# Thermodynamics and Heat Transfer

Ideal gas processes, Carnot efficiency and COP, conduction, convection and radiation, heat exchangers, mixing, water vapor pressure and thermal expansion.

## How to pay

Machine-payable over x402. USDC on: Base (eip155:8453), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), Polygon (eip155:137), Arbitrum One (eip155:42161).
No accounts. No API keys. No signup. The paying wallet is the account.

## Machine-readable

- OpenAPI: https://thermo-heat-calc.x402tookit.com/openapi.json
- x402 manifest: https://thermo-heat-calc.x402tookit.com/.well-known/x402
- Catalog (free): https://thermo-heat-calc.x402tookit.com/catalog
- Health (free): https://thermo-heat-calc.x402tookit.com/health
- Uptime (free): https://thermo-heat-calc.x402tookit.com/uptime

## Endpoints (8)

### GET /carnot-efficiency — $0.02
Carnot limit for a heat engine, refrigerator and heat pump from hot and cold absolute temperatures, with work and heat flows.
Params: hotK: number, coldK: number, heatInputKw?: number, coolingLoadKw?: number, heatingLoadKw?: number, actualEfficiency?: number
Example: https://thermo-heat-calc.x402tookit.com/carnot-efficiency?hotK=500&coldK=300&heatInputKw=100

### GET /conduction-heat-transfer — $0.03
Steady conduction heat flow through a slab or cylinder wall of layers in series, with R-values and interface temperatures.
Params: geometry: string, layers: string, hotC: number, coldC: number, areaM2?: number, innerRadiusM?: number, lengthM?: number, hInner?: number, hOuter?: number
Example: https://thermo-heat-calc.x402tookit.com/conduction-heat-transfer?geometry=slab&layers=0.2%3A0.72%3B0.05%3A0.04&hotC=20&coldC=-10&areaM2=1

### GET /convection-radiation — $0.02
Newton convection, Stefan-Boltzmann net radiation with emissivity, the radiation coefficient and combined heat loss.
Params: surfaceC: number, ambientC: number, areaM2: number, hConvection?: number, emissivity?: number, surroundingsC?: number
Example: https://thermo-heat-calc.x402tookit.com/convection-radiation?surfaceC=100&ambientC=20&areaM2=1&hConvection=10&emissivity=0.9

### GET /heat-exchanger-lmtd — $0.03
Heat exchanger LMTD (counterflow or parallel) with duty and area, or counterflow effectiveness-NTU outlet temperatures.
Params: mode?: string, hotInC: number, coldInC: number, hotOutC?: number, coldOutC?: number, arrangement?: string, uWPerM2K?: number, areaM2?: number, dutyW?: number, hotCapacityWPerK?: number, coldCapacityWPerK?: number, uaWPerK?: number
Example: https://thermo-heat-calc.x402tookit.com/heat-exchanger-lmtd?mode=lmtd&hotInC=100&hotOutC=60&coldInC=20&coldOutC=50&arrangement=counterflow&uWPerM2K=500&areaM2=2

### GET /ideal-gas-process — $0.03
Ideal gas isothermal, isobaric, isochoric or adiabatic process: final state, work, heat and internal energy change.
Params: process: string, massKg: number, initialPressureKpa: number, initialTemperatureK: number, gas?: string, gamma?: number, gasConstantJPerKgK?: number, finalPressureKpa?: number, finalVolumeM3?: number, finalTemperatureK?: number
Example: https://thermo-heat-calc.x402tookit.com/ideal-gas-process?process=adiabatic&gas=air&massKg=1&initialPressureKpa=100&initialTemperatureK=300&finalPressureKpa=200

### GET /saturation-pressure-water — $0.02
Saturation vapor pressure of water from 1 to 100 C by Antoine and Magnus equations, or the boiling point at a pressure.
Params: temperatureC?: number, pressureKpa?: number
Example: https://thermo-heat-calc.x402tookit.com/saturation-pressure-water?temperatureC=25

### GET /specific-heat-mixing — $0.03
Final temperature of mixed masses (water, ice, steam, solids) with specific heats and water latent heats of fusion and boiling.
Params: items: string
Example: https://thermo-heat-calc.x402tookit.com/specific-heat-mixing?items=0.1%3Aice%3A0%3B0.5%3Awater%3A25

### GET /thermal-expansion — $0.02
Linear, area and volume change of a solid for a temperature change, with typical coefficients for common materials.
Params: tempFromC: number, tempToC: number, material?: string, coefficientPerKE6?: number, lengthM?: number, areaM2?: number, volumeM3?: number
Example: https://thermo-heat-calc.x402tookit.com/thermal-expansion?material=steel-carbon&lengthM=10&tempFromC=20&tempToC=70

## Terms

Thermodynamics arithmetic computed locally from the numbers given, using standard textbook formulas, provided as is. Educational estimates only: not for design or code compliance. Real systems have losses, property variation and safety limits that need a licensed engineer.