5-4
解:B=0.106 先求B值,
p??xp??2x2p?es111s22Bx2xP?es112Bx1x2P2s
代入表中数据得B?0.093
?1?e
20.093x2?1.071
1.071?0.1398?28.437?0.1683
25.3y1??1x1P1sP?同理算得其他的yi, 5-6 解:
lnP1S?16.8967?3803.98S 得P.558KPa 1?100T?41.683816.44 得P2S?43.924KPa
T?46.13
lnP2S?16.2884?汽液平衡关系式Pyi??ixiPis
当x1?0.8943
?1?Py1P101.3???1.0074 ssP1x1P1100.558Py2P101.3???2.3063 P2sx2P2s43.924?2?将x1?0.8943 x2?0.1057 ?1?1.0074 ?2?2.3063代入
??12??21ln?1??ln(x1??12x2)?x2???
x??xx??x1222211??1??12??21ln?2??ln(x2??21x1)?x1???
x??xx??x1222211??1得:?12? ?21?
因?12,?21可近似看作常数, 利用P??xP??2x2P和y1?S111S2?1x1P1sP
Mpa,给定x1值,代入Wilson方程求得?1,?2。利用上述方程已知P?0.1013试差求解T,y1值。
5-13
解:PR方程P?ai(T)RT ?V?biV(V?bi)?bi(V?bi)其中ai(T)?a(Tc)?(Tr,?)
2RTciR2Tci a(Tc)?0.45724 bi?0.0778PciPci??(Tr,?)?0.5?1?k'(1?Tri0.5)
k'?0.37464?1.54226??0.26992?2
组分逸度系数的计算
?2?xa?biA?iiijbi??Z?2.414B? ln?i?(Z?1)?ln(Z?B)??ln????bmambm22B?Z?0.414B?????其中am???(yiyjaij)
?ijbm??(yibi)
iaij?(aiaj)(1?kij)
A?amPbmPPVZ?B?,,
RTRTR2T2?Vi?Li12气液平衡关系式yi??xi?
5-13采用PR方程计算甲烷(1)-二甲氧基甲烷(2)体系在313.4K、x1=0.315时泡点压力与汽相组成。查得组分的临界参数如下:
组分 Tc∕K pc∕MP ω 甲烷 190.6 4.60 0.008
二甲氧基甲烷 480.6 3.95 0.286
PR方程的二元相互作用参数kij=0.0981
解:(1)列出所需要的计算公式 PR方程
p?ai(T)RT(1) ?V?biV(V?bi)?bi(V?bi)其中ai(T)=a(Tc)α(Tr,ω)(2)
bi?0.0778RTCi (3)
PCiR2T2Ci(4) a(Tc)?0.45724PCi[?(Tr,?)]0.5?1?k'(1?Tri0.5)(5)
k'?0.37464?1.54226??0.26992?2(6)
组分逸度系数计算
bAln?i?i(Z?1)?ln(Z?B)?[bm22B其中am??2?xiaijiam?biZ?2.414B]ln[](7) bmZ?0.414B??(yya) (8)
ijijijbm??(yibi)(9)
iaij?(aiaj)(1?kij)(10)
A?ampbmpPV,B?,Z?(11) R2T2RTRT12?v?x??L泡点汽液平衡关系式yi?iii(12)
(2)由已知条件得Tr1=1.6443 Tr2=0.6521代入式(2)-(6)得
k'1?0.3870 k'1?0.7936
?1(Tr,?)?0.7934 ?2(Tr,?)?1.3288
a1(Tc)?0.2496 a2(Tc)?1.8481
b1?2.6801?10?5 b1?7.8700?10?5
a1(T)=0.1980 a2(T)=2.4558 ∵p?ai(T)RT ?V?biV(V?bi)?bi(V?bi)a1(T)RT ?V?b1V(V?b1)?b1(V?b1)∴p1??v?1 设p1=60kPa代入上式,试差法得VL=43.4268,设?1由式(8)-(11)得
LLa12=0.6289 am?6.235?10?5 A=1.2756×105 ?1.4434 bm﹣
B=1.4357×106 Z=1
﹣
?xiaij=2.3735
将以上数据代入(7)
?1L=0.999965
?Lx1?y1?v1?0.315
??1?把y1=0.315由于y1=x1=0.315 所以
vv得am?6.235?10?5 ?1.4434 bm由PR方程求在p=60kPa下Vv=43.4268
﹣﹣
所以A=1.2756×105 B=1.4357×106 Z=1 代入式(7)得?1=0.999965
?V?L0.315?0.999965x1?y1?v1?0.315
?0.999965?1
所以y1?0.315 ∵p?ai(T)RT?
V?biV(V?bi)?bi(V?bi)a2(T)RT?
V?b2V(V?b2)?b2(V?b2)∴p2??v?1 设p2=60kPa代入上式,试差法得VL=43.4268,设?2由式(8)-(11)得
LL?6.235?10?5 A=1.2756×10﹣5 am?1.4434 bmB=1.4357×106 Z=1 将以上数据代入(7)
﹣
?2=0.999976
?Lx2?y2?v2?0.685
??2?L把y2=0.685代入式(8)-(10)
vv得am?6.235?10?5 ?1.4434 bm由PR方程求在p=60kPa下Vv=43.4268
﹣﹣
所以A=1.2756×105 B=1.4357×106 Z=1 代入式(7)得?2=0.999976
?V?L0.685?0.999976x2?y2?v2??0.685
?0.999976?2?y1?y2?1 ∴y1=0.315 P=60kPa
5-14
解:已知压力,温度,摩尔分数,由P-K-T系列图查得Ki,再由yi?Kixi 5-17
解:两个公式在热力学上若正确,须满足恒T P的G-D方程,即
x1dln?1dln?2?x2?0 dx1dx2dln?1dln?2?x2?x1(b?a?2bx1)?x2(?b?a?2bx2) dx1dx2x12?a(x2?x1)?b(x2?x1)?2b(x2?x12)
?(a?b)(x2?x1)?(a?b)(1?2x1)?0
(a?b)
所以这两个公式在热力学上不正确。
5-21 解:
(1)G2在图中为A点。(纯溶液的点,即x1?0点)