Mollier (h-s) Diagram Plotter mechanism

Model scope

The instrument concept is valid, but the specification is incomplete. Add explicit IF97 region-selection rules, independent-variable units, interpolation or full-equation behavior, admissible phase constraints, process-path equations, extrapolation policy, and a precision/rounding policy before implementation.

• The specification gives only a data source, not a complete algorithm. It must define how pressure, temperature, quality, and phase-region inputs are converted into h and s using IAPWS-IF97.
• The phrase 'derived from steam table h,s pairs along isobars/isotherms/quality lines' is insufficient: interpolation rules, grid resolution, and property-consistency rules are unspecified.
• The process-line algorithm is unspecified. A straight line between start and end h-s coordinates is not generally the thermodynamic path for an isobaric, isothermal, isentropic, throttling, or turbine-expansion process.
• Quality-line calculations require the explicit formulas h = hf + x(hg-hf) and s = sf + x(sg-sf), with 0 <= x <= 1.
• The implementation must distinguish IAPWS-IF97 regions, including compressed liquid, superheated vapor, two-phase mixture, and the critical/saturation boundaries.

Units and conventions

• Pressure is absolute, not gauge pressure; test vectors use kPa or MPa as explicitly stated.
• Specific enthalpy h is in kJ/kg and specific entropy s is in kJ/(kg·K).
• Temperature is in degrees Celsius for table lookup, with Kelvin used only where an entropy or thermodynamic equation explicitly requires absolute temperature.
• Steam-table values are IAPWS-IF97 values rounded to the displayed precision; interpolation of rounded values reproduces the displayed test results, not necessarily full-precision IF97 results.
• The plotted horizontal coordinate is s and the vertical coordinate is h.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "process_type": "saturation_dome_boundary",
    "start_state": {
      "phase": "saturated_liquid",
      "temperature_C": 100
    },
    "end_state": {
      "phase": "saturated_vapor",
      "temperature_C": 100
    }
  },
  "expected_outputs": {
    "start_point": {
      "h_kJ_per_kg": 419.04,
      "s_kJ_per_kg_K": 1.307
    },
    "end_point": {
      "h_kJ_per_kg": 2675.54,
      "s_kJ_per_kg_K": 7.354
    },
    "process_polyline": [
      {
        "s_kJ_per_kg": 1.307,
        "h_kJ_per_kg": 419.04
      },
      {
        "s_kJ_per_kg": 7.354,
        "h_kJ_per_kg": 2675.54
      }
    ]
  },
  "reference_data": {
    "saturation_row_100C": {
      "temperature_C": {
        "value": 100,
        "source_convention": "IAPWS-IF97 saturation relation; widely tabulated standard value"
      },
      "saturation_pressure_kPa": {
        "value": 101.325,
        "source_convention": "IAPWS-IF97; widely memorized standard value for water boiling at 100 C"
      },
      "hf_kJ_per_kg": {
        "value": 419.04,
        "source_convention": "IAPWS-IF97 steam tables; widely tabulated standard value"
      },
      "hg_kJ_per_kg": {
        "value": 2675.54,
        "source_convention": "IAPWS-IF97 steam tables; widely tabulated standard value"
      },
      "sf_kJ_per_kg_K": {
        "value": 1.307,
        "source_convention": "IAPWS-IF97 steam tables; widely tabulated standard value"
      },
      "sg_kJ_per_kg_K": {
        "value": 7.354,
        "source_convention": "IAPWS-IF97 steam tables; widely tabulated standard value"
      }
    }
  },
  "working": "1. At 100 C, the saturation pressure is 101.325 kPa, so both states lie on the saturation boundary at the same absolute pressure. 2. Saturated-liquid point: h = hf = 419.04 kJ/kg; s = sf = 1.3070 kJ/(kg K). 3. Saturated-vapor point: h = hg = 2675.54 kJ/kg; s = sg = 7.3540 kJ/(kg K). 4. Therefore the plotted endpoints are (s,h) = (1.3070,419.04) and (7.3540,2675.54), with the displayed process polyline joining them."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The critical-point input makes the standard quality formula evaluate to 0/0, so a quality-based implementation must explicitly reject or special-case it. Inputs just above quality one also expose an invalid two-phase extrapolation unless the plotter switches to a superheated lookup branch. Process-direction conventions can additionally reverse the reported signed changes.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche7/tranche7-results.json
• BOUNDARY_HAZARD_CATALOG.json