Mollier (h–s) Calculator

Two‑Phase (Saturated) Region

Uses mixing rules: h = h_f + x(h_g−h_f), s = s_f + x(s_g−s_f). Saturation properties are approximated from T_sat.

Saturation temperature T_sat (°C)

Quality x (mass vapor)

Enthalpy h (kJ/kg)

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Entropy s (kJ/kg·K)

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Specific volume v (m³/kg)

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Internals: h_f≈4.18·T_°C, L≈2501−2.36·(T_°C−100), h_g=h_f+L; s_f≈c_plln(T_K/273.15), Δs_vap≈L/T_K; v_f≈0.001 m³/kg, v_g≈R·T_K/p_sat (p_sat from a crude fit).

Superheated Steam

Uses h ≈ h_g(T_sat) + c_p(T − T_sat), s ≈ s_g(T_sat) + c_p ln(T/T_sat) at given pressure.

Pressure p (bar)

Estimate T_sat from p (editable) — °C

Temperature T — °C

c_p (kJ/kg·K)

Enthalpy h (kJ/kg)

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Entropy s (kJ/kg·K)

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Specific volume v (m³/kg)

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T_sat(p) is seeded by a rough fit T_°C ≈ 100 + 22·ln(p_bar). Edit it if you have tabulated T_sat for your p.

Compressed/Subcooled Liquid

Approximates liquid properties as temperature‑dependent only: h ≈ h_f(T), s ≈ s_f(T).

Temperature T (°C)

c_p,l (kJ/kg·K)

Enthalpy h (kJ/kg)

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Entropy s (kJ/kg·K)

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Specific volume v (m³/kg)

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Reference state h=s=0 at 0 °C (273.15 K). Change assumptions in code if you need a different reference.