Report on dc dc converter for solar water Pumping

8/13/2019 Report on dc dc converter for solar water Pumping

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SOLAR POWERED WATER PUMP IMPROVEMENTS

by

Miguel Jorge Hauat-Elias

A Thesis Submitted to the Faculty of theDEPARTMENT OF AGRICULTURAL ENGINEERING

In Partial Fulfillment of the RequirementsFor the Degree ofMASTER OF SCIENCE

In the Graduate CollegeTHE UNIVERSITY OF ARIZONA

1

1988


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STATEMENT BY THE AUTHOR

This thesis has been submitted in partialfulfillment of requirements for an advanced degree atThe Universityf Arizonand is deposited in theUniversity Library to be made available to borrowers under -the rules of the library.Brief quotations from this thesis are allcwablewithout special permission, provided that accurateacknowledgement of source is made. Requests for permissionfor extended quotation from or reproduction of thismanuscript in whole or in part may be granted by the headof the major department or the Dean of the Graduate Collegewhen in his or her judgement the proposed use of thematerial is in the interests of scholarship. In all otherinstances, however, permission must be obtained from -n eauthor.

APPROVAL BY THESIS DIRECTORThis thesis has been approved on the date shown below:

7g2D.L. LARSONDatAssoc. Prof. of Agricultural Engineering


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3DEDICATION

The author of this thesis would like to dedicatethis thesis to his mother Nahuma Jorge Hauat for sharingwith him the most troublesome years of his life.


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aACKNOWLEDGEMENTS

The author would like to thank his adviser Dr.Dennis L. Larson for his infinite patience, help, guidance,and dedication throughout the whole project. Special thanksgo to the members of his committee, Dr. Frank Wiersma forhis assistance, and for making available equipment for thecompletion of this project and to Dr. Henry Perkins for hisassistance in the formulation of this thesis.

Recognition goes to Marion L. Stevens, ResearchTechnician IV, Department of Agricultural Engineering, forhis cooperation and most appreciated help. Recognition alsogoes to my good friend Charles Defer, Instrument Maker,Department of Agricultural Engineering, for his technicaladvice and support.

Appreciation goes to my good friend Euzebio Silvafor his help. He is a scholar, a gentleman, and an exampleto be followed. Recognition also goes to my good friendsJoseph Sottosanti and Mr. Hickman for sharing with me theirexperience and wisdom through the years of work at theStudent Union Memorial Building.

Greatest recognition goes to my wife Marilia-Therezinha for her dedication and her love.


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5TABLE OF CONTENTS

PageLIST OF ILLUSTRATIONSLIST OF TABLESABSTRACT0CHAPTER 111CHAPTER 213

Liquid Piston Pump3Water Cooled Pump7Diaphragm or Piston Pump0CHAPTER 323CHAPTER 424Original System4Design Evolution7System Modifications1CHAPTER 541Experimental Procedures1Equipment2CHAPTER 643Performance of the System3Reliability8Economics0CHAPTER 751


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6TABLE OF CONTENTS -- CONTINUED

PageCHAPTER 852APPENDIX A: SCHEMATIC DRAWINGS OF THE S.P.0 SYSTEM3APPENDIX B: SAMPLE CALCULATIONS2APPENDIX C: SYSTEM LOAD DESCRIPTION5Appendix D: EQUIPMENT DESCRIPTION3LIST OF REFERENCES1


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Figure1.2.

LIST OF ILLUSTRATIONS

Liquid Piston PumpMcCracken,955)odified Liquid Piston PumpChadwhich,980)41 63. Water Cooled PumpRoa and Roa,976) 84. Modified Water Cooled PumpSudhakar,979) 95. Diaphragm Solar Water Pump SystemS.P.C,979)1 . Motor Developed by Solar Pump Corporation3.2.0,

1979). Modified Valve Mechanism (Version 1) 3

8. Modified Valve Mechanism (Version 2) 09a. Modified Valve Mechanism (Version 3)b. Modified Valve Mechanism (Version 3) Top View3

10. Ramp Mechanism511. Stopper Stem Assembly712. Valve Actuator Mechanism313. Motor Timing014. Mechanical Performance of the Motor415. Frequency of the Motor as a Function of Pressure.16. Thermodynamic Performance of the Motor717. Pumping Rate of the Motor9A-1. Solar Pump Corporation Solar Thermal System

(S.P.C,979) 5


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LIST OF ILLUSTRATIONS--CONTINUEDFigureageA-2. Adjustable Pressure ValveS.P.C,979) 6A-3. Diaphragm MotorS.P.C,979) 7A-4. Valve MechanismS.P.C,979) 2A-5. Freon Feed PumpS.P.C,979) 9A-6. Lever Arm Pump Shaft AssemblyS.P.C,979) 1B-1. Sample of Temperature Recorded During the

Experiment3B-2. Thermodynamic Properties of Refrigerant 11Reynolds,979) 7B-3. Solar Beam Data for 4/26/19880B-4. Total Global Insolation on theorizontal Datafor 4/26/19881B-5. Thermodynamic Schematics for the Solar Motor4C-1. Load Simulation7


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9LIST OF TABLES

TableageB-1ressure, Temperature,and Frequency the Motor andFeed Pump Around Solar Noon4


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I CABSTRACT

An improved valve mechanism for the solar motordeveloped by the Solar Pump Corporation was developed toovercome weaknesses discovered in earlier tests. Va17eactuation was changed from parallel to perpendicular to themotion of the piston to facilitate valve adjustment and ccfree the valve seals from being compressed by the mainspring. Inlet and outlet valves were replaced withpurchased check valves to reduce machining requirements.

Mechanical efficiency of the modified motor wasfound to rangefrom 0.23 to 0.34 and thermodynamicefficiency from 0.027 to 0.032 in a day-long test. Overallenergy conversion efficiency was computed to be 0.008 atnoon when pumping with a head of 8.25 m.

The modified valve mechanism met design objectivesof requiring simpler manufacturing processes, and simpleand minimal servicing. The manufacturing cost is estimatedto be less then $2000.00 for the solar motor.


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1.1CHAPTER 1

INTRODUCTION

As development in agriculture in the Third WorldCountries progresses, small scale solar powered water pumpsare expected to be widely used if the systems can be madereliable and cost effective. Fossil fuels often areunavailable or are costly, but solar energy is a locallyavailable resource. Solar thermal systems utilizing Rankinecycle motor are devices which can be manufactured andmaintained with low technology.

Engineers and Technologists have developed severaldifferent types of solar powered systems for water pumpingapplications. A World Bankeview (1982a) reported thatthe first solar thermal motor was developed in theearly 1870's and that in 1913 an open loop steam motor wasinstalled in Egypt by Shuman and Boys of U.S.A. Themajority of the systems developed recently use organicfluids of the refrigerant type (e.g., Freon) in Rankine orSterlingycle motor which are compatible with operaticnwith low temperature heating provided by flat plate solarcollectors (Garg, 1987).

One of the devices developed to utilize solar


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19thermal energy for water pumping is the diaphragmmotor developed by the Solar Pump Corporation (Solar PumpCorporation, 1979). The motor concept is very simple, withpotential to become a very reliable system. Nevertheless,the motor was found to require substantial improvement tobecome more reliable, easily maintained and manufacturablein earlier tests at The University of Arizona (Larson,1979). This project focused on the development andevaluation of an improved valve system for this diaphragmmotor.


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13CHAPTER 2

LITERATURE REVIEW

Severalowemperature solar thermal energyconversion systems were developed in the past two decadesfor the main purpose ofpumping water for agriculture inThird World Countries. According to the report submitted byStarr et al., (1982) over 200 Solar Powered Water Pumps ofvarious types were in use throughout the World in 1982. Themost common types are:

1- Liquid Piston Pump2- Water Cooled Pump3- Diaphragm or Piston Pump

LIQUID PISTON PUMP

The first Liquid Piston Pump was patented byThomas Savory in 1698 (Murphy, 1985). McCracken (1955)developed a Liquid Piston Pump consisting of a vaporgenerator (a cylinder containing a floater), U-shaped tube,condenser with a ubber diaphragm, and pressureaccumulator, Figure 1. Solar energy is used to boil a lowboiling point organic fluid (e.g. Freon). The vaporized


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Figure 1: Liquid Piston Pump (McCracken, 1955)

14


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15working fluid pushes the floater down into the generator.When vapor reaches the bottom of the U-tube, the vapormoves from the heat generator into the- condenser, thus,forcing water to exit through the pressure accumulator atthe top. Oscillations of the liquid column in the condenserare generated by cyclical evaporation and condensation ofthe working fluid. Tests have shown this system issuitable for a pumping head no greater then 3 m, and thereis a risk of water contamination by the working fluid ifthere is any failure of the various seals in the system(Garg, 1987 ).

Chadwhich (1980) proposed two main modifications toMcCracken's system: 1) heating of the expansion chamber tominimize heat losses from the external walls, and, 2) useof a cylindrical float to control vaporization of theliquid and prevent vapor-lock, Figure 2. Additionalproblems encountered with the McCracken system included: 1)air accumulation in the condenser chamber, 2) sticking ofthe float valve, and 3) vapor-lock when too much vapor isproduced before condensation. Despite the attempt to reduceheat losses, the system thermal efficiency attained wasonly about 1.2% when pumping from a head of 3 m.

Independent analysis of a similar type of pump


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A T E R D I S CH A R G E HEAT GEN ERATO RU-SHAPE TUBE R11 IN LET

16

Figure 2:Modified Liquid Piston Pump (Chadwhich, 1980)


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17by Boldet (1978) produced similar results to those reportedby Chadwhich. Murphy (1985) evaluated the effect ofdifferent evaporator geometry and repositioning of theheater and condenser. These changes proved to have littleeffect on the performance of the system.

WATER COOLED PUMP

The so-called Water Cooled Pump proposed by Roaand Roa (1976) consists basically of a collector usingwater as the collector fluid, a flash tank where theworking fluid, typically Freon, is vaporized, a recycletank used to condense the working fluid, and a water tanklocated below the water table, Figure 3. The working fluidcan be cooled either by air or by the pumped water. Thissystem also has the disadvantage of possible watercontamination by leakage of the working fluid. In addition,a water tank has to be placed in the well, which requires abigger well opening and makes maintenance more difficult.

A modification of the Water Cooled Pump toprevent contamination of the water is illustrated inFigure 4 (Sudhakar et al., 1979).udhakar proposedconnecting two additional tanks in series with the water


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Figure 3: Water Cooled Pump (Roa ana Roa, 1976)

18


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19


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20tank. The first tank is filled with water and has afloater. As the working fluid enters the tank, the water isforced into the second tank from the bottom, which causesthe air in the second tank to move into the water tank andlift a column of water. The modifications proved to be asuccess. Nevertheless, the system requires extended anddifficult installation and maintenance.

DIAPHRAGM OR PISTON PUMP

A small single piston diaphragm pump wasdeveloped by the Solar Pump Corporation (1979), Figure 5.The system consists of a linear actuator utilizing adiaphragm and a piston. The system operates on the Rankinecycle. An organic fluid (e.g.Freon) is vaporized in thecollector. The vapor enters the motor and forces a pistondownward. This motion is transmitted to the pump shaft ofthe water pump through a lever arm. After leaving themotor, the working fluid passes through a water cooledcondenser and is returned to the collector by a smalldiaphragm pump. The return force is provided by the weightof the pump shaft and lever arm.

This system was found to need further


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21

o


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23CHAPTER 3

OBJECTIVES

The objectives of this research were to:1) Redesign, build, and test an improved valve

mechanism for the Solar Thermal Motordeveloped by the Solar Pump Corporation to

a) Provide more adequate valve sealing,h) Facilitate and minimize maintenance

requirements,c) Improve reliability and lifetime of the system.

2) Evaluate the performance of the system bydetermining the mechanical, thermal, andoverall efficiencies of the systemand the work output.

3) Estimate the cost of the modified motor.


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2 5


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26Hence, in case of compaction of the seals, componentreplacement is required to stop leakage. Adjustment of thevalve stem nut to set valve actuation timing anddisplacement requires motor disassembly to make itaccessible. Adjustment for optimum nut location isaccomplished Cnly by trial and error procedure (detailedschematics of the system are presented in Appendix A).


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27DESIGN EVOLUTION

The first design of a modified valve mechanism isillustrated in Figure 7. This design was an attempt tochange the valve stem motion from parallel to perpendicularwith respect to the piston motion to facilitate valveadjustment and maintenance. The system consisted of a valvestem (1) which pushed on the valve shaft (2) as the camfollowers '(3) moved along the valve stem ramps. Theadjustment of the valve was performed by screwing the valveseats (6) in or out.

The construction of this valve mechanism showedthat the mechanism required a substantial amount ofaccurate machining work. In addition, tests performed withcompressed air yielded unsatisfactory performance of themechanism due to the following reasons:

1 - The system required large displacement of thevalve stem.

2 - A large spring force was necessary to overcomeresistance and push the valve stem.

3 - The inlet valve did not seal properly becausethe valve closed against the inlet pressure.

4 - Major external leakage occurred through the


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28

CI,


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29threads of the valve seats and valve seals.

A second version of the valve mechanism wasconstructed to eliminate the problems listed above, Figure8. The inlet valve adjustment was altered by changing thevalve shaft length by turning the adjustable screw (1); theoutlet valve adjusted by turning adjustable screw (1').Spring travel was reduced by replacement of the dual slopestem with the single slope ramp (2) and the spring forcerequired to close and open the discharge valve (3) wasreduced. Considerable operating and maintenance improvementwere achieved by this valve mechanism. External leakageproblems were overcome and better valve seating wasprovided. Nevertheless, a field test showed that themechanism required substantial spring force to move thevalves, resulting in valve failure. In addition, machiningtime and accuracy were still high and internal leakagethrough the valve seals could not be stopped.

A third and final version of the valve mechanismthen was developed to overcome the limitations of the twoprevious designs. It is discussed in full in the nextchapter.


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31MODIFIED SYSTEM

Three major modifications of the original systemwere made to improve valve performance. The modificationswere as follows: 1) to change the valve motion fromparallel to perpendicular to the motion of the piston, 2 )to move the valve adjustment location to the outside of themotor, and 3) to replace the machined valves with purchasedcheck valves.

The modifications are illustrated in Figure 9a and9b and component details are shown in Figures 10 through12. The system consists of a C-shaped hook (3) connected tothe top of the spring rod (2). As the spring snaps up ordown, it pulls or pushes on the two valve rod stoppers (4)moving the valve cam ramp either up or down. During thedischarge stroke, as the ramp is pushed upward by theaction of the valve rod, the cam followers (6) connected tothe valve actuators (7) roll up the ramp and push the valveactuators to the right. The inlet valve seal (9) then isforced open and the discharge valve seal is closed. Whenthe ramp is pulled down, the valve actuators are moved tothe left by the action of the return spring (8). Adjustmentof the nut locations (4) accomplished


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34through a lateral opening in the valve housing (10),eliminating the need for motor disassembly. The top view ofthe valve mechanism is illustrated in Figure 10. The valveseals (9) are forced closed by the valve springs (11). Thedischarge valve is pulled open by the adjustable lengthcable 12) which connects the valve with its actuator.Inlet valve rod length is set by adjusting nut 9 )position. Thus, valve openings are controlled by adjustingthe buckle (13) on the outlet cable and the nut (14) on theinlet valve.

RAMP

The ramp cam assembly is illustrated in Figure 10.The ramp (1) lateral position is controlled by the twoparallel shafts (2). Therefore, the ramp can only slideupward and downward along the shaft. The shafts are screwedinto the bottom bracket (3) and held at the top bracket 4 )by nuts (5) which facilitate disassembly. Both brackets arewelded to the valve housing to insure that the brackets arestationary. The spring stopper stem (6) passes through anoversize drilled hole in the bottom bracket and is screwedinto the bottom of the ramp. The displacement of the ramp


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35

Cf /


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36is approximately 1.5 cm and the valve travel distances are0.32 cm to provide sufficient inlet and discharge openings.The ramp slope was set at be 13 degrees to minimize valverod bearing resistance but provide rapid movement.

STOPPER STEM

The spring stopper stem consists of a long threadedbolt (3) and attached stoppers (1) consisting of washerswelded to nuts, Figure 11. After being located to meetvalve timing requirements, the stoppers are secured inposition by lock nuts (2).

VALVE ACTUATOR

The valve actuator mechanism, shown in Figure 12,consists of two 0.50 cm O.D. bearings (1) fastened to thecam shaft (2). The cam shaft is connected to the dischargevalve actuator (3) and the inlet valve rod (3'). The valveactuators are held in position by the center bracket (4).The end of the inlet valve actuator is threaded to allowthe adjustable bolt (5) to be positioned. The adjustablebolt is secured in position by the lock nut (6). The


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I S T O P P E R S2L OC K NUT S3 STOPPER STEM

Figure 11: Stopper Stem Assembly


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39discharge valve actuator length is adjusted by the bucklenut (7).

The valve actuator is set such that it will keepthe inlet valve open and the discharge valvelosed. Bothvalves are normally closed by the action of the returnsprings. Figure 13 shows the position of the valvesrelative to the position of the piston. When the piston isat the bottom dead center position, the discharge valve isopen and the inlet valve is closed. When the piston is atthe top dead center position, the valve positionsreversed. The valve actuation occurs in only a fractiona second since the spring velocity is high and tradistance small.

The discharge port opening was set at 102 mm indiameter to allow rapid Freon discharge. The inlet portopening was set at 61 mm in diameter to slow the motorcyclical operating speed to 24 cycles per minute. Vibrationand pounding of the motor were considered too high when themotor operated at a higher speed.


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41

CHAPTER 5TESTING PROCEDURE AND ANALYSIS

EXPERIMENTAL PROCEDURES

The motor was tested with variable loading andsolar thermal input. Three pumping heads were simulated byvarying the static loads lifted by the lever arm (seeAppendix C for full description of the simulation). Coolantwater flow rate was set to correspond with water pumpingrate. The operating fluid pressures in the expander,collector and condenser were measured by pressure gages.Freon temperatures at the expander inlet and outlet points,as well as the temperatures across the condenser and insidethe feed pump were measured by thermocouples connected to adatalogger. The total global solar insolation on ahorizontal plane and the total beam terrestrial insolationwere obtained from the Atmospheric Science Department atThe University of Arizona.

For each test day the system started independentlyat about 9:30 a.m. The initial frequency of the motoroscillation was slow, but increased gradually until 10:30a.m. The motor operated at a fairly constant frequency of22 cycles per minute from 10:30 a.m. until approximately


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42

3:00 p.m. Then, motor oscillation decreased gradually infrequency until the motor ceased operation at around 5:00p.m. The measurements of motor performance were recordedfrom 10:00 a.m. to 4:30 p.m.

EQUIPMENT

Performance of the modified Solar Pump Corporationsystem was evaluated in day-long operating tests.Thermocouple readings were recorded by a Fluke model 2240-Bdatalogger. A complete description of the test equipment isprovided in Appendix D.


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43

CHAPTER 7RESULTS AND DISCUSSIONPERFORMANCE OF THE SYSTEM

A test was conducted to evaluate the performance ofthe modified energy conversion system with loadscorresponding to pumping heads of 4.95 m, 8.25 m, and 14.85m. The test data was used to determine mechanical (Em),thermodynamic (Et), and overall (Eo) energy conversionefficiencies. Mechanical, thermodynamic, and overallefficiencies are defined by the ratio of the actual workdone by the motor to the 1) total energy input to themotor, 2) total energy collected by the collector, and 3 )total energy input to the collector, respectively (Samplecalculations are presented in Appendix B).

Engine mechanical efficiencies were computed andare plotted versus local time for the three different testloads in Figure 14. It is observed that mechanicalefficiency is about 0.21 at 10:00 a.m., decreases to 0.14at noon and then increases again to 0.2 at 4:00 p.m. forthe pumping head of 4.95 m. With 8.25in head mechanical

efficiency was 0.31 at 10:00 a.m., 0.23 at noon, and 0.34at 4:00 p.m. With 14.85 head mechanical efficiency was


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0.36 at 10:00 a.m., 0.4 at noon, and 0.47 at 4:00 p.n. Thisvariation occurs because motor frequency does not increaseafter attaining a rate of 22 - 24 cycles per minute eventhough the inlet pressure increases to over 0.29 MPa,Figure 15. The differences in mechanical efficiency for thethree loads indicate that motor design and adjustment canbe optimize for different loads, and that this system wasmore productive with the highest load.

The mechanical efficiency curve for the 14.85 head,unlike the other two curves, shows a steady increasenroughout the day. This happened because the system was

over filled with Freon. This caused early high pressure. Atabout 11:00 a.m. excess Freon was drained out, and thesystem then operated at normal pressure range.

Motor thermodynamic efficiencies were relativelyconstant throughout the day, Figure 16. The maximumefficiencies, occurring at noon, were 1.9%, 3.1%, and 5.5%for simulated hydraulic heads of 4.95 m, 8.25 m, and 14.85m, respectively. The low thermodynamic efficiency values

observed are a onsequence of the low operatingtemperature. At these operating temperatures the maximumRankine cycle efficiency is no greater than 7.2 %.

The overall efficiencies for the solar


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50However, the modified system is likely to have a longerlife and reater reliability than the original systemsince the valves are no longer compressed by the mainspring, a principal cause of prior valve failures. Inaddition, external seal adjustment reduces maintenance timesubstantially.

ECONOMICS

The installed cost of the Solar Pump Corporation ssystem was estimated to be $2,000.00 (World Bank, 1982).The only modification to the system was replacement of thevalve mechanism. It is estimated thatthe modified valve mechanism requires approximately 45% ofthe machining time required for the original valvemechanism due to the reduction in machining accuracy andthe purchase of valve assemblies. The purchased valves arecommercially available. It is estimated that themodifications couldeduce system production cost byapproximately $200.00.


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51

CHAPTER 7CONCLUSIONS

The tests of the modified system resulted insatisfactory performance. The exterior adjustment of valvetiming and check valve seating was performed easily andsuccessfully. The adjustment of the valve timing does notrequire motor disassembly and the check valve spacing canbe set with minimal effort.

A reduction in the machining time and accuracyrequired for valve production was achieved by the newdesign. Valve sealing appeared to be more reliable andcomplete and seal wear was minimal during the limitedtesting of the new valve assembly.

The overall efficiency of the system was found tobe comparable to that reported for other typical systems ofthis type. Thus, the modified motor appears to meet thedesign objectives of:

1) Simple manufacturing procedures2) Reliable operation3) Simple, minimal servicing effort4) Manufacturing cost of less than 2,000.00


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52

CHAPTER 8RECOMMENDATIONS

Progress in theevelopmentfreliable,inexpensive low temperature thermal engine was achieved bythis research. The system needs further improvement beforecommercialization. An improved valve cam to replace thespring plus cam mechanism would furthereduce andfacilitate maintenance.lubrication system for thevarious moving parts or use of permanently lubricatedbearings would decrease friction and reduce wear, thereby,decreasing the necessity for adjustment and partsreplacement. More research is necessary to determine thereliability and lifetime of the system and estimate itsoperating cost.


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APPENDIX A53

DETAILED DRAWINGS OF THE ORIGINAL SYSTEM


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56

Figure A-2: Adjustable Pressure Valve (S.P.C, 1979)


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1 PISTON2PISTON ROD3VALVE MECHANISM4MOTOR HAUSING

57

Figure A-3: Diaphragm Motor (S.P. C, 1979)


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I INLET V A L V E2O U T L E T V A L V E3M A I N SPRING4V A L V E S T EM

Figure A-4: Valve Mechanism (S.P. C, 1979)


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5 9

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60lever arm pushes on the pump rod (4) and Freon is pumpedout into the collector.

The motor actuates the water pump by means of alever arm, Figure A-6. The lever arm, attached to a pivotpoint on the collector frame (1), magnifies the 0.04 mdisplacement of the piston to a 0.303in displacement of thepump shaft (2). The actuation of the feed pump is providedby the roll bearing (3).


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APPENDIX B62

SAMPLE CALCULATIONS


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63The data used in this sample calculation was

obtained in an April 26, 1988 test with a load equivalentto pumping with an 8.25in head. The values presented arefor solar noon (approximately 12:23 p.m. Tucson time).

Figure B-1 shows the record of temperatures fromthe thermocouple recorder. The numbers 0 through 9represent the thermocouple labels.

9;4 N0 N8%57 0 t7401644 N2 N51145445 N19 N3 1 949245

6144 9 9214 N111 NS8022980229116:12:21:0816:12:01:18Figure B-1: Sample of the Temperatures Recorded Duringthe Experiment.

Pressures at the feed pump and motor inlet andoutlet points and the motor frequency are shown in TableB-1.


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The mechanical efficiency is defined byEquation 3-1.

Water Pumping Workw * g * ZEm8-1)Motor Mech. Work* f dVWhere:w = Mass flow rate of the pumped waterg = Acceleration due to gravityZ = Pumping headP = Pressure inside the motor during

expansiondV = Change in volume of the motor (e.g.

0.00257 m 3

For a load equivalent to the pumping of 1.8 Kg ofwater per cycle, lift of 8 .25 i nand pressure of 0.29 MPa

(1.8 kg)*(9.81 m/sec 2 )*(8.25m)

65

Em 19.98 %0.29 MPa)* 0.00257d)The thermodynamic efficiency is defined by

Equation B-2.

Water Pumping Workw * g * ZEt = B-2)Thermal Workc * (Ho - Hi)Where:c = Mass flow rate of the working fluid


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66Ho = Enthalpy of the fluid entering the

motorHi = Enthalpy of the fluid entering the

collector

Mass flow rate of the working fluid wasdetermined from values for P, T, and volume of the motorFrom Figure B-2 with Pout and Tout values of 0.16 MPa. and347 K, respectively, the specific volume is found to be:

3v = 0.13523 m/Kgthe mass contained in the motor is

0.00257 m 0.019436 kg30.13523 m/Kg

The enthalpies Ho and Hi were obtained from FigureB-2 by entering the appropriate pressures and temperatures,were Ho=312,000 J/Kg and Hi=85,000 J/Kg. From Equation B-2,

(1.8 Kg).(9.81 m/sec 2 ).(8.25 m)Et = 0.019436Kg). (312,095 J/kg - 85,000 J/Kg)

= 3.31

The overall efficiency of the system isdefined by Equation B-3.


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. 1 1 1 i i111R001121011....14 1 7 . 1 1 1 M 3 1 1 111.111071111110 1 1 1 1 1 1 3 6 0 R 1 1 1'4 11111110LCAMIL10 1 1 1 1 1 1 1 7 1 : 3 C111112L

1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 _

1 1 1 1 I kIE R4 1 1 1 1 E . ;itiiI211111Atillf iT61811.21111111ntqM=1' 1 % 4 0 5 6 1 V I N I I i i L LI1 0 ;1, cummar m inm i c R 1 1 1 1 1 2 1 1 1 1 1 1 1 1 6 8 1 1 -iil1 1 1 1 :11 1 1 V 1 1 1 1 1E vsswommmi.....m.U4j me MOB MIMI &OM1111111101.111=...11111111W1 UI l lgi l imiimeammuuneCAVE011511ITSLIILIN111111:MMILIEUE1111i.111=VO SI M M EI N 1111110 11111111110011MIMEUSSULL111111 1 1 1 1 1 ol a r EM ISTONCYBUNIMM IKEL I1111111111111MOMINCLNIONENLI I IL1 1 1 1 1 1 1 1 1 1 1 11'.WIMIRM1109 1 1 1 1 1 F O RMONION10411Eli.1111111111111111111EMION11311MIElliL..1111111111111111nag nOISII IM IM IKII IL1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 M 1 Nnssammesmiunrimu Nockweem,11111111111111111111 TIONSINOIEUL1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 = 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 = 1 1 1 1 1 1 1 1 1 MIRA a1 1 1 1 M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 M I N 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 M 1 1 1 1 1 1 1 1 11 1 1 M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 M 1 1 1 1 1 1 1 1 1 1 1 = 1 1 1 1 11 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 = 1 1 1 0 1 1 I N N I M M 1 1 1 1 1

2

67


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C O

03r-

? ,q ;9-S 8 0N

7 0

( i i u l y 0 :0) r f c e A r i O S


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t onOnoIm MIWOMNMPMI m m oWSam. I=BMDNMIImbMNMINMRIM = c o .MIMSMO OMIMSMD OIMPMD=I I INSMNMID

eM 0DMDMOn. l NMMD DIMDIMO1 1 = 1 1 OMMO1=b MIllMD

NMM.NMMOMri...., ...MSII=IMO O

NMNMMP MIIMOMIMa MDMDl

MIMMDMD M I=DAIMIIIMM IMNMMD MNM

MDI =OM110

NM EMlir.IIIM

NM IMPPMI IM I MM

NMI =D

I MbINM- 03.- ..--I

.

...e isqasssga

4 9 4 4 0 ) reirDSN 190- 1 d 1 0 1

71


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Hence, from Figure B-5 Etc is:(H1 - H2) - (H4 - H3)Etc (H1 - H4)Assuming that the energy used by the feed pump is

negligible, the Rankine efficiency at solar noon is:

312,095 KJ/Kg - 295,012 KJ/KgEtc 312,095 KJ/Kg - 85,000 KJ/Kg= 7.5 96

73


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76

Three hydraulic pumping loads were simulatedusing different static loads, Figure C-I. For a test waterpump which delivers 1.8 Kg/cycle with a lever armdisplacement of 0.33 m, the work done by the motor is:

Work=m*d*Where i n= Mass delivered per cycle

d = Distance liftedg = Acceleration due to gravity

Work =1.8 Kg/cycle)*(5 i n* 9.81 m/sec 2 = 88.3 J/cycleThe equivalent static load for d = 0.33 m is:

88.29 J/cyclei n=

* g0.33 m)*(9.81 m/sec 2 = 27.27 Kg/cycleThe equivalent static loads for the 8.25 i nand14.85 m heads were 45.0 Kg and 81.0 Kg. Actual static loadswere increased by 5 percent to account for the water pumpmechanical losses and pipe friction losses, as suggested byM.R. Starr (1982).


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7 7


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APPENDIX D8

EQUIPMENTDESCRIPTION


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79ENGINE

Manufacturer Solar Pump CorporationNumber of Piston OneMotor Bore 0.067 Square MeterMotor Displacement : 0.04 Meter

DATA LOGGER

Manufacturer John Fluke ManufacturerModel2240-BTypeDigital Recorder, Printer OutputSerial numberA146275

PRESSURE GAUGES

ManufacturerJ/B IndustryModelAurora Dial Type Pressure GaugeRange0 - 200 PSI


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FLOW METER

ManufacturerCoradTypeElaborateSerial number433609STOP WATCH

ManufacturerHauerModelTrack StarTypeAnalogReference number593VERNIER CALIPER

ManufacturerBrown & SharpeModelCCMBTypeCaliperSerial number599-578-1 80


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81

LIST OF REFERENCES

1 - Boldt, J. 1978. Solar Powered Pump for the Rural ThirdWorld. Report, Department of MechanicalEngineering Laboratory for Energetics. TechnicalUniversity of Denmark, Lyngby, Denmark.

2 - Burton, R. 1983. A Solar Powered Diaphragm Pump.Solar Energy Vol. 31 (5): 523 - 52 5.

3 - Chadwhich, D.G. 1980. Design of a Cost Effective SolarPowered Water Pump. Water Research Laboratory,Utah State University. Paper UWRL/H - 80/02, PP. 5- 9.

4 - Garg, H.P. 1987. Advances in Solar Energy Technology.First ed., Volume 3. D. Reidel Publishing Company.pp. 199 - 205 .

5 - Howell, B.V. 1982. Solar Thermal Energy Systems. Firsted., McGraw-Hill. pp. 45 - 82, 87 - 95, and 279 -307.

6 - Kishore, V.V.N., M.R. Gandhi, N. Pathak, S.D. Gomkaze,K.S. Rao, P. Jaboyyedoff, W. Lehmann, C.H.Marquis. 1986. Development of Solar (Thermal)Water Pump Prototype - an Indo - Swiss Experience.Solar Energy, Vol. 36 (3): 257 - 265 .

7 - McCracken, C.D. 1955. The Solar Powered Thermopump.Paper presented at the Association for AppliedSolar Energy Conference on Solar Energy: TheScientific Basis, Tucson Arizona,Oct. 31 - Nov. 1.Arizona 1955 .

8 - Murphy, C.L. 1985. Review of Liquid Piston pumps and


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82Their Operation With Solar Energy. SolarEngineering, Vol. 107, pp. 79 - 84 .

9 - Rao, D.P. and Rao, K.S. 1976. Solar Water Pump forLiftIrrigation. Solar Energy, Vol. 18, pp. 405 -411.

10 - Reynolds, W.C. 1979. Thermodynamic Properties in SI.Published by the Department of MechanicalEngineering, Stanford University, Stanford, CA.pp. 70 and 71.

11 - Reynolds, W.C. C.R. and Henry C. Perkins. 1970.Engineering Thermodynamics.Second ed. McGraw-Hill, pp. 50 - 56, 105 - 120, and 293 - 30 0.

12 - Starr, M.R. 1982. The Technical and EconomicRequirements for Small-Scale Solar Powered PumpingSystems. Paper presented at the Annual Meeting-Conference, of the American Solar Energy Society,Houston, Texas,

13 - Starr, M.R., Derrick A., & Freankel, P.L. 1982. SolarEnergy for Developing Countries, Refrigeration andWater Pumping. Proceedings of ISES Solar WorldForum, Conference C-28 at the Geological Society,London, pp. 57 - 68.

14 - Solar Pump Corporation, (S.P.C). 1979. System Manual.Solar Pump Corporation, Las Vegas, NV. 197 9.

15 - Sudhakar k., Murali M. Krishna, Rao D.P., and R.S.Soin. 1979. Analysis and Simulation of a SolarWater Pump for Lift Irrigation. Solar Energy,Vol. 24 , PP. 71 - 81.

16 - World Bank. 1983a. Small-Scale Solar-Powered Pumping


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83Systems: the Technology, Its Economics andAdvancement. UNPD Project GLO/80/003, Main Report.pp. 6.1 - 6.9.

17 - World Bank. 1983b. Small-Scale Solar-Powered PumpingSystems: The Technology, Its Economics andAdvancement. UNPDroject GLO/80/004, MainReport. pp. 6.1 - 6.20 .

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