During the measurement of a furnace the following data became available. The steam produced per hour is ?ms = 6000 kg/h, while its enthalpy is hs = 3200 kJ/kg. The temperature of the feeding water is tw = 80?C and the consumption of the coal (H = 13.5MJ/kg) is ?mc = 1.6tons/h. Calculate the e?ciency of the furnace if the speci?c heat capacity of the water is cp = 4.2kJ/(kgK) and the zero level of enthalpy is at 0?C! (η = 79.6%)