2-11 解: 1) 理想气体态方程状
pVmRT
3)RK方程 查表,水的Tc647.3Kpc22.05MPa
4)L-K方程
ZZ0Z1
查表Z0.96240
Z10.036610.344
查水蒸气表,473K,1.0MPa下水蒸汽(过热蒸汽)的摩尔体积为3.7110mmol 2-13
解:根据理想气体状态方程
331
p
nRT
1.638MPa V
pc3.394MPa
查表,Tc126.2K则 Tr3.7480查表
0.040
pr0.4828
Z01.0048
对照图2/7-2,可知理想气体状态方程适用。
若用L-K方程,根据上面的条件计算出新的p,进一步查表得到新的Z值,直至p收敛,结果p1.647MPa。
2-16 解:
查表,Tc425.2K则 Tr1.0818
pc3.799MPa
0.193
p
r0.4001
3
1
若以B
0.265mkmol计算,
相对偏差=0.06%
3
1
mmol,根据实验值若p1Mpa,根据普遍的virial方法,Vm3.560
Vm3.560m3mol1
2-19 解: 1)Antoine方程
查表,A15.8333
B2477.07C39.94
lnpsA
B2477.07
15.83339.3693
TC423.1539.94
ps11722.89mmHg1.542MPa
2)Pitzer关联方程
查表,正戊烷的Tc469.6K则 Tr
pc3.374MPa
0.251
423.15
0.9011
469.6
6.096486
1.28862lnTr0.169347Tr0.6137Tr
f(0)(Tr)5.92714
15.68756
f(1)(Tr)15.251813.4721lnTr0.43577Tr0.5213
Tr
则 lnprf
s
(0)
(Tr)f(1)(Tr)0.7445
prs0.4749
ps0.47493.3741.602Mpa
2-18 解:查表,
Tc425.2KZc0.274
pc3.799MPa
0.193
Vc255cm3mol1
则Tr
T
0.9246Tc
pr
p
0.5791 pc
Rackett方程
(1Tr)
VVcZc
0.2857
137.37103m3kmol1
RK方程
q
3/20.42748Tr0.73073/25.5494 0.08664
pr0.086640.04540.05426 Tr0.7307
Zk1Zk(Zk)(
1Zk
)
q
Z00迭代,得Z0.1149 V
ZRT
170.68103m3kmol1 p
2-20 解: Virial方程
2
By12B11y2B222y1y2B12132.58cm3mol1
V
RT
B0.415m3kmol1 p
RK方程
查表
N2C4H10
Tc126.2KTc425.2
pc3.394MPapc3.799MPa
对于N2,
Tr3.6529 a0.42748
Tr
1/2
R2Tc2
0.07255Pam6K0.5mol2
pc
b0.08664
RTc
26.7840cm3mol1 pc
对于C4H10,
Tr1.0842 a0.42748
Tr
1/2
R2Tc2
1.3505Pam6K0.5mol2
pc
则
b0.08664
RTc
80.6218cm3mol1 pc
2
ay12a1y2a22y1y2a1a20.7997Pam6K0.5mol2
by1b1y2b264.4705cm3mol1
bp
0.1177 RTa(T)q3.2365
bRT
Z1q
初值1迭代,
Z
Z(Z)
Z0.7463
V
ZRT
0.409m3kmol1 p
3-22 解:
查表,水的Tc647.3K则Tr0.7309
pc22.05MPa
0.344
pr0.0635 0.422
0.61376Tr1.6
B00.083
0.172
B10.1394.20.50247
TrB
RTc0
(BB1)1.920104m3mol1 pc
R
故 V
B1.920104m3mol10.0107m3kg
dB00.675
2.61.5247dTrTr
R
dB10.722
5.23.6838 dTrTr
dB0B0dB1B1)()]966.1Jmol1 故 HprRT[(
dTrTrdTrTr
dB0dB1
SprR()1.4738Jmol1K1
dTrdTr
R
查水蒸气表,得到实际气体的各项性质。理想气体的各项性质由三相点为零点开始
计算。 3-21 解:
查表,丙烯Tc365.0K
则 Tr则
pc4.620MPa
473
0.7307647.3
pr
1.0
0.0454 22.05
q
3/20.42748Tr0.73073/24.3332 0.08664pr0.086640.0454
0.1720 Tr0.7307
对于水蒸汽,
Z1q
Z
Z(Z)
利用Z1的初值进行迭代,收敛结果为 Z0.4291 则
HR3Z
(Z1)qln()2.76178 RT2ZHR9138.65Jmol1
3-24
解:
剩余性质:丙烯Tc365K
1)2.53Mpa & 400K
pc4.62Mpa 0.148
Tr1.0959pr0.5476
H
RTc
R0
0.5302
R
R0
H
RTc
R1
0.3555
HH
RTc
RTc
H
RTc
R1
R1
0.5828
S
R
R0
0.3390
S
R
0.3263
SS
R
R0
RR
S
R
R1
0.3873
Z00.8458 Z10.007308
ZZ0Z10.8469
2) 12.67Mpa & 550K
Tr1.5068pr2.7424
H
RTc
R0
1.4050
R
R0
H
RTc
R1
0.0603
HH
RTc
RTc
H
RTc
R1
R1
1.3961
S
R
R0
0.7015
R
R0
S
R
R1
0.1926
SS
R
R
S
R
0.7300
Z00.8034 Z10.22675
ZZ0Z10.8371
R1
HmHidmHRmCiddTHm11218.16Jmol p
SmSidmSRmV(
Cid
pT
dTR
dp
SRm12.81Jmol1K1 p
ZRT
)0.00081m3mol1 p
3-28 解:
1)V1
113.640cm3mol1
dV
dx1
V2101.460cm3mol1
dV
dx1
2)以0.2为例
V1V(1x1)V2Vx1
中心差商
dVdx1
x10.2
1
(Vx10.1Vx10.3)12.58 0.2
3
1
则 V1114.086cmmol
V2101.486cm3mol1
3)以0.2为例
mixVV(x1V1x2V2)0.106cm3mol1
4) 边值差商
dV
dx1
x11
1
(Vx11Vx10.98)11.55 0.02
V2Vx11
同理,
dVdx1
102.09cm3mol1
x11
V1114.31cm3mol1
3-35 解:
118F
4-8 解: 过程能量守恒,忽略位能和动能的变化,则
h1wqh2
k1
kws,r1kp2
WZRT11
k1p1
s
1
Jmol
Z1
p1V1
1.0787RT1
p2V2
0.8827 RT2
注MCO244.010gmol1
Z2
Z
则
1
Z1Z20.9807 2
wWMCO210003.42105Jkg1
qh2h1w287.75kJkg1
放热
4-9 解: 1)7atm
2)~0.13
83-85K
~34kcal/kg 3)190K 4-21 解: 查水蒸汽表,各点状态如下 1:(81.33
C,50kPa,H1340.49kJkg1)
泵做功
wppV(100050)1.0301030.9785kJkg1
2:(82C,1000kPa,H2H1
1wp351.47kJkg) 3:(500
C,1000kPa,H1
33478.5kJkg) 4:(81.33
C,50kPa,H42645.9kJkg1
)
则
1)
H3H4
HH26.5%
32
2)r
p
H00118
3H0.4
3)m
3600kJ
H4.32kgh1
3H4
4-22 解: 各点状态如下:
1:(20
C,H1340.49kJkg1
)
(忽略体积变化)
2:(20C,H2383kJkg)
则
3:(35C,H3423kJkg)4:(35C,H4250kJkg)
1
1
1
(最高为等熵过程对应值)
w
H2H1
3.325
H3H2
QH4H3173kJkg1
5-10 解: 丙酮所含元素的标准yong为:
(C)410.515kJmol1
(H)117.575kJmol1
1
(O)117.575kJmol1
对于液态,fG(C3H6O(l))155.73kJmol
液态标准yong(C3H6O(l))fG(C3H6O(l))
1
1783.242kJmol
i
1
对于气态,fG(C3H6O(g))153.05kJmol
液态标准yong(C3H6O(g))fG(C3H6O(g))
1785.922kJmol
i
1
计算125C,0.5MPa下yong值,
1.判断汽液态(以对应状态下yong值为标准值) 2.参见公式(5/2-32 5/2-35) 5-11 解:
说明:1.以298.15K的饱和水为参考态
2.数据由水蒸气表而来(内插法)
3.yong变 (HH0)T0(SS0) 4.质能系数(HH0)
5.温度越高,压力越大,质能系数越大 5-14 解: 参见5/3-2,注意内部yong损失 6.8 解:
临界性质:Tc=425.2K Pc=3.799Mpa w=0.193 对比性质:Tr=1.0818 Pr=0.3948 对于RK方程
q
0.427483/2
Tr4.3848
0.08664
Pr
0.086640.03162
TrZk11q
ZK
Zk(Zk)
以Z0=1代入上式迭代,Z=0.9131
Iln
Z
0.03404 Z
lnZ1ln(Z)qI0.1100
0.8958
fP1.344MPa
6.9 解:
临界性质:Tc=365.0K 对比性质:Tr=1.3096 查附录B5内差可得
Pc=4.620Mpa Pr=1.4892
w=0.148
00.79992
11.119381
0(1)w0.8134
fP5.596MPa
6.10 解:
以200℃,6kPa的水蒸气状态作为理想气体,fipi6kPa 则
*
*
hi*2879.7Jg1si*9.1398Jg1K1
p1Mpa,
hi2827.9Jg1si6.6940Jg1K1
fiM(H2O)hihi**ln*(ssii)5.0624 fiRT
fi
157.6967fi*
fi947.82kPa
i
fi
0.9478 p
6.11 解:
临界性质:Tc=369.2K Pc=4.975MPa 计算饱和蒸汽的逸度系数(Ps=0.267Mpa) 对比性质:Tr=0.82611 Pr=0.05367 对于RK方程
q
0.427483/2
Tr6.5711
0.08664
Pr
0.086640.005629
Tr
ZK
Zk(Zk)
Zk11q
以Z0=1代入上式迭代,Z=0.9702
Iln
Z
0.005785 Z
lnsZ1ln(Z)qI0.03174
s0.9688
Vl4.810486.4691034.1505105m3kg1
Vl
fPexp[(PPs)]0.3238MPa
RT
l
s
s
6-15 解: 1.溶解度参数法 查B10表,可得
环己烷116.77(MJm)
32
V1l0.108m83kmo1l
l
3
1
苯 218.23(MJm) V20.0894mkmol
又有x10.4 则
2
V1lx2
1220.058385 ln1RT
32
x20.6
T313.15K
V2lx12
1220.021322 ln2RT
所以
11.0601 a11x10.4240
21.0216 a22x20.6129
2.Margules模型
知A120.1640 A210.1462 则
2
A122A21A12x10.0539136 ln1x2
ln2x12A212A12A21x20.0268096
所以
11.0554 a11x10.4222
21.0272 a22x20.6163
6-17 解: 气相视为理想气体,则有
yipxiipis
另 故
GE
xii RT
p/Mpa
0.3018 0.2768 x1
0.25 0.50 y1
0.188 0.378 ln1 ln2
GE
RT
x1x2GERT
E
GRTx1x2
-0.68005 0.00814 -0.16391 -0.87417 -1.14394
-0.76121 0.060575 -0.35032 -1.40127 -0.71364
x1
所以
x1x2
与x1线性关系较好,选用van Laar模型。 E
GRT
6-18 解:
由G 又有
E
RTx1x2Ab12x1和GERTx1x2A21x1A12x2,则
A21AB A12AB
2
A122A21A12x1 ln1x2
ln2x12A212A12A21x2
GE
xii
RT
1.活度系数
11.0732 11.0796
2.混合热
mixHH
3.超额熵
E
GERT
RTT
2
8.314112
2
0.07010.0759-189.74Jmol115.74109
HEGE89.740.07368.314112S0.189Jmol-1K1
T112
E
7-19
解: 1)353.15K时有
V1l76.92cm3mol1
V2l18.07cm3mol1
lnp1s16.6780
3640.20
T53.54
p1s92.59kPa
sp247.39kPa(水蒸汽表)
a124250.11Jmol1
a215374.81Jmol1,则
ij
VjVi
exp
aijRT
(ij)
120.055241210.682434
x10.25,则
ln1ln(x1x212)x2(
1221
)0.819152
x1x212x2x121
1221
)0.220654
x1x212x2x121
ln2ln(x2x221)x1(
12.26857521.246892
气相视为理想气体,则有
yipxiipis
y1p0.252.26857592.59233y2p(10.25)1.24689247.39
,且y1y21,则
y10.5423y20.4577
p96.83kPa
2) 已知y10.4
y20.6
p101.325
假设迭代初始温度为T0353.15,则
V1l76.92cm3mol1
V2l18.07cm3mol1
lnp1s16.6780
3640.20
T53.54
p1s92.59kPa
sp247.39kPa(水蒸汽表)
假设迭代初始10201.0,则
yipxiipis
x10.437726x21x10.562274
计算1和2
a124250.11Jmol1a215374.81Jmol1,则
ij
VjVi
exp
aijRT
(ij)
120.055241210.682434
ln1ln(x1x212)x2(
1221
)0.3782
x1x212x2x121
1221
)0.445035
x1x212x2x121
ln2ln(x2x221)x1(
11.459655
s
21.560545
计算新的p1
y2p1s
pp()103.8835 s
12p2
s1
y1
计算新的T
T
3640.20
53.54356.0146K
lnp1s16.6780
以新的T问初始温度进行上述迭代,注意水蒸气表的利用内插取值,每一步迭代中要用的i和pi为上次迭代的结果,直至收敛。
s
x10.0296x20.9704
111.3375
p120.80kPaT359.85K
7-16 解: 气相视为理想气体,则有
另
s
1
21.0100
p62.03kPa
s2
yipxiipis
GE
xilni RT
y1p0.63424.4
2.2323 s
x1p10.30023.1
1)1
2
10.63424.41.2694y2p s
x2p210.30010.05
GE2)xilni0.300ln2.2323(10.300)ln1.26940.4079
RTmixGGEmixGidGExilnxi
0.2030 3)
RTRTRTRTRT
4)活度系数大于1,故正偏差