1. The problem statement, all variables and given/known data A boiler is to produce 6250 kg/h of steam superheated by 40 oC at a pressure of 2.1 MN/m2. The temperature of the feedwater is 50 oC. If the thermal efficiency of the boiler is 70%, how much fuel oil will be consumed in one hour? The calorific value of the fuel oil used is 45000 kJ/kg, cp of superheated steam is 2.093 kJ/kg K. for pressure 2.1 Mn/m2 Hfg = 1880 kJ/kg Hf = 920 kj/KG sat temp - 214.9 2. Relevant equations I want to know how to calculate the enthalpy of the feed water to put back into the boiler efficiency question. why am i given cp? 3. The attempt at a solution using the formula : boiler efficiency = m x (H2-H1) / fuel consumption x calorific value H1 is the feed water enthalpy and i am told not to use thermodynamic tables I got some help from a university lecturer and solved it.