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Unformatted text preview: Note Title 2/18/2008‘ 1 (20 points]. The ideal gas equation of state relates absolute pressure P (Po), gas volume V
(m3), number of moles n (mol), and absolute temperature T ( : PV= 11 RT where R = 8.314 meol K
,=. Convert the equation to one relating P (psig) V (ﬁg) 11 (Eb—mole) and T ("1*"). Note that + PMQTMD
P<Pm>  V (m‘) ~— Qa. “4—1 (h m1e>UU<>>
4/ 0:
P‘s it a are yr (9 FWD: (P (F513) + ’4' 54") LW meat Fm 3
{99 VCMAI) : U CR3) <35L31J1FE1> L'lz‘l' =_ (9,3018% 2 (30 points). A stream of humid air containing 1. 0 mole % water (vapor) and the balance dry n  humidiﬁed to a water content of 10 mole '34:. For this purpose liquid water (density— — fed throu I a ﬂowmeter to a humidiﬁer and evaporated into W
wmeter reading a 5D. The ﬂowmeter calibration equation is 111(11er3 N3) = 1.625 >< R +1561 . b“ (a) Draw the ﬂowchart for this process and label all known and unknown variables. (1}) Do the degreeof—freedom analysis. Write down the mlknowns and the independent
equationsfspeciﬁcations to clarify your DOF calculation. 44,,“me (mum/0:40,) _21w(mwo—2spa?¥_ = D 190,17
3mlaumns LAUHL, Vb) , 3‘qu — (“W/Law], L: 0 {90? (c) Estimate the molar ﬂow rate (moler'h) of the humidiﬁed (outlet) air. dqmrbmlémvc [email protected]: 0,4069 M54, 1L
i'Di’d [min/wan @4 0’ $69 .— ﬂaqu/é"? ”ML/['1 ﬂ! __ g386°n~=1¢/A 3 (50 points). The waster water from a metal ﬁnishing plant contains 5.15 wt% Cr. The waster
water stream is fed to a treatmult unit that removes 95% of the chromium in the feed and recycles it to the plant. The residual liquid stream leaving the treatment unit is sent to a waste
lagoon. The treatment unit has a maximum capacity of 45m kg wastewaterfh. If the wastewater
leaves the ﬁnishing plant at a rate higher than the maximum capacity of the treatment unit, the
excess (anything above 4500 kgfh) bypasses the unit and combines with the residual liquid living
the unit1 and the combined stream goes to the waste lagoon. (a) Complete the ﬂow chart by labeling all known and unknown variables. @_  Cn’h} [no water] ' ’ of Cr In feed to unit Wastewater To wa telagoon Cr
lOlt M/ (b) Without assuming a basis of calculation (i.e., mpmgmﬁ are not speciﬁed}, do the degreeof “w
ﬁ'eedom analysis for the following units. In each DOF calculation, write the unknowns and the
independent equationsr' speciﬁcations to justify your calculation. (i) bypass point 6 MW Cm,,m«,me) (if Wm. ' \ {facile ’— lPOP ill5"" $40W,ﬂoy.im‘_&—,_QLJ=.
(ii) treatmentunit 077‘. >45”, ‘HNM whfsqgw’
(4 Imlmwnd ’— Shmm\ lfﬁecﬁeg [DVF m‘ ._. ”459
”(‘2' W4! mflfyf aS' '
(iii) mixing point / ’? Cf “Cad +41”, wt 5; (M4 5 WW“ (”l’S. "L'sJ WMane) , 9 54W 2 3 Wit— (iv) overall system AWVU (‘(;“H“l"'4.)';"‘é,9§(,> exhale/moo = ”100‘: (e) Wastewater leaves the ﬁnishing plant at a rate ml = ﬁmﬂkgr’h. Calculate the ﬂaw rate ef
liquid tn the waste lagoon, #16 (kgfh), and the mass ﬂactien of Cr in this liquid, 1.5 (kg Crlkg _
liquid). e = ’V “k 2 222° 5;?
sf , m4 . 4m: x 0,m$‘_IS‘ .1 A ’— T‘ ’L,’_' Mn: Lm‘l_(\/V\4 2 427(5)“ ”k v , I 4. .2. a v“; .2. l A A
0(5 «,0 003.303 (3;
ﬁMLeLJ‘Q. W W Allin . M (/5!— W IVE
MI I
_____ ’ / , a ': 4‘ 15‘7"an , ...
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 Spring '08
 SEONGKIM
 Mass Balance

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