A heat exchanger produces dry steam at 100°C from feed water at 15°C at a rate of 2.4 kgs?1. The heat exchanger receives heat energy at a rate of 6.5 MW from the fuel used. The specific heat capacity of water is 4187 Jkg?1K?1 and its specific latent heat of vaporisation is 2257 KJkg?1.Determine the heat energy received per kilogram of steam produced.
It seems that in every second, the heat exchanger receives 6.5 MJ and produces only 2.4 kg of steam; so the heat energy received per kg of steam produced is 6.5 MJ/2.4 kg = 2.71 MJ/kg. Why we are also given heat capacities is uncertain, but the minimum heat needed to turn 15-C water into steam should be (85K)(4.187 kJ/kg-K) + 2257 kJ/kg = 2.61 MJ. Never mind; the answer to the question is in my previous paragraph.
