Steam Tables – Specific Properties of Water and Steam

Steam tables contain the basic and key properties of water and steam, such as pressure, temperature, enthalpy, density, and specific heat, which are tabulated along the vapor-liquid saturation curve as a function of both temperature and pressure. They are very useful for engineering calculations.

Water and steam are common fluids used for heat exchange in the primary circuit (from the surface of fuel rods to the coolant flow) and in the secondary circuit. It is used due to its availability and high heat capacity, both for cooling and heating. It is especially effective to transport heat through vaporization and condensation of water because of its very large latent heat of vaporization.

A disadvantage is that water-moderated reactors have to use the high-pressure primary circuit to keep water in the liquid state and achieve sufficient thermodynamic efficiency. Water and steam also react with metals commonly found in industries such as steel and copper, oxidized faster by untreated water and steam. In almost all thermal power stations (coal, gas, nuclear), water is used as the working fluid (used in a closed-loop between boiler, steam turbine, and condenser), and the coolant (used to exchange the waste heat to a water body or carry it away by evaporation in a cooling tower).

Water and steam are common media because their properties are very well known. Their properties are tabulated in so-called “Steam Tables”. In these tables, the basic and key properties, such as pressure, temperature, enthalpy, density, and specific heat, are tabulated along the vapor-liquid saturation curve as a function of both temperature and pressure. The properties are also tabulated for single-phase states (compressed water or superheated steam) on a grid of temperatures and pressures extending to 2000 ºC and 1000 MPa.

Further comprehensive, authoritative data can be found at the NIST Webbook page on thermophysical properties of fluids.

Special Reference: Allan H. Harvey. Thermodynamic Properties of Water, NISTIR 5078. Retrieved from //www.nist.gov/sites/default/files/documents/srd/NISTIR5078.htm

Chart: Absolute pressure as a function of temperature of water

Chart: Density as a function of temperature of water

Chart: Dynamic viscosity as a function of temperature of water

Examples

Evaporation of water at atmospheric pressure

Calculate heat required to evaporate 1 kg of water at the atmospheric pressure (p = 1.0133 bar) and at the temperature of 100°C.

Solution:

Since these parameters correspond to the saturated liquid state, only latent heat of 1 kg of water vaporization is required. From steam tables, the latent heat of vaporization is L = 2257 kJ/kg. Therefore the heat required is equal to:

ΔH = 2257 kJ

Note that the initial specific enthalpy h_{1} = 419 kJ/kg, whereas the final specific enthalpy will be h_{2} = 2676 kJ/kg. The specific enthalpy of low-pressure dry steam is very similar to the specific enthalpy of high-pressure dry steam, despite having different temperatures.

Evaporation of water at high pressure

Calculate heat required to evaporate 1 kg of feedwater at the pressure of 6 MPa (p = 60 bar) and at the temperature of 275.6°C (saturation temperature).

Solution:

Since these parameters correspond to the saturated liquid state, only latent heat of 1 kg of water vaporization is required. From steam tables, the latent heat of vaporization is L = 1571 kJ/kg. Therefore the heat required is equal to:

ΔH = 1571 kJ

Note that the initial specific enthalpy h_{1} = 1214 kJ/kg, whereas the final specific enthalpy will be h_{2} = 2785 kJ/kg. The specific enthalpy of low-pressure dry steam is very similar to the specific enthalpy of high-pressure dry steam, despite having different temperatures.

Evaporation of water at high pressure - Energy balance in a steam generator

Calculate the amount of primary coolant, which is required to evaporate 1 kg of feedwater in a typical steam generator. Assume that there are no energy losses. This is only an idealized example.

Balance of the primary circuit

The hot primary coolant (water 330°C; 626°F; 16MPa) is pumped into the steam generator through the primary inlet. The primary coolant leaves (water 295°C; 563°F; 16MPa) the steam generator through the primary outlet.

h_{I, inlet} = 1516 kJ/kg

=> Δh_{I} = -206 kJ/kg

h_{I, outlet} = 1310 kJ/kg

Balance of the feedwater

The feedwater (water 230°C; 446°F; 6,5MPa) is pumped into the steam generator through the feedwater inlet. The feedwater (secondary circuit) is heated from ~230°C 446°F to the boiling point of that fluid (280°C; 536°F; 6,5MPa). Feedwater is then evaporated, and the pressurized steam (saturated steam 280°C; 536°F; 6,5 MPa) leaves the steam generator through the steam outlet and continues to the steam turbine.

h_{II, inlet} = 991 kJ/kg

=> Δh_{II} = 1789 kJ/kg

h_{II, outlet} = 2780 kJ/kg

Balance of the steam generator

Since the difference in specific enthalpies is less for primary coolant than for feedwater, it is obvious that the amount of primary coolant will be higher than 1kg. To produce 1 kg of saturated steam from feedwater, about 1789/206 x 1 kg = 8.68 kg of primary coolant is required.

Todreas Neil E., Kazimi Mujid S. Nuclear Systems Volume I: Thermal Hydraulic Fundamentals, Second Edition. CRC Press; 2 edition, 2012, ISBN: 978-0415802871

Zohuri B., McDaniel P. Thermodynamics in Nuclear Power Plant Systems. Springer; 2015, ISBN: 978-3-319-13419-2

Moran Michal J., Shapiro Howard N. Fundamentals of Engineering Thermodynamics, Fifth Edition, John Wiley & Sons, 2006, ISBN: 978-0-470-03037-0

Kleinstreuer C. Modern Fluid Dynamics. Springer, 2010, ISBN 978-1-4020-8670-0.

U.S. Department of Energy, THERMODYNAMICS, HEAT TRANSFER, AND FLUID FLOW. DOE Fundamentals Handbook, Volume 1, 2, and 3. June 1992.