In an industrial process 10 kg of water per hour is to be heated from 20∘C to 80∘C. To do this steam at 150∘C is
passed from a boiler into a copper coil immersed in water. The steam condenses in the coil and is returned to
the boiler as water at 90∘C. how many kg of steam is required per hour.
(Specific heat of steam = 1 calorie per gm°C, Latent heat of vaporization = 540 cal/gm)