Chapter-1
INTRODUCTION 1|Page
DESIGNING AND TESTING OF A SPIRAL TUBE WATER WHEEL PUMP Problem formulation: Setting up a water pumping system is one of the major difficulties in poor rural communities in India.
All the commercial pumps available available in the market, may not be
affordable to some of of the end users, users, as they need either electricity or fuel to operate. So the people there, generally use the pumps that are hand powered. But the problem is that these hand powered pumps pumps can’t even raise water beyond their structures. So a new and innovative solution is required in order to solve this problem.
Problem statement: How can we lift the water from a place to certain height (generally more than 10 meter) without using electricity or fuel?
Proposed Solution: Since India has a lot of rivers, streams, and canals, making use of these available water sources provides an effective solution to the above problem. For the convenience and benefit of people living in river side areas, one possible solution to this problem is the spiral tube water wheel pump, which is capable of pumping water from rivers to a higher point. This project is independent and does not rely on electric and fuel f uel supplies. It is operational as long as there is water flowing in, to drive the paddles. The spiral water wheel pump consists of tubes coiled in a spiral manner that serves as a passage way of water under pressure delivering it to the discharge pipe. The spiral water wheel pump is practical for domestic and agricultural use. For better functionality and durability, the water wheel should be made of lightweight materials. For the same reason, it has to be mounted on a floater or a support that can be adjusted to the water’s critical level as well as its location. If the water flow is not available, then this pump can also be hand powered.
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DESIGNING AND TESTING OF A SPIRAL TUBE WATER WHEEL PUMP Problem formulation: Setting up a water pumping system is one of the major difficulties in poor rural communities in India.
All the commercial pumps available available in the market, may not be
affordable to some of of the end users, users, as they need either electricity or fuel to operate. So the people there, generally use the pumps that are hand powered. But the problem is that these hand powered pumps pumps can’t even raise water beyond their structures. So a new and innovative solution is required in order to solve this problem.
Problem statement: How can we lift the water from a place to certain height (generally more than 10 meter) without using electricity or fuel?
Proposed Solution: Since India has a lot of rivers, streams, and canals, making use of these available water sources provides an effective solution to the above problem. For the convenience and benefit of people living in river side areas, one possible solution to this problem is the spiral tube water wheel pump, which is capable of pumping water from rivers to a higher point. This project is independent and does not rely on electric and fuel f uel supplies. It is operational as long as there is water flowing in, to drive the paddles. The spiral water wheel pump consists of tubes coiled in a spiral manner that serves as a passage way of water under pressure delivering it to the discharge pipe. The spiral water wheel pump is practical for domestic and agricultural use. For better functionality and durability, the water wheel should be made of lightweight materials. For the same reason, it has to be mounted on a floater or a support that can be adjusted to the water’s critical level as well as its location. If the water flow is not available, then this pump can also be hand powered.
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History of pumps that run without w ithout electricity in chronological order Long before recorded history, people used buckets and pots to lift and carry water from its source. Wheels and paddles also were employed. The devices could be powered by humans or animals, by wind, or by the water itself. Human-powered devices traditionally were used to move water short distances and up low grades.
THE SHADUF: An old and simple device that evolved from the hand-carried bucket and that was used by the ancient Persians and Egyptians. It consists of a pole with a bucket or pot on one end and a counter weight at the other end and supported in between by a vertical post. A person grasps the pole and dips the bucket into a body of water such as a stream or river in order to fill it with water. The counter weight lifts the bucket and the bucket is swung over and emptied into an irrigation ditch. It’s still used in rural Egypt.
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THE BAIL BAIL: It consists of a sheet or bucket stretched between two people by ropes used to irrigate small plots of land. Water scooped from a stream or lake is quickly emptied into an adjacent irrigation ditch or field. It was widely used in Ancient China.
WHEELS AND LOOOPS: Advancement over devices that used a reciprocating cycle. It was in use after 5 th century. The SAKKIA introduced by Ancient Persians, uses animal power to turn a wheel or chain that has numerous evenly spaced buckets. At the lowest point, the buckets are filled with water and emptied at the highest level. Human powered water wheels probably were developed more than 2000 years ago during china’s chin dynasty.
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NORIA: It’s similar to wheel shaped or belt like devices. The Noria is a wheel with evenly spaced compartments arranged around its periphery. As the wheel turns, the compartments are dipped one-by-one into the water and then emptied at the top into a holding tank ,canal or Aqueduct. The Noria is powered by water current paddles attached to the wheel’s rim turn it in reaction to the force of flowing water.
ARCHEMEDIES SCREW: The first screw pump was assumed to be devised by Archemedies around 250 B.C.E. It has thus come to be called the Archemedies screw used where water needs to be raised less than 1.5 metres (5 feet). It’s a water lifting device consisting of an enclosed cylinder containing a screw , whose turning blades bring up the water.
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LIFT AND HAND PUMPS : Also called “Positive-Displacement pump” .It consists of a piston and cylinder positioned vertically. Raising a handle that is attached to a piston enclosed in a pipe operates the lift pump. Subsequent pumps of the piston pull more water into the chamber , which eventually overflows, spilling water out a spout. The pump will support a column of water no higher than about 10 metres (33 feet).
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HYDRAULIC PUMP: A Hydraulic ram is a self-powered devise which pumps water using only water pressure. The ram pump was invented in 1773 in England and first patented in France in 1796. It’s independent of external power source. If a ram is properly located and periodically maintained, it can pump continuously for decades. They use the Hydraulic head or height difference , between the relatively elevated water source and lower-elevated ram. Heavy duty rams can lift water as high as about 90 metres (nearly 300 ft) For a ram installation it requires about 1mt of driving hand and steady inflow of approximately 95 litres (25 galloons) per minute which cannot much serve the purpose much better.
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HISTORY AND THEORY OF SPIRAL TUBE WATER WHEEL PUMP
In 1746, A spiral tube pump has been recreated and tested at wind farm Museum using light weight and inexpensive modern materials. It can be turned or otherwise driven to provide a low cost, efficient pump.
In 1746 by H.A.WIRTZ invented spiral pump to provide water for dye works .The Wirtz pump spiral pump was constructed so the end of the outside pipe coil opened into a scoop. The inner coil led to the centre of the wheel where it joined a Rotary fitting at the axis of the machine.
Ewbank reports these pumps to have been highly successful and states they were used in Florence as well as Archangelsky in the later part of 18th century.
In 1784, a machine in Archangelsky is recorded to have raised “a hogshed of water in a minute to an elevation of 74 feet”, through a pipe 700 feet long. Lead or sheet metal was probably used to fabricate the coils which must have made the machine extremely heavy problems encountered with the weight are mentioned as well as the general unwieldiness of the larger machines. These slow turning, cumbersome pumps become obsolete with the development of high speed steam Engines.
An Ideal Wirtz pump would follow Boyles pressure-volume relationship and the coil volumes would change with respect to changes in the entrapped air volumes.
Tubing of uniform diameter would not be formed as a spiral or a Helix. This was understood by Olinthus Gregory in his work entitled TREATISE OF MECHANICS, edition of 1815.
Gregory states on page 230 of volume I that ,”If ,therefore, a pipe of uniform bore be wrapped round a conic frustum____, the spirals will be nearly such as will answer the purpose”.
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In 1849, Ewbank cited helical pump having coils of the same diameter. But through experimental analysis it was found that the Helical pump can apparently only pump to a limited head of 54 feet.
Ewbank also stated that when compressed air and water occupied more than the volume of an inner coil, the water “Will run back over the top of succeeding coil, into the right hand side of the next one and push water within it backwards and raise the other end”.
Windform Museum built a spiral Wirtz pump to evaluate the potential to reach higher pressures and pump to high heads.
A Danish Guide and south Association project on the Nile river near Juba in southern Sudan use raft-mounted paddle-wheel-driven, helical wirtz for irrigation.
The first pump used there had four sets of 2” ID(52 mm) tubing which was wound on a flat-mounted drum which was paddle wheel driven pump to a head of 13’4”(4 metres). These pumps were reported very successful pumping to that head.
The second Wirtz pump project was built by Peter Morgan, was probably the first person to built a Wirtz pump. He got that idea when he was adjusting a pipe carrying gas from a biomass digester.
Peter Morgans work with the Wirtz or spiral pump has been published in a local Zimbabwe science Magazine “Science News” in 1983.
Earlier it was assumed that the pressure produced would be directly related to the wheel diameter and number of coils.
After some deliberation, it was felt that a smaller wheel with proportionately smaller coils might not provide high enough pressures for a realistic evaluation of working sized machines. 9|Page
Two different pipe sizes were used to form coils on the wheels to provide a broader range for tests.
The pump stand or mounting frame was built so that the Wirtz spiral pump could become a permanent operating exhibit and a teaching tool.
In 1978, in Mark’s standard Handbook for Mechanical 8 th edition, it was said that Air lift pumps can have an efficiency of 50%.
Again a new, inclined coil Wirtz pump was developed by David Hitton of Australia on July 1987. The great advantage of the inclined pump for low head pumping is that it does not require a rotary fitting.
With a 20 feet pipe inclined about 20 degrees, this pump coil rise water to a height of 7’ or over 2 metres.
Later David Hitton described an alternative construction in which a drum is fixed to extend from the lower end of pipe. The Helical coil or coils are wound around the drum and connected to the pipe and is made to float on the water source.
The lower end of the pipe is laterally positioned by two vertical stakes driven near the drum. This allows a rise and fall in the body of water being pumped.
Building and testing the spiral pump at wind-farm Museum demonstrated that the design of the pump allows great altitude. Unlike the test wind-farm pump, the innermost coil should be more than the half of the radius of the outermost coil to limit internal flow over in the spiral and resulting reduced output and low effi ciency.
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ADVANTAGES:
•
•
It is a Beautiful piece of alternative Technology. Spiral water pumps can provide water up to 30 metres higher than the river
due
to the system of compressed air in the spiral tubes. •
The pumps provide water without the need for fuel or Electricity which is very useful for poor rural communities.
•
Once established the pumps do not require any further investments.
•
The water pumps are easily constructed with flexible PVC tubing.
•
Overall the pump can be easily constructed with available local resources.
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LIMITATIONS:
There are several losses in the wirtz pump that affect its efficiency. 1) There is a chance of occurring a small head loss. 2) Another small loss would result from drag as the outer coils and the scoop turn in water to be pumped. 3) In the Delivery pipe there are two losses which reduce efficiency, fluid flow resistance and air lift slippage.
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Chapter-2
DESIGN AND CONSTRUCTION OF SPIRAL PUMP 13 | P a g e
BASIC DESIGN The Water Wheel itself is very simple consisting of a series of paddle wheels attached through spokes to a central hub mounted on a hollow steel axle. The axle is supported on either side of the canal through a brick built pillar.
Wheels have been made of steel,
hardwood and Aluminum depending on the availability of suitable materials. The number of paddle wheels is 16 - the arrangement of this number being particularly easy. The water pump itself consists of a poly pipe tube arranged so that it forms a spiral fixed either on the sides of the wheel or preferable so that it within the paddles of the wheel (see diagram). The latter arrangement gives the wheel great strength since the spiral tubs act as reinforcing struts supporting the spokes. In most operating wheels two spiral tube pumps are used, placed within the wheel in horizontally opposed positions. Water enters the spiral tube through an enlarged pipe which acts as a water collector. The collector picks up enough water to half fill one complete spiral of the pump. Thus a core of water is picked up followed by a core of air. Thus a series of "airlocks" is built up in the spiral tube. The inner most spiral of the tube delivers water into the axle of the wheel and there it is led through a simple water seal, made of neoprene, to a static rising water pipe which delivers water to a header tank above the wheel.
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OPERATION As the wheel revolves each paddle in turn becomes submerged in the water passing around it. Thus once per revolution each water collector also dips into the water. Just after the water collector passes the horizontal position and begins to rise, it takes in a "gulp" of water expelling air previously contained within it.
When the collector rises out of the canal it is
full of water. This charge of water runs back into the first spiral of the tube pump and is followed by a charge of air. As it dips into the water, the collector picks up another charge of water and the cycle is repeated. As the wheel revolves a pressure head develops within each coil of the spiral tube, water in the ascending coils being higher than in the descending coils (see diagram). Cores of water contained in the spiral compress air between them as they travel around the tube and both water and air are expelled under pressure into the hollow axle of the wheel. The water which is under pressure sure rises up the pipe and this process is assisted by the compressed air which lifts water above it in its attempt to escape through the pipe. The water is discharged into the header tank in a series of bursts jets of water being followed by jets of compressed air. The height to which water can be pumped depends on the number of coils in the spiral tube. As an example - a 2 meter diameter wheel can pump water up to approximately 8 meters with 6 complete coils, the same wheel being able to pump up to 6 meters with 4 complete coils and 4 meters with 2 complete coils. For larger wheels where the diameter of the coils is nearly the same as the diameter of the wheel an approximation can be made by multiplying the diameter of the wheel by the number of coils. A 4 meter diameter wheel with 3 coils should be able to pump water up to a height of 12 meters. Te volume of water pumped depends on the capacity of the spiral tube pump. Naturally, the wheel will only pump water if there is sufficient energy in the canal to turn the wheel against the weight of water h eld in the
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rising spiral tube.
The head of water in each spiral varies through a cycle, with optimum
pressures being developed as the water load in the rising main reaches a maximum. The volume of water pumped also depends on the speed of the wheel as well as the capacity of the spiral tube. The wheel should not move too fast however, as the effects of centrifugal force will have an influence and may carry water over the head of the wheel, and break the essential air lock between each core of water. The wheel could not pump water at all through the spiral tube if the air locks did not exist. It is possible to fit a single collector pipe and connect this to the axle through a single spiral tube. More water can be pumped however, when two collectors are fitted to two spiral tubes The exact arrangements may depend on whether more water is required at a small head or less water is required but at a greater head.
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CONSTRUCTION
1) WHEEL 2) ROTARY FITTING 3) SPIRAL COIL 4) SCOOP 5) TANK
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WHEEL When considering the building of a spiral pump, we assumed that the pressure produced would be directly related to the wheel diameter and the number of coils. It was felt that a smaller wheel with proportionately smaller coils might not provide high enough pressures for a realistic evaluation of working sized machines. The wheel was built in a 8 spoke fashion
It consists of 16 spokes with each 42 inches length
All the spokes are connected to a hub of length 9 inches
The total length of working sized wheel is 90 inches
A 1-1/4 inch hole was drilled in the centre of wheel to allow passage of a pipe leading from inner most coil to rotary fitting
The hub was made with hard wood and the spokes are made of light weight steel
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ROTARY FITTING The rotary fitting, while it is easily fabricated, is a critical part of the spiral pump. It must provide a relatively watertight seal to prevent fluid and pressure loss. The inner coil of the pipe is attached to the galvanized steel pipe which is passing through the centre of the wheel with the help of a 1-1/4 inch bush and 1-1/4 inch Tee-joint.
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COIL PIPE: 1-1/4 inch pipe size was used to form coils on the wheel to provide a broader range for the tests. The first series of tests were performed on the wheel with the coils formed from 195 feet of 1-1/4 inch ID flexible polyethylene pipe (rated 100 psi at 73°F).Each successive coil was wound closely within the outer coil to maintain the largest possible diameter for all the coils. This provided sixteen coils with the radius of the outer coil being 35 inches and the radius of the innermost coil being 16 inches.
Outer most coil radius- 35 inches Inner most coil radius- 16 inches Total number of coils – 16 Total length of the pipe used – 60 metres weight of the pipe – 28 kg.
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A method of approximating the number of spiral pump coils for a given delivery head up to 100 feet mounted on a given size wheel has been derived using Boyle's pressure-volume law. The following assumptions have been made to arrive at this approximation.
1) The first is that the coils are represented as a static series of pressurized interconnected u-tubes. Each tube is sized to be equal to the volume of the water (assumed to remain constant and equal to one-half the total volume of the first coil) plus that of the air. Since the air is compressible, the total volume of each respective u-tube would decrease as the centre of the wheel is approached. 2)
Another assumption is that within the first coil and all the other coils, the head within each coil is assumed to be equal to the diameter of that coil. Actually, the maximum head in a given coil extends from the upper wall of the pipe at the bottom of the coil to the lower wall of the pipe at the top of the coil. However, this assumption would give less than a 5% error in the case of the outer first coil of a six foot wheel with 1-1/4 I.D. pipe.
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SCOOP The length of the scoop - 16 inches Diameter of the scoop - 75mm Volume of the scoop = 1796
3
The scoop is designed so that it takes a maximum amount of water into the outercoil (above 50%)
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TANK Dimensions: Length- 10 ft Breadth- 3ft Depth- 2.5 ft Volume- 2.123 cubic metres 1 cubic metre = 1000 litres So total volume of the tank is 2123 litres
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MOUNTING THE WHEEL Once the wheel has been finished and the spiral tube pump fitted, the wheel can be placed in the tank. Two bricks pillars are built on either side of the tank at the correct height and distance apart so that the wheel will sit nicely on its bearings and well immersed in the tank water. It is wise to have the water seal ready when the wheel is fitted because water will be delivered under pressure as soon as the wheel turns.
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RISING MAIN AND STORAGE TANK:
The rising main fitted to the axle pipe should rise vertically and be fitted with a curved pipe at its head so that water is led into the storage tank. Smaller wheels have rising mains made of 25mm pipe, large wheels with 50mm pipe. A tank stand can be made of concrete or steel bolted together. Once the water it has been delivered to the tank it can be reticulated to the domestic supply through some form of purification system.
MAINTENANCE:
Provided the wheel has been made strongly and the bearings are lubricated, the wheel should provide long and trouble free service almost without being touched. The water seal need tightening or replacing from time to time – but a well made seal should last for many years.
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THEORITICAL CALCULATIONS
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Calculating the delivery head The delivery head can be calculated by assuming that the average head between the first and the nth coil multiplied by the number of coils will give the total head. D = h1 = Wheel & Outer coil Diameter and the outer coil head H = delivery head n = number of coils d = pipe diameter hn=head in n-th coil (( D + hn) /2) x n = H As we know that n= 16 coils and D = 6.5 feet So H = 8( 6.5+ hn) = 52 + 8hn.....................eq (1) Knowing the pressure and the volume of the first coil ( atmospheric pressure and the diameter of the wheel) and the delivery head or gauge pressure required at the nth coil, then the volume of the nth coil, which is its head or diameter in this simplification, can be determined. Applying Boyle’s Law:
P1 V1
=
PnVn
P1 = Patm + D Pn = Patm + H V1 = air volume in first or outer coil Vn = air volume in last or inner coil
2
V1 = π x
(2) x D
Vn = π x
(2) x hn
2
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Calculating
The delivery head at nth coil P1 v1 = PnVn hn = (Patm + D) D/ (Patm +H) we know that Patm = 14.5 psi = 34 feet (head)
( since 1 psi = 2.31 feet)
diameter of the wheel is 6.5 feet So hn = (34 + 6.5) x (6.5)/ (34 +H) ................eq (2) Substituting eq (1) in eq (2) hn = 263.25/ (86+8hn) solving for hn hn = 2.48 feet substituting in eq (1) H = 72 feet So the delivery height to which the pump can raise water is 72 feet. But due to constraints we performed the experiment at 40 feet H = Height pumped
= 40 feet
Diameter of the pipe = 1.250 inch RPM = speed of the wheel = 2 REV = revolutions of the wheel = 6 F = Force in pounds exerted at wheel circumference = 26.1 lb
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Discharge (gal) = N x Π x
=Nx Πx
2
(2) . Length of the water slug 2
(2) x Π x R
= 6 x Π x (1.25 x 2.54/2)^2 x Π x (3.25) x 12 x 2.54 cm^3 = 14783.4837cm^3 = 14.783 ltr = 3.91 gal
(1gal=3.7854ltr)
W-out = Discharge (gal) x H (ft) x 8.34 lb/gal = (3.91) x (40) x 8.34 = 1304.376 lb-ft W-In
= force (lb) x distance (ft) = force(lb) x Rev x Wheel dia(ft) x Π = (26.1) x6 x( 6.5) x π = 3197.827 lb-f
Efficiency
= W-Out/ W-In = 1304.376/3197.827 = 40.78%
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Chapter-3
TESTING 30 | P a g e
Testing apparatus The pump was mounted on the stand at a proper height from the tank in order to ensure a proper submerged ratio. As the flow water power cannot be used in the experimental area, we made it hand powered. In order to gather information on the actual height to which the pump could deliver water, the discharge was directed up a nearby 40 feet roof. At each test head or level to which the water was being pumped, a catchment system was setup that allowed the discharged water to be directed into or out of a bucket with control lines operated from ground level. The catchment bucket funneled the discharge into a drain pipe which led to measuring containers below. To measure the torque required for pumping, a rope and a 50 lb spring scale is used. The rope was attached to and wrapped around the circumference of the wheel and led over a pulley placed on the test stand.
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Testing procedure: TESTS
Total three groups of tests were carried out to determine the parameters of the spiral pump. 1) The first tests were performed to determine the capacity of the pump at different speeds. 2) The second group of tests were performed to determine the effect of different sizes of scoops. 3) The final group of tests were carried out to determine whether the submerged ratio has any effect on the pump discharge.
The initial tests to determine the pump discharge with respect to its rotational speed measured discharge while varying the revolutions per minute(rpm) from two to twelve over three minute intervals. The wheel for these tests mounted the coils of 11/4 inch ID tubing. The scoops for these tests was of 5 i nch ID pipe 16 inches long.
The first test showed the positive displacement nature of the spiral pump as the water delivered remained fairly constant with different wheel speeds. This indicated the tests on the scoops of different capacities could be made at a single selected rpm. The historical references suggested that the scoop be sized so that one half the volume of the outer coil is collected with each revolution of the wheel.
The second tests also carried out the 1-1/4 inch ID tubing coils mounted on the wheel. The scoops were of 5 inch ID plastic pipe and had their open ends cut at an angle so that they were level with the water upon exiting. The scoop lengths used were 1, 12, 16 and 22 inches. Scoop length was measured from the square cut end to
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the center of the angle cut. Discharge and torque measurements were made at heads of twenty and forty feet for all scoop sizes.
The torque was measured by attaching 50lb spring scale to the rope wrapped around the periphery of the wheel and pulling in a steady manner.
The final group of tests were performed whether the submersion ratio has any effect on the pump discharge.
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TEST-1 To determine the pump discharge w.r.t rotational speed measured discharge while varying
pump. EQUIPMENT
1-1/4 inch ID flexible polyethylene pipe
A water wheel with 1-1/4 inch hole drilled in the center of wheel to allow passage of a pipe leading from the innermost coil to the rotary fitting.
DATA
H = Height pumped = 40 feet Length of 5’’ ID scoop portion = 16’’ RPM= speed of the wheel REV = revolutions of wheel F= force in pounds exerted at wheel circumference W-out (ft-lb) = Discharge(gal) x H(ft) x (8.34)lb/gal W-in (ft-lb)
= force(lb) x distance(ft) = f(lb) x REV x wheel dia (ft).pi
Efficiency = W-out/W-in
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TABLE – 1 TEST
RPM
REV
DIS (gal)
FORCE (Lb)
W OUT
W IN
(ft- lb)
(ft-lb)
Eff. (%)
Press.
Head
(psig)
(ft)
* L-sc (inches)
2
6
3.67
26.1
1224.3
2950.5
41
18
40
16
3
9
5.42
26.1
1808.1
4425.1
41
18
40
16
4
12
7.33
26.1
2445.3
5900.4
41
17
40
16
6
18
10.92
26.1
3642.9
8850.6
41
16.5
40
16
8
24
14.67
26.1
4893.9
11800.8
41
16
40
16
12
12
8.08
26.1
2695.5
5800.4
45
15.5
40
16
*L-sc = length of the scoop
table no.1
These tests found that spiral pump to be a positi ve displacement pump.
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TEST-2
To determine the effect of different scoop sizes EQUIPMENT
Diameter of the scoop = 5 inches. Effective scoop lengths = 1, 12, 22 Number of pump turns = 3 rpm = 9 turns TABLE DIS
HEAD
(gal)
( ft)
FORCE
L-SC
W-IN
W- OUT
(lb)
(in)
( ft-lb)
(ft-lb)
EFF
%volume
%
(1st coil)
5.75
40
26.1
22
4425.5
1918.2
43
75
5.67
40
24.5
12
4154.2
1854.8
45
62
3.88
40
20.2
1
3425.1
1294.4
37
36
6.39
20
18.5
22
3136.9
1065.9
34
75
5.85
20
15.9
12
2696
974.1
36
62
4.41
20
14.9
1
2566.4
735.6
29
36
table no.2
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TEST-3
To determine the effect of sub merged ratio on the pump discharge RPM = 3 turns REV = 9 revolutions of the wheel over 3 minutes Submerged ratio = length of the wheel in water/ total length of the wheel Submerged ratio
Pump discharge
0.12
5.42
0.14
5.48
0.154
5.54
0.168
5.59
0.183
5.6 table no.3
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TERMS USED IN THE TEST : Flow Over
During the tests there is a chance that a rush of water flows from inner coils backward to outer coils. This verified Ewbank's 1849 indication that this flow took place. The flow appears to take place only when the inner coils have insufficient volume to contain the compressed air and water passing to them. Although it reduces pump output, it is not certain to what extent this internal flow influences the characteristics of the spiral pump. It may maximize the effect of the air columns or cumulative heads of the inner coils. As suggested by Gregory in 1817, a spiral pump could be designed to minimize or eliminate this internal flow. The extent that such a design may result in higher pump efficiency remains to be investigated.
Blow-back Blow-back occurs when the pump pressure exceeds the cumulative pressures of the coils. The blow-back pressure is the pressure at which this occurs. This pressure can be determined for each wheel configuration by closing the valve on the pump output and pumping until there is a sudden drop in pressure and a surging of water and air back through the scoop. During the tests, the blow-back is expected to happen under different conditions for the two pipe diameters tested.
Air Lift The very principle that allows this pump to create columns of water within its coils, that of alternately taking in air and water, also acts to increase the delivery head. The air, which is compressed as it moves toward the center of the wheel, expands as it goes up the delivery pipe, producing a lift effect on the water. Testing should prove that this effect by showing that the actual head reached was greater than that indicated by the pressure gauge in the system. The air lift effect was most evident when pumping to heights greater than those indicated by the blow-back pressure .The air lift effect is also expected to vary for the two pipe diameters tested. 38 | P a g e
Pump Efficiency
There are several losses in the Wirtz pump that affect its efficiency. Within the coil, fluid flow losses are quite small. If the pump is turning at 9 rpm, water in the outer coil is moving about 2.8ft/sec and in the inner coil at about 1.4ft/sec. The average flow rate in the length of tubing is about 2.3 ft/sec, greater than the mere average of the two speeds, as more of the tubing forms larger diameter coils than smaller ones. From the pipe flow tables, the head loss for 1-1/4 inch tubing would be about 5 ft of water. Even this small loss would be considerably reduced as the coil is not completely filled with water but has small portions filled with air which has a vastly lower flow resistance. Another small loss would result from drag as the outer coils and the scoop turn in water to be pumped. A much larger loss in the pump coil is the result of "flow over" as described above. The inner coil can't hold the water scooped by the outer coil and the compressed air. As a result, torque which has been expended raising water on one side of the coils is lost as water runs down the other side. The efficiency of the pump pumping to a head of one atmosphere would be greatly improved if the inner coil was 3/4 the diameter of the outer coil. The half of the volume of the outer coil of water and the half the volume of the outer coil filled with air and compressed to one atmosphere would then just fill this 3/4 diameter inner coil without flow over losses, when pumping to lower heads under one atmosphere, a helical pump is probably easier to construct and about as efficient as a spiral pump.
In the delivery pipe there are two losses which reduce efficiency, fluid flow resistance and air lift slippage .Fluid flow losses are reduced by larger diameter delivery pipes, but air lift losses are lessened by smaller diameter pipes. Conventional air lift pumps bubble a steady stream of compressed air into the bottom of a riser pipe submerged below the water surface in a well. If the weight of water and air in the riser pipe is less than that of the water above the bottom of the riser pipe, water will flow up the riser pipe to be pumped from the tank. As reported in Marks' Standard Handbook for Mechanical Engineers, Eighth Edition, 1978, air lift pumps can have an efficiency of 50%. At any rate, an overall efficiency of up to 75% would be indicated for a well designed spiral pump. 39 | P a g e
Chapter-4
CONCLUSION
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DISCUSSION: The results of the first group of the test performed on the spiral pump showed that it is a positive displacement pump at low speeds. As long as the wheel turned at all, there was output. For the larger size pipe the machine also performed well at maximum speed tested, 12 rpm. It actually had 4 % increase in efficiency at higher speed. The maximum speed for this wheel is appeared to be not much greater than 18 rpm as this speed causes considerable difference when scoop enters into the water. Any higher speed would possibly decreases its efficiency. The second tests performed on the scoop sizes found the suggestion of the historical references that the scoop collect one half the volume of the outer coil to appear to be accurate. The volume collected by the scoop is the sum of 5 inch diameter scoop and volume of the immersed and water scooping portion of the outer coil. If we observe the results, we can find that at 40 feet head the 12 inch scoop filling 62% of the outer coil was 2% more efficient than the 22 inch scoop filling 75% of the outer coil. The third group of tests performed on the coil pump suggested that the pump discharge is almost independent of the submersion ratio and the optimum submersion ratio would be 0.154. As the submersion ratio increases the force required to turn the wheel also increases.
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FURTHER ADVANCEMENTS: The theoretical concept developed on the spiral pump demonstrates the excellent potential of this preindustrial concept when combined with today's available technology. One of most attractive ways of powering the spiral pump is to mount it on a paddle wheel placed in a river or stream. A series of paddle wheel driven spiral pumps may be connected to a common delivery pipe for a higher volume output. In some circumstances, hand or motor driven spiral pumps could be used to pump to high heads from canals, lakes, or very slow flowing rivers. Low maintenance and ease of construction would make a driven spiral pump a good choice compared to a piston pump.
As there are no valves or moving parts except for the wheel and the rotary fitting, the spiral pump will have a very long service life and has a renewed future providing water for irrigation, fish farming, village or home.
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CONCLUSION: The search for the cost effective pumps is a top research priority worldwide. Studies to develop models that can powered by renewable energy sources, which can pump water to a higher head than pump structure itself and which can be built out of available materials by local crafts men have produced this beautiful type of stream driven pump i.e spiral tube water wheel pump. It is a 240 year age old invention and all that it requires is an engineering measurement and scientific calculation. So by using proper measurements, assumptions, calculations and historical references, we built a proto type of the spiral pump with 2.25 m overall diameter at our college and tested its efficiency by conducting various experiments at different heads by varying the speed of the wheel with different scoop sizes and submersion ratios. We established that the pump was most efficient (over 50 percent) with a high head, a slow rotational speed, a smaller diameter tube and with a scoop of 100-120 percent of the outer coil volume. Considering the high efficiency of pump at high heads and slow speeds of rotation, its nonuse of fossil fuel and its adaptability to existing natural conditions (i.e where a strong stream flow stream in narrow rivers or irrigation canals is available), spiral pumps are an excellent alternative, in particular for developing countries without their own oil resources.
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REFERENCES: Ewbank, Thomas. 1849. A Description and Historical Account of Hydraulic and Other Machines for Raising Water , Greeley and McElrath Publishers, New York. Belcher, A. E. (1995). Recovery of Revenues Lost to Fish Passage. Proceedings of the American Society of Civil Engineers International Conference on Hydropower, July 25 - 28, San Francisco. Ohlemutz, Rudolf E. (1975). "The Hydrostatic Pump and Other Water-lifting Devices in the Context of the Intermediate Technology Approach", Dissertation, University of California, Berkley. Morgan, Peter R. (1979). "A New Water Pump: Spiral Tube", The Zimbabwe Rhodesia Science News. 13(18):179-180. Stuckey, A.T., Wilson E. M.(1980). "The Stream-powered Manometric Pump", Proceedings of the Institute of Civil Engineers Conference on Appropriate Technology in Civil Engineering,London, 105-108. Tailer, Peter. (2005). The Spiral Pump, a High Lift, Slow Turning Pump. http://lurkertech.com/water/pump/tailer/, Retrieved April 6, 2011. Mortimer, G. H. and Annable, R.(1984). 'The Coil Pump - Theory And Practice', Journal of Hydraulic Research, 22: 1, 9-22. Kassab, S. Z., Abdel Naby, A. A., Abdel Basier, E. (2005). Coil Pump Performance Under Variable Operating Conditions. Ninth International Water Technology Conference, IWTC9 2005, Sharm El-Sheikh, Egypt, 655-672. 44 Reysa, G. (2005). Building an Undershot Waterwheel http://www.builditsolar.com/Projects/Hydro/UnderShot/WaterWheel.html
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