
#1
May1707, 07:57 AM

P: 16

Hello again...i was wondering if you can help?
I am using enthalpy equations to try and find h1 and h2 to work out 'work and heat transfers' for water, for a piston type question. I have calculated work done using: [w = PDV] To find the heat transfer i need to use: [Q=m.(h2h1)] i have obtained h1 using: h1 = hf + x(hghf) (using steam tables) This has been calculated at 1826 kg/m3, from a revision guide all it states to calculate h2 is: ''From the steam table using h1 find h2?'' This is the only piece of information i need to complete the heat transfer calculation (to find h2) can you help at all? I dont now how to find h2. I know m = 0.15, and h1 is 1826kg/m3 and Q is 223 kj But h2?!?!?! Guidance on how to look this up would be appreciated. 



#2
May1807, 02:59 AM

P: 157

It would help if you could post the complete problem statement. For these types of problems, it usually helps to draw out the PV and TS diagrams. I suspect the equation relating enthalpy and work will help here, it should be somewhere in your text




#3
May1910, 07:16 AM

P: 1

Posting the whole question would have got the job done but anyway have you tried these formulas
h2=hf2+(x2hfg) since hf2 can be found on the tables and hfg or w=h1h2 


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