1) Water is heated in a cylinder fitted with a piston under constant pressure from a weight placed on top. 2) As heat is supplied, the temperature of the water rises until it reaches its boiling point, which depends on the pressure acting on the water. 3) When the boiling point is reached, there is a slight increase in the volume of water as some of it changes from liquid to gas (steam) at a constant temperature.

1. Vishwakarma govt engg

2. EME: Steam formation
 Prepared by :
• Name: soni kunjan r.
• Branch: mechanical
• Enroll: 140170119058
• Sem: 2 𝑛𝑑

3. Steam formation
 Consider a cylinder fitted with a piston which can move freely
upward and downward in it. consider 1 kg of water at 0. C under
the piston. A weight w is placed over the piston so that it exert
constant pressure p on water. Now if heat supplied to water, a rise in
temp will be noticed and this will continue till boiling point is
reached .
 The temperature at which the water boil , depends on the pressure
acting on it
 When the boiling point of water is reached , there will be slight
increase in volume of water shown in fig. below slide.

4. Cylinder with w Wight .

5. Steam formation graph

6. IMPORTANT TERMS RELATING
STEAM FORMATION
 Sensible heat of water (hf ): It is defined as the quantity of heat
absorbed by 1 kg of water when it is heated from 0°C (freezing
point) to boiling point. It is also called total heat (or enthalpy) of
water or liquid heat invariably.
 Latent heat or hidden heat (hfg): It is the amount of heat required to
convert water at a given temperature and pressure into steam at
the same temperature and pressure. It is expressed by the symbol hfg
 Total heat or enthalpy of wet steam (h):It is defined as the quantity
of heat required to convert 1 kg of water at 0°C into wet steam at
constant pressure. It is the sum of total heat of water and the latent
heat and this sum is also called enthalpy.

7.  Total heat or enthalpy of wet steam (h):It is defined as the quantity of
heat required to convert 1 kg of water at 0°C into wet steam at
constant pressure. It is the sum of total heat of water and the latent
heat and this sum is also called enthalpy.
 Superheated steam: When steam is heated after it has become dry
and saturated, it is called superheated steam and the process of
heating is called superheating. Superheating is always carried out at
constant pressure. The additional amount of heat supplied to the
steam during superheating is called as ‘Heat of superheat’

8. Thank you