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