STEAM TABLES
(Thermodynamics\ Level 1\
CONSTANT PRESSURE HEATING OF WATER TO PRODUCE STEAM
Temperature
Saturation temperature or boiling point
Fusion temperature or freezing point

Superheated steam 

Saturated water 




Wet steam 

Water 
Dry saturated steam 



Ice 




Heat supplied
âˆ‘Water changes into steam at the saturation temperature (boil
âˆ‘The saturation temperature increases with increasing pressur
âˆ‘Water at its boiling or saturation temperature is known as sa
âˆ‘The temperature remains constant while water is being chang
âˆ‘Steam at its saturation temperature is known as dry saturate
âˆ‘When water is changing to steam, a water/steam mixture kn exists
âˆ‘Steam above its saturation temperature is known as superhea
Steam does not obey the Gas Laws
âˆ‘Never use the Gas Laws for steam
âˆ‘Always use Steam Tables for finding the properties of w
âˆ‘The recommended tables are:
âˆ‘Thermodynamic & Transport Properties of Fluids (SI & Mayhew
Note that temperature and pressure are not independent at the condition, so a saturated fluid is defined if we know either its te pressure. To put it another way, water and steam can only
Thermodynamic & Transport Properties of Fluids (SI unit by Rogers & Mayhew
These tables use the following notation and units:
Property 
Symbol 
Units 



Pressure 
p 
bar 



Temperature 
t 
oC 
Specific volume 
v 
m3/kg 
Specific internal 
u 
kJ/kg 



Specific enthalpy 
h 
kJ/kg 



Specific entropy 
s 
kJ/kgoK 
SUBSCRIPTS USED IN THE TABLES
frefers to water at its boiling point or saturation temperatu
grefers to dry steam that is still at the saturation temperat steam)
fg refers to the change from boiling water to dry saturated pressure
s refers to the saturation temperature or pressure
PROPERTIES OF WATER BELOW ITS BOILING POINT
A liquid that is below its boiling point or saturation temperat compressed liquid. (Sometimes also known as subcooled liquid)
Water is highly incompressible so its properties are little affec pressure.
For this reason the actual temperature of the water is taken saturation temperature and the actual pressure is ignored. So:
v = vf (page 10) 
u = uf (pages 3 â€“ 5) 
h = hf (pag 



Do not forget to insert two zeros after the decimal point in each cas For example, at 25o C, vf = 0.0010030 m3 / kg and not 0.10030 m3 /
PROPERTIES OF WATER AT ITS BOILING POINT
This is water at its saturation temperature. It is known as â€œsat Subscript â€œf â€ applies. So:
v = vf (page 10) 
u = uf (pages 3 to 5) 
h = hf 



Do not forget to insert two zeros after the decimal point in ea For example, at 25o C, vf = 0.0010030 m3 / kg and not 0.1003
PROPERTIES OF DRY SATURATED STEAM
Dry saturated steam is steam that has no particles of water c that is still at the saturation temperature (boiling point) at whi Subscript â€œgâ€ applies. So:
v = vg (pages 3 to 5) u = ug (pages 3 to 5) h = hg
PROPERTIES OF WET STEAM
Wet steam is a mixture of boiling (saturated) water and dry saturat during the change of phase from boiling water to dry saturated stea The proportion of dry steam that is present in a wet steam mixture i

Dryness fraction x 




\Drynessfraction x 
the mass of dry steampresent in the wet steamm 

the total mass of the wet steammixture 





Thus in 1 kg of wet steam with dryness fraction x
Mass of dry steam present = x kg,
Mass of water present = (1 â€“ x) kg
Therefore
v = xvg + (1 â€“ x)vf 
u = xug + (1 â€“ x)uf 
h = xh 



Expanding the expression for h gives
h = xhg + hf â€“ xhf or h = hf + x(hg â€“ hf) or h = hf + xhfg
But why bother? Just understand the first method. Values of uf, hf, ug, hg and hfg are given on pages 3 â€“ 5 of the tables. Values of vf are given on page 10 of the tables.
Do not forget to insert two zeros after the decimal point in each cas For example, at 25o C, vf = 0.0010030 m3 / kg and not 0.10030 m3 /
All the above equations can be
For instance, h= 

(( 
)) so if we know either the temperature or the pressure o 
and one of the properties v, u, h or s of the wet steam, we can find x fraction. This is often very useful.
APPROXIMATE EXPRESSION FOR SPECIFIC VOLUME O
The volume of water present in wet steam is normally negligible volume of dry steam that is present. The volume of the water p ignored and thus
The approximate specific volume of wet steam v
Do not attempt any similar approximation for any of the other prop
PROPERTIES OF SUPERHEATED STEAM
This is steam that has been heated to temperatures in excess temperature corresponding to the steam pressure.
v, u and h are given in the tables at various pressures and tem 6 â€“ 8.
To determine values of v, u and h at temperatures that are at diff temperatures to those given in the tables, linear interpolation may
STEAM TABLES  EXERCISE
Use steam tables to determine the specific enthalpy (h), the specific and the specific volume (v) for the following cases.
Remember that the pressures in the tables are expressed in bars.
Note 
100 kN/m2 = 105 N/m2 = 1 bar 

Also 
1 MN/m2 = 106 N/m2 = 10bar 



Answers in kJ / kg or m3 / kg 

1 
Water at 88o C and 1 bar 
[369, 369, 0.001034] 

2 
Water at it saturation temperature at 2.7 bar[546, 546, 0.00107] 

3 
Dry saturated steam at 5 bar 
[2749, 2562, 0.3748] 
4Wet steam with dryness faction 0.9 at 10 bar[2576.5, 2401.8, 0.1
5Superheated steam at 6 bar and 250o C[2958, 2722, 0.394]
6Superheated steam at 6 bar and 260o C[2978.8, 2737.8, 0.4021]
7Water at normal atmospheric pressure and 80o C[334.9, 334.9, 0.
8Water at its saturation temperature at 200 kN/m2[505, 505, 0.001
9 Saturated steam at 400 kN/m2 [2739, 2554, 0.4623] 


10 
Wet steam with dryness fraction 0.8 at 2 MN/m2 
[2421, 2 
11 
Steam at 1 MN/m2 and 225o C 
[2886.5, 
12 
Water at 165o C and 600 kN/m2 
[697, 69 
13 
Boiling water at 2.6 MN/m2 
[972, 96 
14 
Saturated steam at 39 bar 
[2801.5, 
15 
Wet steam with dryness fraction 0.92 at 16.5 bar 

Use the approximate method to determine v[2640.18, 2457.86, 0. 16 Steam at 550 kN/m2 and 320o C [3104.9,
(Thermodynamics\ Level 1\
Simple Steam Engine
CLOSED SYSTEMS 
Real continuous boundary 
Work output from system W 

when valves are closed 







CLOSED SYSTEM 
P 

i 




s 

CYLINDER & PISTON 
t 

o 




n 
(thermo\cylinder.sdr)


Heat transfer into system Q 


THE 

Q  W = (U2  U1) 
or 
q  w = (u2  u1) per kg 
(U2  U1) is the change in internal energy of the system
STEAM TABLES
âˆ‘Steam does not obey the Gas Laws
âˆ‘Do not use the Gas Laws for steam
âˆ‘Always use Steam Tables for finding values of internal energy, specific volume, ent steam.
âˆ‘The recommended tables are:
âˆ‘Thermodynamic & Transport Properties of Fluids (SI units) by Rogers & Mayhew
WORK DONE IN
Process 
Process law 
Work done W 








Constant volume 
V1 = V2 =constant 
Zero 





Constant pressure 
p1 
= p2 = constant 
p(V2 â€“ V1) 




Hyperbolic 
p1V1 
= p2V2 = constant 
p1V1ln(V2 / V 




Polytropic 
p1V1n 
= p2V2n = constant 
(p1V1 â€“ p2V2) / (n 




âˆ‘A hyperbolic process following the law pV=constant is NOT an isothermal process (con when the working fluid is steam, (although it is when the working fluid is a gas)
âˆ‘When steam undergoes an adiabatic process (zero heat transfer, Q = 0), it does NOT fo constant (this only applies to gases undergoing an adiabatic process)