Chap08prac - This one way to make “dry ice.” You...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
P. 8.1) CO2 at 15MPa and 25 ° C is throttled to 0.1Mpa. Determine the temperature and fraction vapor. (NOTE: there is a typo. Part (c ) makes no sense at 1.5MPa.) Solution: Ebal for a valve, 0 = H (a) assume ideal gas, () K T T Cp H 298 0 2 = = = (b) by PREOS.XLS with Ref=224.1K,0.1MPa, “Liquid”. H2 = H1 = 9695 J/mol, then “T2sat” = 184.1K. q=(9695-0)/(17066-0)= 57% Note: This is just an estimate, because CO2 is not really liquid at 0.1MPa Note2: If you solved this using 1.5MPa, you get 281K. ( c ) Note: for the problem statement at 1.5MPa, there is no difference from (b). At 5.27bar, 216.6K, Hsolid=HsatVap-Hsub, Hsub=Hvap+Hfus=17829-2420+43.2*44*4.184=23362 Hsolid=17829-23362= -5533. C-Ceq ln(Psat/Pref)= -(Hsub/R)*(1/T-1/Tref) 1/T=1/216.6-ln(1/5.27)/(23362/8.314)=0.005208 T=192 At 1bar, 192K=HsatVap=17322 Hsolid=17322-23362= -6040 q = (9695+6040)/(23362) = 67% FYI:
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: This one way to make “dry ice.” You throttle/spray it into “bag” and compress it into a block. See also CO2 chart in Perry’s Handbook, Chapter 3. P8.2) CO is liquefied from 300bar,150K to 1bar. Compute q and Sgen. Soln: Ref=82.0K,0.1MPa,liq. H(150,30)=4139. Ebal: ∆ H=0; q=(4139-0)/(6048-0)=68% Sf=0.68*73.83+0 = 50.2; S(150,30)=27.365 ⇒ Sgen=50.2-27.4 = 22.8 J/mol-K. P8.3) Same CO using 90% efficient turbine. ∆ Srev=0 ⇒ q=27.635/73.83=0.374; Wrev=0.374*6048-4139= -1877J/mol ⇒ Wact=-1689 Hout=4139-1689=2450 ⇒ q = 2450/6048=40.5% ⇒ 1-q=59.5% P8.4) Methane at 300K, 250bar is liquefied (~Linde style) with outlet pressure = 30bar. Compute fraction liquefied. Soln: Ref=111.8K,1bar; qH8+(1-q)H6=H3=10654; Tsat(30bar)=176.7K HsatVap=8289;HsatLiq=4104; H8=H(300,3MPa)=13455; q=(10654-4104)/(13455-4104)=70% ⇒ 1-q=30%...
View Full Document

This note was uploaded on 01/31/2010 for the course CHEM 2106 taught by Professor Liz during the Spring '08 term at University of Minnesota Crookston.

Ask a homework question - tutors are online