Source: https://guthlabs.ai/docs/instrument-workflows/heat-path/

instrument cross-check / verified-workflow-definition

# Heat-Transfer Path

Conduction, convection, radiation composed — with the LMTD/NTU double-solve.

Status: **observed**Lifecycle: **verified-workflow-definition**

## Goal

Conduction, convection, radiation composed — with the LMTD/NTU double-solve.

## Instrument chain

- 01

**[Fourier Conduction (Plane Wall) Calculator](<https://guthlabs.ai/docs/instruments/fourier-conduction-plane-wall-calculator/>)**

walls

VERIFIED

- 02

**[Cylindrical/Spherical Conduction Resistance Calculator](<https://guthlabs.ai/docs/instruments/cylindrical-spherical-conduction-resistance-calculator/>)**

pipes/shells

VERIFIED

- 03

**[Composite Wall R-value / U-value Calculator](<https://guthlabs.ai/docs/instruments/composite-wall-r-value-u-value-calculator/>)**

assemblies

VERIFIED

- 04

**[Radiation Heat Transfer Calculator](<https://guthlabs.ai/docs/instruments/radiation-heat-transfer-calculator/>)**

radiation

VERIFIED

- 05

**[Fin Effectiveness/Efficiency Calculator](<https://guthlabs.ai/docs/instruments/fin-effectiveness-efficiency-calculator/>)**

extended surfaces

VERIFIED

- 06

**[Biot Number / Lumped Capacitance Validity Check](<https://guthlabs.ai/docs/instruments/biot-number-lumped-capacitance-validity-check/>)**

model gate

VERIFIED

- 07

**[Overall Heat Transfer Coefficient (U) Calculator](<https://guthlabs.ai/docs/instruments/overall-heat-transfer-coefficient-u-calculator/>)**

combined U

VERIFIED

- 08

**[LMTD Heat Exchanger Calculator](<https://guthlabs.ai/docs/instruments/lmtd-heat-exchanger-calculator/>)**

exchanger method 1

VERIFIED

- 09

**[NTU-Effectiveness Heat Exchanger Calculator](<https://guthlabs.ai/docs/instruments/ntu-effectiveness-heat-exchanger-calculator/>)**

exchanger method 2

VERIFIED

- 10

**[Heat Sink Thermal Resistance Calculator](<https://guthlabs.ai/docs/instruments/heat-sink-thermal-resistance-calculator/>)**

electronics tie-in

VERIFIED

## Handoffs and cross-checks

Resistances sum to U; U×A feeds both LMTD and NTU on the same exchanger.

## PointGuard stance

Solve every exchanger BOTH ways — LMTD and NTU must agree on q; that redundancy is the point (would have caught the t4-180 halving).

## Sources and evidence

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

- `INSTRUMENT_COMBOS.json`

- `VERIFIED_LEDGER.json`