CCP Performance Characteristics of A Centrifugal Pump Abstract Lab

User Generated

nffrz

Engineering

Community College of Philadelphia

Description

Unformatted Attachment Preview

Experiment: Performance Characteristics of a Centrifugal Pump Introduction and Theory Centrifugal pumps are the most commonly used pumps in the industry. In order to properly design a pipe system, or select the appropriate pump for an existing system, engineers use performance charts provided by pump manufacturers. An example of such a chart for a small size centrifugal pump is shown in Figure 1 below (it is not for the pump tested here). Figure 1 An example of manufacturer’s pump chart. In Figure 1, the horizontal axis is the volumetric flow rate through the pump and the horizontal axis is the increase of the total head across the pump. The total head at any V2 location is defined as H = + + z , where P is pressure,  is specific weight of the fluid,  2g P V is the (average) velocity and z is elevation (measured from an arbitrary level). Therefore, the change of total head from the inlet to the outlet of the pump is: H = Pout − Pin  + 2 Vout − Vin2 + ( zout − zin ) 2g In this experiment (and for most applications) the changes in velocity and elevation are negligible, and the change of total head can be expressed simply as H = Pout − Pin  . Other Useful Equations W pump =V  P  = 2N / 60 Wshaft =T    = W pump / Wshaft 100% 1. Pumping power: 2. Angular velocity: 3. Shaft power: 4. Pump efficiency Where N = rotational speed (RPM) V = volumetric flow rate T = shaft torque Experimental Goal To determine the following characteristics of the investigated centrifugal pump: H (V ) , Wshaft (V ) and  (V ) , each at two (or more) rotational speeds. Uncertainties on all reported quantities must be calculated and reported (error bars). Test Stand Description The centrifugal pump system used in the experiment is presented in Figure 2. Flow Meter Needle Valve Pout Tachometer Pin Variable Speed D.C. Motor Torque Meter Pump Sump Tank Figure 2 Centrifugal Pump System Water is pumped from the sump tank, through the tested centrifugal pump, needle valve, flow meter and back to the tank. The inlet and outlet pressures of the pump are monitored by pressure gauges Pin and Pout, respectively. The pump is driven by a DC motor controlled with a SCR (semiconductor-controlled rectifier) controller. The coupling between the motor and the pump is instrumented with a torque meter and a tachometer generator which measure torque and rotational speed, respectively. The torque meter and drive couplings are covered for safety reasons. Technical Details of the Equipment 1. Centrifugal Pump: The pump is a typical fractional horsepower water pump capable of delivering flow rate of 26 gallons per minute (gpm). 2. Electric Motor: The motor is a Permanent Magnet DC motor rated at ½ HP and 1725 full load RPM. The motor RPM may be varied continuously from 0 to full-load RPM. 3. Torque Meter: The pump torque is measured by means of the torque meter, which is mounted in-line between the pump and motor. Torque is read on a calibrated scale, using stroboscopic light while the instrument is rotating. Torque may be read to an accuracy of ½% of the full scale (FS). The torque range is 0-25 lb-in. 4. Tachometer: The Tachometer Generator is mounted to one side of the motor and connected by a belt/pulley arrangement. The Tachometer Indicator is mounted on the vertical panel. The range of the device is 0-2000 rpm with  2% of accuracy (FS). 5. Flow meter: The Flow meter is a direct reading glass rotameter with a SS 316 float. The maximum flow rate is 30 gpm with a  2% accuracy (FS). See the manufacturer’s instructions for the location of the float reading edge. 6. Pressure gages: The inlet pressure gage has the range of -20 to 40 inH20 and the accuracy of  1 inH20. The outlet pressure gage has the range of 0-10 psig and accuracy of  0.2 psi. The uncertainty associated with every direct measurement in this experiment must be estimated and recorded as a part of measured results. Starting the Test Stand Warning: Do not operate the pump with the needle valve fully closed. 1. 2. 3. 4. Ensure that master speed dial is set to 0 and FWD/BRAKE/REV switch to BRAKE position. Close the needle valve about half way, turn ON/OF switch of the motor to ON, set the FWD/BRAKE/REV switch to FWD Turn master speed dial to desired speed setting. Adjust the needle valve until the desired flow rate is reached and take measurements Presentation of Results H , the shaft  power Wshaft and the pump efficiency  , all as functions of the volumetric flow rate V . Graph the Based on the direct measurements recorded, calculate and graph the head increase results for all speeds together (two curves per graph). Based on the estimated uncertainties of all direct  and measurements calculate the uncertainties of V , H , W shaft  (see lecture notes or [1]). Include error bars when graphing results. Discuss all the observed trends. Then compare qualitatively the experimental curves with the typical pump characteristics of Figure 1. Discuss possible sources of experimental error. References (1) J.P. Holman, Experimental Methods for Engineers, 7th Edition, McGraw Hill, New York, 2001 (2) Centrifugal Pump System Model 9010 Instructions by Technovate, Pompano Beach, FL Abbreviated Individual Reports The lab reports for Experiments 6 through 8 will follow an abbreviated format. The following items are now required (see sample report on next pages): • Title Page with Abstract • Experimental Results – follow the instructions from each lab handout and present all the results in tables and/or graphs. Include the most important equations, as needed • Sample calculations, including units • References, as needed Writing an Abstract Abstract is a stand-alone autonomous paragraph which describes all the work done in a nutshell. It should not refer to tables or graphs in the report. Abstract should not exceed 250 words and should discuss the following: • Intro statement of the problem investigated, including the objective • How was the objective pursued • Summary of most important results and conclusions • Relevance of the conclusions to engineering See the sample below. 1 (Sample Abbreviated Report) Abbreviated Report, ME 304, Session# 3, Exp. #8 Performed by Team A on 1/6/2020 Submitted by: Mark Smith on 1/13/2020 Venturi and Orifice Flow Meters Abstract In principal, any calibrated obstruction could be used as a flow meter by measuring the pressure drop across the obstruction. This laboratory investigates two types of obstruction flow meters that are commonly used in industry: Venturi flow meter and orifice flow meter. The main objective of the lab was to determine calibration curves for the two flow meters. Using an instrumented pipe system, water was pumped through a reference flow meter (rotameter type) and through the two investigated obstruction flow meters (all in series) and both the flow rate Q and the pressure drop P across each of the two flow meters were recorded at various flow rates Q. The determined calibration curves Q(P) were shown to follow closely (within 5%) the form Q = a P , where a is a constant. The orifice flow meter showed about 100% higher flow rates than the Venturi flow meter at the same pressure drop. This laboratory demonstrated how measurement of pressure drop across an obstruction flow meter can be used to determine the flow rate in a duct. This can be a very convenient and cost-effective method of flow measurement, especially for large ducts. 2 Experimental Results The measured results are presented for each flow rate in Table 1 and all values converted to SI units are presented in Table 2. In the tables ΔPV and ΔPO are the pressure drops across the Venturi and the orifice flow meters, respectively. Table 1 Averaged Measured Values ΔPV (mbar) 1.0 7.4 18.1 22.9 31.0 39.2 48.3 57.9 Q (GPM) 2 4 6 7 8 9 10 12 Table 2 Averaged Measured Values in SI units ΔPO (mbar) 0.4 2.6 6.2 6.6 10.3 12.7 17.3 21.5 Q (m3/s) ΔPV (Pa) ΔPO (Pa) 0.000126 100 40 0.000252 740 260 0.000379 1810 620 0.000442 2290 660 0.000505 3100 1030 0.000568 3920 1270 0.000631 4830 1730 0.000757 5790 2150 The data of Table 2 was used to create Figure 1, which graphs two calibration curves: one for the Venturi flow meter Q(PV) and the other for the orifice flow meter Q(PO). 0.0008 0.0007 0.0005 3 Q (m /s) 0.0006 0.0004 Venturi 0.0003 Orifice 0.0002 0.0001 0 0 1000 2000 3000 4000 5000 6000 P V , P O (Pa) Figure 1 Calibration curves for the tested Venturi and orifice flow meters. The two solid lines in Figure 1 represent least square fits of the form Q = a P . Sample Calculations 3 4 gpm V_dot [m^3/s] gpm Trial 1 50 +/in^3/min 9 10 13 12 17 19 15 16 22 24,5 15 20 2 60 3 70 2079 2310 3003 2772 3927 4389 3465 3696 5082 5659,5 3465 4620 0 Average γh P1 Psi inches P1 Head 139,536 139,536 139,536 139,536 139,536 139,536 139,536 139,536 139,536 139,536 139,536 139,536 -1,8 -2 -3 -2,5 -4 -5 -3 -3 -7 -9 -3 -5,5 Psi P2 Psi +/psi -0,065 -0,07222 -0,10833 -0,09028 -0,14444 -0,18056 -0,10833 -0,10833 -0,25278 -0,325 -0,10833 -0,19861 0 0,036 0,036 0,036 0,036 0,036 0,036 0,036 0,036 0,036 0,036 0,036 0,036 1,00 0,90 0,20 0,50 0,50 0,30 1,20 1,10 1,00 0,50 2,20 1,50 Change in head at various volumetric flow rates 80,00 70,00 60,00 ΔH [in] 50,00 40,00 30,00 20,00 10,00 0,00 0 1000 2000 3000 4000 5000 6000 V_dot [in^3/min] Low RPM Mid RPM High RPM Linear (Mid RPM) Linear (High RPM) Inches P2 Head 27,69 24,92 5,54 13,85 13,85 8,31 33,23 30,46 27,69 13,85 60,92 41,54 Mid RPM High RPM Linear (Mid RPM) Linear (High RPM) 12,0 10,0 8,0 Efficiency [%] Low RPM 6,0 4,0 2,0 0,0 -2,0 -4,0 Data +/psi 0,2 0,2 0,2 0,2 0,2 0,2 0,2 0,2 0,2 0,2 0,2 0,2 P2-P1/SW Delta_H +/Head in 29,49 26,92 8,54 16,35 17,85 13,31 36,23 33,46 34,69 22,85 63,92 47,04 6,54 6,54 6,54 6,54 6,54 6,54 6,54 6,54 6,54 6,54 6,54 6,54 Delta_p +/Psi psi 1,07 0,97 0,31 0,59 0,64 0,48 1,31 1,21 1,25 0,83 2,31 1,70 N [rpm] rpm 2*pi*N/60 omega [-] rad/s T in*lb 0,24 0,24 0,24 0,24 0,24 0,24 0,24 0,24 0,24 0,24 0,24 0,24 3080 3080 3102 3085 3085 3088 3088 3090 3090 3090 3092 3091 4 4 4 4 4,5 4,5 4,5 4,5 5 5 5 5 323 323 325 323 323 323 323 324 324 324 324 324 Shaft power at various volumetric flow rates 0,3000 0,2500 W_sh [hp] 0,2000 0,1500 0,1000 0,0500 0,0000 0 5 10 15 V_dot [GPM] Low RPM High RPM Expon. (Mid RPM) Mid RPM Expon. (Low RPM) Expon. (High RPM) 20 25 30 High RPM Expon. (Mid RPM) Expon. (Low RPM) Expon. (High RPM) Pump efficiency at various volumetric flow rates 12,0 10,0 Efficiency [%] 8,0 6,0 4,0 2,0 0,0 0 5 10 15 -2,0 -4,0 V_dot [GPM] Low RPM Mid RPM High RPM Poly. (Low RPM) 20 25 30 V_dot*Delta_P W_p W_p lb*in/min hp 2214 0,00559 2246 0,00567 926 0,00234 1636 0,00413 2531 0,00639 2109 0,00533 4533 0,01145 4466 0,01128 6367 0,01608 4669 0,01179 7998 0,02020 7848 0,01982 unc +- lbin/min unc +- hp 639 0,00161 681 0,00172 752 0,00190 737 0,00186 1017 0,00257 1103 0,00279 1001 0,00253 1041 0,00263 1375 0,00347 1451 0,00367 1140 0,00288 1328 0,00335 T*omega W_sh hp 0,1955 0,1955 0,1969 0,1958 0,2203 0,2205 0,2205 0,2206 0,2451 0,2451 0,2453 0,2452 unc +- hp 2,18E-08 2,18E-08 2,19E-08 2,19E-08 2,27E-08 2,27E-08 2,27E-08 2,27E-08 2,35E-08 2,35E-08 2,35E-08 2,35E-08 W_p/W_sh Efficiency % 2,9 2,9 1,2 2,1 2,9 2,4 5,2 5,1 6,6 4,8 8,2 8,1 unc eff % 0,8 0,9 1,0 1,0 1,2 1,3 1,1 1,2 1,4 1,5 1,2 1,4 γ N Unc. lb/ft^3 2% 62,4 rpm lb/in^3 40 0,036111 rad/s 4,18879 power 1 HP Flow meter Unc (in^3/min) Density 62,4 ft-lb/s 550 Torque Unc. (in-lb) 0,125 Flow meter Unc (gpm) 0,6 Flow meter Unc (in^3/min) 139,536 Gravity 32,2 in-lb/min 396000 Experimental Results: Low RPM (891) V_dot [gpm] 9,0 10,0 13,0 12,0 ± ΔH [in] 0,60 29,5 0,60 26,9 0,60 8,5 0,60 16,3 ± W_p [hp] 6,5 0,00559 6,5 0,00567 6,5 0,00234 6,5 0,00413 ± W_sh [hp] 0,00161 0,1955 0,00172 0,1955 0,00190 0,1969 0,00186 0,1958 ± η [%] 2,18E-08 2,9 2,18E-08 2,9 2,19E-08 1,2 2,19E-08 2,1 ± 0,8 0,9 1,0 1,0 ± η [%] 2,27E-08 2,9 2,27E-08 2,4 2,27E-08 5,2 2,27E-08 5,1 ± 1,2 1,3 1,1 1,2 Experimental Results: Mid RPM (1153) V_dot [gpm] 17,0 19,0 15,0 16,0 ± ΔH [in] 0,6 17,8 0,6 13,3 0,6 36,2 0,6 33,5 ± W_p [hp] 6,5 0,00639 6,5 0,00533 6,5 0,01145 6,5 0,01128 ± W_sh [hp] 0,00257 0,2203 0,00279 0,2205 0,00253 0,2205 0,00263 0,2206 Experimental Results: High RPM (1444) V_dot [gpm] 22,0 24,5 15,0 20,0 ± ΔH [in] ± W_p [hp] 0,6 34,7 6,54 0,01608 0,6 22,8 6,54 0,01179 0,6 63,9 6,54 0,02020 0,6 47,0 6,54 0,01982 ± W_sh [hp] 0,00347 0,2451 0,00367 0,2451 0,00288 0,2453 0,00335 0,2452 ± 2,35E-08 2,35E-08 2,35E-08 2,35E-08 η [%] ± 6,56 1,42 4,81 1,5 8,23 1,17 8,08 1,37
Purchase answer to see full attachment
User generated content is uploaded by users for the purposes of learning and should be used following Studypool's honor code & terms of service.

Explanation & Answer

Attached.

Abstract
Centrifugal pumps use the mechanism of transforming input power into kinetic energy in a fluid
through the acceleration of the fluid using an impeller (rotating device). In this experiment, the
elevation and velocity changes are negligible. The experiment aims to determine the values
affecting the flow performance of the centrifugal pump, which include the change in efficiency
of the pump  (V ) , head H (V ) , and shaft power Wshaft (V ) , each at different rotational speeds.
The pump efficiency, head increase, and the shaft power are calculated and graphed, as a
function of the volumetric flow rate. The result is compared with the tested/manufacturer’s
centrifugal pump charts. The process of the experiment involves pumping of water from the
sump tank, through the experiment’s centrifugal pump, needle valve, flow meter and finally
redirected into the sump tank. Measurements of the torque the rotational speed and the inlet
pressure, outlet pressure were recorded. The results of the experiment show that the test data
values of at each rpm vary and are generally less than the manufacturer’s numbers. The shaft
power is relatively constant at for the multiple tests at each rpm. The efficiency decreases with
an increase in flow rate. The error in the results could be caused by zero offsets in pressure
transducers or pressure loss between the pressure transducer and the centrifugal pump. The other
cause for the error is the level of stability of the flow and pressure head due to flow and pressure
surges. This lab experiment can be used to confirm and compare the operational integrity of a
centrifugal pump through comparison and validation of the manufacturer’s data.

Use this one which have been reduced to 250 words. Thanks

Abstract
Centrifugal pumps use the mechanism of transforming input power into kinetic energy in a fluid
through the acceleration of the fluid using an impeller (rotating device). In this experiment, the
elevation and velocity changes are negligible. The experiment aims to determine the values
affecting the flow performance of the centrifugal pump, which include the change in efficiency
of the pump  (V ) , head H (V...


Anonymous
I was struggling with this subject, and this helped me a ton!

Studypool
4.7
Trustpilot
4.5
Sitejabber
4.4

Related Tags