Add diagram workbench UI with Modelica DoF coaching and ISO glyphs.

Ship the Next.js cycle editor with CAD chrome, technical HX symbols, Fixed/Free boundary guidance, and secondary water/air pressure drop support in the solver stack.

Co-authored-by: Cursor <cursoragent@cursor.com>

crates/solver/tests/emergent_pressure_cycle.rs

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+//! End-to-end integration test for the **emergent-pressure** refrigeration cycle.
+//!
+//! This test assembles the REAL thermodynamic components
+//! (`IsentropicCompressor`, `Condenser`, `IsenthalpicExpansionValve`,
+//! `Evaporator`) — not mocks — with a real CoolProp fluid backend and solves the
+//! canonical 4-component loop with the Newton solver.
+//!
+//! Unlike the fixed-design-point path (where the compressor pins
+//! `P_cond = P_sat(t_cond_k)` and the EXV pins `P_evap = P_sat(t_evap_k)`), every
+//! component here runs in **emergent-pressure mode**:
+//!
+//! | Component | emergent equations | pins |
+//! |-----------|--------------------|------|
+//! | Compressor | ṁ = ρ_suc·V_s·N·η_vol ; h_dis(P_suc,h_suc,P_dis) | ṁ, h_dis |
+//! | Condenser  | P2=P1 ; ṁ(h1−h2)=ε·C·(T_cond(P1)−T_sec,in) ; h2=h_satliq(P1)−cp·ΔT_sc | **P_cond** |
+//! | EXV        | h3=h2 (isenthalpic only) | h3 |
+//! | Evaporator | P4=P3 ; ṁ(h4−h3)=ε·C·(T_sec,in−T_evap(P3)) ; h4=h(P3,T_evap+SH) | **P_evap** |
+//!
+//! DoF (same-branch series loop): 2 + 3 + 1 + 3 = **9 equations / 9 unknowns**.
+//! The condensing/evaporating pressures are therefore EMERGENT: they are
+//! determined by the heat-exchanger ↔ secondary balance, not imposed by the
+//! compressor/EXV design points. The test verifies that varying the secondary
+//! (water) inlet temperature genuinely moves the emergent pressures and COP.
+//!
+//! Requires the `coolprop` feature (entropy + saturation properties), which the
+//! mock `TestBackend` does not provide:
+//!   cargo test -p entropyk-solver --features coolprop --test emergent_pressure_cycle
+#![cfg(feature = "coolprop")]
+
+use std::sync::Arc;
+
+use entropyk_components::isentropic_compressor::VolumetricEfficiency;
+use entropyk_components::{Condenser, Evaporator, IsenthalpicExpansionValve, IsentropicCompressor};
+use entropyk_fluids::{CoolPropBackend, FluidBackend};
+use entropyk_solver::solver::{NewtonConfig, Solver};
+use entropyk_solver::system::System;
+
+/// State-vector layout (CM1.4 same-branch series loop, 9 unknowns):
+/// `[ṁ, P0,h0, P1,h1, P2,h2, P3,h3]` where
+///   E0 comp→cond, E1 cond→exv, E2 exv→evap, E3 evap→comp.
+const N_STATE: usize = 9;
+
+/// Result of a converged emergent-pressure solve, in engineering units.
+struct CycleResult {
+    m_dot: f64,  // kg/s
+    p_cond: f64, // Pa (emergent condensing pressure, edge E0)
+    p_evap: f64, // Pa (emergent evaporating pressure, edge E3)
+    w_comp: f64, // W  (compression power)
+    q_evap: f64, // W  (cooling capacity)
+    cop: f64,    // -  (Q_evap / W_comp)
+}
+
+/// Assembles and solves the emergent-pressure cycle for the given secondary
+/// (water) inlet temperatures and returns the converged operating point.
+fn solve_emergent_cycle(cond_sec_temp_k: f64, evap_sec_temp_k: f64) -> CycleResult {
+    let backend: Arc<dyn FluidBackend> = Arc::new(CoolPropBackend::new());
+    let fluid = "R134a";
+
+    // ── Compressor: emergent ṁ via volumetric displacement ────────────────────
+    // ṁ = ρ_suc · V_s · N · η_vol.  V_s·N ≈ 3.25e-3 m³/s ⇒ ṁ ≈ 0.05 kg/s.
+    let comp = Box::new(
+        IsentropicCompressor::new(0.70, 318.15, 278.15, 5.0)
+            .with_refrigerant(fluid)
+            .with_fluid_backend(backend.clone())
+            .with_displacement(6.5e-5, 50.0, VolumetricEfficiency::Constant(0.92)),
+    );
+
+    // ── Condenser: emergent P_cond via subcooling outlet closure ──────────────
+    let cond = Box::new(
+        Condenser::new(766.0)
+            .with_refrigerant(fluid)
+            .with_fluid_backend(backend.clone())
+            .with_secondary_stream(cond_sec_temp_k, 1500.0)
+            .with_emergent_pressure(5.0),
+    );
+
+    // ── EXV: emergent (isenthalpic only, drops the P_evap fix) ────────────────
+    let exv = Box::new(
+        IsenthalpicExpansionValve::new(278.15)
+            .with_refrigerant(fluid)
+            .with_fluid_backend(backend.clone())
+            .with_emergent_pressure(),
+    );
+
+    // ── Evaporator: emergent P_evap via superheat outlet closure ──────────────
+    let evap = Box::new(
+        Evaporator::new(1468.0)
+            .with_refrigerant(fluid)
+            .with_fluid_backend(backend.clone())
+            .with_secondary_stream(evap_sec_temp_k, 2000.0)
+            .with_emergent_pressure(),
+    );
+
+    let mut system = System::new();
+    let n_comp = system.add_component(comp);
+    let n_cond = system.add_component(cond);
+    let n_exv = system.add_component(exv);
+    let n_evap = system.add_component(evap);
+
+    system.add_edge(n_comp, n_cond).unwrap(); // E0 comp→cond
+    system.add_edge(n_cond, n_exv).unwrap(); // E1 cond→exv
+    system.add_edge(n_exv, n_evap).unwrap(); // E2 exv→evap
+    system.add_edge(n_evap, n_comp).unwrap(); // E3 evap→comp
+
+    system.finalize().unwrap();
+
+    // DoF must be exactly balanced (2+3+1+3 = 9 == 9 unknowns).
+    assert_eq!(
+        system.full_state_vector_len(),
+        N_STATE,
+        "emergent same-branch loop must be 1 ṁ + 4×2(P,h) = 9 unknowns"
+    );
+
+    // Physically-consistent seed near the expected operating point.
+    // P_sat(R134a): 5 °C ≈ 3.50 bar, 45 °C ≈ 11.6 bar.
+    let initial_state = vec![
+        0.05, // ṁ  [kg/s]
+        11.6e5, 445e3, // E0 comp→cond : P_cond, h_dis
+        11.6e5, 262e3, // E1 cond→exv  : P_cond, h_liq
+        3.50e5, 262e3, // E2 exv→evap  : P_evap, h (isenthalpic)
+        3.50e5, 405e3, // E3 evap→comp : P_evap, h_suction (superheated)
+    ];
+
+    let mut config = NewtonConfig {
+        max_iterations: 200,
+        tolerance: 1e-6,
+        line_search: true,
+        use_numerical_jacobian: false,
+        initial_state: Some(initial_state),
+        ..NewtonConfig::default()
+    };
+
+    let converged = config
+        .solve(&mut system)
+        .expect("emergent-pressure cycle must converge");
+
+    let sv = &converged.state;
+    let m_dot = sv[0];
+    let (p_cond, h_dis) = (sv[1], sv[2]);
+    let h_cond_out = sv[4];
+    let (p_evap, h_suc) = (sv[7], sv[8]);
+    let h_evap_in = sv[6];
+    let h_evap_out = sv[8];
+
+    let w_comp = m_dot * (h_dis - h_suc);
+    let q_evap = m_dot * (h_evap_out - h_evap_in);
+
+    // Sanity: subcooled liquid at condenser outlet, superheated vapour at suction.
+    assert!(h_dis > h_suc, "discharge enthalpy must exceed suction");
+    assert!(
+        h_cond_out < h_suc,
+        "condenser outlet must be subcooled liquid"
+    );
+    assert!(w_comp > 0.0, "compression power must be positive");
+    assert!(q_evap > 0.0, "cooling capacity must be positive");
+
+    CycleResult {
+        m_dot,
+        p_cond,
+        p_evap,
+        w_comp,
+        q_evap,
+        cop: q_evap / w_comp,
+    }
+}
+
+/// The emergent-pressure loop must converge and produce a physical operating
+/// point (positive capacity, positive power, plausible pressures/COP).
+#[test]
+fn test_emergent_cycle_converges_to_physical_point() {
+    let r = solve_emergent_cycle(303.15, 285.15); // cond water 30 °C, evap water 12 °C
+
+    // Emergent pressures land in a physically reasonable R134a window.
+    assert!(
+        (5.0e5..20.0e5).contains(&r.p_cond),
+        "emergent P_cond out of range: {:.0} Pa",
+        r.p_cond
+    );
+    assert!(
+        (1.5e5..6.0e5).contains(&r.p_evap),
+        "emergent P_evap out of range: {:.0} Pa",
+        r.p_evap
+    );
+    assert!(
+        r.p_cond > r.p_evap,
+        "condensing must exceed evaporating pressure"
+    );
+    assert!(r.m_dot > 0.0, "mass flow must be positive: {}", r.m_dot);
+    assert!(
+        (1.5..12.0).contains(&r.cop),
+        "COP out of physical range: {:.2}",
+        r.cop
+    );
+}
+
+/// **Core emergence claim**: warming the condenser secondary (water) inlet must
+/// raise the emergent condensing pressure and reduce COP — the machine
+/// performance is genuinely qualified by the secondary conditions, not fixed by
+/// compressor design points.
+#[test]
+fn test_warmer_condenser_water_raises_pcond_and_lowers_cop() {
+    let cool = solve_emergent_cycle(303.15, 285.15); // 30 °C condenser water
+    let warm = solve_emergent_cycle(313.15, 285.15); // 40 °C condenser water
+
+    assert!(
+        warm.p_cond > cool.p_cond + 1.0e4,
+        "warmer condenser water must raise emergent P_cond: {:.0} → {:.0} Pa",
+        cool.p_cond,
+        warm.p_cond
+    );
+    assert!(
+        warm.w_comp > cool.w_comp,
+        "higher lift must increase compression power: {:.0} → {:.0} W",
+        cool.w_comp,
+        warm.w_comp
+    );
+    assert!(
+        warm.cop < cool.cop,
+        "warmer condenser water must lower COP: {:.2} → {:.2}",
+        cool.cop,
+        warm.cop
+    );
+}
+
+/// Warming the evaporator secondary (water/brine) inlet must raise the emergent
+/// evaporating pressure and increase cooling capacity.
+#[test]
+fn test_warmer_evaporator_water_raises_pevap_and_capacity() {
+    let cold = solve_emergent_cycle(303.15, 283.15); // 10 °C evaporator water
+    let warm = solve_emergent_cycle(303.15, 291.15); // 18 °C evaporator water
+
+    assert!(
+        warm.p_evap > cold.p_evap + 1.0e4,
+        "warmer evaporator water must raise emergent P_evap: {:.0} → {:.0} Pa",
+        cold.p_evap,
+        warm.p_evap
+    );
+    assert!(
+        warm.q_evap > cold.q_evap,
+        "warmer evaporator water must increase capacity: {:.0} → {:.0} W",
+        cold.q_evap,
+        warm.q_evap
+    );
+}