ABSTRACT
This experiment was about the study of plate heat exchanger (PHE). PHE is one of the
heat exchanger used in industry and is more effective than the shell and tube heat exchanger.
The objectives of this experiment were to calculate and analyse heat transfer at steady state,
to determine effect of liquid flow rate on heat transfer and to compare effectiveness of flow
arrangement namely co current vs counter current.
The experiment has two parts which were Experiment A and Experiment B. The
Experiment A was Counter-Current Plate Heat Exchanger while Experiment B was Cocurrent Plate Heat Exchanger. For Experiment A, the valves HV5, HV7, HV9, HV10, HV12,
and HV13 were set as open. Next, the hot tank temperature was set at 50◦C then the pump
(P1, P2) and air cooler were switched on. Then, valve HV1 was adjusted to set flow rate for
hot water at a constant 10 LPM while HV4 to set the flow rate cold water stream. Then, the
system was allowed to reach the steady state. The data related were recorded. The steps were
repeated for next three different cold water flow rate. While in Experiment B, the valves
HV7, HV8, HV11, HV12 and HV13 were set as open. The rest of the procedures are similar
to the experiment A. After finishing everything, the equipment was shutted down.
As the flow rate of cold water increases, the temperature outlet for both hot and cold
stream decreases. However, the temperature outlet for counter current is higher than the cocurrent. Generally, the result shows that heat transfer is more effective in counter current flow
than co-current.
1
METHODOLOGY
Experiment A: Counter-Current Plate Heat Exchanger
The general start up
procedures were carried
out. HV5, HV7, HV9,
HV10, HV12 and HV13
opened
Valves HV1 was
adjusted to set flow
rate for hot water
stream and HV4 was
adjusted to set the
flow rate for cold
water stream
The hot tank temperature
was set at 50◦C. When the
temperature was constant,
the pump (P1,P2) and air
cooler were switched on
The system was allowed
to reach the steady state.
The data related were
recorded
Step 3 until 5 were
repeated for next 3
different cold water
flowrate. The equipment
was shutted down after
finishing the experiment.
Experiment B: Co-current Plate Heat Exchanger
The general start up
procedures were carried
out. HV7, HV8, HV11,
HV12 and HV13
opened.
Valves HV1 was
adjusted to set flow rate
for hot water stream and
HV4 was adjusted to set
the flow rate cold water
stream.
The hot tank temperature
was set at 50◦C. When the
temperature was
concstant, the pump
(P1,P2) and air cooler
were switched on
The system was allowed
to reach the steady state.
The data related were
recorded
Step 3 until 5 were
repeated for next 3
different cold water
flowrate same as
counter current case.
The equipment was
shut down after
finishing the
experiment.
2
RESULT
FLOW RATE 1 (FI1):
Flow Rate 2
(FI2)
LPM
Hot Water
Inlet
(TT1 or TI1)
(oC)
Hot Water
Outlet
(TT2 or TI2)
(oC)
Cold Water
Outlet
(TT3 or TI3)
(oC)
Cold Water
Inlet
(TT4 or TI4)
(oC)
Actual
Temperature
(°C)
5
52.12
42.94
45.16
32.00
49.40
10
52.40
40.86
42.02
32.32
50.10
15
52.28
39.40
38.46
32.94
49.20
20
52.24
38.68
38.62
33.46
49.80
Table 1: Counter-Current Plate Heat Exchanger Data Analysis
FLOW RATE 1 (FI1):
Flow Rate 2
(FI2)
LPM
Hot Water
Inlet
(TT1 or TI1)
(oC)
Hot Water
Outlet
(TT2 or TI2)
(oC)
Cold Water
Inlet
(TT3 or TI3)
(oC)
Cold Water
Outlet
(TT4 or TI4)
(oC)
Actual
Temperature
(oC)
5
51.26
43.86
33.60
42.68
50.00
10
52.16
42.78
33.78
40.98
50.10
15
52.18
41.30
33.84
39.24
48.40
20
52.19
40.00
34.92
37.84
50.30
Table 2: Co-Current Plate Heat Exchanger Data Analysis
3
DISCUSSION
Heat Loss and Efficiency
As the flow rate is in volumetric unit, the flow rate has to be changed to mass unit.
Volumetric flow rate (LPM)
Mass flow rate (kg/s)
5
0.0833
10
0.1667
15
0.2500
20
0.3333
Table 3: Conversion of Volumetric Flow Rate to Mass Flow Rate
Heat Load, 𝑞ℎ = 𝑚̇ℎ 𝑐𝑝 (𝑇ℎ𝑖 − 𝑇ℎ𝑜 )
Heat Absorbed, 𝑞𝑐 = 𝑚̇ 𝑐 𝑐𝑝 (𝑇𝑐𝑜 − 𝑇𝑐𝑖 )
Heat loss, 𝑞 = 𝑞ℎ − 𝑞𝑐
Efficiency, η = (𝑞𝑐 /𝑞ℎ ) × 100%
𝑚ℎ = 𝑚𝑎𝑠𝑠 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑓𝑜𝑟 ℎ𝑜𝑡 𝑠𝑡𝑟𝑒𝑎𝑚
𝑚𝑐 = 𝑚𝑎𝑠𝑠 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑓𝑜𝑟 𝑐𝑜𝑙𝑑 𝑠𝑡𝑟𝑒𝑎𝑚
𝑐𝑝 = 𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑐 ℎ𝑒𝑎𝑡 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟
𝑇ℎ𝑖 = 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑖𝑛𝑙𝑒𝑡 𝑜𝑓 ℎ𝑜𝑡 𝑠𝑡𝑟𝑒𝑎𝑚
𝑇ℎ𝑜 = 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑜𝑢𝑡𝑙𝑒𝑡 𝑜𝑓 ℎ𝑜𝑡 𝑠𝑡𝑟𝑒𝑎𝑚
𝑇𝑐𝑜 = 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑜𝑢𝑡𝑙𝑒𝑡 𝑜𝑓 𝑐𝑜𝑙𝑑 𝑠𝑡𝑟𝑒𝑎𝑚
𝑇𝑐𝑖 = 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑖𝑛𝑙𝑒𝑡 𝑜𝑓 𝑐𝑜𝑙𝑑 𝑠𝑡𝑟𝑒𝑎𝑚
By assuming that C𝑝 of water is 4.19 kJ/kgoC. Then, we can calculate heat loss and efficiency
by using the above equation:
Counter Current Process
𝐦̇ 𝐡
(kg/s)
𝐦̇ 𝐜
(kg/s)
Heat Load,
qh (Kj/s)
Heat
Absorbed,
qc (Kj/s)
Heat Loss,
q (Kj/s)
Efficiency, 𝛈
(%)
0.1667
0.0833
5.1687
4.5932
0.5755
88.87
0.1667
0.1667
6.5517
6.7752
-0.2238
103.41
0.1667
0.2500
7.5994
6.3060
1.2934
82.98
0.1667
0.3333
8.5144
7.2061
1.3083
84.63
Table 4: Heat Loss and Efficiency Percentage of Counter Current Process
4
Co-Current Process
𝐦̇ 𝐡
(kg/s)
𝐦̇ 𝐜
(kg/s)
Heat Load,
qh (Kj/s)
Heat
Absorbed,
qc (Kj/s)
Heat Loss,
q (Kj/s)
Efficiency, 𝛈
(%)
0.1667
0.0833
5.1687
3.1692
1.9995
61.32
0.1667
0.1667
5.8532
5.7275
0.1257
97.85
0.1667
0.2500
7.5994
6.6285
0.9709
87.22
0.1667
0.3333
8.4795
4.7786
3.7009
56.35
Table 5: Heat Loss and Efficiency Percentage of Co-Current Process
Log Mean Temperature, ∆Tm
For Counter current flow:
For Co-current flow:
Where:
T1 – Inlet temperature of hot stream
T2 – Outlet temperature of hot stream
t1 – Inlet temperature of cold stream
t2 – Outlet temperature of cold stream
Flowrate 1(FT1)
(LPM)
5.00
10.00
15.00
20.00
(T1-t2) –(T2 – t1)
Ln(T1-t2)/(T2-t1)
∆Τm
(K)
(K)
(K)
-1.68
-0.1788
9.395
2.18
0.2169
10.05
5.48
0.5508
9.9497
9.27
1.0384
8.9269
Table 6: Log Mean Temperature for Counter Current Flow
5
Flowrate 2(FT2)
(LPM)
5.00
10.00
15.00
20.00
(T1-t1) –(T2 – t2)
Ln(T1-t1)/(T2-t2)
∆Τm
(K)
(K)
(K)
16.48
2.7058
16.58
2.3180
16.28
2.1864
15.11
2.0789
Table 7: Log Mean Temperature for Co-Current Flow
6.0906
7.1527
7.4461
7.2684
Heat Transfer Coefficient
𝑼=
𝒒𝑨𝑽𝑮
𝑨∆𝑻𝒍𝒎
𝑈 = 𝐻𝑒𝑎𝑡 𝑡𝑟𝑎𝑛𝑠𝑓𝑒𝑟 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 (𝑘𝑊 ⁄𝑚2 𝐾)
𝑞𝐴𝑉𝐺 = 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 ℎ𝑒𝑎𝑡 𝑡𝑟𝑎𝑛𝑠𝑓𝑒𝑟 𝑟𝑎𝑡𝑒 (𝑘𝑊)
𝐴 = 𝐴𝑟𝑒𝑎 𝑜𝑓 ℎ𝑒𝑎𝑡 𝑒𝑥𝑐ℎ𝑎𝑛𝑔𝑒𝑟 (m2)
∆𝑇𝑙𝑚 = 𝐿𝑜𝑔 − 𝑚𝑒𝑎𝑛 − 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 (K)
𝑞𝐴𝑉𝐺 =
𝐻𝑒𝑎𝑡 𝐿𝑜𝑎𝑑 + 𝐻𝑒𝑎𝑡 𝐴𝑏𝑠𝑜𝑟𝑏
2
𝐴 = Total plate area × Number of plates
𝑑𝑇 −𝑑𝑇
2
1
𝑇𝑙𝑚 = ln(𝑑𝑇
/𝑑𝑇
2
Mass flow
rate of cold
stream (kg/s)
0.0833
0.1667
0.2500
0.3333
Mass flow
rate of cold
stream (kg/s)
0.0833
0.1667
0.2500
0.3333
2)
Average heat
Area of heat
Log-MeanHeat transfer
2
transfer rate
exchanger (m )
Temperature (K) coefficient
(kW)
(kW/m2K)
4.8810
28.8
9.395
0.01804
6.6635
28.8
10.05
0.02302
6.9527
28.8
9.9497
0.02426
7.8603
28.8
8.9269
0.03057
Table 8: Heat Transfer Coefficient, U for Counter Current Flow
Average heat
Area of heat
Log-MeanHeat transfer
2
transfer rate
exchanger (m )
Temperature (K)
coefficient
(kW)
(kW/m2K)
4.1690
28.8
6.0906
0.02377
5.7904
28.8
7.1527
0.02811
7.1140
28.8
7.4461
0.03317
6.6291
28.8
7.2684
0.03167
Table 9: Heat Transfer Coefficient, U for Co Current Flow
6
Plate Coefficient of Counter Current Flow
Flow rate of cold
T2-T1 (K)
lnT2/T1 (K)
Plate Coefficient
stream (kg/s)
0.0833
-9.18
-0.1937
24.62
0.1667
-11.54
-0.2488
30.75
0.2500
-12.88
-0.2828
31.82
0.3333
-13.56
-0.3005
39.73
Table 10: Clod Stream Plate Coefficient for Counter Current Flow
Plate Coefficient of Co-Current Flow
Flow rate of cold
T2-T1 (K)
lnT2/T1 (K)
Plate Coefficient
stream (kg/s)
0.0833
-7.40
-0.1559
47.47
0.1667
-8.38
-0.1751
47.85
0.2500
-10.88
-0.2338
46.53
0.3333
-12.19
-0.2660
45.83
Table 11: Hot Stream Plate Coefficient for Co-Current Flow
Heat Transfer Coefficient (kW/m2K)
Heat Transfer Coefficient vs Cold Water Flow Rate
0.035
0.03
0.025
0.02
0.015
0.01
0.005
0
5
10
15
20
Flow Rate (LPM)
Counter Current
Co Current
Figure 1: The Graph of Heat Transfer Coefficient vs Cold Water Flow Rate
7
Efficiency vs Cold Water Flow Rate
120
Efficiency (%)
100
80
60
40
20
0
5
10
15
20
Flow Rate (LPM)
Counter current
Co current
Figure 2: The Graph of Efficiency vs Clod Water Flow Rate
Based on the graph above, it shows that the higher the flow rate, the higher the heat
transfer coefficient. However, heat transfer coefficient for co current is higher than the co
current. This experimental result is not right as heat transfer coefficient for counter current
should be higher than the co current. This is because the higher the heat transfer coefficient,
the higher the heat transfer rate. The higher the heat transfer rate, the higher the percentage of
efficiency. This error could be possibly because of some technical errors like the air
resistance as the experiment was done in large laboratory that the fans were all facing toward
the plate heat exchanger. Besides, it may be due to the inconsistent of flow rate as it
fluctuated. Then, it probably because of parallax error while adjusting the flow rate because
the digital reading was not accurate too. Plus, it may be due to the heat loss or heat gain from
the environment that causes the slight change in the reading.
The graph also shows that counter current flow has higher efficiency than co current.
This is because for a co current flow, the hot stream and cold stream mean temperature
differences are large and decrease gradually. Whereas in a counter current flow, the mean
temperature differences between the two streams are negligible in fluctuation and fairly
consistent. LMTD is also higher in counter current flow than the co current flow. This is
because heat transfer depends largely on the temperature difference, therefore counter current
flow is better.
8
CONCLUSION & RECOMMENDATIONS
As the conclusions, the heat transfer process increased for all the conditions by
increasing time. The effect of liquid flow rate on the overall heat transfer coefficient shows
that the higher the flow rate, the higher the heat transfer coefficient. This means flow rate is
directly proportional to the heat transfer coefficient.
In co-current process, the temperature outlet of hot water stream is always higher
than the cold water stream. In counter-current process temperature outlet of hot water is also
higher than the cold water. This means that counter current process has higher effectiveness
than co-current process. The objectives of the experiment are achieved.
There are few recommendations for this experiment. Firstly, set the flow rate for the
plate exchanger accordingly and right to avoid faulty in heat exchanging reading. Then, avoid
the plate exchanger away from wind that could affect the heat loss during experiment.
Finally, measure the liquid flow rate on heat transfer periodically and calculate the average
for more subtle result.
9
REFERENCE
1. Fundamentals of Heat Exchanger Design, R.K. Shah, August 2003.
2. Process Heat Transfer: Principles, Applications and Rules of Thumb, Robert W. Serth
& Thomas Lestina, March 2007.
3. Fouling of Heat Exchangers, T.R. Bott, 1995.
4. Basmadjian, D. (2007). Mass Transfer and Separation Processes: Principles and
applications. Boca Raton: CRC Press.
5. Geankoplis, C. J. (1995). Transport process and unit operations. Engelwood Cliffs,
NJ.
10
APPENDICES
The main control panel of the plate
heat exchanger.
There are two tanks which
containing cold water (left) and
hot water (right).
11