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Thermofluids Laboratory: Rankine Power Plant
Experiment Findings · September 2019
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MENG343: Thermofluids Lab
Lab#1: Rankine
Instructor:
John Valente
Student:
Wesam Alnahri 1259884
Date of Lab Activity:
September 18, 2019
Report Submission Date:
September 25, 2019
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Table of Contents
Abstract ........................................................................................................................................... 1
Theory ............................................................................................................................................. 1
Equipment ...................................................................................................................................... 2
Experimental Procedure ................................................................................................................ 3
Results............................................................................................................................................. 4
Conclusions .................................................................................................................................... 4
References ...................................................................................................................................... 6
Appendix ......................................................................................................................................... 7
Figures
Figure 1: Open Rankine cycle diagram. ......................................................................................... 3
Equations
Equation 1: Carnot efficiency. ........................................................................................................ 1
Equation 2: Turbine efficiency using enthalpies ............................................................................ 1
Equation 3: Boiler efficiency. ......................................................................................................... 1
Equation 4: Valve efficiency. ......................................................................................................... 2
Equation 5: Power plant efficiency. ................................................................................................ 2
Tables
Table 1: Efficiency of components and overall efficiency as well as Carnot. ................................ 4
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Abstract
The main purpose of this laboratory was becoming familiar with the operation of power plants
facilities. The laboratory consisted of a power plant mechanism resembling the Rankine cycle but
without a pump which is considered an open-cycle. The power plant mechanism consisted of a
boiler, propane, turbine, electric generator, condenser and valve. By measuring the temperature
and pressure in the boiler, turbine inlet, turbine outlet, condenser inlet, the voltage and current for
the generator, and the propane flow rate during steady state we were able to find the efficiency of
the power plant, boiler, and turbine.
Theory
The Rankine cycle converts the expansion of the fluid within the boiler from the heat input by the
fuel combustion into mechanical energy in the turbine which drives an electric generator that
converts the mechanical energy into electricity. However, in theory we can never exceed the
Carnot efficiency which is a function of highest and lowest temperatures of the fluid as expressed
in equation 1. The Carnot efficiency has many assumptions such as perfectly insulated apparatus
of the power plant which is not the case in our mechanism. Thus, we want to confirm that our
efficiency is below the Carnot efficiency and reason why so.
Equation 1: Car not efficiency.
𝜼𝑪𝒂𝒓𝒏𝒐𝒕 =
𝑻𝒉𝒐𝒕 − 𝑻𝒄𝒐𝒍𝒅
𝑻𝒄𝒐𝒍𝒅
=𝟏−
𝑻𝒉𝒐𝒕
𝑻𝒉𝒐𝒕
Equation 1
Equation 1 Note: where ηCarnot is the Carnot efficiency of the cycle, Thot is the boiler
temperature, and Tcold is the condenser temperature. The Carnot efficiency in theory determines
the highest efficiency to convert heat into mechanical energy by idealizing the system. For
instance, all processes are reversible, all components are perfectly insulated, friction of walls
are zero, friction of turbine is zero, and all mechanical energy are converted into electrical
energy in the generator.
Equation 2: Tur bine efficiency us ing enthalpies
𝜼𝑻𝒖𝒓𝒃𝒊𝒏𝒆
𝒉𝒊𝒏𝒍𝒆𝒕 − 𝒉𝒐𝒖𝒕𝒍𝒆𝒕
=
𝒉𝒊𝒏𝒍𝒆𝒕 − 𝒉𝒊𝒔𝒆𝒏𝒕𝒓𝒐𝒑𝒊𝒄
Equation 2
Equation 2 Note: The turbine efficiency using the actual and isentropic enthalpies at inlet and
outlet. The isentropic enthalpy is determined by assuming the entropy of inlet and outlet are the
same but at different pressures.
Equation 3: Bo iler efficiency.
𝜼𝑩𝒐𝒊𝒍𝒆𝒓 =
𝒎̇𝒔𝒕𝒆𝒂𝒎 (𝒉𝒊𝒏𝒍𝒆𝒕 − 𝒉𝒐𝒖𝒕𝒍𝒆𝒕 )
𝒎̇𝒑𝒓𝒐𝒑𝒂𝒏𝒆 𝑳𝑯𝑽𝒑𝒓𝒐𝒑𝒂𝒏𝒆
Equation 3
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Equation 3 Note: The boiler efficiency is the difference in enthalpies between inlet and outlet
multiplied by the mass flow rate of the vapor inside the cycle as a ratio to the amount of heat
input as the fuel mass flow rate multiplied by the lower heating value of the fuel.
Equation 4: Va lve efficiency.
𝜼𝑽𝒂𝒍𝒗𝒆 =
𝒉𝒊𝒏𝒍𝒆𝒕 − 𝒉𝒊𝒔𝒆𝒏𝒕𝒓𝒐𝒑𝒊𝒄
𝒉𝒊𝒏𝒍𝒆𝒕 − 𝒉𝒐𝒖𝒕𝒍𝒆𝒕
Equation 4
Equation 4 Note: The efficiency of the throttling valve is determine by examining the difference
between the inlet and exit enthalpies then compared to the case without change to determine
how efficient the flow was.
Equation 5: Power plant efficiency.
𝜼𝑷𝒐𝒘𝒆𝒓𝑷𝒍𝒂𝒏𝒕 =
𝑽𝑰
𝒎̇𝒑𝒓𝒐𝒑𝒂𝒏𝒆 𝑳𝑯𝑽𝒑𝒓𝒐𝒑𝒂𝒏𝒆
Equation 5
Equation 5 Note: The power plant efficiency is determined by the amount of heat added by the
fuel and how much of that heat was converted into electricity where VI gives the electrical
power.
Equipment
Open Rankine Cycle: the system consists of:
o Components:
• Boiler: well insulated container to heat the water.
• Turbine: blades that move when pushed by the steam to feed the generator.
• Condenser Tower: converts the steam back into liquid.
• Generator: converts the rotation of the turbine blades into electricity.
• Propane Tank: holds the fuel used to input heat to the boiler.
o Controls:
• Steam Admission Valve: used to adjust the flow of steam into the turbine.
• Gas Valve: used to adjust the flow of propane gas.
• Load Rheostat: used to adjust the load on the generator to maintain an appropriate RPM.
o
•
•
•
•
Indicators:
Boiler water level sight glass
Local pressure gauge
Voltmeter
Amperemeter
o
•
•
•
DAQ:
Propane volumetric flow rate
P and T at: (Boiler, Turbine Inlet, Turbine Outlet)
Volts
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•
•
Amps
Turbine RPM
Figure 1: Open Rankine cycle diagram.
Experimental Procedure
1. Making sure the gas valve is off, the master key is off, the boiler valve is off and all other
safety procedures are followed.
2. Plug in the propane tank.
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3. Sink the propane tank in water to check for leakage and to keep it cool.
4. Start the system.
5. Heat the boiler until it reaches 90/110 psig then preheat the turbine by slightly opening the
valve and adjusting the load accordingly until half the pressure.
6. Heat the boiler again while the valve is closed until it reaches 90/110 psig and manage to
keep the pressure at those values by balancing the valve and the load.
7. Taking note throughout the experiment from the DAQ, the water level, and the propane mass
Results
According to the retrieved data shown in the appendix, the efficiencies tabulated in table 1 were
calculated.
Table 1: Efficiency of components and overall efficiency as well as Carnot.
Run 1 (110psig)
Run 2 (90psig)
ηBoiler
19%
27.7%
ηTurbine
1.3%
2.7%
ηValve
6.4%
3.2%
ηCycle
0.02%
0.022%
ηCarnot
16.2%
23.3%
The setup time was around 18 mins for the second run and the steady state was around 11 mins.
Thus, assuming an average propane volumetric rate of 5.23 L/min, the propane mass used to reach
steady state is 188.3 g which yields 0.415 lb which produces heat of 8262 BTU.
The efficiencies are extremely low which can be due to the leakages such as within the valve and
the heat lost in the pipes and the boiler toward the surroundings. Moreover, the friction forces
inside the pipes especially if they were rusty although we did not have any obvious indication of
rust or pipe wall friction. Also, the bends of the pipes would affect the efficiency.
The sources of error in this lab are too many to account for in my opinion. To name some of error
sources, pipe friction, pipe bends, heat loss via pipes, heat loss via boiler, heat loss via heating
components, mass not really conserved (leakages), the imbalance between valve and rotation,
impurity of water, inaccuracy of basil level, water density during filling changes since temperature
changes and so on.
Conclusions
The efficiencies are extremely low mainly due to accounting for the heat input during the setup
period where it accounts to about more than half the time of the experiment. Moreover, the ideal
cycle is supposed to be well insulated but our experiment consisted of heat losses to the
environment. Also, the valve was leaking during the experiment and there was obvious water drops
as well as some vapor leakage aside from the condenser tower. Additionally, the cycle itself is not
closed which would also affect the efficiency since the condenser temperature is changing and the
actual input temperature of the boiler is not obvious. Furthermore, there was too many problems
with the data such as the start time of the pre-set phase and the end time for the actual experiment
especially in the second run. This caused the amount of propane used to be accounted for even
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though it was used as a setup process also the amount of water was not clear since the water was
filled more than the basil level in the experiment. In real life scenarios the ratio of fuel used for
setup to the ratio of steady state would be extremely low which would help increase the efficiency
of the power plant. The overall experiment is as expected in that our efficiency did not exceed the
Carnot efficiency and the turbine efficiency is lower than 10% and the boiler efficiency is lower
than 85%. Over all, the lab familiarized us with the reality of operating a power plant facility and
the obstacles associated with it more than power generation itself. In my opinion, the efficiencies
would have been better represented if the data was collected from the beginning (once the flame
of the propane ignited) to the end of putting out the flame. Furthermore, if the data was taken via
a flashdrive and if the lab introduction included clearer instruction of how to find the enthalpies
and what assumption are to be made. I believe that the lecture focused on operating the experiment
and give little insights of how to treat the data.
I expected the efficiency to be better at the higher pressure since at higher pressure the boiler’s
saturation temperature would be higher thus a higher efficiency since the Th is higher. However,
the lab showed better efficiency for the lower pressure. I believe it was mainly due to the
limitations and operational specifications of the Rankine cycle since the maximum allowable range
of the boiler pressure is less than 120psig and the higher pressure run (run 1) was an average of
110 psig. Thus, the experiment would have best represented at a 45 and 90, and 110 psig to
determine the differences between operation at the midrange of the boiler pressure and closer to
the maximums pressure.
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References
Propane LHV: https://h2tools.org/hyarc/calculator-tools/lower-and-higher-heating-values-fuels
BlackBoard File: MENG 343 F19 Instructional Lab on Rankine Cycle-1-5.
BlackBoard File: Module VI - Rankine Cycler.pdf
Thermodynamic properties found by XSteam via MATLAB retrieved from:
https://www.mathworks.com/matlabcentral/fileexchange/9817-x-steam-thermodynamicproperties-of-water-and-steam
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Appendix
Raw Data:
Group 1 Raw Data 110 PSIG
Time
Seconds
Elapsed
Seconds
Elapsed
Before
The
Reading
Boiler
Pressure
(PSIG)
Turb
Inlet
Press
(PSIG)
Turb
Outlet
Press
(PSIG)
Boiler
Temp
(C)
Turb
Inlet
Temp
(C)
Turb
Outlet
Temp
(C)
DC
Amps
(A)
DC
Volts
(V)
Turbine
RPM
Fuel
Flow
(L/min)
7:56:31
7:57:03
7:57:58
7:58:33
7:59:02
7:59:32
0
32
87
122
151
181
0
32
55
35
29
30
110
111.16
111.65
109.05
106.69
104.98
0.26
8.57
16.83
18.42
17.95
16.96
0.27
1.72
3.31
3.64
3.51
3.3
170
171
172
172
172
171
99
112
122
123
123
122
97
99
102
103
103
102
0
0.084
0.328
0.307
0.356
0.313
0
5.274
3.408
7.438
5.941
6.048
108.79
1392.7
936.77
1918.2
1550.9
1576.2
5.3
5.292
5.29
5.288
5.283
5.291
8:00:03
8:00:32
8:01:02
8:01:34
8:02:05
8:02:32
212
241
271
303
334
361
31
29
30
32
31
27
103.61
103.05
105
107.12
109.01
109.59
16.68
14.98
11.42
11.63
11.91
13.75
3.24
2.88
2.17
2.21
2.25
2.61
171
171
171
171
171
172
121
120
115
116
116
118
102
101
99
100
99
100
0.296
0.252
0.156
0.15
0.156
0.192
5.746
5.127
4.773
5.853
6.066
7.1
1504.4
1352.3
1282.5
1530.6
1582.9
1827.6
5.293
5.293
5.291
5.299
5.293
5.293
8:03:05
8:03:47
8:04:36
8:05:52
8:06:57
8:08:00
394
436
485
561
626
689
33
42
49
76
65
63
109.57
108.32
107.25
108.05
109.63
109.49
14.27
14.56
13.84
14.12
13.2
13.43
2.7
2.74
2.59
2.63
2.44
2.49
173
177
182
189
196
202
119
119
118
118
117
118
100
101
101
102
102
101
0.26
0.285
0.279
0.295
0.25
0.282
7.83
6.321
6.085
6.17
6.33
6.463
2015.6
1639.3
1581.8
1600.2
1684.2
1678.9
5.301
5.284
5.287
5.287
5.282
5.283
8:08:32
8:09:31
8:10:38
8:11:43
8:14:04
721
780
847
912
1053
32
59
67
65
141
109.53
109.48
108.69
109.93
109.01
13.61
12.67
12.56
11.61
12.57
2.53
2.32
2.28
2.09
2.26
206
212
220
228
248
118
117
128
129
126
101
101
101
101
102
0.29
0.255
0.259
0.239
0.27
6.497
7.061
6.268
6.006
6.617
1686
1823.8
1623.5
1558.7
1282.4
5.282
5.274
5.28
5.273
5.268
8:15:10
8:17:38
1119
1267
66
148
100.15
28.821
2.38
9.27
0.6
1.72
255
252
102
127
99
100
0.016
0.201
0.113
0.215
134.94
157.14
0.234
0.008
8:17:55
1284
17
23.523
6.74
1.3
2300 mL of Water Used During Operation at SSSF
250
7
122
100
0.089 0.144
149.57
0.008
0.969 Lbs of Propane Used During Entire Operation
Alnahri
Group 2 Raw Data 90 PSIG
Time
Seconds
Elapsed
Seconds
Elapsed
Before
The
Reading
Boiler
Pressure
(PSIG)
Turb
Inlet
Press
(PSIG)
Turb
Outlet
Press
(PSIG)
Boiler
Temp
(C)
Turb
Inlet
Temp
(C)
Turb
Outlet
Temp
(C)
DC
Amps
(A)
DC
Volts
(V)
Turbine
RPM
Fuel
Flow
(L/min)
0
0
0
88.723
13.55
2.7
165
118
99
0.229
6.375
1657.2
5.323
1:35
95
95
88.315
13.43
2.66
167
117
99
0.22
6.879
1780.4
5.322
3:00
180
85
90.208
11.74
2.28
174
116
98
0.191
7.107
1841.9
5.308
4:00
240
60
88.286
13.59
2.64
180
118
99
0.266
7.604
1954.7
5.307
5:15
315
75
88.08
12.08
2.32
187
116
98
0.25
8.278
2116.8
5.304
6:25
385
70
89.845
12.19
2.34
194
116
98
0.261
8.278
2117.9
5.301
7:45
465
80
88.58
10.47
2
202
114
99
0.209
7.561
1944.6
5.295
9:15
555
90
88.784
11.14
2.11
212
125
99
0.23
7.764
1993.5
5.298
10:25
625
70
88.452
12.29
2.31
222
128
100
0.269
8.349
2133.5
5.294
11:06
666
41
87.362
11.24
2.1
227
128
101
0.242
7.223
1845.1
2600 mL of Water Used During Operation at SSSF
0.836 Lbs of Propane Used During Entire Operation
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