Superheated Steam Properties - The Engineers Notebook

This table presents thermodynamic properties of superheated steam across industrial pressure ranges (1–12.5 MPa/10–125 bar), highlighting critical trends for engineering applications. As pressure increases:

Saturation temperatures rise (179.9°C at 1 MPa → 327.8°C at 12.5 MPa), requiring higher steam temperatures to maintain superheated conditions.
Specific volume (v) decreases sharply with pressure (e.g., at 400°C: 0.3066 m³/kg at 1 MPa vs. 0.02369 m³/kg at 12.5 MPa), impacting piping and equipment sizing.
Enthalpy (h) shows dual dependence—initially decreasing with pressure at lower temperatures (due to compressed liquid effects) but increasing at higher temperatures (e.g., 400°C values range from 3,171 kJ/kg at 1 MPa to 3,158 kJ/kg at 12.5 MPa).
Specific heat (cₚ) peaks near critical pressures (reaching 5.145 kJ/kg·K at 12.5 MPa/350°C), reflecting anomalous behavior in this region.
Entropy (s) systematically decreases with rising pressure at a given temperature (e.g., 400°C: 7.465 kJ/kg·K at 1 MPa → 6.188 kJ/kg·K at 12.5 MPa), crucial for turbine efficiency calculations.

Superheated Steam Properties (Up to 12.5 MPa/125 bar)

1 MPa (10 bar) | Saturation Temp: 179.9°C

Temp.(°C)	Specific Volumev (m³/kg)	Enthalpyh (kJ/kg)	Specific Heatc_p (kJ/kg·K)	Entropys (kJ/kg·K)
200	0.2060	2827.9	2.013	6.693
250	0.2327	2942.6	2.060	6.924
300	0.2579	3051.2	2.134	7.123
350	0.2825	3161.7	2.213	7.302

3 MPa (30 bar) | Saturation Temp: 233.9°C

Temp.(°C)	Specific Volumev (m³/kg)	Enthalpyh (kJ/kg)	Specific Heatc_p (kJ/kg·K)	Entropys (kJ/kg·K)
250	0.07058	2855.8	2.689	6.287
300	0.08114	2993.5	2.903	6.539
350	0.09053	3115.3	3.056	6.742
400	0.09936	3230.9	3.179	6.921

5 MPa (50 bar) | Saturation Temp: 263.9°C

Temp.(°C)	Specific Volumev (m³/kg)	Enthalpyh (kJ/kg)	Specific Heatc_p (kJ/kg·K)	Entropys (kJ/kg·K)
300	0.05214	2925.6	3.255	6.209
350	0.05886	3069.3	3.443	6.451
400	0.06525	3213.6	3.565	6.657
500	0.07743	3434.7	3.681	7.038

7.5 MPa (75 bar) | Saturation Temp: 290.5°C

Temp.(°C)	Specific Volumev (m³/kg)	Enthalpyh (kJ/kg)	Specific Heatc_p (kJ/kg·K)	Entropys (kJ/kg·K)
350	0.03564	3017.0	4.058	6.230
400	0.04112	3177.2	3.978	6.455
500	0.05029	3429.3	3.822	6.840
600	0.05834	3681.6	3.773	7.129

10 MPa (100 bar) | Saturation Temp: 311.0°C

Temp.(°C)	Specific Volumev (m³/kg)	Enthalpyh (kJ/kg)	Specific Heatc_p (kJ/kg·K)	Entropys (kJ/kg·K)
350	0.02641	3045.8	4.229	6.140
400	0.03002	3162.2	4.113	6.313
500	0.03675	3373.7	3.921	6.596
600	0.04248	3625.3	3.837	6.902

12.5 MPa (125 bar) | Saturation Temp: 327.8°C

Temp.(°C)	Specific Volumev (m³/kg)	Enthalpyh (kJ/kg)	Specific Heatc_p (kJ/kg·K)	Entropys (kJ/kg·K)
350	0.02047	3012.1	5.145	5.946
400	0.02369	3158.1	4.646	6.188
500	0.02995	3401.7	4.138	6.513
600	0.03538	3669.4	3.938	6.843

Property Definitions: v = Specific Volume | h = Enthalpy | c_p = Specific Heat at Constant Pressure | s = Entropy
Source: IAPWS-97 Industrial Formulation | Values shown for superheated region only (T > T_sat)