Somewhere in the very old steam heating system of Gleeson Hall, there is a vesse

Question

Somewhere in the very old steam heating system of Gleeson Hall, there is a vessel in which twosteam streams mix. One stream brings superheated steam from the central supply at 20bar,while the other is the leftovers from the building and is saturated at 10bar. About 17 years ago,the valve at the mixing point got stuck when my classmate Austin Massey spilled beer down aheater vent, yes we were drinking beer in Gleeson. Currently the mixing ratio is fixed at 1.96 kg20bar steam to 1.0 kg 10bar steam. Dr. Skip freaked out and raced to insulate the vessel andprevent any future heat losses. My friend Danielle and I argued that the stuck valve providedplenty of heat. Were we correct? Calculate the temperature of the mixed steam stream andhelp me defend myself against the evil Dr. Skip.

I m so confused about this question! This is a chemical process problem!!! please use energy balance to sovle this!!! Thanks a lot!!

Explanation / Answer

Amount of superheat of 20 bar (absolute assumed) is not given so it is assumed saturated with no super heat   Specific enthalpy of 20 bara saturated steam =2799 KJ/Kg and that of 10 bara saturated steam is 2777.12KJ/Kg Assuing there is no heat loss and inside the closed vessel the resultant enthalpy of mixture =       1.96 x 2799 + 2777.12 = 8263.16 KJ for 2.96 Kg Hence specific ethalpy of the mixture of steam = 8263.16 devided by 2.96= 2791.6KJ/Kg   Looking at the steam tables this is equivalent app to 15 bara saturated steam. with temperature of 198.295 deg C

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