Lab_Experiment_8_1

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Lab Experiment #8: Centrifugal pump CE 336: Fluids Mechanic Laboratory Instructor: Andres Acosta, MS, PE Submitted by: Steven Ramirez Eddie Rangel Selena Nguyen Shakir Shihabudeen Justin Nguyen Date of performing lab experiment: 11/30/2022 Date of submitting lab report: 12/19/2022 Introduction
1 This experiment examines the efficiency of the pump and the arrangement of the pumps singly and parallel. The pump's overall head is calculated by reading the pressure head of its input and output gauges. Calculating the system's efficiency can be done using its total head. To derive a total head equation, Bernoulli's equation will be combined with other assumptions. To evaluate the performance of a centrifugal pump, use its total head found. Purpose of Study The objective of this experiment is to determine the characteristics of a centrifugal pump. We will operate a single pump as well as two pumps in parallel. At a fixed motor speed, the flow rates through the pumps will be varied and corresponding efficiency of the pump will be determined. We will compute pump efficiency at various other operating speeds. Theory Centrifugal pumps are radial flow rotodynamic machines. Fluid enters the rotor or impeller and is thrown outwards by the centrifugal action. Because of the high speed of rotation, liquid acquires a high kinetic energy and is thrown by centrifugal action. Figure 1. Centrifugal pump The total head a pump provides H = P 2 P 1 ? +( z 2 z 1 )+ V 2 2 V 2 1 2 g On the experimental apparatus, diameters of the inlet and outlet pipes are similar, so, the velocity head difference is considered insignificant. Therefore, H = P 2 P 1 ? +( z 2 z 1 )+ 0 Pressure heads can be directly read in meters of H 2 O from the inlet and teh outlet gauge of the test apparatus. The equation can be written as, H =( h 2 h 1 )+( z 2 z 1 )=( h 2 h 1 )+ h d Datum is taken through the center of the pump impeller and each position is given a datum head correction factor. Following variables are used to measure pump characteristics or performance,
2 Qt = V / t Wo = γ QtH Power W ( ¿¿ o / W i ) × 100% ( ¿¿ out / Power ¿ ) × 100% = ¿ η p = ¿ Where Q t is the flow rate through the pump, W o is the power output and W i is the power input. W i is directly read the value from the inverter, explained in the procedure. Equipment A stopwatch (phone) F1-27 Centrifugal pump test accessory Hydraulic bench F1-10 Equipment Diagram: Figure 2. Equipment Setup Figure 2.2 Single Pump Setup
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3 Figure 2.3 Parallel Pump Setup Experimental Setup & Procedures: - Experimental Set-Up The F1-27 pump will be used to as the single pump for this experiment 1) The inlet of the single pump should be connected to the sump drain valve of the F1- 10.The sump drain valve should be left fully open. 2) Place the discharge manifold on the operating channel of the hydraulic bench. 3) The outlet of the single pump should be connected to the discharge manifold. The F1-27 pump will also be used in parallel with the pump in the hydraulic bench. 1) The inlet of the F1-27 pump should be connected to the sump drain valve of the F1-10 and the sump drain valve should be fully open. 2) The discharge manifold will be on the operating channel of the bench. 3) The outlet of the F1-27 will be connected to the end of the Tee connector. One end of the Tee connector will be connected to the outlet of the hydraulic bench. The other outlet will be connected to the discharge manifold. - Procedure for Single Pump Operation 1) The sump drain valve on the hydraulic bench should be open. 2) The discharge control valve on the F1-27 should be kept closed. 3) The motor should be turned on and be set to 50.00 hz. 4) The FUNC/DATA key can be used to through different settings and the up/down key can be used to change the motor’s speed. 5) The discharge control valve can open fully. Take measurements of the inlet and outlet pressure head gauges. 6) To get the flow rate, either use the table that is in the lab manual, if the water is above 1.4 L/s. If it is below, you must find how long it takes to get 5L of water. 7) Slightly close the discharge control valve and get the measurements of the inlet + outlet pressure head gauges. 8) Once the valve is fully closed, get the data for no flow rate. 9) Repeat steps 5-8, for 45 Hz, 40 Hz, 35 Hz, and 30 Hz. - Procedure for Parallel Pump Operation
4 1) Keep the control valve on the hydraulic bench closed and the sump valve open. Keep the discharge valve closed as well. 2) Turn on the hydraulic bench and open the control valve fully. 3) The motor should be turned on as well and set to 50 Hz. 4) Fully open the discharge valve 5) Change the settings by having the valve fully open to fully closed. Record the inlet and outlet pressure head gauges. The outlet head can be read from the F1-27 gauge and the outlet head can be read from the discharge control manifold. 6) For flow rates below 1.4 L/s, record how long it takes to get 5L of water in the tank 7) For flow rates over 1.4 L/s, get the flow rate from the table from the lab manual. To do this remove the sealing ball and weight from the tank. Let the water level in the tank stabilize before getting the reading value from the tank. Calculations: Table 1: Reference flow rate Scale Reading (liters) Flow rate (L/s) Scale Readings (liters) Flow rate (L/s) 0 1.41 20 2.00 1 1.44 21 2.02 2 1.48 22 2.05 3 1.51 23 2.07 4 1.54 24 2.09 5 1.57 25 2.12 6 1.60 26 2.14 7 1.63 27 2.16 8 1.66 28 2.19 9 1.69 29 2.21 10 1.72 30 2.23 11 1.75 31 2.25 12 1.78 32 2.27
5 13 1.81 33 2.29 14 1.84 34 2.31 15 1.86 35 2.33 16 1.89 36 2.35 17 1.92 37 2.37 18 1.94 38 2.39 19 1.97 39 2.40 40 2.42 1. Motor speed (n) is measured directly in Hertz from an inverter. 2. The volumetric flow rate ( Q v ) by collecting 5 L of water and finding the time to collect that amount of water. Q v = V t = 0.005 m 3 6.24 s = 0.00801 m 3 / s 3. Inlet head and outlet head are read from inlet and outlet gauges. 4. For the Inlet and Outlet head correction factors h di = 0.02 m h do = 0.17 m 5. Pump power input W i is read directly from the inverter by using the FUNC/DATA key. 6. Total head H d =( h do h di )+( h o h i ) H d =( 0.17 0.02 )+( 5.3 0 )= 5.45 m 7. Pump power output w o = ρg H d Q v = γ H d Q v =( 9810 N / m 3 )( 5.45 m )( 0.00175 m 3 / s )= 93.56 W 8. Overall turbine efficiency η p = W o W i × 100% = 93.56 730 × 100% = 12.82% Table 2: Single Centrifugal pump experiment. Motor speed: 50 Hz. No of Obs Moto r Spee d n (Hz) Volu me of wate r Vol Time to colle ct t (sec) Flow rate Q v (m 3 /s ec) Inlet Head hi (m of wate Inlet head corre ction h di (m) Outl et Head h 0 (m of Outl et head corre ction h d0 Pum p pow er Input W i Total Head H (m of wate Pum p powe r outp ut Over all Pum p Effic iency
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6 (m 3 ) r) wate r) (m) (Watts) r) W 0 (Watts) η p (%) 1 50 0 0 0.00 1750 00 0 0.02 5.3 0.17 730 5.45 93.5 6 12.8 2 2 50 0 0 0.00 1600 00 0 0.02 5.5 0.17 720 5.65 88.6 8 12.3 2 3 50 0 0 0.00 1620 00 -0.3 0.02 5.7 0.17 720 6.15 97.7 4 13.5 7 4 50 0 0 0.00 1660 00 0 0.02 5.2 0.17 720 5.35 87.1 2 12.1 0 5 50 0 0 0.00 1630 00 -0.2 0.02 6.5 0.17 710 6.85 109. 53 15.4 3 6 50 0 0 0.00 1510 00 -0.6 0.02 8.7 0.17 680 9.45 139. 98 20.5 9 7 50 0 0 0.00 1410 00 -0.7 0.02 11.1 0.17 550 11.9 5 165. 29 30.0 5 8 50 0.00 5 6.24 0.00 0801 00 -0.7 0.02 11.5 0.17 530 12.3 5 97.0 4 18.3 1 9 50 0.00 5 16.9 0 0.00 0295 80 -0.8 0.02 19.2 0.17 430 20.1 5 58.4 7 13.6 0 10 50 0 0 0 -0.6 0.02 20.1 0.17 380 20.8 5 0 0 Table 3: Single Centrifugal pump experiment. Motor speed: 45 Hz. No of Obs Moto r Spee d n Volu me of wate r Time to colle ct t Flow rate Q v (m 3 /s ec) Inlet Head hi (m of Inlet head corre ction h di Outl et Head h 0 (m Outl et head corre ction Pum p pow er Input Total Head H (m of Pum p powe r outp Over all Pum p Effic
7 (Hz) Vol (m 3 ) (sec) wate r) (m) of wate r) h d0 (m) W i (Watts) wate r) ut W 0 (Watts) iency η p (%) 1 45 0 0 0.00 1520 00 -0.6 0.02 4.7 0.17 580 5.45 81.2 7 14.0 1 2 45 0 0 0.00 1480 00 -0.7 0.02 6.2 0.17 560 7.05 102. 36 18.2 8 3 45 0 0 0.00 1440 00 -0.8 0.02 6.3 0.17 560 7.25 102. 42 18.2 9 4 45 0 0 0.00 0146 00 -0.7 0.02 5.0 0.17 570 5.85 8.38 1.47 5 45 0 0 0.00 1410 00 -0.6 0.02 8.0 0.17 540 8.75 121. 03 22.4 1 6 45 0.00 5 4.08 0.00 1225 49 -0.7 0.02 10.1 0.17 500 10.9 5 131. 64 26.3 3 7 45 0.00 5 7.06 0.00 0708 22 -0.7 0.02 14.0 0.17 420 14.8 5 103. 17 24.5 6 8 45 0.00 5 13.5 3 0.00 0369 55 -0.8 0.02 15.2 0.17 360 16.1 5 58.5 5 16.2 6 9 45 0.00 5 32.7 1 0.00 0152 86 -0.8 0.02 15.4 0.17 330 16.3 5 24.5 2 7.43 10 45 0 0 0 -0.8 0.02 16.0 0.17 320 16.9 5 0 0 Table 4: Single Centrifugal pump experiment. Motor speed: 40 Hz. No of Obs Moto r Spee d Volu me of wate Time to colle ct Flow rate Q v (m 3 /s Inlet Head hi (m Inlet head corre ction Outl et Head h 0 Outl et head corre Pum p pow er Total Head H (m Pum p powe r Over all Pum p
8 n (Hz) r Vol (m 3 ) t (sec) ec) of wate r) h di (m) (m of wate r) ction h d0 (m) Input W i (Watts) of wate r) outp ut W 0 (Watts) Effic iency η p (%) 1 40 0 0 0.00 1410 00 0 0.02 4.0 0.17 430 4.15 57.4 0 13.3 5 2 40 0.01 6.25 0.00 1600 00 0 0.02 4.0 0.17 430 4.15 65.1 4 15.1 5 3 40 0.01 6.84 0.00 1461 99 0 0.02 5.0 0.17 410 5.15 73.8 6 18.0 2 4 40 0.01 7.56 0.00 1322 75 0 0.02 5.5 0.17 400 5.65 73.3 2 18.3 3 5 40 0.01 9.09 0.00 1100 11 0 0.02 7.0 0.17 380 7.15 77.1 6 20.3 1 6 40 0.00 5 6.05 0.00 0826 45 0 0.02 9.0 0.17 340 9.15 74.1 8 21.8 2 7 40 0.00 6 12.3 5 0.00 0485 83 0 0.02 12.0 0.17 290 12.1 5 57.9 1 19.9 7 8 40 0.00 6 25.7 7 0.00 0232 83 0 0.02 12.5 0.17 260 12.6 5 28.8 9 11.11 9 40 0.00 6 37.9 8 0.00 0157 98 0 0.02 13.0 0.17 250 13.1 5 20.3 8 8.15 10 40 0 0 0 0 0.02 13.5 0.17 240 13.6 5 0 0 Table 5: Single Centrifugal pump experiment. Motor speed: 35 Hz. No of Obs Moto r Spee Volu me of Time to colle Flow rate Q v Inlet Head hi Inlet head corre Outl et Head Outl et head Pum p pow Total Head H Pum p powe Over all Pum
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9 d n (Hz) wate r Vol (m 3 ) ct t (sec) (m 3 /s ec) (m of wate r) ction h di (m) h 0 (m of wate r) corre ction h d0 (m) er Input W i (Watts) (m of wate r) r outp ut W 0 (Watts) p Effic iency η p (%) 1 35 0.01 7 0.00 1410 00 0 0.02 2.5 0.17 310 2.65 36.6 6 11.8 2 2 35 0.01 7.49 0.00 1335 11 0 0.02 2.5 0.17 310 2.65 34.7 1 11.2 0 3 35 0.01 7.87 0.00 1270 65 0 0.02 4.0 0.17 300 4.15 51.7 3 17.2 4 4 35 0.01 10.8 7 0.00 0919 96 0 0.02 5.0 0.17 280 5.15 46.4 8 16.6 0 5 35 0.00 5 6.72 0.00 0744 05 0 0.02 7.0 0.17 250 7.15 52.1 9 20.8 8 6 35 0.00 6 10.1 8 0.00 0589 39 0 0.02 8.5 0.17 240 8.65 50.0 1 20.8 4 7 35 0.00 6 12.4 9 0.00 0480 38 0 0.02 9.0 0.17 230 9.15 43.1 2 18.7 5 8 35 0.00 6 15.7 0 0.00 0382 17 0 0.02 9.5 0.17 220 9.65 36.1 8 16.4 4 9 35 0.00 6 32.2 8 0.00 0185 87 0 0.02 9.5 0.17 200 9.65 17.6 0 8.80 10 35 0 0 0 0 0.02 10.0 0.17 190 10.1 5 0 0 Table 6: Single Centrifugal pump experiment. Motor speed: 30 Hz. No of Moto r Volu me Time to Flow rate Inlet Head Inlet head Outl et Outl et Pum p Total Head
10 Obs Spee d n (Hz) of wate r Vol (m 3 ) colle ct t (sec) Q v (m 3 /s ec) hi (m of wate r) corre ction h di (m) Head h 0 (m of wate r) head corre ction h d0 (m) pow er Input W i (Watts) H (m of wate r) 1 30 0.01 9 0.00 1410 00 0 0.02 2.0 0.17 230 2.15 29.7 4 12.9 3 2 30 0.01 8.90 0.00 1123 60 0 0.02 2.0 0.17 220 2.15 23.7 0 10.7 7 3 30 0.01 9.25 0.00 1081 08 0 0.02 3.0 0.17 220 3.15 33.4 1 15.1 9 4 30 0.01 10.3 4 0.00 0967 12 0 0.02 3.0 0.17 220 3.15 29.8 9 13.5 8 5 30 0.00 5 5.72 0.00 0874 13 0 0.02 4.0 0.17 200 4.15 35.5 9 17.7 9 6 30 0.00 5 9.49 0.00 0526 87 0 0.02 5.5 0.17 190 5.65 29.2 0 15.3 7 7 30 0.00 6 17.1 2 0.00 0350 47 0 0.02 6.5 0.17 170 6.65 22.8 6 13.4 5 8 30 0.00 6 24.3 8 0.00 0246 10 0 0.02 6.5 0.17 170 6.65 16.0 5 9.44 9 30 0.00 6 47.6 7 0.00 0125 87 0 0.02 7.0 0.17 160 7.15 8.83 5.52 10 30 0 0 0 0 0.02 7.0 0.17 150 7.15 0 0 Table 7: Parallel pump configuration (pump speed 50 Hz) No of Moto r Volu me Time to Flow rate Inlet Head Inlet head Outl et Outl et Pum p Total Head
11 Obs Spee d n (Hz) of wate r Vol (m 3 ) colle ct t (sec) Q v (m 3 /s ec) hi (m of wate r) corre ction h di (m) Head h 0 (m of wate r) head corre ction h d0 (m) pow er Input W i (Watts) H (m of wate r) 1 50 0 0 0.00 1860 00 0 0.02 7.0 0.17 230 7.15 130. 46 56.7 2 2 50 0 0 0.00 1720 00 0 0.02 8.0 0.17 220 8.15 137. 52 62.5 1 3 50 0 0 0.00 1630 00 0 0.02 10.0 0.17 220 10.1 5 162. 30 73.7 7 4 50 0 0 0.00 1410 00 0 0.02 14.0 0.17 220 14.1 5 195. 72 88.9 7 5 50 0.00 5 5.55 0.00 0900 90 0 0.02 17.0 0.17 200 17.1 5 151. 57 75.7 8 6 50 0.00 5 8.31 0.00 0601 68 0 0.02 19.0 0.17 190 19.1 5 113. 03 59.4 9 7 50 0.00 5 9.23 0.00 0541 71 0 0.02 20.0 0.17 170 20.1 5 107. 08 62.9 9 8 50 0.00 5 12.7 0 0.00 0393 70 0 0.02 21.0 0.17 170 21.1 5 81.6 9 48.0 5 9 50 0.00 5 46.5 8 0.00 0107 34 0 0.02 23.0 0.17 160 23.1 5 24.3 8 15.2 4 10 50 0 0 0 0 0.02 24.0 0.17 150 24.1 5 0 0 9. Graph of measured total head H d for different flow rate Q v for rotational speed 50 Hz.
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12 Figure 1: Total head vs Flow rate for 50 Hz speed 10. Plot the total head H d for different flow rate Q v for rotational 45 Hz, 40 Hz, 35 Hz, 30 Hz. Figure 2: Total head vs Flow rate for 45 Hz, 40 Hz, 35 Hz and 30 Hz 11. Plot measured efficiency for different flow rate for rotational 50 Hz, 45 Hz, 40 Hz, 35 Hz, 30 Hz.
13 Figure 3: Measured efficiency vs Flow rate for 50 Hz Figure 4: Measured efficiency vs Flow rate for 45 Hz
14 Figure 5: Measured efficiency vs Flow rate for 40 Hz Figure 6: Measured efficiency vs Flow rate for 35 Hz
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15 Figure 7: Measured efficiency vs Flow rate for 30 Hz 12. Plot measured power output vs flow rate. Figure 8: Power output vs Flow rate for 50 Hz
16 Figure 9: Power output vs Flow rate for 45 Hz Figure 10: Power output vs Flow rate for 40 Hz
17 Figure 11: Power output vs Flow rate for 35 Hz Figure 12: Power output vs Flow rate for 30 Hz 13. Graph of head H d for different flow rates using a dataset for different settings of sump drain valve opening.
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18 Figure 13: Total head vs flow rate for parallel pump Questions and Discussion: 1. In terms of pump head, efficiency and rotation speed, discuss shape of the pump characteristics curves for a single pump or parallel pump settings. a. For a single pump, pump head, efficiency , and rotation speed have distinct characteristics when related to flow rate. According to Figure 1, pump heads seem to decrease as flow rate increases. This is a disproportionate linear relationship to flow rate. According to Figures 2-6, efficiency has a parabolic relationship to flow rate. This non-linear relationship shows how this pump runs more efficiently at a certain flow rate that is not the highest. According to Figures 7-11, power also has a nonlinear relationship to flow rate. They are closely related to the efficiency graphs, which means there is a flowrate that produces the most power that isn't the fastest flow rate. This information is useful because it means that the pump can save energy by just running at the most efficient flow rate and not the highest to produce the largest amount of water. 2. How the head and flow rates are affected when the pumps are in series or in parallel? a. When in series the total head increases while flow rate remains the same. In parallel, the total head will decrease and flow rates will increase. Exercise 1 1. Based on the Head vs Flow rate graph, discuss how the pump characteristics curve changed with the rotational speed. a. In both series and parallel head vs flow rate graphs, the total head decreased in a linear manner as the flow rate increased. It can be concluded that the total head is disproportionately related to the flow rate. 2. Based on efficiency vs Flow rate graph, discuss how the pump characteristics curve changed with the rotational speed. a. Based on Figures 2-6, there is a non-linear relationship between efficiency of the pump and the flowrate. There seems to be a negative parabolic relationship
19 between the two. This means there is a flow rate, that is not the fastest, that is the best for operating the pump. 3. Based on the power vs Flow rate graph, discuss how the pump characteristics curve changed with the rotational speed. a. Like the efficiency graphs, there is a non-linear relationship between power output and flow rate. There is a negative parabolic relationship between the two. This means there is a flow rate, that is not the fastest, that produces the most amount of power. This is important to understand when trying to save the most amount of operation cost. 4. Based on the Head vs Flow, efficiency vs Flow rate, and power vs flow rate, what is the optimum operating point at each speed tested. a. The most optimum operating point seems to be around 0.0014 m 3 sec across all different types of graphs. 5. Discuss using the plot of head H_d vs Q_v (the dataset for different settings of sump drain valve opening) the effect of inlet suction head on the performance of the pump. a. According to Figure 13, there seems to be a negative linear relationship in the plot between Total head and flow rate for different settings of sump drain valve opening. This means that the effect of inlet suction on the head is disproportionately related to the performance of the pump. Exercise 2 1. Discuss the pump characteristics curve for two pumps in parallel settings. a. Two pumps in a parallel setting mean that the sum of both single flow rates will be the total head of the system. Overall, the flowrate of the system will be higher than that of a single pump. When the overall flow rate of the system increases, the total head will decrease. 2. Discuss if you get two different flow rates when two pumps are operating in parallel. a. There will not be two different flow rates when two pumps are operating in parallel. The sum of the two individual flow rates will be the one flow rate for the whole system. 3. Are there any differences between observed and theoretical heads? Provide reasons for any differences a. There is a slight difference in observed head and theoretical head. Between each different flow rate the heads differ by around .15 m of water. Possible reasons for any differences may include energy losses in the system. Conclusion: In this experiment we were to observe the characteristics of both a single and parallel centrifugal pump. In the experiment, we ran the pump at different flow rates at different motor speeds. Overall the results of the experiment showed us that in a single pump, having a constant flow rate that doesn't flow too fast, will result in having an efficient pump.This can be seen from figures 2-6, as the flow rate remained at a constant speed, the pump was working most efficiently. This also is the same for the power produced by the pump. From figures 8-12, we see that as the flow rate remains at a constant speed, the pump produces the most amount of power. So for both pump efficiency and power, it is related to the flow rate. It also showed us that if the flow rate increases, the total head will also decrease disproportionately. For a parallel pump,
20 generally the flow rate will be higher than a single pump. So as the parallel pump increases in flow rate, the total head will also decrease as well.Overall, a big takeaway from this experiment, shows us that flow rate can affect how both pumps work. References Sultana, Rebeka. “Lab #8 Centrifugal pump.” Fluid Mechanics Laboratory Student Manual. 2017. Print.
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