Recent content by Nemo's

1)114472vf^2+18691vf-197550=0 so vf=1.2346 and pf=160063 2)114472vf^2+18691vf-195180=0 so vf=1.243 and pf=159113.8 and for the ideal gas pf=160979 These values for pf all seem pretty close to me the pressure lies around 160kPa so why did we calculate twice, once at 1.5 bars and the other at 3...

Thanks you for the helpful material you attached. From the second attachment I concluded that COPR=(h1-h4)/(h2-h1) so I was able to get h1 from the tables at -20οC. for R12 h1=178.73 and similarly I got h2=74.59. However,I don't know the temperature at 3 or 4 so I can't get h4. What should I do?

I'm afraid I don't know the value for gas constant R in case of the superheated steam. Can I even use the ideal gas equation in this case or is it just an approximation like you said earlier? So now I'm supposed to select a value for vf right? e.g: Pf=114472vf+18691 so if vf=1.317 Pf=169450 Is...

I'm still confused about one thing though, the saturated steam table gives specific values for the pressure and specific volume at a certain temperature. e.g at 160οC pressure is 6.1823 bar and specific volume is 0.30678 for saturated vapour. So what other combinations could there be?

P=Pο+mg/A+kΔx/A =143240+8800Δx/A Now I have the pressure in terms of A and Δx. Vf = 1.008+2.222AΔx P=Pο+mg/A+km(Vf-Vi)/(A^2) =143240+8800AΔx How can I get the final state from steam tables when Δx is still unknown? Am I doing something wrong?

Thanks for correcting me I switched the values for 0.9 and 0.1. Yes, I see. So in the final state can I use PV = mRT assuming all the liquid is turned into vapour? Or maybe the superheated vapour isn't an ideal gas so I can't do so. I still need to find the final pressure.

specific volume of saturated liquid = 0.0010516 m^3/kg vapour =1.2093 m^3/kg weighted average volume = (0.0010516*0.9*0.45+1.2093*0.1*0.45)/2 = 0.027422 m^3 change in volume in terms of A and x = AΔx Final volume...

Homework Statement In an ideal refrigeration cycle, the temperature of the condensing vapour is 40oC and the temperature during evaporation is -20oC. Determine the coefficient of performance of this cycle for the working fluids; R12 and ammonia. Homework Equations C.O.Pc = TL/(TH-TL) The...

I solved it . Thank you anyway

saturated vapour pressure P= 143.24 k Weight of the piston: at Δx=0 mg=143.24A-PοA so now I can get mg. I actually understand what 90% dryness fraction means or how can I use it.

O.k thanks a lot

Thanks for letting me pay attention to the tables. h1=2789.88 v=0.132 Now if I can only get the area I can use m= A*c1/ρ1 to get m and then substitute in 1 to get c2.

Homework Statement Steam, at 15 bar and 280oC, enters a nozzle with an initial velocity of 125 m/s. The steam enthalpy at the exit section is 2800 kJ/kg and the heat loss is 25 kJ/kg. What is the exit steam velocity?. Homework Equations 1)Qin - Qout = m [h2-h1+((c22-c12))/2] 2)h = Pv + u...