How to Calculate Efficiency of Boiler

The efficiency of boiler depends on so many factors such as the design of the boiler, heat cycle employed, built in losses, heat lost to flue gases, properties of water and hot gases, convective and radiative loss, losses due to incomplete burning of fuel etc.

The boiler efficiency is given as
n= heat content of outgoing steam separated/heat energy supplied by the fuel
= ma*(hf-hf1)/C
Where
ma*(h – hf1) is the heat gained by the steam from the boiler per unit time
ma = mass of steam in kg
C is the calorific value of steam in KJ/kg
h=enthalpy of steam at predefined pressure and temperature
h = hf (specific enthalpy) for hot water at pressure p
h = hf +hfg for dry saturated steam at pressure p
h = hf +x*hfg for steam with dryness fraction x at pressure p
X is known as steam quality or equivalent evaporation
h= hf + hfg + cp*(Tsup-Ts) for superheated steam at pressure p and temperature
Tsup and Ts is the saturation temperature corresponding to the pressure at the outlet of boiler.
The values of hf, hfg, cp, Ts can be obtained from steam tables. In the steam tables specific enthalpies, specific heat, heat capacity, steam saturation temperature will be given for specific intervals of pressure. The intermediate values of hf, hfg, cp, Ts which are not available in the steam table can be interpolated linearly. Typical boiler efficiencies are in the range of 75-90%.

So if you are interested in calculating the efficiency of boiler, please feel free to Email zg@zzboiler.com or Call 86-371-86062323.