Selection Of Pump And Piping For A System

It is required to provide the system characteristic in order to select a commercially available pump. You have to select a pump and you must: 

1)Give reasons for your choice of piping (diameter and material). NB Ensure that the velocities in the system are; high enough to entrain air; low enough to ensure noise will not be a significant problem and; also check to see that the velocity in the condenser is suitably high to prevent fouling

2)Calculate the systems characteristic using a constant value of “f” based on the size of the pipe from 1) above and a strainer (filter) selected by yourself from the internet. Plot the system characteristic (head loss vs flow rate) for your pipe type keeping the value of “f’ constant.

3)Select a pump from the provided pump catalogue (or any suitable pump catalogue online) that will enable the system to pass a flow > 0.2X litres/second, where X is the last digit of your student number. Plot the pump curve on the system curve to locate the intersection point. The pump location shown below may not be the best possible position. Indicate where you will locate the pump and state the reason for its location.

4)To calculate the Reynolds number and any other relevant parameters you can just use an average temperature through the system of 20 degrees C.

5)Check that the inlet to the pump is at sufficiently high pressure to avoid cavitation at the inlet pressure and temperature – note some manufacturers give the allowable inlet static pressure to ensure a long life. If this is not given for a pump you select you must still check that cavitation will not occur at the inlet.

6)Calculate the K value for the valve if the cooling requirements dictate the flow to be halved (assume that the pump characteristic gives a constant head vs flow rate) – plot this on the system/pump characteristic graph.

7)Comment on how you think the performance of the system will vary with time

8)Write a well presented FORMAL report which addresses the six points above in order – please be reminded that a maximum 7 page limit for this assignment (including the cover page). You must provide a brief (half page) summary on the cover page.

Pipe Material

Frequently the construction material confines the accessible pipe sizes and schedules. For instance, polyvinyl chloride (PVC) pipe is accessible in huge numbers of indistinguishable sizes from steel pipe, yet it is just accessible in schedule 40 and 80 pipe dimensions. In any case, the internal pipe distance across (ID) can be extraordinary, giving fluctuating outcomes in head misfortune.

Pipe is accessible in various sizes and schedules or wall thicknesses. Clients regularly erroneously utilize the pipe's ostensible size rather than the genuine ID instead of performing out the head loss estimations.

The Crane Technical Paper 410 suggests a liquid speed in the scope of 5 to 10 feet per second (ft/sec) in a pump release pipeline, and a liquid speed of 2.5 to 5 ft/sec on the pump suction pipeline when the liquid is water. This is a building cost choice either pay more for the pipe and less for the pump and pumping expense or the other way around. Legitimate comprehension can prompt finding the ideal pipe estimate in view of liquid speed.
d =

Where
d = optimum inside pipe diameter (inches)
Q = flow rate (m3/s)
v = fluid velocity
Consider what diameter should be chosen to pump fluid at 2.18 *10-4 m3/s through steel schedule 40 pipes with a sizing velocity of 2.5 m/sec. The ideal pipe size for this condition is
Note: 1 m3/s = 1000 litres/s
Therefore,
0.218 litres/s = 2.18 *10-4 m3/s
d =
d =
d = 5.97 *10-3 m

Each channel has points of interest and hindrances. Not all channels can be utilized as a part of any circumstance. For each situation, individuals pick a specific sort of pipe. Because of the way that advance pushes ahead, there are new materials. In any case, one of the key parameters in choosing channels is obtaining costs. In any case, not all the new materials have ease. That is the reason we have such an expansive choice of funnels of various materials. Pipe material for water supply is chosen relying upon the required quality of the material and the nature of water. Additionally critical is the temperature of the water and its weight and obviously, the monetary practicality of the material is vital. Obviously the client can pick the material to the water supply for the building. Each client needs to spare time and cash on its task. Be that as it may, then again, the entertainers need to get more cash for their work. Likewise, if the client is ineffectively versed in this issue it is anything but difficult to induce and welcome him to variant of the draft which will be more costly, contending that the high caliber of administrations, materials, contrasted and what the client has picked. I need to recognize the most imperative viewpoints that ought to be focused on while picking a water supply pipe. The most vital of them, as I would like to think, are the heaviness of the material, the capacity to protect the water clean and for purchasers, the cost of materials, capacity to keep up the coveted temperature and weight.

Pipe Size

The first step requires calculating the Reynolds number of the fluid in the pipeline. During this step, fluid properties of density and viscosity are considered.
Where: d = Inside pipe diameter (metres)
Re = Reynolds number (unitless)
Q = Volumetric flow rate (m3/s)
ρ = Fluid density (Kg/m3 )
μ = Fluid viscosity (centipoise (cP))

Re = 50.66
Re = 50.66*
= 33.21

Determination of a systems characteristic using a constant value of “f” based on the size of the pipe

f =
=
= 1.06

Head loss in a pipe
At the point when liquid flows inside a pipeline, friction do occurs between the moving liquid and the stationary pipe walls. This friction proselytes a portion of the liquid's hydraulic energy. This thermal energy can't be changed back to hydraulic energy, so the liquid encounters a drop in pressure. This transformation and loss of energy is known as head loss. The head loss in a pipeline with Newtonian liquids can be resolved using the Darcy condition
hL = f
hL = 0.0311
Total length = 16.5 m
Where:
hL = Head loss
f = Darcy friction factor (unitless)
L = Pipe length (m) = 16.5 m
D = Inside pipe diameter
v = Fluid velocity
g = Gravitational constant
d = Inside pipe diameter (m)
Q = Volumetric flow rate (m3/s)

Assessing the Darcy condition gives understanding into factors influencing the head loss in a pipeline. On the off chance that the length of the pipe is double, the head loss will reduce by halve. If the inside pipe diameter is doubled, the head loss will be reduced by half. If the flow rate is doubled, the head loss increases by a factor of four. Except for the Darcy friction factor, each of these terms can be effortlessly estimated. For this situation, little data about the properties of the procedure liquid or the surface unpleasantness within the pipe material is accessible. In spite of the fact that these components appear to a great many people to affect head loss, the Darcy equation does not account for them.
hL = 0.0311
= 0.121
Q (m3/s) 2.0 *10-4 2.2*10-4 2.4*10-4 2.6*10-4 2.8*10-4
hL (m) 0.102 0.124 0.147 0.173 0.2

A graph of head loss against flow rate

The pump used to circulate fluid in the above system is UNILIFT AP358-05-06-A1 as the power which is posses overcomes the actual head loss in the system and can be easily adjust to match the required volume flow rate. According to the required output of the pump. UNILIFT AP358 – 50 -06-A1 pump has a greater output so that in future even if the efficiency of the pump decreases with passage of time, the pump output will still be enough to carry out the process in the system smoothly and effectively.
The pump as per the given schematic is placed around 2m after the condenser which provides enough time for the fluid to overcome the change in pressure due to corrosion will not be a major problem

For commercial steel pipe, the roughness height, e = 0.045 mm. the flow velocity in the pipe is
D = 0.28 litre/sec = 2.8 * 10-4 m3/s

V =
= 10 m/s
The friction coefficient can be obtained from the moody diagram (f = 0.016)
The pipe friction losses are then
hL = f
= 0.016 * = 225.38 m
Total head
NPSH = hsp + hs – hf – hvp
hsp = statistic pressure head (mH2O)
hs = elevation difference (m)
hvp = vapour pressure of liquid (mH2O)
hf = frictio loss (m)

NPSH = 1.5 + 3.5 + 3.3 + 225.38 = 233.68 m

From selection chart figure 1, pump II and III may be used for project
Q(L/s) V (m/s) Nr f hf hsh
0.2 7.14 3.2 * 105 0.0165 118.49 126.79
0.3 10.72 3.8 * 105 0.0160 259.12 267.42
0.4 14.29 5.1 * 105 0.0155 445.87 445.17
0.5 17.86 7.2 *105 0.0150 674 682.3
0.6 21.43 8.4 * 105 0.0145 938.04 946.34

The value of Hsh verses Q (system head curve) are graphed on the pump characteristic curve superimposing this system curve characteristic of pumps II and III as provided by the manufacturer
flow rate HSH effeciency (%)
0.2 126.79 65.8
0.3 267.42 70
0.4 445.17 73.5
0.5 682.3 69
0.6 946.34 66

Graph of NSH and efficiency against flow rate

To move a given volume of fluid through a pipe requires a specific measure of vitality. A vitality or weight distinction must exist to make the fluid move. A segment of that vitality is lost to the protection from stream. This protection from stream is called head misfortune because of rubbing.
The state of within a pipe additionally greatly affects the head loss of the stream of fluid. The rougher it is, the thicker the layer of non-moving or moderate moving fluid close to the pipe divider. This diminishes within breadth of the pipe, expanding the speed of the fluid. With the expansion in speed comes an increment in erosion misfortunes.

Reference

Egli, A., Geberit Ag and Keramag Keramischewerke AG, 1992. Double pipe connection on plastic pipes. U.S. Patent 5,150,926.
Perrusquia, G., 1991. Bedload Transport in Storm Sewers. Stream Traction in Pipe Channels (Doctoral dissertation, Chalmers University of Technology).
Perrusquia, G. and Nalluri, C., 1995. Modelling of bed-load transport in pipe channels. In International Conference on the Transport and Sedimentation of Solid Particles, Prague.