ABSTRACT Regarding on the experiment we done, we are able to understand the aspects of single pump operation with variable pump speeds and flow rate. Centrifugal pump and dynamic pumps was used to undergo the experiment. As we know that a pump is a device for compressing, transferring or raising fluid.
A fluid may be any liquid or gasses. Pumps are the most regular mechanical devices which are used by the industry or factory. Because of this different type of pumps are available in the market.
Mainly, it separated into dynamic and positive displacement pumps. These pumps often used for transport hot and chill water and also the industrial fluids in the industry. Moreover, Centrifugal pumps are also used to transport fluids by conversion of rotational kinetic energy to hydrodynamic energy of the fluid flow. The impeller speeded up the fluid enter the pump impeller along to the rotating axis.
It gains the water at low velocity on the interior edge of the moving impeller vanes, then it Eject from the outer edge along with the kinetic energy sufficient so that the fluid rise to a desired height; the energy will transform from kinetic energy to pressure energy by passing through the expanding spiral passage.Based on the result we obtained, a centrifugal pump with distinct flowrate which increase by 10 LPM output and adjustable flowrate output for analyzed the performance characteristics curve. Along with the flowrate of the pump increases, the decreases of the power consume has been observed.
The efficiency for the pump is decreases at the point of on point 0.0012m³/s of the flowrate and the efficiency increase back at the point 0.0017m³/s. According to the result the single pump, the higher the flow rate the lower the power consumed. Base on table 2 shows that the pump head (m) value decrease until 62.5 LPM, the value of the fluid speed also decreases due to the pump head.At last of the experimentation, we can figure out some errors are Illustrate with energy loss all over the system outstanding to impoverished measurements of pump head as well as the tubes not being predictable flat. The purpose for this experiment is to define and rise our comprehension for the characteristics of centrifugal pumps operate at single speed and also for the centrifugal pumps operate are noticeably revealed.
INTRODUCTIONObjectives• To obtain knowledge regarding on the typical of single pump operation with variable flow rate and pump speeds.Theory Pumps are normally used in almost majority characteristic of industry and engineering from feeds to reactors and distillation columns in chemical engineering to pumping storm water in civil and mother nature. They are an integral part of engineering and an understanding of how they work is crucial.Pumps are machines that transfer mechanical energy from a prime mover into fluid energy to provide the flow of liquids. There are two broad classifications of pumps. Such as, positive displacement and dynamic.
a) Dynamic PumpsThe action of rotating blade can add energy of Dynamic pumps to the fluid, which increases the velocity of the fluid. Figure 1 shows the construction features of a centrifugal pump, the most mainly used type of dynamic pumps.Figure 1: Construction features of a centrifugal pump.b) Horizontal Single Stage Centrifugal PumpCentrifugal pumps have two significant components:• The impeller consists of a number of curved blades (also called vanes) attached in a regular pattern to one side of a circular hub plate that is connected to the rotating driveshaft.• The housing (also called casing) is a stationary shell that enclosed the impeller and supports the rotating drive shaft via a bearing.
A centrifugal pump works as follows. When the prime mover rotates the driveshaft, the impeller fluid is drawn in axially through the centre opening (called the eye) of the housing. The fluid then makes a 900 turn and flows radially outward. As energy is added to the fluid by the rotating blades (centrifugal action and actual blade force), the pressure and velocity enlarge until the fluid make it to the outer tip of the impeller.
The fluid then enters the volute-shaped housing whose expanded flow area causes the velocity to drop. This action results in a reduce in kinetic energy and an accompanying rise in pressure.The volute-shaped housing also produces a continuous expand in flow area in the direction of flow to provide a uniform velocity as the fluid travels around the outer portion of housing and discharge opening. Although centrifugal pumps provide smooth and continuous flow, their flow rate output (also called discharge) is decreasing as the external resistance is get bigger. In fact, by closing a system valve (thereby creating theoretically infinite external system resistance) even while the pump is running at design speed, it is possible to block pump output flow completely. In such a case, no harm occurs to the pump unless this no-flow condition occurs over extended period with resulting excessive fluid temperature build up. Thus, pressure relief valves are not important.
The tips of the impeller blade merely shear through the liquid, and the rotational speed maintains a fluid pressure corresponding to the centrifugal force set.c) Pump Head versus Flowrate Curves for Centrifugal PumpsFigure 2 shows pump head versus flowrate curves for a centrifugal pump. The solid curve is for water, whereas the dashed curve is for a more viscous fluid such as oil. Most published performance curves for centrifugal pumps are for pumping water. Notice from Figure 2 that using a fluid having a bigger viscosity than water results in a lower flowrate at a given pump head. If the fluid has a viscosity higher than 300 times that of water, the performance of a centrifugal pump deteriorates enough that a positive displacement pump is regularly suggested.Figure 2: Pump head versus flowrate curves of centrifugal pump for water and for a moreviscous liquid.
The maximum head provided by a centrifugal pump is called pump shutoff head because an external system valve is closed and there is no flow. Notice from Figure 2 that as the external system resistance become less (which occurs when a system valve is opened more), the flowrate rises at the expense of reduced pump head. Because the output flowrate converts importantly with external system resistance, centrifugal pumps are hardly ever used in fluid power systems. Zero pump head exists if the pump discharge port were opened to the atmosphere, such as when filling nearby open tank with water. The open tank represents essentially no resistance to flow for the pump.
Figure 2 shows why centrifugal pumps are desirable for pumping stations used for delivery water to homes and factories. The demand for water may go to closer to zero during the evening and reach a peak during the daytime, but a centrifugal pump can readily handle these large changes in water demand. Since there is a best deal of clearance between the impeller and housing, centrifugal pumps are not self priming, dissimilar positive displacement pumps. Thus, if a liquid being pumped from a reservoir located below a centrifugal pump, priming is required. Priming is the prefilling of the pump housing and inlet pipe with the liquid so that the pump can initially draw the liquid. Priming is required because there is too much clearance between the pump inlet and outlet ports to seal against atmospheric pressure. Thus, the displacement of a centrifugal pump is not positive where the same volume of liquid would be delivered per revolution of the driveshaft. The lack of positive internal seal against leakage means that the centrifugal pump is not forced to provide flow when there is a very big system resistance to flow.
As system resistance getting low, less fluid at the discharge port slips back into the clearance spaces between the impeller and housing, resulting in an enlarge in flow. Slippage occurs because the fluid follows the path of lowest resistance.METHODS AND APPARATUS Figure 3: Pump Test Rig (Model FM 07A)1. Pump, P1 4. Speed Sensor 2.
Pump, P2 5. Pressure Gauge 3. Water Tank 6.
Pressure Transmitter Before we start the experiment, we already filled the circulation tank with water. Then the main power supply was being turn on. After that, we were turn on the main switch on the control panel. Next, we opened valve V5 slightly (turn approximately 720° or 2 rounds). Then, we have checked the valve V1 AND V4 position was fully opened but the valve V2 and V3 was fully closed. The important step, we have done to make sure the speed controller is at minimum before the pump is on. The pump speed controller was turned clockwise to increase pump speed or anti-clockwise to decrease the pump speed.
The pump (Pump 1) has been switched on. The speed of the pump has been slowly adjusted to increase until approximately 2000 RPM. After that, the flowrate (adjust V5) was adjusted to give a value of approximately 40 LPM. The reading of flowrate, pump speed, power, and pressure (PT1 and PT3) has been recorded in Table 1.
We were increase the flowrate by approximately 10 LPM and recorded the required readings in Table 1. We were continued until the reading of flowrate is 100 LPM. The speed was adjusted to 2100 RPM. The reading of pump speed, flowrate, power, and pressure (PT1 and PT3) was recorded in Table 2.
The speed was decrease by approximately 100 RPM and the required readings was recorded in Table 2. We were continued until the reading of speed is 1400 RPM. The pump was switched off. Before we ended our experiment we already make sure valve V5 is in fully close position and the main switch on the control panel has been turn off. Lastly, the main power supply has been switched off.RESULTSData and AnalysisFlow Rate, Q(LPM) Speed(RPM) PowerPump(Watt) PT1(bar) PT3(bar) PT3-PT1(bar) Pump Head, H(m) Flow Rate, Q(m³/s) Powerfluid(Watt) Efficiency(%)42.
9 2000 185.2 1.0 1.6 0.6 6.1162 0.000715 42.9 21.
2350.4 1996 197.5 1.0 1.6 0.
6 6.1162 0.00084 50.4 25.5260.1 1990 199.
1 1.0 1.5 0.5 5.0968 0.001 50.0 25.
1170.1 1988 202.9 1.0 1.4 0.4 4.0775 0.0012 48.
0 23.6680.4 1985 201.3 1.0 1.
3 0.3 3.0581 0.0013 39.0 19.3790.
1 1983 203.7 0.9 1.1 0.
2 2.0387 0.0015 30.0 14.73100.1 1980 202.5 0.9 1.
1 0.2 2.0387 0.0017 34.0 16.79Table 1: Single pumps operation with variable flowrate.
Graph 1: Pump Head Vs Flow Rate Graph 2: Efficiency Vs Flow Rate Table 2: Single pumps operation with variable pump speeds.Speed(RPM) FlowrateQ(LPM) PowerPump(Watt) PT1(bar) PT3(bar) PT3-PT1(bar) Pump Head, H(m)2100 97.6 234.5 0.9 1.1 0.
2 2.03872000 93.2 203.6 0.
9 1.1 0.2 2.03871901 96.6 175.
3 0.9 1.1 0.
2 2.03871800 92.8 155.7 1.0 1.1 0.1 1.01941700 78.
4 135.7 1.0 1.1 0.1 1.
01941600 71.8 122.4 1.0 1.1 0.1 1.
01941501 65.8 102.8 1.0 1.0 0.0 01400 62.5 90.
1 1.0 1.0 0.0 0Graph 3: Flow Rate Vs Pump Speed Graph 4: Pump Head Vs Pump Speed Calculation• Pump Head, • Efficiency, • • FLOW RATE, *Sample CalculationFlow Rate, Q(LPM) Speed(RPM) PowerPump(Watt) PT1(bar) PT3(bar) PT3-PT1(bar) Pump Head, H(m) Flow Rate, Q(m³/s) Powerfluid(Watt) Efficiency(%)42.9 2000 185.2 1.0 1.6 0.
6 6.1162 0.000715 42.9 23.
16> , m> , > , Watt> , DISCUSSIONPump is a machine-driven machine using suction or pressure to raise or move liquids, compress gases, or force air into inflatable objects such as tyres. Centrifugal pump is a dynamic axisymmetric work absorbing machine. Centrifugal pumps are used to carriage fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. The rotating energy typically comes from an engine or electric motor. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing centrifugally outward into a diffuser or housing (casing), from where it exits.Based on the graph of the experiment, we can determine the advantages and disadvantages of the single pump operation. We can see that from table 1 and 2 the advantages in using single pump is enable to pump fluid from low level to relatively high level. This is because, single pump has a longer life with no fluid cross-contamination.
Otherwise, the disadvantage is low fluid flow rate can be transfer. Other advantage of single pump is no secondary lube circuit means less maintenance. The flowrate and pump speed are charted and drawn in graph at different operation which is variable pump flowrate and variable pump speed. The change of flowrate depends on pump head are observed. Based on table 1, we can see that at the lowest flowrate is 42.
9 LPM with highest number of head pump is 6.1162m. The highest of flowrate is 100.1 LPM with lowest number of pump head is 2.
0387m which has lowest efficiency of 14.73%. We can conclude that the higher the flowrate the lower the number of pump head which is lower in efficiency. The chart display based on the outcome after experiment which is for our guide to select the better pump in any complaint places. There are type of error that can affect the readings in doing experiment. Such as, systematic error is a permanent deflection in the same direction from the true value. It can be corrected.
Partiality and long-term changeability are controlled by monitoring measurements against a check standard over time. Besides that, random error too is a short-term scattering of values around a mean value. It cannot be corrected on an individual measurement root. Random errors are expressed by statistical methods. Moreover, lack of gauge resolution one of the error that effect the readings. This is because, resolution discrimination is the ability of the measurement system to detect and faithfully indicate small enough changes in the characteristic of the measurement result.
The safety of team member is the first significance while we were doing the experiment. Any wound could happen during the conduction of the experiment. We did remind each of the member during the experiment to avoid any injuries before and after the experiment. While we recorded the result, we had to make sure that there was no parallax error and machine error occurred during the experiment. There are safety precautions that we have to follow during in the lab:Never do unauthorized experiments.• · Never work alone in laboratory.• · Keep your lab space clean and organized.
• · Do not leave an on-going experiment unattended.• · Never taste anything. Never pipette by mouth; use a bulb.• · Never use open flames in laboratory unless instructed.• · Check your glassware for cracks and chips each time you use it. Cracks could cause the glassware to fail during use and cause serious injury to you or lab mates.• · Maintain unobstructed access to all exits, fire extinguishers, electrical panels, emergency showers, and eye washes.• · Do not use corridors for storage or work areas.
• · Do not store heavy items above table height. Any overhead storage of supplies on top of cabinets should be limited to lightweight items only. Also, remember that a 36″ diameter area around all fire sprinkler heads must be kept clear at all times.• · Areas containing lasers, biohazards, radioisotopes, and carcinogens should be posted accordingly.
However, do not post areas unnecessarily and be sure that the labels are removed when the hazards are no longer present.• · Be careful when lifting heavy objects. CONCLUSION Last but not least, the characteristics of single pump process with different flow rate and variable pump speed were carry out and the outcomes were accomplished.
The pump power, head pump and pump efficiency can be calculated or verify by using dissimilar speed of pump in addition which interchange of flow rate. During the experiment, there were some form by centrifugal pump. When the pressure increased, the cavitation of the pump could be stopped.
Furthermore, the speed of the pump impeller and the flowrate of the liquid will be reduced. In conclusion, some human errors were affected during the experiment. The regularly error was the reading error, for the single pump process with variable flowrate (table 1) the power of fluid should be decreased gradually but it increased at the point 50.4 LPM. REFERENCESBook1. B.
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