Lecture 17 - 1 step model processes
Many "real" thermodynamic processes (apart from irreversibility) can be modeled as composed of a succession of "one-step" processes. Important examples of these building-block processes are: workfree (no change in
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CHE 220 Introduction to Chemical Engineering Thermodynamics
Lecture 24:examples of open system energy balances Flow calorimetry Mixing Adiabatic turbine Sudden expansion
1
Example 1: a flow calorimeter operates at steady state and conditions noted
ChE 220 - Spring 2014
Homework Set 14
Due: Will not be collected
Reading: Sections 6.76.
Note: the nal will cover chapters 1-6, up to and including section 6.9.
Problems: 6.27, 6.29. 6.30, 6.31, 6.39
1
Problem 1 A rigid pressurized cylinder contains steam at 22 bar, 400 C. The cylinder is placed in a heat
bath at 100 C and is allowed to reach thermal equilibrium.
a) Calculate the amount of heat.
b) Calculate the entropy generation.
c) Calculate the volu
ChE 220 - Spring 2014
Homework Set 9
Due: March 27
Reading: 4.34.11, review of chapter 4
1
Problem 1 Solution Outline: For reversible isothermal process,
Q D TS
The work is then obtained as
W D U
Q
Numerical substitutions (in standard steam-table units) T
ChE 220 - Spring 2014
Homework Set 2
Due: January 30
Reading: Chapter 2: 2.12.3
1
Problem 1 Solution a) 25 C, 1 bar: liquid, because the temperature is below the saturation temperature
at 1 bar (99.63 C).
10 bar, 80 C: liquid, because the temperature is b
ChE 220 - Spring 2014
Homework Set 14
Due: Will not be collected
Reading: Sections 6.76.
Note: the nal will cover chapters 1-6, up to and including section 6.9.
1
QB
heat in
1
2
boiler
work in
work out
pump
turbine
WB
WT
condenser
3
4
heat out
QC
Problem
ChE 220 - Spring 2014
Homework Set 12
Due: Friday April 18
Reading: Chapter 6, 6,16.5
1
Problem 1 Solution a)
W D
45 J=mol K
H D CP .T2
Q D H
T1 / D
W D
9083 J=mol
4583 J=mol
b)
S D Cp ln
T2
T1
R ln
P2
D
P1
1:01778 J=mol K
d)
Wideal D H
T0 S D
2
8779:55 J
ChE 220 - Spring 2014
Homework Set 11
Due: Will not be collected
Reading: Chapter 5, sections 5.85.11
1
Problem 1 Solution a) The residual properties can be calculated as follows:
H
S
R
R
P
D
V
P
Z
@V
dP
T
@T P
@V
dP
@T P
0
Z
D
0
R
P
with the integrations
ChE 220 - Spring 2014
Homework Set 3
Due: (Will not be collected)
Reading: Review of sections 2.1, 2.2; 2.32.5
1
Problem 1 Solution a) At 1 bar, 210 C, the specic volume of steam is found by interpolation to be
V D 2219:2 cm3 /g D 2:2192 m3 /kg
Since the
ChE 220 - Spring 2014
Homework Set 4
Due: February 13
Reading: 2.32.12, review of chapter 3. Read ahead sections 3.1-3.3
Problems: 2.15, 2.18, 2.20, 2.25.
Problem 1 Solution a) The second virial coefcient is directly related to the slope of an isotherm on
ChE 220 - Spring 2014
Homework Set 5
Due: February 21
Reading: 3.33.6
1
Problem 1 Solution a) For this constant-pressure expansion, the amount of work is
1
1
W D P0 .Vs Vl / D P0
s
l
where P0 D 1 bar is the atmospheric pressure, V is the specic volume, is
ChE 220 - Spring 2014
Homework Set 6
Due: February 27
Reading: Chapter 3, sections 3.63.7; read ahead 3.83.9.
1
Problem 1 Solution From the steam tables at 6 bar we nd (in standard steam table units):
V
U
H
Liquid 0:0011 669:72 670:5
Vapor 0:3156 2566:8 2
ChE 220 - Spring 2014
Homework Set 10
Due: April 3
Reading: review of chapter 4; 5.15.7.
1
Problem 1 Solution The ideal-gas heat capacity of nitrogen is
ig
CP .t/ D 8:231
10
12
t 4 C 1:3053
10
8
t 3 C 5:8198
10
7
t2
2:17
10
3
t C 29:423
ig
with T in K and
ChE 220 - Spring 2014
Homework Set 8
Due: March 20
Happy Spring Break!
Reading: Chapter 4: 4.1, 4.2
1
Problem 1 Solution Entropy change of ice: The process is conducted under constant pressure (dQ D
dH ), therefore, the entropy change will be calculated a
ChE 220 - Spring 2014
Homework Set 7
Due: Will not be collected
Reading: 3.8-3.10; review of chapter 3.
1
Problem 1 Solution a) At the initial state:
P1 D 5 bar;
T1 D 151:84 C;
V1 D 0:3748 m3 =kg;
U1 D 2560:7 kJ=kg
The mass in the tank is
m D V tank =V1 D
ChE 220 - Spring 2014
Homework Set 1
Due: January 23
Reading: Chapter 1
1
Problem 1 Solution
We will need the following unit conversions:
1 ft D 0:3048 m;
1 lb D 0:454 kg;
1 lbmol D 454 mol
(Note on the conversion mol to lbmol: one mol has a mass equal to
4000
Mollier diagram of steam
3900
C
0
T. Matsoukas 2014
75
700 C
3800
650 C
3700
600 C
3600
550 C
1000
bar
800
bar
bar
3500
400
bar
bar
600
3400
40 b
bar
0.1
5b
ar
0.2
8b
ar
350 C
300 C
0.0
2900
6b
3000
0.0
ar
0.0
3100
400 C
bar
0.1
100
60 b
ar
150
bar
ChE 220 - Spring 2014
Homework Set 3
Due: (Will not be collected)
Reading: Review of sections 2.1, 2.2; 2.32.5
Problems: 2.3, 2.6, 2.8, 2.9, 2.11, 2.12
The rst four problems of this assignment cover review material from sections 2.1-2.2. The last two prob
Lecture 16 - Internal energy
For a system of a single component, U must be a function of T, P (or T, v or P, v), since there are only two independent state functions Expand the differential of this state function, then, in T and v: dU = (U/T )V dT +