A power plant absorbs 1200MJ of heat from combustion and eje

A power plant absorbs 1,200MJ of heat from combustion and ejects 800MJ of waste heat with the rest going towards mechanical work in the steam turbine. Assuming a conversion efficiency of 85% for the conversion of mechanical work to electricity, what is the total kWh generated by 1,200MJ?

Solution

Energy absorbed by the power plant = 1200 MJ

Energy ejected in the form of waste heat = 800 MJ

Hence,energy going towards mechanical work in turbine = (1200 - 800) MJ = 400 MJ

Now,efficiency of steam turbine = 85%

Hence, productive energy = 85% of 400 MJ = 85*400/100 = 340 MJ

Hence, energy in kwh = 340* 0.277777778 kwh

Taking upto two decimal places we get 340*0.27 = 91.8 kwh