Correct Answer: ratio of heat actually used in producing steam to the heat liberated in the furnace
3. The boiler efficiency is given by (where m = Total mass of water evaporated into steam in kg/h, mf = Mass of fuel in kg/h, C = Calorific valve of fuel in kJ/kg of fuel, h = Total heat of steam in kJ/kg, and hf1 = Sensible heat of feed water in kJ /kg)