Fin Effectiveness/Efficiency Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-156

Effect

Computation or source lookup only

Input and validation requirements

The raw formulas expose undefined behavior for k = 0, and the zero-length limiting case produces a 0/0 effectiveness unless the calculator explicitly applies the limiting value or rejects the effectiveness output.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "geometry": "rectangular",
    "t_m": 0.002,
    "w_m": 0.048,
    "L_m": 0.04904,
    "k_W_per_mK": 200,
    "h_W_per_m2K": 19.2,
    "theta_b_K": 80,
    "A_c_m2": 0.000096,
    "P_m": 0.1,
    "L_c_m": 0.05
  },
  "expected_outputs": {
    "m_per_m": 10,
    "eta_fin": 0.92423431,
    "q_fin_W": 7.09811954
  },
  "working": "A_c=t·w=0.002·0.048=0.000096 m²; P=2(t+w)=2(0.002+0.048)=0.1 m; L_c=L+A_c/P=0.04904+0.000096/0.1=0.05 m; m=√(hP/(kA_c))=√(19.2·0.1/(200·0.000096))=√100=10 m⁻¹; mL_c=10·0.05=0.5; tanh(0.5)=0.46211716; η_fin=0.46211716/0.5=0.92423431; √(hPkA_c)=√(19.2·0.1·200·0.000096)=√0.036864=0.192; q_fin=0.192·80·0.46211716=7.09811954 W."
}

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-tranche4/tranche4-results.json