Lab Final Report Heat Exchanger – check and make the fixes on my final report listed in the comment and fixed all the comment. Testing the Effect of Heat E
Lab Final Report Heat Exchanger – check and make the fixes on my final report listed in the comment and fixed all the comment. Testing the Effect of Heat Exchanger Type on Effectiveness in a Counter Current Flow,
and the Effect of Flow Configuration on the Effectiveness of a Shell and Tube Heat
Exchanger
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
Abstract:
This experiment had the purpose of comparing the performance of a tube and tube heat
exchanger and shell and tube heat exchanger under countercurrent flow by calculating the
effectiveness. The change in the effectiveness of the shell and tube heat exchanger between
countercurrent or co-current flow configurations were also compared.. For each data point, three
trials were done. The rate of flow will be kept constant at 0.252 kg per second. Each trial will
begin with a steady temperature of 40degrees F. A single trial took five minutes, and the readings
were done after fifteen seconds. A second experiment will be done three times and the readings
taken after every fifteen seconds, but unlike the first experiment, the initial setup will involve a
shell and tube heat exchanger in an arrangement of co-current configuration then the
configuration was changed to counter-current configuration. The process was repeated three
times and the readings taken down. Therefore, four sets of data were collected with each set
consisting of three trials. It was expected that the flow of the counter-current configuration 0.336
and it would give better effectiveness compared to co-current configuration which has flow
0.317 because of the arrangement of the tube and the shell. The mean effectiveness for each of
the trials ranged from 0.296±0.012 to 0.404±0.035. The shell and tube exchanger is also
expected to be more efficient than the tube and tube exchanger
2
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
Introduction:
In this lab the difference between two types of heat exchangers will be explored. In an
engineering setting equipment selection will be an integral part of the optimal operation of any
chemical process. It is important to know the technical limitations of different types of
equipment and applications that they are the most suited for. While this lab will be focusing on
the testable parameters with two different types of heat exchangers, this type of testing can be
expanded. For any application it is important to know how a piece of equipment will behave to
ensure the smooth operation of the process to limit downtime and financial loss. This type of
testing can be done on a pilot scale for many different applications to ensure the best operation
possible.
The objective of this lab is to compare the effectiveness of a shell and tube heat
exchanger to a tube and tube heat exchanger while being operated as counter current.
Additionally, the change in effectiveness of a shell and tube heat exchanger will be tested for co
current and counter current flows.
Theory:
Heat exchangers are equipment used to transfer heat energy from one fluid stream to
another. Different considerations in the design and sizing of heat exchangers is important to
minimize the cost of a heat exchanger while increasing the rate of heat transfer. Conduction and
convection are the two mechanisms that are present in heat exchangers and have the dominant
effect on heat transfer rates. Different materials and construction are an important way to
optimize heat exchangers and the latter is being considered for this lab. There are many different
types of construction for heat exchangers such as shell and tube, tube and tube, plate and frame
and double pipe. For this lab the effect of construction on the heat transfer will be explored
between the shell and tube and the tube and tube heat exchanger types.
Heat exchangers are extremely common pieces of equipment in all types of chemical
processes, and it is therefore important to be able to size them accordingly. There are two main
methods of sizing heat exchangers, the log mean temperature difference method, and the
effectiveness method. For this lab the effectiveness method will be used. The effectiveness
method is used when the size, type, flow rates, and inlet temperatures into the heat exchanger is
known but the outlet temperatures aren’t. For this approach, the first variable to be defined is the
effectiveness, which is defined as the ratio of the actual heat transfer rate over the maximum heat
transfer rate [1].
The actual heat transfer rate is easily calculated from the measured temperatures of the
inlet and outlet of the heat exchanger as seen in equation 1. This equation is a conservation of
energy equation for an open system. Several key assumptions must be true in order for the
equation to be valid. The outside of the heat exchanger is considered adiabatic so no heat is
transferred to the surroundings. The logical conclusion of this is that the only heat transfer that
occurs is between the two heat exchange fluids. In order for the testing to be as accurate as
3
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
possible, the hot water should be run through the inner tubes of the heat exchangers to make the
assumptions valid. This will have the added benefit of limiting possible exposure to hot heat
exchanger surfaces. Another assumption is that there are no reactions or work produced in the
heat exchanger. The actual heat transfer rate for a heat exchanger is calculated by multiplying the
mass flowrate ṁ by the specific heat capacity of water Cc, and the change in temperature from
the cold outlet to the cold inlet Tc,out and Tc,in respectively [1].
= ṁ ( , − , )
1
The next step in the effectiveness method is to calculate the maximum possible heat
transfer rate. The maximum heat transfer would occur at the maximum temperature difference
which is the difference between the inlet hot and cold fluid temperatures. The heat exchangers in
this lab will be using water for both of the fluids and because the temperature range influence on
the heat capacity is small, the heat capacity will be assumed to be constant at 4.187 kJ/kg K. This
leads to equation 3 the maximum possible heat transfer rate ̇ .
= ṁ ( ℎ, − , )
2
Where ṁ is the mass flow rate, Th,in is the temperature of the hot inlet, and Tc,in is the temperature
of the cold side inlet.
Once both of these heat transfer rates have been calculated, the effectiveness of the heat
exchanger can be calculated by dividing the actual heat transfer rate (equation 1) by the
maximum heat transfer rate (equation 2). There is another method for calculating the
effectiveness of heat exchangers called the NTU method as showed in (equation 3). Where the
effectiveness factor, c is is the capacity ratio, and NTU is the number of transfer units. While the
counter current effectiveness can be computed by the formula unfortunately, in this lab the heat
transfer coefficients for the heat exchangers in use are unavailable and therefore this method will
not be possible to use. Once the effectiveness for all of the trials have been calculated, as well as
the effectiveness for the co current and counter current flow they can be compared using
statistical tests as described in the statistical analysis section of the report. Some additional
parameters that could be changed to test their effects on effectiveness would be to vary the flow
rate of water through the heat exchangers, add insulation to the outside of the heat exchangers,
and to run the hot water on the outside of the heat exchanger. The effects of the last two would
be particularly interesting to test how well the conservation of energy equations assumptions
hold up to reality.
1− [− (1− )]
= 1− [− (1− )]
(Equation 3)
4
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
Methods
Apparatus
For this lab two different heat exchangers was used, a tube and tube, and shell and tube
heat exchanger both manufactured by the company Exergy. Three trials were conducted on each
of the heat exchangers. The flow was kept constant at four gallons per minute by the rotameter. It
was important to make sure that they are equal after changing the heat exchanger, because the
heat exchangers have different pressure drops. Each heat exchanger was setup in the appropriate
flow configuration until the temperature sensors on both the inlets and outlets have reached
steady state. Steady state was defined as less than a one degree deviation in any of the
temperature probes over a fifteen second period. Once the readings are recorded the heat
exchanger was disconnected, drained, and the other heat exchanger will be set up for testing.
Figure 1 shows the setup that will be used for both heat exchangers. Note the counter current
flow configuration.
Figure 1: Schematic for testing effectiveness of tube and
tube and shell and tube heat exchangers
Experimental Design
The purpose of this experiment is to test the effectiveness of two different types of heat
exchangers and the effectiveness of the shell and tube heat exchanger with co current and
counter current flow. The configuration of all of the equipment can be seen in figure 1 above. In
order to be able to run a t-test on the results both of the datasets collected must only have one
variable changing between the two. For the first test, this will be the heat exchanger, and for the
second test this will be the flow configuration through the heat exchanger. For the first
experiment the type of heat exchanger is the independent variable. The parameters that will not
be varied in the two tests are the water flow rates (4GPM), and the configuration of the flow
5
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
within the heat exchanger. For the second experiment, the flow configuration will be the
independent variable. The parameters that will not be varied will be water flow (4 GPM) rate and
the heat exchanger type. A random number generator will be used to determine which of the
heat exchangers will be tested first. Each trial will begin when the temperatures of the inlet and
outlet streams have reached steady state, and will be conducted for five minutes. Steady state, as
previously defined, will be reached when the temperature of the sensors does not deviate more
than one degree F over the course of fifteen seconds. After the first trial has been run they will
alternate until all of three trials are completed to get a representative sample. For the second
experiment the shell and tube heat exchanger will be first setup in a co current configuration and
one trial will be completed and then alternated with the counter current configuration for three
trials. Readings will be taken every fifteen seconds for five minutes for each trial after the
temperature has reached steady state.
Results and Discussion:
The two types exchangers were tested three times and the results are shown in the Tables
1 to 12 below. Temperature data was collected for the shell and tube heat exchanger for the two
different flow configurations, each configuration being done three times. The results are shown
in Tables 1 to 6. The inlet temperature was 40 degrees Celsius with no deviation in their
readings. However, for the first trial of tube and tube heat exchanger, the cold inlet temperature
was 42 degrees F. The last three columns of the tables show the results after working out Qmax
and QActual and the efficiency.
From the results, the mean effectiveness of the shell and tube heat exchanger was
evaluated to be more while the tube and tube was less. Its effectiveness was evaluated to be more
by about 0.12 of the tube and tube exchanger. Hence, it is better than the tube and tube heat
exchanger. From the two configurations done using shell and tube exchanger, co-current
configuration gave higher mean effectiveness.
Since the flow rate was too high at 0.25 kg/s, the effectiveness of the co-current was
higher than the counter current. The mean effectiveness for the co-current was 0.355±8.28E-03,
and the mean effectiveness for the countercurrent was 0.301±7.16E-03.
The t-test showed that the P value was 2.09E-46 which is smaller than the alpha value. This
indicate that the shell and tube and tube and tube heat exchanger were different at 0.25 kg/s flow
rate and the null hypothesis was rejected.
Conclusion:
To sum up, since the efficiency of the shell and tube exchanger is higher than that of tube
and tube exchanger, it can be concluded that shell and tube is more efficient than tube and tube.
Furthermore, results of the second experiment indicate that co-current configuration had higher
6
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
effectiveness. Hence, it should be more preferred over the counter-current configuration. So,
decreasing the flow rate for the resident time will indicate an excellent data.
Appendix:
Table 1: Data Collected
7
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
HX Type
Shell and Tube
Trial 1
Cold Inlet
Hot Inlet
Cold Outlet
Hot Outlet
Time
Temp
Temp
Temp
Temp
0:00
40
120
68
90
Shell and Tube
0:15
40
120
68
91
Shell and Tube
0:30
40
120
69
91
Shell and Tube
0:45
39.5
120
69
91
Shell and Tube
1:00
39.5
120
69
91
Shell and Tube
1:15
39.5
120
69
91
Shell and Tube
1:30
40
120
69
91
Shell and Tube
1:45
40
120
69
91
Shell and Tube
2:00
40
120
69
91
Shell and Tube
2:15
40
120
69
91
Shell and Tube
2:30
40
120
69
91
Shell and Tube
2:45
40
120
69
91
Shell and Tube
3:00
40
120
68
91
Shell and Tube
3:15
40
120
68
91
Shell and Tube
3:30
40
120
67
91
Shell and Tube
3:45
40
120
67
91
Shell and Tube
4:00
40
120
67
91
Shell and Tube
4:15
40
120
67
91
Shell and Tube
4:30
40
120
67
91
Shell and Tube
4:45
40
120
67
91
Shell and Tube
5:00
40
120
67
91
HX Type
Shell and Tube
Trail 2
Cold Inlet
Hot Inlet
Temp
Temp
Time
0:00
40
Cold Outlet
Temp
122
68
Hot Outlet
Temp
92
8
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
Shell and Tube
0:15
40
122
68
92
Shell and Tube
0:30
40
122
68
92
Shell and Tube
0:45
40
122
68
92
Shell and Tube
1:00
40
122
68
92
Shell and Tube
1:15
40
122
68
92
Shell and Tube
1:30
40
122
68
92
Shell and Tube
1:45
40
122
68
92
Shell and Tube
2:00
40
122
68
92
Shell and Tube
2:15
40
122
68
92
Shell and Tube
2:30
40
122
68
92
Shell and Tube
2:45
40
122
68
92
Shell and Tube
3:00
40
122
68
92
Shell and Tube
3:15
40
122
68
92
Shell and Tube
3:30
40
122
68
92
Shell and Tube
3:45
40
122
68
92
Shell and Tube
4:00
40
122
68
92
Shell and Tube
4:15
40
122
68
92
Shell and Tube
4:30
40
122
68
92
Shell and Tube
4:45
40
122
68
92
Shell and Tube
5:00
40
122
68
92
HX Type
Shell and Tube
Trail 3
Cold Inlet
Hot Inlet
Temp
Temp
Time
0:00
40
Cold Outlet
Temp
121
66
Hot Outlet
Temp
92
9
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
Shell and Tube
0:15
40
121
66
92
Shell and Tube
0:30
40
121
67
92
Shell and Tube
0:45
40
121
67
92
Shell and Tube
1:00
40
121
67
92
Shell and Tube
1:15
40
121
67
92
Shell and Tube
1:30
40
121
67
92
Shell and Tube
1:45
40
121
67
92
Shell and Tube
2:00
40
121
67
92
Shell and Tube
2:15
40
121
67
92
Shell and Tube
2:30
40
121
67
92
Shell and Tube
2:45
40
121
67
92
Shell and Tube
3:00
40
121
67
92
Shell and Tube
3:15
40
121
67
92
Shell and Tube
3:30
40
121
67
92
Shell and Tube
3:45
40
121
67
92
Shell and Tube
4:00
40
121
67
92
Shell and Tube
4:15
40
121
67
92
Shell and Tube
4:30
40
121
67
92
Shell and Tube
4:45
40
121
67
92
Shell and Tube
5:00
40
121
67
92
Type
Tube and Tube
Time
Trail 1
Cold Inlet
Hot Inlet
Cold Outlet Hot Outlet
Temp
Temp
Temp
Temp
0:00
45
119
69
97
10
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Type
Tube and Tube
0:15
0:30
0:45
1:00
1:15
1:30
1:45
2:00
2:15
2:30
2:45
3:00
3:15
3:30
3:45
4:00
4:15
4:30
4:45
5:00
44
43
43
43
43
42
42
42
42
42
42
42
42
42
42
42
42
42
42
42
119
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
Trail 2
Cold Inlet
Hot Inlet
Temp
Temp
Time
0:00
40
68
68
68
68
68
68
68
68
68
68
68
68
68
68
68
68
68
68
68
68
Cold Outlet
Temp
119
65
97
97
97
97
97
97
96
96
96
96
96
96
96
97
97
97
97
97
98
98
Hot Outlet
Temp
95
11
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
Tube and Tube
0:15
40
119
65
95
Tube and Tube
0:30
40
120
65
95
Tube and Tube
0:45
40
120
65
95
Tube and Tube
1:00
40
120
64
95
Tube and Tube
1:15
40
120
64
95
Tube and Tube
1:30
40
120
64
95
Tube and Tube
1:45
40
120
64
95
Tube and Tube
2:00
40
120
64
95
Tube and Tube
2:15
40
120
64
95
Tube and Tube
2:30
40
120
64
95
Tube and Tube
2:45
40
120
64
95
Tube and Tube
3:00
39
120
64
95
Tube and Tube
3:15
39
120
64
95
Tube and Tube
3:30
39
120
64
95
Tube and Tube
3:45
39
120
63
96
Tube and Tube
4:00
39
120
63
96
Tube and Tube
4:15
39
120
63
96
Tube and Tube
4:30
39
120
63
96
Tube and Tube
4:45
39
120
63
96
Tube and Tube
5:00
39
121
63
96
Type
Time
Trail 3
Cold Inlet
Hot Inlet
Temp
Temp
Cold Outlet
Temp
Hot Outlet
Temp
12
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
Tube and Tube
0:00
0:15
0:30
0:45
1:00
1:15
1:30
1:45
2:00
2:15
2:30
2:45
3:00
3:15
3:30
3:45
4:00
4:15
4:30
4:45
5:00
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
119
119
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
96
Trail 1
Type
cross current
Cold Inlet
Temp
Time
0:00
Hot Inlet
Temp
40
Cold Outlet
Hot Outlet
Temp
Temp
121
68
91
13
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
cross current
0:15
40
121
68
91
cross current
0:30
40
121
68
91
cross current
0:45
40
121
68
91
cross current
1:00
40
121
68
91
cross current
1:15
40
121
68
91
cross current
1:30
40
121
68
91
cross current
1:45
40
121
68
91
cross current
2:00
40
121
68
91
cross current
2:15
40
121
68
91
cross current
2:30
40
121
68
91
cross current
2:45
40
121
68
91
cross current
3:00
40
121
68
91
cross current
3:15
40
121
68
91
cross current
3:30
40
121
68
91
cross current
3:45
40
121
68
91
cross current
4:00
40
121
68
91
cross current
4:15
40
121
68
91
cross current
4:30
40
121
68
91
cross current
4:45
40
121
68
91
cross current
5:00
40
121
68
91
Type
Time
Trail 2
Cold Inlet
Hot Inlet
Temp
Temp
Cold Outlet
Temp
Hot Outlet
Temp
14
Sherwood, Alhilal, Alanazi, Alhumaidan- group T2
cross current
0:00
40
121
65
91
cross current
0:15
40
121
65
91
cross current
0:30
40
121
65
91
cross current
0:45
40
121
66
91
cross current
1:00
40
121
66
91
cross current
1:15
40
121
66
91
cross current
1:30
40
121
66
91
cross current
1:45
40
121
66
91
cross current
2:00
40
121
66
91
cross current
2:15
40
121
66
91
cross current
2:30
40
121
66
91
cross current
2:45
40
121
…
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