DRY SATURATED STEAM:-

The state of steam after complete evaporation of water at saturation temperature is called dry saturated steam. The amount of heat energy, needed to convert 1kg of water at 0°C into dry-saturated steam.

hg = hf + hfg

SENSIBLE HEAT OF WATER:-

The amount of heat energy to be supplied to convert 1kg of water at 0°C to its saturation temperature (ts) corresponding to a given steam pressure(P). It is denoted by hf and its unit is kJ/kg.

hf = Cpw (ts-to)

Total Enthalpy of Steam:- The Enthalpy is defined as the total heat content in the system. The amount of heat required to convert the water in to the superheated steam is called as the total Enthalpy of steam

Total enthalpy= Enthalpy of saturated liquied + Enthalpy of dry saturated steam

h= hf + x hfg

DRYNESS FRACTION:- It is defined as ratio of amount of dry steam to the total amount of water vapour mixture.

x=1 for dry steam

x=0 for saturated steam

x is in between 0 and 1 for wet steam.

x = ms/(ms+mw)

Where ms- mass of dry steam mw- mass of moisture

v)Latent heat of vaporization:

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 and its value is available from steam tables. The value of latent heat is not constant and varies according to pressure variation.

vi) 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’ and can be calculated by using the specific heat of superheated steam at constant pressure (CpsCps), the value of which varies from 2.0 to 2.1 kJ/kg K depending upon pressure and temperature IF Tsup,Ts are the temperatures of superheated steam in K and dry steam, then

(Tsup− Ts) is called is called degree of superheat.