Source: https://guthlabs.ai/docs/instruments/stirling-cycle-efficiency-calculator/mechanism/

instrument mechanism / verified-clean

# Stirling Cycle Efficiency Calculator mechanism

The inspectable method record for Stirling Cycle Efficiency Calculator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The honest label correctly states the ideal-regenerator and no-real-loss assumptions. Verdict remains NEEDS_REVIEW because the exact ambiguity is that the specification claims to output net work per cycle but supplies only the single-isothermal-leg formula and does not explicitly define the net-work combination, R value, or input units.

- η=1−Tc/Th is correct for a reversible ideal Stirling cycle with perfect regeneration, provided Th and Tc are absolute temperatures in kelvin and 0≤Tc≤Th.

- W=nRT·ln(V2/V1) is correct for one reversible isothermal leg, with the sign determined by the direction of the volume change; it is not by itself the net work per cycle.

- The net-work formula is not explicitly stated. For the standard Stirling cycle with hot-leg expansion V1→V2 and cold-leg compression V2→V1, it must be Wnet=nR(Th−Tc)·ln(V2/V1).

- The specification does not state the required value and units of the gas constant R, nor explicitly state that the hot and cold isothermal legs use the same V1 and V2.

## Units and conventions

- Th and Tc are in kelvin; using degrees Celsius directly in η=1−Tc/Th is invalid.

- V1 and V2 must be positive and expressed in identical volume units; only the ratio V2/V1 affects the logarithm.

- n is the amount of working gas in moles.

- R is assumed to be 8.314 J/(mol·K), so net work is reported in joules per cycle.

- η is dimensionless; the ideal-regenerator assumption makes the Stirling efficiency equal to the Carnot efficiency.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "Th": 600,
    "Tc": 300,
    "V1": 1,
    "V2": 2,
    "n": 1,
    "temperature_unit": "K",
    "volume_unit": "L"
  },
  "expected_outputs": {
    "η": 0.5,
    "net_work_per_cycle_J": 1728.85
  },
  "working": "η=1−Tc/Th=1−300/600=1−0.5=0.5. Wnet=nR(Th−Tc)ln(V2/V1)=1×8.314×(600−300)×ln(2/1)=8.314×300×0.693147=2494.2×0.693147=1728.85 J/cycle."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The calculator must reject V1=0 because the volume ratio divides by zero and the logarithm is undefined. It also needs explicit unit handling for absolute temperature; interpreting Celsius values as kelvin gives a wrong efficiency.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/stirling-cycle-efficiency-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/stirling-cycle-efficiency-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/stirling-cycle-efficiency-calculator/qualification/>)

## 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`

- `BOUNDARY_HAZARD_CATALOG.json`