MCPCalc

Thermodynamics State Calculator

Estimate thermodynamic state properties from two known ideal-gas variables for air or steam-vapor approximations.

Scratchpad (not saved)

kPa
°C
m³/kg

What This Calculator Does

This calculator solves a simplified thermodynamic state for either dry air or idealized steam vapor using two known state properties. It is intended for quick engineering estimates where an ideal-gas approximation is acceptable.

It combines Substance, Known Pair, Pressure, Temperature to estimate Temperature, Pressure, Specific Volume.

Formula & Method

Core equations: The state equation is Pv=RTPv=RT. With constant heat capacity, specific enthalpy is approximated by h≈cpTh\approx c_pT and specific entropy relative to a reference state by s−s0≈cpln⁡(TT0)−Rln⁡(PP0)s-s_0\approx c_p\ln\left(\frac{T}{T_0}\right)-R\ln\left(\frac{P}{P_0}\right).

Notation used in the formulas: RR = Temperature; x1x_{1} = Substance; x2x_{2} = Known Pair; x3x_{3} = Pressure; x4x_{4} = Temperature; x5x_{5} = Specific Volume.

Method summary: inputs are normalized to consistent units, core equations are evaluated, then secondary values are derived and rounded for display.

Use it for fast air-cycle and vapor-estimate calculations when you know two of pressure, temperature, and specific volume and need the remaining idealized state properties without opening a property table.

Inputs Used

  • Substance: Used directly in the calculation.
  • Known Pair: Used directly in the calculation.
  • Pressure: Used directly in the calculation.
  • Temperature: Used directly in the calculation.
  • Specific Volume: Used directly in the calculation.

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