King Saud University – College Of Engineering
Dept of Chemical Engineering
CHE 551 TUTORIAL 1
1) -Locate the following points for Methane using T-S diagram and determine the
remaining properties.
A) S= 3.0J/g.K, T= 130K B) p=2atm S= 3.0j/gr.K C) h=200J/gr P=100atm
D)Sat liquid, P= 1 atm E) Sat vap
T= 140K
2) Determine the following parameters from a P-h Diagram for R22, IF TEV=10C, and Tc=35C
1 ----2 Isentropic compression, 2-----3 Isobar condensation,
expansion, 4------1 isobar evaporation.
3-----4 Isenthapic
3) – A Carnot cycle machine operates between the temperatures limits of t1=34C, and
t2= -10C, determine the COP, when it is operated as a refrigerating machine, and as a
heat engine.
- Plot the variation of the COP the evaporator temperatures for a condensing
temperature = 34C, Tev=10C, 0C, -8C, -20C.
4) Find the max , and Wmin for 1KW of cooling, for the following gas, Oxygen \
(90K), Nitrogen (77K), Methane (111K), Hydrogen (20.4K), Helium (4.2K), water
(373K) if To= 30C.
5) determine the exergy of the following points, and determine the loss of the exergy
across the equipement., if we assume that the gas molar flow rate is as follows, (pts 1
and2 = 1mole), pts3 =0.4 mole, pts 4, 5, 6 =0.7 mole.
1
2
4
5
3
6
King Saud University – College Of Engineering
Dept of Chemical Engineering
CHE 551 TUTORIAL 2
1) An ideal cycle vapor compression refrigerating system using R22 Operates
-
through a reversed carnot cycle with an evaprating temperature =-15 C, and a
condensing temperature = 45C, to provide a total cooling load =.The refrigerant
leaves the condenser as a saturated liquid and leaves the evaporator as a saturated
vapor.
Represent this cycle in P-h chart
Calculate the refrigerant effect, the mass flow rate of the refrigerant
Determine the ideal theoretical work, and power for the compressor
Calculate the coefficient of the performance for this cycle
2) The system descibed above is to be used to liquefy Ammonia in the evaporator.
IF The mass flow rate of the refrigerant is constant and = 1.2kg/sec, determine the
quantity of ammonia to be liquefied for the following conditions
a) NH3
tev= 212 K
b) NH3
tev = 265k
c) NH3
tev = 214 K
In each determine the ideal work required to drive the compressor.
King Saud University – College Of Engineering
Dept of Chemical Engineering
Che 551 Tutorial 3
1) A process for cooling nitrogen is shown in figure 1 and the associated properties of the
fluids are given in table 1. Calculate for the nitrogen cooler;
- the process efficiency
- The losses over the Joule/ Thompson valve and the nitrogen cooler.
Assume that the compressors and expander have an efficiency of 80percent
Data for Exergy calculations
T0= 20 C
For nitrogen h0= 11926 Kj/Kmol, so= 111.3Kj/kmol ho - Toso= -20700Kj/Kmol
For Freon 22 h0= 23429 Kj/Kmol, so= 98.83Kj/kmol ho - Toso= -5530KJKmol
Ho= enthalpy, To= absolute temperature so= entropy
PT
Pressure
Atm
Temperature
Flow
K
Kmol/hr
Enthalpy
KJ/Kmol
Exergy
KJ/Kmol
Nitrogen
1
2
3
4
5
6
10
11
12
18
19
6.2
13.6
13.5
29.6
29.5
42.7
40.0
6.5
6.4
1.45
1.35
309
41.3
313
416
313
361
183
113
169
173
118
1000
1000
1000
1000
1000
1000
1000
1000
1000
1063
1063
12340
15388
12432
15434
12340
13747
7974
6430
8184
8397
6760
4433
6927
6346
8804
8240
9303
10029
7642
5646
1806
3373
20252
28109
8112
9112
577.2
6808
5020
3291
Freon
14
15
16
17
1.05
15.1
15.0
1.15
235
387
313
235
13.1
13.1
13.1
13.1
King Saud University – College Of Engineering
Dept of Chemical Engineering
CHE 551 TUTORIAL 4
-
Pt
1
2
3
4
5
6
7
- A simple Linde cycle is used to liquefy air, as shown in figure 1.
- Represent this cycle in a T-S diagram
- Calculate the fraction liquefied and complete table 1
Determine the exergy supplied to the system, the exergy taken out of the system, and the
exergy loss.( excluding the compressor)
Locate the biggest exergy loss (heat exchanger or expansion valve)
Calculate the ideal work per kg liquefied
( no heat is assumed to enter or leave the equipmenT)
To=300K, Po= 1atm
So= 0.904Kcal.kg.K
T
P
K atm
300
174
86
----298
300
200
-1.3
----1.0
1.0
h
s
kcal/kg kcal/kg.k
113.8
66.4
---24.0
69.8
121.8
122.1
0.522
0.316
0.526
0.026
0.566
0.900
0.904
e
kcal/kg
--------------------------
M
kg/hr
1
------------------------
H
kcal/hr
---------------------------------
E
kcal/hr
----------------------------
King Saud University – College Of Engineering
Dept of Chemical Engineering
CHE 551 TUTORIAL 5
A Claude system is to be used for air liquefaction with air at 70 F, 14.7 Psia. The air is
compressed to 800 Psia and 60 percent of the compressed air is expanded in an engine
having an isentropic efficiency of 70 percent. The ait at the inlet to the expander is at
20F.
- Represent this cycle in a TS diagram
- Determine the net work supplied per unit of air compressed and per unit of liquid air produced
assuming that the expander work is utilised for compression.
- Determine the effect on the answers if a heat in leak of 3BTU/ lb air compressed.
King Saud University – College Of Engineering
Dept of Chemical Engineering
CHE 551 TUTORIAL 6
Q1
-A low temperature double distillation column is used to upgrade Natural gas conatining
80percent CH4, 20 percent Nitrogen (more volatile component) in order to produce pure (N2)
and s pure (CH4), by means of the low temeprature process as shown in figure. The binary feed
is initially at Pressure= P1, , the operating pressure of the lower column. The bottom product
from the lower column (E) contains 15 percent of N2 is saturated liquid, is expanded to a lower
pressure P2 which is the operating pressure of the top column. The overhead product of the
lower column (D) is pure Nitrogen and saturated liquid is first cooled and then expanded to P2 in
the top section of the upper column.. The main products obtained are pure Nitrogen (P), saturated
vapour, and pure Methane (B) saturated liquid..
- Locate points representing the various streams involved in the process on the
enthalpy composition diagram by explaining the method of location, the main assuptions
proposed
Q 2 A mixture of 60percent propylene and 40 percent propane is to be separated into
essentially pure components in a distillation column operating with a reflux ratio of 12:1.
The column is incorporated in a vapour recompression cycle as shown in figure 1.
On the basis of the data presented in figure 1
a) Determine the flow of propylene to the compressor per 100 kg of feed mixture.
b) Evaluate the total and minimum work required for the process and hence its
thermodynamic efficiency.