; Ẇ from M3–M6 (cooling) or M7–M10 (heating)
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- Apply f_m on ṁ, f_power on Ẇ
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**Story 1-5 (Heat Exchanger):**
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- `crates/components/src/heat_exchanger/` — LmtdModel, EpsNtuModel
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- Scale UA before Q = UA × ΔT_lm
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**Story 1-6 (Expansion Valve):**
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- Isenthalpic; ṁ continuity. Apply f_m if flow model exists.
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**Story 1-8 (Pipe):**
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- Darcy-Weisbach; apply f_dp on ΔP
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### Technical Requirements
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**Calib struct:**
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```rust
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/// Calibration factors for matching simulation to real machine test data.
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/// Short name: Calib. Default 1.0 = no correction. Typical range [0.8, 1.2].
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/// Refs: Buildings Modelica, EnergyPlus, TRNSYS, TIL Suite, alphaXiv.
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#[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize)]
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pub struct Calib {
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/// f_m: ṁ_eff = f_m × ṁ_nominal (Compressor, Valve)
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#[serde(default = "one", alias = "calib_flow")]
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pub f_m: f64,
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/// f_dp: ΔP_eff = f_dp × ΔP_nominal (Pipe, HX)
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#[serde(default = "one", alias = "calib_dpr")]
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pub f_dp: f64,
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/// f_ua: UA_eff = f_ua × UA_nominal (Evaporator, Condenser)
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#[serde(default = "one", alias = "calib_ua")]
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pub f_ua: f64,
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/// f_power: Ẇ_eff = f_power × Ẇ_nominal (Compressor)
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#[serde(default = "one")]
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pub f_power: f64,
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/// f_etav: η_v,eff = f_etav × η_v,nominal (Compressor displacement)
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#[serde(default = "one")]
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pub f_etav: f64,
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}
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fn one() -> f64 { 1.0 }
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```
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**Validation:** 0.5 ≤ f ≤ 2.0. Reject otherwise.
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### File Structure
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**New:** `crates/core/src/calib.rs` (or `calibration.rs`)
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**Modified:**
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- `crates/components/src/compressor.rs` — f_m, f_power, f_etav
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- `crates/components/src/pipe.rs` — f_dp
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- `crates/components/src/heat_exchanger/model.rs` — f_ua
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- `crates/components/src/expansion_valve.rs` — f_m
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- `crates/core/src/lib.rs` — export Calib
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### Testing
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- `test_calib_default_all_one`
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- `test_f_m_scales_mass_flow`
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- `test_f_dp_scales_pressure_drop`
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- `test_f_ua_scales_heat_transfer`
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- `test_f_power_scales_compressor_power`
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- `test_calib_json_roundtrip`
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- `test_calib_aliases_backward_compat` (calib_flow → f_m)
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### References
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- **Epic 7.6:** planning-artifacts/epics.md
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- **Buildings.Fluid.HeatPumps.Calibration:** simulationresearch.lbl.gov/modelica
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- **EnergyPlus VRF:** bigladdersoftware.com/epx/docs
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- **TRNSYS Type 941:** Correction Factor
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- **TIL Suite:** Zeta, heat transfer multiplier
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- **alphaXiv:** calib_flow, calib_dpr, UA, η_vol, η_is
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- **Reddy RP-1051:** Calibration methodology
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- **Purdue IIAR:** Volumetric/isentropic efficiency calibration
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### Optional / Future (out of scope for this story)
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- **f_cap**: Capacity correction factor (TRNSYS, EnergyPlus) — system-level Q scaling; for component-level, f_ua suffices.
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- **PLF / Part-Load**: EnergyPlus PLF curve — transient/cycling; steady-state out of scope.
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---
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## Dev Agent Record
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### Agent Model Used
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Auto (dev-story workflow)
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### Debug Log References
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### Completion Notes List
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- Calib struct added in crates/core (calib.rs) with serde, validation 0.5–2.0, and doc with calibration order.
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- Compressor: calib field, f_m on mass_flow_rate(), f_power on power_consumption_cooling/heating; calib(), set_calib().
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- Expansion valve: calib field, f_m in mass flow residual and jacobian; calib(), set_calib().
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- Pipe: calib field, f_dp in pressure_drop(); calib(), set_calib().
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- HeatExchanger: calib field; LmtdModel and EpsNtuModel: ua_scale, effective_ua(), set_ua_scale(); exchanger syncs calib.f_ua to model.
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- Evaporator and Condenser: calib() and set_calib() delegate to inner HeatExchanger.
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- Unit tests: test_f_m_scales_mass_flow, test_f_power_scales_compressor_power, test_f_dp_scales_pressure_drop, test_f_ua_scales_heat_transfer; core: test_calib_json_roundtrip, test_calib_aliases_backward_compat.
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### File List
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- crates/core/src/calib.rs (new)
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- crates/core/src/lib.rs (modified)
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- crates/core/Cargo.toml (modified: dev-deps serde_json)
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- crates/components/src/compressor.rs (modified)
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- crates/components/src/expansion_valve.rs (modified)
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- crates/components/src/pipe.rs (modified)
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- crates/components/src/heat_exchanger/exchanger.rs (modified)
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- crates/components/src/heat_exchanger/model.rs (modified)
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- crates/components/src/heat_exchanger/lmtd.rs (modified)
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- crates/components/src/heat_exchanger/eps_ntu.rs (modified)
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- crates/components/src/heat_exchanger/evaporator.rs (modified)
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- crates/components/src/heat_exchanger/condenser.rs (modified)
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- _bmad-output/implementation-artifacts/sprint-status.yaml (modified)
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- _bmad-output/implementation-artifacts/7-6-component-calibration-parameters.md (modified)
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### Change Log
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- 2026-02-17: Story 7-6 implemented. Calib in core; f_m, f_power on compressor; f_m on expansion valve; f_dp on pipe and heat exchanger (field); f_ua on LMTD/ε-NTU and evaporator/condenser. JSON round-trip and scaling unit tests added.
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