Estimation of Power and Efficiency of Hydraulic Ram Pump with Re-circulation System

Transcription

1 International Journal of Computer-aided Mechanical Design and Implementation Vol.1, No. 1, (2015), pp Estimation of Power and Efficiency of Hydraulic Ram Pump with Re-circulation System Sampath S S 1, Sawan Shetty 2, Allan Mathew Pendanathu 3, Waleed Javaid 4 and Chithirai Pon Selvan M 5 1 1, 2 Assistant Professors, School of Engineering & Information Technology, Manipal University, Dubai, United Arab Emirates 3, 4 Under Graduate Mechanical Engineering Students, School of Engineering & Information Technology, Manipal University, Dubai, United Arab Emirates 5 Associate Professor, School of Engineering & Information Technology, Manipal University, Dubai, United Arab Emirates selvan@manipaldubai.com Abstract There are lots of limitations of conventional energy especially in the rural regions. Hence more attention of designers is diverted towards the use of unconventional energy. A mechanical device is designed works on the principle of conversion of potential energy to kinetic energy which is governed by gravity and runs on zero running cost. Present work involves in design and fabrication of hydraulic ram pump which is powered by the falling water from a small height to lift a part of that water required elevation. The current work emphasizes in the calculation of the discharge, power and the efficiency of the ram pump. The above is modified in terms of providing re-circulation system to avoid the wastage of water. The results which are obtained are validated with respect to standard fluid mechanics calculations. Keywords: Renewable energy, delivery valve, impulse valve, discharge 1. Introduction Hydraulic ram pump is widely used to provide energy for agriculture and domestic purposes [3]. This type of pump is used by farmers and middle class people in rural areas for its zero running cost [4]. It is a water pumping device that is powered by falling water which works by using the energy of water running down a drive pipe to the body of the ram pump [3]. It pumps water from stream, creek and other water sources with flowing water. This device uses the kinetic energy of the falling water and it lifts it to the higher elevation than the source [1][3]. Existing ram pumps have various limitations like complexity of usage; cost factor, maintenance etc. [3]. Therefore it is very much required to design a simpler system for the smooth usage [1]. A hydram or impulse pump is an automatic pumping device [7] which doesn't use electricity or any other power source [2][6]. Hydram pumps the water to increases the water head which can be used in hydropower plants where high pressure water impinges on the turbine. It can have advantage of increasing the potential energy with a minimum set up and maintenance cost [5]. Also it can tap energy at low velocity streams and the system can be affordable and scalable to Pico and micro hydropower systems [5]. Various kinds and Article history: Received (May 26, 2015), Review Result (July 14, 2015), Accepted (August 12, 2015) Print ISSN: , eissn: IJCMDI Copyright c 2015 GVSchoolPublication

2 Estimation of Power and Efficiency of Hydraulic Ram Pump with Re-circulation System designs of hydrams were tried and the main challenges were the high noise from the waste valve, consistence wear on the waste valve rubber and corrosion problems. This research addresses these challenges by making uses of aluminum alloy and optimizing on the weights at the waste valve [6]. A hydram is a structurally simple unit consisting of two moving parts. These are the impulse valve (or waste valve) and the delivery (check) valve. The system also consists of an air chamber and an air valve. The operation of hydram is alternating due to the cyclic opening and closing of the waste and delivery values. The closure of the waste valve creates a high pressure rise in the drive pipe. An air chamber is required to transform the high intermittent pumped flows into a continuous stream of flow. The air valves allow air into the hydram to replace the air absorbed by the water due to the high pressure and mixing in the air chamber [7]. Recent studies showed that simulation is created i.e. computer model is developed to investigate the effects of parameter variation [8]. Figure 1. Construction of hydraulic ram pump [11] Basically force of moving water gives the power it needs which uses the momentum of the relatively large amount of moving water to pump a relatively small amount of water uphill [2]. The pump which has a valve that allows water to flow through this pipe and build up speed. Once the water reaches its maximum speed, the valve slams shut. Due to this the flowing water develops a great deal of pressure in the pump because of its inertia [1]. The pressure forces open a second valve. High-pressure water flows through the second valve to the delivery pipe which has an air chamber to allow the delivery pipe to capture as much high-pressure water as possible during the impulse [7]. The pressure in the pump falls. The first valve re-opens to allow water to flow and build up momentum again. The second valve closes. A hamlet setting can be supplied with water using hydram as shown in figure 2. The water is purified in treatment plant (chlorination, filtration, solar distillation) before it is supplied to the destination. 10 Sampath S S, Sawan Shetty, Allan Mathew Pendanathu, Waleed Javaid4and Chithirai Pon Selvan M

3 International Journal of Computer-aided Mechanical Design and Implementation Vol.1, No. 1, (2015), pp.9-24 Figure 2. Schematic representation of village water supply with a hydram 2. Related study Arnold F. Dumaoal Sr [1] et. al worked on the design and construction of downdraft type of ram pump to use it in rural areas. Paper reaches an important conclusion that Downdraft type hydraulic ram pump which is installed, occupies less space that the traditional types of ram pump. Nwosu and Madueme [2] constructed hydraulic ram pump which is used to increase the head of the falling water. The rate of flow of water, from the tank and pumping water into the tank are designed to operate in an optimum manner. A controlled actuator is used In order to maintain the flow rates. The underground tank is made to store rain water and is capable of meeting the water need of the micro hydropower plant for the off rain periods. Zoller [3] et. al built a ram pump, the design stressed with a goal of improving the performance of the pump in terms of delivery flow and efficiency. Mainly this work was carried out to facilitate the irrigation. Seemin Sheikh [4] et. al studied the literature available and prepared a structured design methodology for hydraulic ram pump (HYDRAM) which covers design parameters, design procedure along with the mathematical relationship used for the design work. Nganga [5] et. al optimized the power generated by low head small hydro plants through the use of hydram used to boost the water pressure before it impinges on the turbine. Fabrication of hydram is carried out with suitable modifications. By adjusting the waste valve stroke length the flow rate in the delivery pipe and the pressure in the hydram were optimized. Results showed that Hydram was able to pump water to a higher head which then increased the power produced by the turbine. Mbiu [6] et. al highlighted on design development of a durable and locally made hydram using inexpensive and readily available materials. A test rig was fabricated and used to analyze the different parameters of the hydram. Optimizing these parameters ensures that the hydram performance is enhanced and as a result giving the pump a longer life. Experimental and analytical modelling results were generalized in performance charts and compared to commercially available types operating characteristics. These results will enable the targeted users to be able to select appropriate sizes for their water pumping needs. Shuaibu Ndache Mohammed [7] designed and fabricated hydram. The setup which was constructed yields desired power and efficiency. The overall cost of fabrication of that hydram proved that the set-up is relatively cheaper than the existing pumps. Verspuy and Tijsseling [8] constructed a simple mathematical model of a hydraulic ram. The model was compared with the previous models in order to validate the results and was used to perform a parameter variation study. Iversen [9] made an attempt to Copyright c 2015 GVSchoolPublication 11

4 Estimation of Power and Efficiency of Hydraulic Ram Pump with Re-circulation System identify the features of the ram, the drive head and flow, the discharge head and flow, the cycle frequency, and the system efficiency. Analytical results are expressed in terms of the ratio of the maximum drive velocity at drive valve closure to the maximum steady state velocity with the drive valve wide open. Comparison of the analysis with experimental results gives a numerical correlation of heads and flows. Martin Basfeld & Ernst August Muller [10] developed a simplified theory from Newton's equations of motion, taking into account loss factors and boundary conditions. Results from that theory were compared with measurements made on a laboratory model; in particular, the time dependence of the flow velocity in the drive pipe, the water volume delivered per work cycle and the efficiency were experimentally determined as functions of various parameters. 3. Methodology Hydram of hydraulic ram is a mechanical device which uses the simple principle of transfer of energy that is from potential to the kinetic energy. Water which is at a higher elevation flows downhill due to gravitational force [4]. Water which will be at one hydraulic head flows into a higher hydraulic head. It basically uses water hammering effect in order to develop the pressure. There is a sudden stoppage of the flow of water in a pipe which creates a very high pressure surge. Equation (1) shows the total discharge of the fluid from the drive pipe [4]. Q = 3.14 r 2 LN. (1) Due to the gravity effect the fluid flows inside the pipe with an velocity which is given by the equation (2).... (2) The nature of flow (Laminar, transitional or turbulent) is determined by using an dimensionless number which is calculated by using equation (3).... (3) Equation (4) represents a mathematical relationship given by Blasius to determine frictional factor f with the use of dimensionless number.... (4) 12 Sampath S S, Sawan Shetty, Allan Mathew Pendanathu, Waleed Javaid4and Chithirai Pon Selvan M

5 International Journal of Computer-aided Mechanical Design and Implementation Vol.1, No. 1, (2015), pp.9-24 Darcy-Wersbach equation which is shown in equation (5) used to evaluate the loss in the head for fluid flow in pipes.... (5) Fluid which is present accelerates enough to close the waste valve this is due to the drag and the pressure in the water which equals the waste valve weight. Equation 6 represents the drag force.... (6) Equation (7) represents the force that accelerates the fluid which is given by... (7) The exit pressure which is much greater than that of the inlet at a point is given by the equation (8).... (8) Equation (9) represents the power developed by the hydraulic ram.... (9) Equation (10) represents the hydraulic pump efficiency.... (10) Copyright c 2015 GVSchoolPublication 13

6 Estimation of Power and Efficiency of Hydraulic Ram Pump with Re-circulation System Calculation of the fall and Elevation is given by equation (11)... (11) Problem Definitio n Literature survey Initial Design & Material Selection Build Prototype Test Prototype Validation Figure 3. Methodology in design and fabrication of an hydraulic ram pump Figure 3 shows the design and fabrication of a hydraulic ram pump. The methodology of the entire process starts with the definition of the problem where the objective is decided. Literature survey includes the collection of data which supports the current modification of the design. Design calculation and the material selection are the key parameters of the plan. A prototype is built based on the requirement. Various tests are conducted by changing the elevation by changing various parameters results a noted. Last phase is validation it involves in comparing of the results with the standards or the existing experiments. 4. Construction and working Figure 4 shows the various parts which are involved in the construction of a hydraulic ram. The water flows from a height through the inlet pipe, passes thought the gate valve and the union, where it reaches a T-joint, which has a swing check valve placed on it in the downward direction. The velocity at which the water flows down causes the check valve to close and the water is forced to move into the second swing check valve, which is placed in the forward direction. The water then moves into another T-joint which has a chamber made of 4 UPVC (Unplastisied poly vinyl chloride) filled up to ¾ with closed cell foam. The air chamber also has a 2-4 reducer attached in between it and the T-Joint. The water passes through the reducer and fills up the air chamber and the foam helps in increasing the pressure of the water, the water is then made to do back down into the reducer which increases the pressure more. At this high pressure the water may go back, which is where the second swing check valve closes and forces the water to move into the forward direction. The water then passes through another reducer of size 2-1. This further increases the pressure due to the change in diameter and allows the water to be pumped to a higher level. The water can be pumped to a height of 9 m for a fall of 3 m at a 45 angle. As the angle of supply line is reduced the water can be forced to maximum distance. Figure 5 shows the construction of the hydraulic ram pump. The entire set up is provided with a waste water collecting reservoir to avoid the loss of water and it is recirculated into the point of inlet. This process avoids the waste water loss unlike the conventional systems and the entire volume is pumped to the desired elevation. 14 Sampath S S, Sawan Shetty, Allan Mathew Pendanathu, Waleed Javaid4and Chithirai Pon Selvan M

7 International Journal of Computer-aided Mechanical Design and Implementation Vol.1, No. 1, (2015), pp.9-24 Figure 4. Working principle of hydraulic ram pump Figure 5. Fully constructed Hydraulic ram pump 5. Experimentation and validation For performing the calculation the specification of the various elements of the hydraulic ram has to be considered. Due to the modification of the dimensions will affect the output greatly. Diameter of the inlet and outlet pipe is 50.8 mm and 25.4 mm. The diameter of the swing check valve is 50.8 mm. There are two reducers which play an important part to increase the pressure has 50.8 mm and 25.4 mm respectively. Air chamber has a diameter of mm and length of 500 mm. The outlet pipe is at 45, where water gets elevated. Copyright c 2015 GVSchoolPublication 15

8 Estimation of Power and Efficiency of Hydraulic Ram Pump with Re-circulation System From experimentation it is determined that water is flowing at 4 litres/ min which is at the inlet due to gravity and at the outlet the water is pumped out at 0.8 litres/ min. Remaining water is exited at the waste valve [3]. The reservoir collects the water at the region of waste valve and it is re circulated into the inlet. This avoids the maximum wastage of water which is very vital in rural areas [1]. Table 1. Pressure at the outlet with the change in the length of drive pipe Sl.no Length of drive pipe (m) Outlet pressure (bar) Figure 6. Variation of outlet pressure with the change in drive pipe length Figure 6 shows the graph and table 1 represents the different pressure obtained at the output pipe for varying length of supply pipe. The pressure of the output increases as the inlet supply length increases. Table 2. Actual & theoretical supply length achieved vs Drive pipe length Sl. No Length of drive pipe (m) Theoretical Supply pipe length (m) Actual Supply pipe length (m) 16 Sampath S S, Sawan Shetty, Allan Mathew Pendanathu, Waleed Javaid4and Chithirai Pon Selvan M

9 International Journal of Computer-aided Mechanical Design and Implementation Vol.1, No. 1, (2015), pp Figure 7. Supply pipe length (m) vs drive pipe length (m) Figure 7 and tables 2 represents the actual & theoretical length to which the water can be pumped to for an angle of 45 taking the pump works at an efficiency of 60 %. Table 3. Length of drive pipe vs. Rate of outlet water flow Sl.no Length of drive pipe (m) Rate of inlet water flow (litres/min) Rate of outlet water flow (litres/min) Copyright c 2015 GVSchoolPublication 17

10 Estimation of Power and Efficiency of Hydraulic Ram Pump with Re-circulation System Figure 8. Variation of rate of outlet water flow with the change in drive pipe length Figure 8 and table 3 represents the amount of water obtained as the output per minute for an inlet water supply of 4litres/min for varying length of fall. Three times the inlet length is taken as the output length. From experimentation it is proved that for a drive pipe length of 2 m, the rate of outlet water flow is maximum compared to the other two cases that is 1 m and 3 m. 18 Sampath S S, Sawan Shetty, Allan Mathew Pendanathu, Waleed Javaid4and Chithirai Pon Selvan M

11 International Journal of Computer-aided Mechanical Design and Implementation Vol.1, No. 1, (2015), pp.9-24 Table 4. Litres of water delivered for a complete day (litres/24 hrs) vs working fall Liters of water delivered in 24 hrs (litres) Lift height (m) Working fall(m) Copyright c 2015 GVSchoolPublication 19

12 Estimation of Power and Efficiency of Hydraulic Ram Pump with Re-circulation System Figure 9. Variation of volume of water delivered per day with the working fall Figure 9 and table 4 show the water output obtained in 24 hours by the pump for an inlet flow of 4 liters/min. It is observed that by maintaining the fall head constant and increasing the lift height there is a drop in the volume of water delivered with respect to the time period. By using equation (11) the elevation to which the water gets pumped could be determined which is shown in table 5. The water required for the household purpose is 500 liters per day (or liters per min) and considering the efficiency of the ram pump is 60% [4]. The amount of water supplied is 3 liters which is much higher than it gets delivered, that is in ram pump around 10 to 12% of the water is elevated and the remaining water goes out of waste valve which will be guided into the inlet by the re circulation system provided. The fall height is considered to be 1.5 m. With the help of equation the total elevation to which the water can be pumped is m. 20 Sampath S S, Sawan Shetty, Allan Mathew Pendanathu, Waleed Javaid4and Chithirai Pon Selvan M

13 International Journal of Computer-aided Mechanical Design and Implementation Vol.1, No. 1, (2015), pp.9-24 Table 5. Determination of the elevated height of water Sl.No Fall Height (m) Flow of water (l/min) Efficiency % House hold requirement (Liters/min) Total elevation to which water gets pumped (m) Table 6 shows the calculation of various parameters involved in the design of the hydraulic ram pump. It is found out that the above designed hydraulic ram pump with given specifications generate the power of 0.73 kw and the efficiency of 59.5%. Table 6. Calculation of various parameters Sl. No Suppl y head (m) Flow discharg e (l/min) Velocit y of the fluid flow Reynol ds Number Frictio nal Factor Head loss (mm) Pressure on waste valve (kpa) Power (kw) Efficien cy (%) ( m/s) The results which are obtained in table 6 is compared with the results obtained in the research paper [4][11], the results are very close. The efficiency of the hydraulic ram obtained is very crucial to determine the height of the delivery. 6. Conclusions Water conservation and sustainable energy is one of the very important thing especially in rural area, therefore the design of hydram plays an important role to lift the water without the aid of external means. Also the installation cost of the entire setup is very less, compact & simple. It could be tested at the region where the horizontal water stream flow has greater pressure and velocity. Steady flow energy equation could be adopted in order to determine the velocities at various points since the discharge at various points in the set up doesn't remain constant. Variation in the diameter of the air chamber will change the outlet pressure and the discharge. Therefore an optimum dimension could be determined by experimentation. By providing water recirculation system maximum wastage of water is prevented which is vital in rural areas. From the graphs plotted, it is proved that with the increase in the length of the drive pipe the outlet pressure also raises. But in the present case that for a drive pipe length of 2 meter the discharge at the outlet is maximum compared to the other two cases. The current system which is designed produces a power of 0.73 kw and the efficiency of 59.5 % which is ideal. Copyright c 2015 GVSchoolPublication 21

14 Estimation of Power and Efficiency of Hydraulic Ram Pump with Re-circulation System By changing the inlet discharge, the power can be calculated and it could be represented with the help of graph. The work can be further continued by using the pumped water in generation the power in hydroelectric plants. That is the elevated water is made to rotate the blades which generates the power. Thus this entire set up behaves like a perpetual motion machine where there is no energy required to generate unlimited power till the infinite time period. The analytical calculations can be made further simple by writing a computer programme which will help to determine the optimum solution. Modelling and analysis can be carried out using Ansys Fluent software which determines the various design parameters. Nomenclature Q= Discharge, l/min h= supply head, m H= delivery head, m d= Pipe radius, m L= Pipe length, m Vd= velocity of fluid, m/s Ad=Area of the pipe, m 2 υ= Kinematic Viscosity, m 2 /s Re=Reynolds number f= friction factor fd= drag force, N Cd= Coefficient of discharge Av= Area of waste valve, m 2 VT= Velocity at the T section, m/s dv/dt = Change in velocity with respect to time, m/s 2 Pw= Pressure on the waste valve, Pa P=Power generated, W Q'= Discharge at the outlet, l/min Qw= waste water discharge, l/min η= Efficiency of the hydram, % References [1] Arnold F. Dumaoal Sr, Franster A. Urbano, Benjay P. Pareja, "Design and performance evaluation of a local downdraft hydraulic ram pump, pp [2] C. A. Nwosu & T. C. Madueme, "Recycled micro hydropower generation using hydraulic ram pump (hydram)", International Journal of Research in Engineering & Technology, Vol. 1, No. 3, pp. 1-10, (2013). [3] F. Zoller, J. Woudstra and M. van der Wiel," Hydraulic ram pumping in rural community development", (2004). [4] S. Sheikh, C. C. Handa and A P Ninawe, "Design methodology for hydraulic ram pump (hydram)", International journal of mechanical engineering and robotic research, Vol. 2, No. 4, pp , (2013) [5] O. B. Nganga, G. N. Nyakoe, W. Kabecha and N. O. Abungu," An experimental prototype for low head small hydro power generation using hydram" pp [6] R.N. Mbiu, S. M. Maranga and M. Mwai," Performance Testing of Hydraulic Ram Pump" Sustainable Research and Innovation (SRI) Conference, pp, 6-8, (2015). [7] S. N. Mohammed, "Design and Construction of a Hydraulic Ram Pump" Leonardo Electronic Journal of Practices and Technologies, Issue 11, pp , (2007). [8] C. Verspuy & A.S. Tijsseling, "Hydraulic ram analysis", Journal of hydraulic research, Vol. 31, No. 2, pp , (1993). 22 Sampath S S, Sawan Shetty, Allan Mathew Pendanathu, Waleed Javaid4and Chithirai Pon Selvan M

15 International Journal of Computer-aided Mechanical Design and Implementation Vol.1, No. 1, (2015), pp.9-24 [9] H.W. Iversen, "An Analysis of the Hydraulic Ram" Journal of Fluids Engineering, Vol. 97, No. 2, pp , (2010). [10] M. Basfeld & E. A. Muller, "The hydraulic ram" Forschung im Ingenieurwesen, Springer link, Vol. 50, No. 5, pp , (1984). [11] O. A. Nnene, I. Okoye & J. C. Agunwamba, Design and Construction of a Water Conservation System", Research gate, pp (2009). [12] E. J. Schiller & P. Kahangire," Analysis and computerized model of the automatic hydraulic ram pump", Canadian Journal of Civil Engineering, Vol. 11, No. 4, pp , (1984). Copyright c 2015 GVSchoolPublication 23

16 Estimation of Power and Efficiency of Hydraulic Ram Pump with Re-circulation System 24 Sampath S S, Sawan Shetty, Allan Mathew Pendanathu, Waleed Javaid4and Chithirai Pon Selvan M