APTD-1358 VAPOR GENERATOR FEED PUMP FOR RANKINE CYCLE AUTOMOTIVE PROPULSION SYSTEM U.S. ENVIRONMENTAL PROTECTION AGENCY Office of Air and Water Programs Mobile Source Pollution Control Program Ann Arbor, Michigan 48105 LEAR MOTORS CORPORATION ------- APTD - 1358 VAPOR GENERATOR FEEDPUMP FOR RANKINE CYCLE AUTOMOTIVE PROPULSION SYSTEM CONTRACT NUMBER 68-01-0437 FINAL REPORT Prepared By Max K. Winkler LEAR MOTORS CORPORATION Reno, Nevada 89510 EPA Project Officers W. Dyer Kenney and Kenneth F. Barber Prepared For U.S. ENVIRONMENTAL PROTECTION AGENCY Office of Air and Water Programs Mobile Source Pollution Control Program Advanced Automotive Power Systems Development Division Ann Arbor, Michigan 48105 December, 1972 LEAR MOTORS CORPORATION ------- The APTD (Air Pollution Technical Data) series of reports is issued by the Office of Air and Water Programs, U.S. Environmental Protection Agency, to report technical data of interest to a limited number of readers. Copies of APTD reports are available free of charge to Federal employees, current contractors and grantees, and non-profit organizations as supplies permit - from the Air Pollution Technical Information Center, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711 or may be obtained, for a nominal cost, from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, Virginia 22151. This report was furnished to the U.S. Environmental Protection Agency by Lear Motors Corporation, Reno, Nevada in fulfillment of Contract Number 68-01-0437. The contents of this report are reproduced herein as received from the Lear Motors Corporation. The opinions, findings, and conclusions expressed are those of the author and not necessarily those of the Environmental Protection Agency. Office of Air and Water Programs Publication Number APTD - 1358 LEAR MOTORS CORPORATION ------- TABLE OF CONTENTS PAGE LIST OF TABLES i v LIST OF FIGURES. v SECTION I. INTRODUCTION 1 II. SUMMARY... 2 III. TECHNICAL DISCUSSIONS 6 A. Feedpump Operating Principle and Description 6 B. Feedpump Design Study 8 C. Feedpump Performance Study 14 D. Material Compatibility Study '18 IV. SYSTEM CONTRACTOR TECHNICAL REQUIREMENTS AND LEAR MOTORS APPROACH A. Steam Engine Systems - Water base fluid - Recriprocating Expander 26 1. Pump performance 27 2. Pump Inlet Envelope 29 3. Pump Drive 31 4. General Requirements 33 B. Aerojet Liquid Rocket Company - Organic Fluid - Turbine Expander 34 1. Pump Performance 35 2. Pump Inlet Envelope 37 3. Pump Drive and Control 39 4. General Requirements 41 LEAR MOTORS CORPORATION ------- TABLE OF CONTENTS cont. SECTION PAGE C. Thermo Electron Corporation - Organic Fluid - Recriprocating Expander 42 1. Pump Performance 43 2. Pump Inlet Envelope 45 3. Pump Drive and Control 47 4. General Requirements 49 V. CONCLUSION 50 REFERENCES 52 APPENDIX - LEAR MOTORS PUMP STANDARDS 53 Pump Test Code ^-1 Pump Rating Criteria A-5 Net Positive Suction Head Definition A-8 Net Positive Suction Head Calculations A-9 LEAR MOTORS CORPORATION 111 ------- LIST OF TABLES TABLE PAGE 1. Summary of Contract Technical Requirements 3 2. System Contractor Feedpump Design Specifications 13 3. Candidate Materials for System Contractor Proposed Feedpumps 25 LEAR MOTORS CORPORATION iv ------- LIST OF FIGURES FIGURE 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. PAGE Estimated System Contractors Feedpump performance. Estimated Feedpump Performance and Typical System Operating Envelope Lear Motors Feedpump and Typical Test Stand.. LMC Feedpump Mechanical Efficiency vs. Flow.. LMC Feedpump Performance LMC Feedpump Net Positive Suction Head Chart. SES Estimated Pump Performance SES Estimated Pump Inlet Envelope SES Pump Outl.ine Drawing ALRC Estimated Pump Performance ALRC Estimated Inlet Envelope ALRC Pump Outline Drawing TECO Estimated Pump Performance TECO Estimated Pump Inlet Envelope TECO Pump Outline Drawing 5 7 15 16 17 28 30 32 36 38 40 44 46 48 LEAR MOTORS CORPORATION ------- INTRODUCTION This report is submitted in fulfillment of Environmental Protection Agency Contract No. 68-01-0437. The data presented herein are the results of preliminary design studies conducted to define feedpumps that satisfy the performance requirements for Rankine Cycle automotive power systems under development for the Environmental Protection Agency. SUMMARY OF SYSTEMS UNDER DEVELOPMENT System Contractor Steam Engine Systems CSES) Aerojet Liquid Rocket Company (ALRC) Thermo Electron Corporation (TECO) Working Fluid Demineralized water. AEF-78 (Organic fluid) Fluorinal 85 (Organic fluid) Type of Expander Reciprocating expander. Turbine expander, Reciprocating expander. LEAR MOTORS CORPORATION ------- II SUMMARY The approach followed in this study consisted of establishing feedpump requirements for three (3) separate applications. This was accomplished in conjunction with the EPA and the three system contractors. The technical requirements as established by the contract and subsequent coordination meetings with the EPA and system contractors are summarized in Table I, and detailed in Section IV. An additional requirement was to select a single design which satisfied both organic systems. However, the final selection could not compromise significant gains in performance or cost reductions resulting from separate designs. Further investigations revealed that the feedpump developed by Lear Motors Corporation satisfies the basic requirements of the three system contractors. This Lear feedpump was used as a baseline for the preliminary design and performance study presented in this report. A description of the Lear feedpump and its operating principle is presented in Section III-A. From the discussion presented in Section III-A, it can be seen that this Lear Motors pump has been designed for, and satisfies the basic requirements of; hermetic sealing of the working fluid, contamination of the working fluid, variable displacement capability, and low N.P.S.H. capability. A summary of the flow requirements and estimated brake horsepower for the three system contractor feedpumps is shown graphically in Figure 1. These data which show system mass flow and brake horsepower versus percent of expander speed illustrate the relative magnitude of the respective requirements. Figure 2 shows the estimated feedpump performance, with a typical system operating envelope superimposed. These data show the affect of pump displacement-speed relationship on pump mechanical efficiency. Details of the contracts technical requirements and the Lear Motors approach for each system contractor are presented in Section IV. These data, showing the estimated pump performance, estimated pump inlet envelope, and pump outline drawing were derived from actual test results and physical relationships of the Lear Motors 4th generation design feedpump. LEAR MOTORS CORPORATION ------- SUMMARY OF CONTRACT TECHNICAL REQUIREMENTS SES ALRC TECO Pump Performance Type of Expander Expander Speed Flow Range and Corner Condition Discharge Pressure Mechanical Efficiency Pump Inlet Envelope Inlet Pressure NPSH Capability Temperature Range Temperature Transients Boost Pump Pump Drive Drive Mechanism & Flow Range Control Working Fluid Reciprocating 300-2500 RPM 0-2.5 6PM Max system flow @ 40% speed 1200 PSIA max. 70% from 30-80% of flow max. 50% min. at 10% of flow max. 0.09 PSIA @ Start 7-50 PSIA operation Minimized to operate without boost 180-250 °F Normal 32-275 °F Start 3° per second for 10 seconds Only if needed Mechanical with provision for;variable speed or variable capacity. Water - Demineralized (Pump to have provision for draining) Turbine 16,800-31,200 1.85:1 Speed Ratio 0.5-28 GPM Max system flow @ 54% speed 1100 PSIA max. 70% from 30-80% of max flow 50% min. at 10% of flow max. 1.0 PSIA @ Start 10.0-40.0 PSIA operation 7 inches min. avail (.45 PSI @ 72 °F) 160-250 °F Normal -40-275 °F Start Only if needed Mechanical with provision for variable speed or variable capacity. Organic S.G. = 1.793 @ 72 °F Reciprocating 300-1800 RPM 0-17 GPM Max system flow @ 45% speed 1000 PSIA max. 70% from 30-80% of max flow 50% min. at 10% of flow max. 0.5 (3 Start 5-90 PSIA during operation 10 inches min. avail. (149 PSI @ 72 °F) 160-250 °F Normal -40-275 °F Start Only if needed Mechanical with provision for variable speed or variable capacity. Organic S.G. = 1.368 @ 72 °F TABLE 1 ------- Q. o •s^< * o 111 0) ESTIMATE OF SYSTEM CONTRACTORS FEEDPUMP PERFORMANCE SYSTEM CONTRACTOR FLOW REQUIREMENTS 10 100 cc ui O Q. HI (/) CC o cc m Q. Q. O LLJ UJ ESTIMATED FEEDPUMP BRAKE HORSEPOWER 10 EXPANDER SPEED ~(%) 0 20 40 60 80 EXPANDER SPEED- (%) 100 ------- ESTIMATED FEEDPUMP PERFORMANCE 100 o CO (/> < D a 70 M TYPICAL NORMAL OPERATING RANGE 100 O z UJ O u. IL UJ o z < X o UJ 20 20 40 60 80 100 EXPANDER SPEED^(%) CONTRACT MECHANICAL EFFICIENCY DESIGN POINTS TYPICAL NORMAL OPERATING RANGE 20 40 60 80 PUMP MASS FLOW~(%) 100 ------- Ill TECHNICAL DISCUSSION In Rankine cycle automotive power systems the feedpump must be capable of efficiently pumping the working fluid up to system pressure while operating at very low net positive suction head conditions and very high fluid inlet temperature to achieve reasonable cycle efficiencies. Three years ago, Lear Motors initiated the development of pump specifically designed for Rankine cycle applications. The results of this development have been used as the basis for these studies. A. LEAR MOTORS FEEDPUMP OPERATING PRINCIPLE AND DESCRIPTION The Lear Motors high pressure feedpump design, incorporates pistons reciprocating within close fitting cylinders filled with oil. A flexible diaphragm is positioned between each cylinder cavity and the working fluid pump chamber. The alternate suction and displacement of oil by the pistons actuates the diaphragms and thus results in an equal displacement in the working fluid chamber. No mechanical connection is required between diaphragm and piston. Since incompressable fluids are present on both sides of the diaphragm, pressure across the diaphragm is always equal. The pump may be operated at any pressure within the structual limits of the pump without stress upon the diaphragms or any reduction in diaphragm 1ife. The pump incorporates a fixed stroke, needle bearing, eccentric on a drive she.ft which is supported by two ball bearings. The eccentric converts shaft rotary motion to reciprocating motion and is used to drive the pistons which are equally spaced around the drive shaft. On the displacement, or pressure stroke, the eccentric drives the piston up, pressurizing the oil chamber above the piston which actuates the diaphragm and displaces the working fluid in the pump chamber through the outlet valve. During the suction, or return stroke, the piston is held to the eccentric by a positive return band and as the piston, oil and diaphragm are drawn back, working fluid enters the pump chamber through the inlet valve. The entire drive shaft and piston assembly is located within the pump's temperature compensating oil reservoir and is completely lubricated. The oil filled chamber above the piston is connected to the oil reservoir through a slot in the piston wall and a LEAR MOTORS CORPORATION ------- LEAR MOTORS TYPICAL TEST STAND LEAR MOTORS FEEDPUMP FIGURE 3 ------- triangular port in the side of the cylinder. The piston slot must be closed before oil can be displaced in the chamber above the piston. That portion of fixed mechanical stroke during which the piston slot is closed is the effective stroke of the pump. By varying the cylinder port with respect to the piston slot, the pump's effective stroke or displacement can be controlled. Each cylinder is linked mechanically, inside the pump, to an external pump displacement control shaft which can be actuated directly or with a small servo mounted outside the pump. There are no sliding or rotating seals in contact with the pumped fluid, allowing the pumped fluid to be hermetically sealed from atmosphere and lubricating oil. All of the highly stressed moving parts in the pump are oil lubricated allowing conventional, low cost materials to be used throughout its construction. Efficient operation of the pump, during low N.P.S.H. conditions of Rankine cycle system, is made possible by utilization of large passages and valves designed for minimum flow losses throughout the inlet circuit of the feedpump. This feedpump, designed specifically for use with the Rankine cycle system, is the result of a continuing feedpump development program at Lear Motors Corporation. B. FEEDPUMP DESIGN STUDY Pump size is determined primarily by the system flow require- ments as defined by the high flow-low speed corner condition. This point and the mass flow at idle define the mass flow-speed characteristics slope. By extending the line to 100% expander speed the flow capability of the pump is defined. Since the system can't utilize the total capability of the pump, variable displacement or capacity is required to allow operation within the system envelope. The corner condition of the pump performance map is determined by vehicle performance in terms of lugging and acceleration capability. If system performance is allowed to degrade then the slope of the pump characteristics can be changed. Thus, a compromise in system performance is required if one pump design is used for both organic fluid system contractors. For this study a penalty in system performance was considered undesirable. Therefore, a separate pump design was prepared for each system contractor. LEAR MOTORS CORPORATION 8 ------- After the high flow-low expander speed corner condition for each system contractor was established, the maximum speed capability of each pump was investigated based on an analysis of both radial and axial piston pump designs. From this analysis it was determined that maximum speed capability of the radial pump is limited by the valve dynamics and speed at which the oil in the pump crank case may be sheared without excessive friction losses, rather than the dynamic unbalance of the fixed eccentric on the crank shaft. Further study revealed that the radial piston design would be physically smaller, lighter in weight, and less expensive to produce. Utilizing the established maximum pump speed in conjunction with the system contractor flow and maximum pressure ripple require- ments, the bore/stroke relationship and number of cylinders were selected. To keep the instantaneous total flow of the pump, for any given crank shaft angle, as smooth as possible, an odd number of cylinders was used. The number of cylinders and the bore/stroke relationship determine the displacement of the pump as well as its smoothness. Obviously the greater the number of pistons for a given flow the smoother the pump will be, however, pump cost and physical size must be considered. After close examination of the parameters involved and based on our four years of feedpump experience, the bore/stroke relationship and number of pistons which would best meet the individual system contractor feedpump requirements was determined. The diaphragm seals for each pump were then examined. These diaphragms are the key to the hermetic sealing capability of the Lear Motors feedpump design. They also enable the pump to produce high pressure working fluid without utilizing the fluid to lubricate highly stressed moving components such as piston seals, gear teeth, or vane tips. The diaphragm effective area selection was based on several factors: 1) The maximum volume it must displace during each piston stroke. 2) The physical design of the seal . 3) The material used to construct this flexible sealing member. As the Lear Motors feedpump has demonstrated excellent per- formance with a flat circular sealing member using an elastomer material, our major effort was directed toward finding elastomers LEAR MOTORS CORPORATION ------- which had the physical properties required and were compatible with the two organic fluids used by the system contractors. A separate study was conducted and limited tests for compatibil- ity were conducted by the organic fluid system contractors on candidate elastomer materials selected and supplied by Lear Motors Corporation. The results of this study indicated that several of the elastomers evaluated, were acceptable for use as sealing diaphragm material. The suggested procedure and test results are shown in Section III-D of this report. An additional investigation into the possible use of a bellows type metal diaphragm was carried out. However, due to the low cycle life and high costs quoted by the venders and available design literature, the use of this type of seal was deemed not practical. Having established a suitable elastomer material for each of the system contractors and selected the flat circular diaphragm design, the minimum effective area required for long diaphragm life was determined. It is apparent that for a given piston displacement the larger the effective or flex area of the sealing diaphragm, the longer the diaphragm life. However, the physical size of the pump, namely its outside diameter, will become proportionately larger. Therefore, the minimum area of diameter of the diaphragm becomes an important individual pump design feature. This sealing member is simply a flexible incompressible barrier which separates two other virtually incompressible fluids; the most important physical characteristic of the elastomer sealing or separating members used in these pumps is the flex life capability of the elastomer. Fortunately, this is what most elastomers are compounded for and the selection of materials is large even when limited by the Rankine cycle system fluid tempera- ture extremes and material compatibility requirements. The designed maximum movement or flex used by Lear Motors is 8 to 10 percent change. For each system contractor a specific diaphragm effective area was determined based on the maximum volume displaced per piston and the 8 to 10 percent flex value which has proved successful in the Lear Motors feedpump. It must be pointed out that during most of the vehicles normal operation the feedpump is LEAR MOTORS CORPORATION 10 ------- functioning at a reduced displacement and the diaphragms would be flexing less than design. Having determined the individual system contractors pump, bore and stroke, number of cylinders, pump speed, and outside diameter required by the pitch circle of the individual diaphragm seals, a preliminary analysis of each pumps bearing requirements and operating mechanics was made. As one of the basic strong points of the Lear Motors feedpump design is that all of the highly stressed bearings and moving parts required by the feedpump are oil lubricated, conventional low cost bearings and materials may be used, making the analysis of the lubricated section of the pump straight forward. One area in this lubricated section required special attention. The pumps unique outlet flow or displacement control, described in Section III-A Feedpump Operating Principle and Description, must be designed to keep orifice and passage losses low to maintain high pump mechanical efficiency. The next basic area which was examined during this design and performance study involved the inlet passages and inlet valve sizing. To reduce the net positive suction head required by the pump for efficient operation, special attention must be given the working fluid inlet of the pump. A description of the term net positive suction head (NPSH) is given in the appendix. Basically, a positive displace- ment pump is not known for its low NPSH characteristics; any entrained vapor in the pumped fluid will cause the pump performance to degrade rapidly. To minimize the NPSH required by the feedpump, the inlet velocity of the working fluid must be kept as slow as possible so that the friction losses are kept to a minimum. Also the inlet valve spring must be kept as light as possible and still allow the valve to operate at high pump speed. Large inlet passages and inlet valves which reduce fluid flow velocities were designed into each of the feedpumps. Maximum inlet velocities of 5 to 6 feet per.second were used in the design of the Lear Motors feedpump and each of the system contractor feedpumps. The estimated inlet envelope showing the NPSH required for each of the pumps is detailed graphically in Section IV of this report. These data, corrected for individual organic fluid specific gravity variations, demonstrate what each of the pumps would be capable of based on actual Lear Motors test data shown in LEAR MOTORS CORPORATION 11 ------- Section III-C of this report. Further examination of the NPSH required by these feedpumps, although low for positive displacement pumps, indicates that some amount of sub-cooling or boost pressure is required to meet the system contractor requirements. Sub-cooling of the working fluid results in a significant loss in Rankine cycle system efficiency due to the power expended in the cooling of the fluid as well as the heat required to bring it back up to a temperature after it has been pumped. Adding boost pressure or head to the inlet of the pump by placing the working fluid reservoir physcially higher than the feedpump is not practical in an automotive Rankine cycle system due to the limits of the engine compartment and the added expander back pressure. However, increasing the inlet pressure to the feedpump with an independently driven centrifugal pump demonstrates several advantages; the centrifugal type of pump has inherently low NPSH characteristics and can be designed to handle significant amounts of vapor. A centrifugal pump can operate at and below the systems working fluid vapor pressure line, allowing greater cycle efficiencies through the minimum sub-cooling required. By mounting a small separately driven centrifugal pump low in the system the feedpump may be conveniently mounted and driven without regard to the systems liquid level. The vehicle will be operational with the absolute minimum sub-cooling because the independently driven centrifugal pump will provide some liquid to the feedpump regardless of the expander speed. An independently driven centrifugal boost pump will allow the system to be started after a hot shutdown. It was concluded after examining the parameters involved that a small independently driven centrifugal pump is important to the efficient operation of an automotive Rankine cycle system. Having concluded the preliminary design portion of this study, an outline or installation drawing for each pump, shown in Section IV, was drawn. It must be pointed out that these pumps were designed specifically to meet the individual system contractors requirements and that their physical size is determined primarily by the systems high flow-low speed corner condition not just the maximum system flow required. Example: A positive displacement pump with flow-speed LEAR MOTORS CORPORATION 12 ------- SYSTEM CONTRACTOR FEEDPUMP DESIGN SPECIFICATIONS Configuration Number of Cylinders Bore Effective Stroke Diaphragm seal effective are per cylinder Pump Design Theoretical Flow 0 85% Vol. Eff. System Flow Requirement Pump Speed (Max. Design) Pump Displacement VoT/Rev. Inlet Velocity @ Max System Flow Estimated Pump Weight with 1. Iron Housing 2. Aluminum Housing* SES Radial Piston, Diaphragm seal 6.2 GPM @ 100 percent speed 2.5 GPM @ 40 percent speed 2400 RPM .77 in3/Rev. 5.1 FPS 16 1/2 pounds 12 pounds AJLRC Radial Piston, Diaphragm seal 52 GPM @ 100 percent speed 28 GPM @ 54 percent speed 2000 RPM 6.52 in3/Rev. 5.9 FPS 108 pounds 81 pounds TECO Radial Piston, Diaphragm seal .68 inches .41 inches 2.08 in2 1 .25 inches .75 inches 6.51 in? 1 .18 inches .67 inches 5.43 in2 40 GPM @ 100 percent speed 17 GPM (3 45 percent speed 2000 RPM 4.64 in3/Rev. 5.5 FPS 66 pounds 46.5 pounds Additional stress analysis required. TABLE 2 13 ------- characteristics capable of producing 26 GPM (gallons per minute) at 50 percent or one-half speed is theoretically capable of producing 52 GPM at 100 percent or maximum speed. While the system may only require 26 GPM mass flow the pump must be physically large enough to produce 52 GPM. The only reduction in pump size, due to the 26 GPM system requirement, will be working fluid flow passage area. From this example it can be seen that any reduction of the system contractors high flow-low speed corner requirement will result in a significant reduction in the feedpump size and weight. C. FEEDPUMP PERFORMANCE STUDIES Estimates of the individual system contractor proposed feedpumps performance and inlet envelope are shown graphically in Section IV. These estimates were obtained by extrapolating actual Lear Motors Corporation feedpump test data. The procedure and feedpump rating criteria used in conducting the tests, which were run specifically for this study, are shown in the Appendix. The proposed feedpump estimated performance curves, showing pump brake horsepower, mechanical efficiency, and flow vs. pump and ex- pander speed, demonstrate the broad range over which these pumps can operate. The lower section of these pump performance maps, indicate the flow characteristics of the pump at various speeds and displace- ment levels. Superimposed are the 50 and 70% mechanical efficiency lines denoting how the pump performs with respect to contractor performance requirements. Also indicated is the pumps full displace- ment flow line the slope of which is determined by the individual system maximum flow-minimum expander speed corner condition and the volumetric efficiency of the pump. Based on Lear Motors Corporation feedpump data, full displacement volumetric efficiency of the proposed pumps will be 85 to 90% depending on outlet pressure and inlet N.P.S.H. Feedpump inlet envelope estimates are also shown in Section IV, under the individual system contractor heading. These inlet envelopes, superimposed over the contractors working fluid vapor pressure characteristics, demonstrate the N.P.S.H. required by the pump to maintain efficient operation. The pressure and temperature limits during normal and extreme operating conditions, as outlined by the LEAR MOTORS CORPORATION 14 ------- 100 90 80 Z w pa w CM z w M u w 3 o MECHANICAL EFFICIENCY VS PUMP FLOW Silver 4-cv Bus Pump Test Conditions: Outlet Press.-- 1000 PSIG Suction Press.- 15 PSIG Water Temp. 75-90° Mech. Eff.= W-H-P- x ion 456 PUMP FLOW~ GPM FIGURE 4 15 ------- 20 30 40 50 60 PUMP SPEED -- PER CENT 70 80 90 100 Full Displacement Mech. Eff. PUMP PERFORMANCE 4-CV Bus Pump Test Conditions: Outlet Pressure - Suction Pressure- Water Temp. - - - - 1000 PSIG - 15 PSIG - 100-160° F s o \ CX, s d. 10 9 8 7 6 5 4 3 2 1 20 30 40 50 60 PUMP SPEED - PER CENT 70 80 90 100 90 80 \ 70 I M 60 M 50 w _] 40 3 30 | 20 s 707. Mech Eff 50% Mech Eff 100 200 400 600 800 1000 1200 " PUMP SPEED ~ RPM 1400 1600 1800 2000 FIGURE 5 16 ------- 92.5 S2.5- NET POSITIVE SUCTION HEAD (NPSH) CHART Fluid - Water Conditions - 5000 Ft Altitude NPSH = hs-(hvp-ha) Where: hs=Static Suction Head at Pump Inlet (Gage) =Vapor Pressure (Absolute) ha=Atmospheric Pressure (Absolute) O -- DATA POINTS PUMP SPEED 1260 RPM Open Pot Boiling Point of Water @ 5000 Ft.Alt. (12.5 PSIA @ 204° F Nominal) 150 160 210 220 TEMPERATURE - 280 290 ------- contract requirements, are also indicated. Minimum N.P.S.H. characteristics shown were taken directly from Lear Motors feedpump data, corrected only for the individual contractors working fluid specific gravity. It has been our experience, as pointed out in the feedpump design studies, that while the minimum N.P.S.H. characteristics of the Lear Motors feedpump design is low, significant gains in Rankine cycle efficiency are obtained by using an externally driven boost pump designed to handle even lower N.P.S.H. conditions. D. MATERIAL COMPATIBILITY STUDY The proposed feedpumps utilize a flexible diaphragm to provide positive hermetic sealing of the working fluid from the atmosphere and oil contamination. Lear Motors Corporation has found that many of the common elastomers demonstrate all of the physical qualities necessary to effect this seal. However, compatibility with the working fluid must be established. At the first contract coordination meeting, due to the small number of elastomers which had been tested, it was decided that each of the organic fluid system contractors should perform compatibility tests on candidate elastomers and non-metallic materials. Samples of the candidate materials and a suggested test procedure were pro- vided by Lear Motors Corporation. The compiled results of these tests as well as additional data from the system contractors and an organic fluid manufacturer are shown. A summary of the elastomers which are acceptable for the feedpump sealing diaphragms follows: THERMO ELECTRON CORPORATION - Organic Working Fluid-Fluorinol 85 Elastomers which have passed initial compatibility tests with the TECO.organic working fluid at 250°F. 1. Silicone Rubber, Parker-Compound No. S455-7. AEROJET LIQUID ROCKET COMPANY - Organic Working Fluid AEF-78 Elastomers which have passed initial compatibility tests with the ALRC organic working fluid at 250°F. 1. Silicon-Rubber - (Dow Corning L-53). 2. Silicon Rubber - (Dow Corning L-63). LEAR MOTORS CORPORATION 18 ------- 3. Chloroprene Rubber - (Dupont "Neoprene"). 4. Polysulfide Rubber - (Thiokol Chemical Corp.). The results of these preliminary tests have demonstrated that elastomers for use with the organic working fluids are available. However, due to the short term and limited scope of these tests, Lear Motors recommends additional investigations. LEAR MOTORS CORPORATION 19 ------- Results of Material Compatibility Tests Performed by Thermo Electron Corp. Test Conditions: Solution - Temperature - LMC Candidate Material Chloroprene Rubber Florinol 85 and oil (10 to 1 ratio) 250°F Percent Weight Change + 6.8 Time (days) 17 Nitrel + 8.3 17 Polyimide (Dupont) Vespel SP-1 Polyamide DFS-20 (experimental-Dupont) CONCLUSIONS + .48 + . 11 Visual Observations Surface corroded, small pin holes, but still strong. Liquid yellow with small black particles hanging, white particles sticking on glass. Grey color at bottom in liquid F-85 immersed portion, also softer at bottom. White spots scattered on surface, white line at interface liquid yellow black colored, with some fine white parti- cles hanging. Color changed to a darker brown, material stron, F-85 and oil light brown, very few suspended fine fibers. Very few brown spots at bottom, more yellow colored material, slightly softer, oil and F-85 light brown. 1. Neither Neoprene nor Nitrel Rubber should be used in the presence of F-85 liquid and oil at 250°F. 2. SP-1 Polyimide may be used in the system at 250°F but preferably a lower temperature in the presence of F-85 liquid and oil. It showed about 0.44% swelling. 3. High temperature Polyamide DFS-20 may be used in the system at 250°F or a lower temperature in the presence of F-85 liquid and oil. It showed about 1.1% swelling with very light softening. 'Based on personal correspondence between Luco R. DiNanno, Development Engineer for Thermo Electron, Corp, and writer, September 13, 1972. LEAR MOTORS CORPORATION 20 ------- Results of Material Compatibility o Tests Performed by Thermo Electron Corp. Test Conditions: Solution - Fluorine! 85 and lubricating oil 10 to 1 ratio Temperature - 250°F Duration - 17 days Material Visual Observation Dow Corning, LS53, The rubber was much softer, lightly attack at Fluorosilicone Rubber bottom in liquid immersed portion, brownish (-2" x 0.07" O.D.) material was sticking on glass and liquid F-85 turned to very light brown. Dow Corning LS63, The rubber was much softer, lightly attack in Fluorosilicone Rubber liquid immersed portion. F-85 turned very (1.5" x 0.1" O.D.) light brown. Parker No. S455-7 The rubber was lightly softer, no apparent Silicon Rubber change, F-85 turned light brown. (2" x 0.1" O.D.) RECOMMENDATIONS: Silicone Rubber - Parker No. S455-7 is recommended to be used in the system at temperature not exceeding 250°F in the presence of F-85 solution and air, Based on correspondence between Dyer Kenney, Contract Project Officer for Environmental Protection Agency, and writer October, 1972. LEAR MOTORS CORPORATION 21 ------- Material Compatibility Information on Elastomers Obtained from the Fluid Manufacturer - Halocarbon Products Corporation Test Conditions: Solution - Fluorinol 85 Temperature - 284°F Duration 7 days Material % Height Change % Thickness Change Ethylene-Propylene Rubber 1.3 to 2.6 1.1 to 1.5 Silicone Rubber 4.7 to 11 2.6 to 3.4 Neoprene 15 to 16 5.2 to 10 Pure Gum & Polyisoprene 20 to 46 8.8 to 16 Flurosilicone Rubber 1.6 to 49 -23 to 18 Viton A 34 to 54 13 to 15 Butyl 16 7.0 Completely Unsatisfactory: Buna N, Buna S and Hypalon. 3Based on correspondence between Mr. Rex Conner, Halocarbon Products Corporation and writer, August, 1972. LEAR MOTORS CORPORATION 22 ------- Results of Material Compatibility Tests Performed by Aerojet Liquid Rocket Co. Test Conditions: Solution - Temperature - Duration - AEF-78 (A.LRC working fluid) 250°F 150 hours LMC Candidate Materials Neoprene (Diaphragm. Stock) Delrin (Dupont) Vespel SP-1 Polyimide (Dupont) Vespel SP-21 Polyimide (Dupont) Polyamide DFS-21, Experimental (Dupont) Nitrel (Diaphragm Stock) Viton (Diaphragm Stock) Polyamide DFS-20, experimental (Dupont)_ Natural Rubber (A.B. Boyd) Silicone Polyurethane (Newage Industries)_ Test Results _Marginal _Not Acceptable Good Good Good _Not Acceptable _Marginal Good _Not Acceptable Good _Marginal 4Based on telephone conversation between A.H. Kreeger, Manager Automotive Rankine Program, Aerojet Liquid Rocket Co. and writer, November, 1972. LEAR MOTORS CORPORATION 23 ------- Results of Elastomer Material Compatibility Tests Performed by Aerojet Liquid Rocket Co. 5 Test Conditions: Solution - Temperature - Duration AEF-78 250°F Long Term Elastomer Silicon Rubber (Dow Corning L-53) Silicon Rubber (Dow Corning L-63) Silicon Rubber (Parker HS 455-7)_ Florosilicon Rubber. Chloroprene Rubber Polysulfide (Thiokol Chemical Corp.) Test Results Good Good Good _Not Acceptable Good Good 5Based on telephone conversation between A.H. Kreeger, Manager Automotive Rankine Program, Aerojet Liquid Rocket Co. and writer, September, 1972. LEAR MOTORS CORPORATION 24 ------- CANDIDATE MATERIALS FOR SYSTEM CONTRACTOR LMC PROPOSED FEEDPUMPS Component Manifold (Inlet & Outlet) Valve Plate Outlet Valve Inlet Valve Valve Spring (Inlet & Outlet) Seals (Enclosed & Static) Diaphragm Seal Materials for Working SES Cast 356 Aluminum Stainless Steel Type 303 Aluminum 6061-T6 Aluminum 6061-T6 Stainless Steel Type 804 Nitrile Rubber "Hydrin" Rubber Fluid Section of Feedpump ALRC TECO Cast 356 Aluminum Cast 356 Aluminum Stainless Steel Type 303 Aluminum 6061-T6 Aluminum 6061-T6 Stainless Steel Type 804 Silicone Rubber Stainless Steel Type 303 Aluminum 6061-T6 Aluminum 6061-T6 Stainless Steel Type 804 Silicone Rubber l.Silicone Rubber* Silicone Rubber* 2. Polysulfide Rubber* Material for1 Oil Lubricate Section of Feedpump Feedpump Housing Bearings (Drive Shaft) Drive Shaft Pistons Bearings (Piston) Cylinders Seals 1. Cast Ductile Iron 2. Cast Aluminum 356-T6** 1. Cast Ductile Iron 1, 2. Cast Aluminum 2, 356-T6** Cast Ductile Iron Cast Aluminum 356-T6** Steel (Anti-Friction) Steel (Anti-Friction) Steel (Anti-Friction) Carborized 4620 Steel Carborized 1117 Steel Aluminum Bronze Cast Nodular Iron Buna "N" Rubber Carborized 4620 Steel Carborized 4620 Steel Carborized 1117 Steel Carborized 1117 Steel Aluminum Bronze Aluminum Bronze Cast Nodular Iron Cast Nodular Iron Buna "N" Rubber Buna "N" Rubber * Preliminary selection based on limited material compatibility study, ** Additional stress analysis required. TABLE 3 ------- STEAM ENGINE SYSTEMS TECHNICAL REQUIREMENTS AND LEAR MOTORS CORP. APPROACH VAPOR GENERATOR FEEDPUMP FOR RANKINE CYCLE AUTOMOTIVE PROPULSION SYSTEM EPA CONTRACT NUMBER 68-01-0437 December 1972 LEAR MOTORS CORPORATION ------- STEAM ENGINE SYSTEMS PUMP PERFORMANCE TECHNICAL REQUIREMENTS 1. Expander Speed The speed of the reciprocating expander during operation will vary from a minimum of 300 rpm to a maximum of 2500 rpm. 2. Flow The flow range shall be from 0 to 2.5 gpm. Maximum system flow (2.5 GPM) shall occur at 40 percent of maximum expander speed The feedpump shall be capable of modulating upon command from the propulsion control system to satisfy any flow condition within the the operating range specified. The feedpump shall be capable of operating with no inlet flow for periods up to one minute without damage. 3. Discharge Pressure The feedpump shall be capable of delivering flow as specified, while discharging to a pressure of 1200 psia. The discharge pressure shall be stable with no high frequency oscillations in excess of 25 psia. 4. Efficiency The feedpump mechanical efficiency shall be 70% or greater over the flow range from 30% to 80% of maximum design flow. The mechanical efficiency shall be 50% or greater at 10% of maximum design flow. 5. Fluid The working fluid for this system will be demineralized water. TECHNICAL APPROACH The estimated performance curves, on the following page, demonstrate how the proposed LMC feedpump would meet the SES technical requirements shown above. This estimate was obtained by extrapolating actual LMC feedpump data. The maximum pressure ripple requirement is met by utilizing an odd number of cylinders which are sized so that the instantaneous total flow of the pump for any given crank angle is as smooth as possible. Additional information regarding the LMC technical approach to the SES feedpump performance requirements may be found in the technical discussions section of this report. LEAR MOTORS CORPORATION 27 ------- 20 30 40 50 60 SPEED -' PER CENT 70 80 90 100 a o \ o fa Full Displacement Mech. ESTIMATED FEEDWATER PUMP PERFORMANCE EPA Contract No. 68-01-0437 System Contractor-Steam Engines Systems Corp. Conditions: Outlet Pressure .... 1200 PSIG Suction Condition ... 5 PSI Min. N.P.S.H. Fluid Temp. .... 160-250°F O System Max. Flow - Low Speed Corner Requirement 40 50 60 70 EXPANDER SPEED - PER CENT 80 90 100 90 80 70 O z w M O 60 £ w 50 40 O 30 20 707» Mech. EFF. 507« Mech. EFF. 100 240 480 720 960 1200 1440 1680 1920 2160 2400 PUMP SPEED ^ RPM 500 1000 1500 EXPANDER SPEED - RPM 2000 2500 FIGURE 7 28 ------- STEAM ENGINE SYSTEMS PUMP INLET ENVELOPE TECHNICAL REQUIREMENTS 1. Inlet Pressure The minimum pressure at the pump inlet valve during start-up maybe as low as 0.09 psia. During system operation, the inlet pressure may vary from a minimum of 7 psia to a maximum of 50 psia. 2. Net Positive Suction Head The net positive suction head required by the feedpump shall be minimized so that the pump can operate without cavitating under low liquid head conditions without the necessity of a boost pump. 3. Temperature Range During system operation, the temperature of the working fluid may vary from 180°F to 250°F. At system start-up the temperature of the working fluid may vary from 32°F to 275°F. 4. Temperature Transients The feedpump shall stand feedwater temperature transients of 3°F per second for periods of 10 seconds without cavitating. 5. Booster Pump A booster pump for providing the required net positive suction head to the feedpump shall be considered only if trade-off studies conducted by the contractor reveal that the utilization of a boost pump will simplify the feedpump design sufficiently to offset the additional cost, weight and power consumption required by the boost pump. TECHNICAL APPROACH The estimated pump inlet envelope on the following page shows the Lear pump capability while operating at the 85% to 90% volumetric efficiency level. The N.P.S.H. values shown are taken from actual data. RECOMMENDATIONS Due to the inherent lower N.P.S.H. characteristics of a centrifugal pump and its ability to handle large quantities of entrained vapor, a separate centrifugal boost pump is recommended for this system. The size and characteristics of this pump will require a trade-off study of the system condenser capability and the amount of sub-cooling allowable before significant decreases in cycle efficiency occur. LEAR MOTORS CORPORATION 29 ------- 112.5 102.5- 92.5- 82.5- 100 90 80 00 ESTIMATED FEED PUMP INLET ENVELOPE Fluid - Water Conditions - 5000 Altitude System Contractor-Steam Engine Systems Normal 'Operating Range \ \l \ Open Pot Boiling Point of Water @ 5000 Ft. ALT. (12.5 PSIA @ 204°F Nominal) 20 I 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 32 TEMPERATURE - °F ------- STEAM ENGINE SYSTEMS PUMP DRIVE TECHNICAL REQUIREMENTS 1. Drive Mechanism The feedpump shall be mechanically driven with power taken from the expander shaft or gearbox. The feedpump shall provide the total range of required flow and pressure with the expander operation at any speed within its specified speed range. The non-linear relationship between expander speed and required feedpump flow and pressure shall be accommodated by variable drive mechanism characteristics and/or variable feedpump and drive mechanism should be capable of being mounted in the power plant as required by the system contractor. TECHNICAL APPROACH An outline drawing of the proposed Lear Motors Pump is shown on the following page. The pump has variable displacement capability and can be directly driven by the expander. Pump to expander speed ratio and interface are not firm and will have to be worked out between Lear Motors and the system contractor. Pump physical size is based on the contracts pump performance requirements, i.e. flow rate, and any change in the design flow rate will directly affect pumps physical size and weight. LEAR MOTORS CORPORATION 31 ------- OUTLINE DWG., PUMP -SCS/ ------- STEAM ENGINE SYSTEMS GENERAL REQUIREMENTS TECHNICAL REQUIREMENTS 1. Vehicle Design Goals Where applicable, "Vehicle Design Goals- Six Passenger Automobile", shall be used as a guide for the design requirements. 2. Materials All materials utilized in the construction of the feedpump shall be corrosive resistant in a water/air environment. 3. Lubrication Any lubricants that may be used within the feedpump and its drive mechanism shall not mix with or contaminate the working fluid. The lubricant shall be the same as that used in the expander. 4. Leakage There shall be no external leakage from the feedpump and its drive mechanism. The unit shall be capable of being hermetically sealed. 5. Working Fluid Drainage The feedpump shall be designed such that all working fluid within the pump will drain back out of the inlet side of the pump into the system sump at shutdown. Care should be taken to assure that all pockets of fluid are adequately drained to prevent damage due to freezing. TECHNICAL APPROACH The Lear Motors pump design, with its flexible diaphragm seal provides inherent hermetic sealing of working fluid from the air and lubricated section of the pump. Working fluid drainage requirement will be met by unseating the inlet valves at system shutdown allowing the fluid in each chamber to drain back to the inlet manifold. This approach would not degrade the pumps performance and would be integral to the pump. Materials used for the construction of the proposed SES feedpump are shown in Table 3. The material used for the pumps flexible sealing member can be constructed from almost any elastometer which can meet the temperature requirements and is compatible with the working fluid. LEAR MOTORS CORPORATION 33 ------- AEROJET LIQUID ROCKET COMPANY TECHNICAL REQUIREMENTS AND LEAR MOTORS CORP. APPROACH VAPOR GENERATOR FEEDPUMP FOR RANKINE CYCLE AUTOMOTIVE PROPULSION SYSTEM EPA CONTRACT NUMBER 68-01-0437 DECEMBER 1972 LEAR MOTORS CORPORATION 34 ------- AEROJET LIQUID ROCKET COMPANY PUMP PERFORMANCE TECHNICAL REQUIREMENTS 1. Speed Range The speed of the turbine expander will vary from a minimum of 16,800 rpm to a maximum of 31,200 rpm. This same speed ratio (1.85:1) will be available from the expander gearbox, if required. 2. Flow The feedpump and its drive mechanism shall be capable of delivering a constant flow of organic fluid from a minimum of 0.5 gpm to a maximum of 28 gpm at a discharge pressure from 650 psia to 1100 psia and at any given expander speed within the range specified. Maximum system flow (28 gpm) shall occur at 59 percent maximum expander speed. 3. Discharge Pressure The feedpump shall be capable of delivering flow as specified while discharging to a pressure of 1100 psia. The discharge pressure shall be stable with no high frequency oscillations in excess of 25 psi. 4. Efficiency The feedpump mechanical efficiency shall be 70% or greater over the flow range from 30% of maximum design flow to 80% of maximum design flow. The mechanical efficiency shall be 50% or greater at 10% of maximum design flow. 5. Fluid The working fluid will be a non-corrosive organic fluid with a density of approximately 100 Ibs/ft^. TECHNICAL APPROACH The estimated performance curves, on the following page, demonstrate how the proposed LMC feedpump would meet the ALRC technical requirements shown above. This estimate was obtained by extrapolating actual LMC feedpump data. The maximum pressure ripple requirement is met by utilizing an odd number of cylinders which are sized so that the instantaneous total flow of the pump for any given crank angle is as smooth as possible. Additional information regarding the LMC technical approach to the ALRC feedpump performance requirements may be found in the technical discussions section of this report. LEAR MOTORS CORPORATION 35 ------- <4U 40 50 60 SPEED -" PER CENT 70 80 90 LOO o \ Cn (Xc S PL, 52 48 44 40 36 32 28 24 20 16. 12 8 4 0" Displacement Mech ESTIMATED FEEDWATER PUMP PERFORMANCE EPA CONTRACT NO. 68-01-0437 System Contractor- Aerojet Liquid Rocket Co. Conditions: Outlet Pressure - 1000 PSIG Suction Condition - 8 PSI Min.N.P.S.H. Fluid Temp - 160-250° F O System Max. Flow - Low Speed Corner Requirement 20 28 GPM=1007. 8 GPM 4 GPMX 30 40 50 60 70 PUMP & EXPANDER SPEED -- PER CENT 80 100 90 80 70 60 50 40 30 20 z w 707. Mech. EFF. 507« Mech. EFF. 90 100 0 0 200 3.1 400 6.2 600 800 1000 1200 1400 PUMP SPEED ^ RPM 9^4 12.5" is'. 6 18.6 2l'.8 EXPANDER SPEED x 10.3"^-RPM 1600 25.0 1800 2000 28.1 31.2 FIGURE 10 36 ------- AEROJET LIQUID ROCKET COMPANY PUMP INLET ENVELOPE TECHNICAL REQUIREMENTS 1. Inlet Pressure The minimum pressure at the pump inlet valve during start-up may be as low as 1.0 psia. During system operation, the inlet pressure may vary from a minimum of 10 psia to a maximum of 40 psia. 2. Net Positive Suction Head The minimum liquid head at the pump inlet is 7 inches. Care must be taken to assure cavitation does not occur during start-up or during abnormal operating conditions resulting in a loss of condenser sub-cooling. 3. Temperature Range During system operation, the temperature of the working fluid may vary from 160°F to 250°F. At start-up the temperature of the working fluid may vary from -40°F to 275°F. 4. Booster Pump A booster pump for providing the required net positive suction head to the feedpump shall be considered only if trade-off studies conducted by the contractor reveal that the utilization of a boost pump will simplify the feedpump design sufficiently to offset the additional cost, weight,and power consumption required by the boost pump. TECHNICAL APPROACH The estimated pump inlet envelope on the following page shows the Lear pump capability while operating at the 85% to 90% volumetric efficiency level. The N.P.S.H. values shown are taken from actual data which has been corrected to meet the system contractors fluid character- istics. RECOMMENDATIONS Due to the inherent lower N.P.S.H. characteristics of a centrifugal pump and its ability to handle large quantities of entrained vapor, a separate centrifugal boost pump is recommended for this system. The size and characteristics of this pump will require a trade-off study of the systems condenser capability and the amount of sub-cooling allowable before significant decreases in cycle efficiency occur. LEAR MOTORS CORPORATION 37 ------- 114.7 104.7- 94.7- 84.7- 100 90 80 70 60 50 40 ESTIMATED FEED PUMP INLET ENVELOPE Fluid- AEF-78 Specific Gravity = 1.793 @72°F System Contractor - Aerojet Liquid Rocket Co. Open Pot Boiling Point For AEF-78 (14.7 PSIA @ 189°F) -20 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 TEMPERATURE °F CO Co ------- AEROJET LIQUID ROCKET COMPANY PUMP DRIVE AND CONTROL TECHNICAL REQUIREMENTS 1. Drive Mechanism The feedpump shall be mechanically driven with power taken from the expander shaft or gearbox. The feedpump shall provide the total range of required flow and pressure with the expander operation at any speed within-its specified speed range. The non-linear relationship between expander speed and required feedpump flow and pressure shall be accommodated by variable drive mechanism characteristics and/or variable feedpump capacity characteristics. The feedpump and drive mechanism should be capable of being mounted in the power plant as required by the system contractor. 2. Control Movement of the vehicle accelerator pedal will provide a mechanical input signal to the feedpump for flow modulation. TECHNICAL APPROACH An outline drawing of the proposed Lear Motors pump is shown on the following page. The pump has variable displacement capability and can be directly driven by the expander. Pump to expander speed ratio and interface are not firm and will have to be worked out between Lear Motors and the system contractor. Pump physical size is based on the contract pump performance require- ments, i.e. flow rate, and any change in the design flow rate will directly affect pump physical size and weight. LEAR MOTORS CORPORATION 39 ------- O ------- AEROJET LIQUID ROCKET COMPANY GENERAL REQUIREMENTS TECHNICAL REQUIREMENTS 1. Vehicle Design Goals Where applicable, "Vehicle Design Goals- Six Passenger Automobile", shall be used as a guide for the design requirements. 2. Leakage There shall be no external leakage from the feedpump and its drive mechanism. The unit shall be capable of being hermetically sealed. 3. Lubrication Any lubricants that may be used within the feedpump and its drive mechanism shall not mix or contaminate the working fluid. The lubricant shall be the same as that used in the expander. 4. Materials Compatibility All materials utilized in the construction of the feedpump shall not corrode or otherwise chemically react with the fluid in any manner. TECHNICAL APPROACH The Lear Motors pump design with its flexible diaphragm seal provides inherent hermetic sealing of working fluid from the air and lubricated section of the pump. Materials used for the construction of the proposed ALRC feedpump are shown in Table 3. The material used for the pumps flexible sealing member can be constructed from elastomers which meet the temperature requirements and is compatible with the working fluid. LEAR MOTORS CORPORATION 41 ------- THERMO ELECTRON CORPORATION TECHNICAL REQUIREMENTS AND LEAR MOTORS CORP. APPROACH VAPOR GENERATOR FEEDPUMP FOR RANKINE CYCLE AUTOMOTIVE PROPULSION SYSTEM EPA CONTRACT NUMBER 68-01-0437 DECEMBER 1972 LEAR MOTORS CORPORATION 42 ------- THERMO ELECTRON CORPORATION PUMP PERFORMANCE TECHNICAL REQUIREMENTS 1. Expander Speed Range The operating speed range of the recipro- cating expander will vary from a minimum of 300 rpm to a maximum of 1800 rpm. 2. Flow Flow range shall be from 0 to 17 gpm. Maximum system flow (17 gpm) shall occur at 45 percent maximum expander speed. The feedpump shall be capable of modulating upon command from the propulsion control system to satisfy any flow condition within the operating range specified. 3. Discharge Pressure The feedpump shall be capable of operating at a constant discharge pressure of 1000 psia while modulating flow over the range specified. The discharge pressure shall be stable with no high frequency oscillations in excess of 25 psi. 4. Efficiency The feedpump mechanical efficiency shall be 70% or greater over the flow range from 30% of maximum design flow to 80% of maximum design flow. The mechanical efficiency shall be 50% or greater at 10% of maximum design flow. 5. Fluid The working fluid will be a non-corrosive organic fluid with a density of approximately 80 lbs/ft3. TECHNICAL APPROACH The estimated performance curves, on the following page, demonstrate how the proposed LMC feedpump would meet the TECO technical requirements shown above. This estimate was obtained by extrapolating actual LMC feedpump data. The maximum pressure ripple requirement is met by utilizing an odd number of cylinders which are sized so that the instantaneous total flow of the pump for any given crank angle is as smooth as possible. Additional information regarding the LMC technical approach to the TECO feedpump performance requirements may be found in the technical discussions section of this report. LEAR MOTORS CORPORATION 43 ------- 20 30 40 50 60 PUMP SPEED -' PER CENT 70 80 90 100 40 36 32 s PM o 1 fa Pu a CM 28 24 20 16 12 Full Displacement Mech. EFF. ESTIMATED FEEDWATER PUMP PERFORMANCE EPA Contract No. 68-01 0437 System contractor - Thermo Electron Corp. Conditions: Outlet Pressure . . . 1000 PSIG Suction Condition . . 7 PSI Min, N.P.S.H. Fluid Temp 160-250°F O System Max. Flow - Low Speed Corner Requirement 20 30 40 50 60 "70 PUMP & EXPANDER SPEED <- Per Cent 80 "90 100 90 6-S 80 I 70 w 60 fa 50 w 40 30 2 a w 20 33 10 70% Mech. Eff 507, Mech. Eff 100 0 0 200 180 400 360 600 540 800 1000 1200 PUMP SPhclD ^ RPM 720 900 1000 EXPANDER SPEED ^ RPM 1400 1260 1600 1440 i 1800 2000 1620 1800 FIGURE 13 44 ------- THERMO ELECTRON CORPORATION PUMP INLET ENVELOPE TECHNICAL REQUIREMENTS 1. Inlet Pressure In the Rankine cycle system, the feedpump inlet pressure is determined by the condensing pressure and the elevation of the pump relative to the condenser. At system start-up, prior to the time when condenser pressure builds up due to heat load, the inlet pressure at the pump may be no greater than 0.5 psia. During operation the inlet pressure may vary from a minimum of 5 psia to a maximum of 90 psia. 2. Net Positive Suction Head The minimum liquid head at the pump inlet is 10 inches. Care must be taken to assure cavitation does not occur during start-up or during abnormal operating conditions resulting in a loss of condenser sub-cooling. 3. Temperature Range During system operation, the temperature of the working fluid may vary from 160°F to 250°F. At start-up the temperature of the working fluid may vary from -40°F to 275°F. 4. Booster Pump A booster pump for providing the required net positive suction head to the feedpump shall be considered only if utilization of a boost pump will simplify the feedpump design sufficiently to offset the additional cost, weight and power consumption required by the boost pump. TECHNICAL APPROACH The estimated pump inlet envelope on the following page shows the proposed LMC pump capability while operating at the 85% to 90% volumetric efficiency level. The N.P.S.H. values shown are taken from actual data which has been corrected to meet the TECO organic fluid characteristics. Due to the inherent lower N.P.S.H. characteristics of a centrifugal pump and its ability to handle large quantities of entrained vapor, a separate centrifugal boost pump is recommended for this system. The size and characteristics of this pump will require a trade-off study of the system condenser capability and the amount of sub-cooling allowable before significant decreases in cycle efficiency occur. LEAR MOTORS CORPORATION 45 ------- 114.7 104.7- 100 Normalv Operating Range \ ESTIMATED FEED PUMP INLET ENVELOPE FLUID - Trifluoroethanol (Fluorinol-85 SPECIFIC GRAVITY = 1.368 @72~F SYSTEM CONTRACTOR - Thermo Electron Corp. Open Pot Boiling Point Fluorinol - 85 (14.7 PSIA @ 166 -20 0 20 40 60 80 100 120 140 160 180 200 220 240 260 28.0 300 TEMPERATURE -F ------- THERMO ELECTRON CORPORATION PUMP DRIVE AND CONTROL TECHNICAL REQUIREMENTS 1. Drive Mechanism The feedpump shall be mechanically driven with power taken from the expander shaft or gearbox. The feedpump shall provide the total range of required flow and pressure with the expander operation at any speed within its specified speed range. The non-linear relationship between expander speed and required feedpump flow and pressure shall be accommodated by variable drive mechanism characteristics and/or variable feedpump capacity characteristics. The feedpump and drive mechanism should be capable of being mounted in the powerplant as required by the system contractor. 2. Control Movement of the accelerator pedal will provide a mechanical input signal to the feedpump for flow modulation. TECHNICAL APPROACH An outline drawing of the proposed Lear Motors pump is shown on the following page. The pump has variable displacement capability and can be directly driven by the expander. Pump to expander speed ratio and inter- face are not firm and will have to be worked out between Lear Motors and the system contractor. Pump physical size is based on the contracts pump performance requirements, i.e. flow rate, and any change in the design flow rate will directly affect pump physical size and weight. LEAR MOTORS CORPORATION 47 ------- 00 ------- THERMO ELECTRON CORPORATION GENERAL REQUIREMENTS TECHNICAL REQUIREMENTS 1. Vehicle Design Goals Where applicable "Vehicle Design Goals- Six Passenger Automobile", shall be used as a guide for the design requirements. 2. Leakage There shall be no external leakage from the feedpump and its drive mechanism. The unit shall be capable of being hermetically sealed. 3. Lubrication Any lubricants that may be used within the feedpump and its drive mechanism shall not mix with or contaminate the working fluid. The lubricant shall be the same as that used in the expander. 4. Materials Compatibility All materials utilized in the construction of the feedpump shall not corrode or otherwise chemically react with the fluid in any manner. TECHNICAL APPROACH The Lear Motors pumo design with its flexible diaphragm seal provides inherent hermetic sealing of working fluid from the air and lubricated section of the pump. Materials used for the construction of the proposed TECO feedpump are shown in Table 3. The material used for the pumps flexible sealing member can be constructed from most elastomers which meet the temperature requirements and is compatible with the working fluid. LEAR MOTORS CORPORATION 49 ------- V CONCLUSION Based on the results of this study and the past experience of Lear Motors in the development of Rankine Cycle Automotive Propulsion Systems, a radial piston, variable displacement feedpump design was selected to satisfy the requirements of the three Rankine Cycle System Contractors. The proposed feedpumps hermetically seal the working fluid from the atmosphere and lubricating oil by utilization of a diaphragm seal. all of the highly stressed moving parts in the pump are oil lubricated allowing conventional, low cost materials to be used throughout its construction. Three separate pumps were determined necessary because of the vast difference in system flow requirements. Due to the high flow at low speed requirements of the two organic systems, these pumps will be physically larger than the pump designed for the water base contractor. Ductile iron was selected as the material of construction for the pump housing. A detailed stress analysis of an aluminum pump housing as a means of reducing weight is recommended. Also, any reduction in the high flow - low speed requirement of the organic systems would allow a significant reduction in size and weight. Projected feedpump performance will contribute to high cycle efficiency; full displacement mechanical efficiencies from 85 to 90 percent are feasible. It is recommended that an externally driven boost pump be used with the proposed feedpumps to assure reliable operation at all system operating conditions. A centrifugal type boost pump was selected because of its capability for pumping at very low NPSH values. A major effort was directed toward finding elastimers which were compatible with the two organic fluids. Several candidates were found acceptable for operation at 250° or lower. Additional investigations are required to determine the long term effects of the fluids on elastomers. The Lear Motors proposed feedpumps will satisfy the requirements of the three Rankine Cycle Automobile Power Systems with one exception; LEAR MOTORS CORPORATION 50 ------- the low flow - high speed region of the estimated pump performances does not fully meet the system contractors mechanical efficiency requirements. The knowledge gained from this study and the background stemming from our four year feedpump development program are incorporated in these proposed pump designs. Reliable operation with a minimum develop- ment time is assured as this basic type of pump has been well developed in the Lear Motor Rankine Cycle Systems. LEAR MOTORS CORPORATION 51 ------- REFERENCES Baumeister, Theodore and Lionel S. Marks, ed., Mechanical Engineer's Handbook, New York: McGraw-Hill, 1958. Binder, R.C., Fluid Mechanics, Englewood Cliffs, New Jersey: Prentice-Hall, 1955. Erast, Walter, Oil Hydraulic Power and Its Industrial Applications, New York: McGraw-Hill, 1960. Gartmann, Hans, ed., Del-aval Engineering Handbook, New York: McGraw-Hill, 1970. Tuve, G.L. and L.C. Domholdt, Engineering Experimentation, New York: McGraw-Hill, 1966. LEAR MOTORS CORPORATION 52 ------- APPENDIX A LEAR MOTORS PUMP STANDARDS LEAR MOTORS CORPORATION 53 ------- 7001-3401 July 26, 1972 PUMP STANDARDS LEAR MOTORS CORPORATION PUMP TEST CODE I. Object This code establishes a procedure for conducting and reporting tests of Rankine Cycle feedwater and condensate pumps. It is intended that the tests shall be made and reported by qualified personnel trained in the proper application and use of the various instruments and methods involved. II. Records Complete records shal'l be kept of all information relevant to a test. The serial number, type, size, or other means of identification of each pump tested shall be recorded in order that mistakes in identity be avoided. III. Measurements The essential measurements for test of feedwater and condensate pumps are: 1. Flow 2. Outlet Pressure 3. Suction Pressure or Vacuum 4. Temperature of pumped fluid 5. Temperature of pump 6. Power input to pump 7. Speed LEAR MOTORS CORPORATION A-l ------- IV. Flow Measurement The rate of flow shall be expressed in gallons per minute (gpm) and be measured with calibrated rotameter compatible with pumped fluid. V. Outlet Pressure Measurement Head or outlet pressure shall be designated in pounds per square inch gage (psig). Measurement will be made with a calibrate pressure gage of the proper range. VI. Suction Pressure or Vacuum Measurement Suction pressure shall be designated in pounds per square inch absolute (psia). Suction vacuum conditions shall be designated in inches of mercury (in. Hq). Measurement will be made with a calibrated pressure gage or mercury manometer of the proper range. VII. Temperature Measurements Temperature will be expressed in degrees fahrenheit (°F). A calibrated thermometer with the proper range will be used. VIII.Input Power Measurements (a) Pump input horsepower may be determined by means of transmission dynamometers, torsion dynamometers or calibrated drivers. (b) Transmission Dynamometers. When pump input horsepower is to be determined by transmission dynamometers, the unloaded and unlocked dynamometer must be properly balanced prior to the test at the same speed at which the test is to be run and the scales should be checked against standard weights. After the test, the balance must be rechecked to assure that no change LEAR MOTORS CORPORATION A-2 ------- (b) Cont. has taken place. In the event of an appreciable change, the test shall be rerun. An accurate measurement of speed is essential. (c) Torsion Dynamometers. When pump input horsepower is to be determined by torsion dynamometers, the unloaded dynamometer shall be statically calibrated prior to the test by measuring the angular deflection for a given torque, the tare reading on the dynamometer scale being taken at rated speed with the pump disconnected. After the test, the calibrations must be rechecked to assure that no change has taken place. In the event of an appreciable change, the test shall be rerun. An accurate measurement'of speed is essential. (d) Calibrated Drivers. When pump input horsepower is to be determined by the use of a calibrated motor, the following shall be applied: 1. All measurements of power input shall be made at the terminals of the motor to exclude any line losses that may occur between the switchboard and the driver itself. Certified calibration curves of the motor must be obtained. The calibration shall be conducted on the specific motor in question, and not on an identical machine. 2. Such calibration curves must indicate the true input- output value of motor efficiency and not some conventional method of determinining an arbitrary efficiency. 3. When the pump is arranged with a speed changing device between the driver and the pump, the input to the pump shall be the actual output of the driving element less the loss through the speed changing device. The value of this loss shall be certified by the manufacturer of the speed changing device. LEAR MOTORS CORPORATION A-3 ------- X. Measurement of Speed (a) Measurement of speed shall be made by means of revolution counters or tachometers. (b) For speed measurements taken by means of a revolution counter, the timing period shall be of sufficient length to obtain a true average speed and the stopwatch used should be checked against a standard timer. (c) When a tachometer is used, it shall be calibrated against a revolution counter before and after test. Tachometer readings should be made at frequent intervals during each test point to obtain an accurate measurement of average speed over the reading period. LEAR MOTORS CORPORATION A-4 ------- PUMP RATING CRITERIA I. Introduction The following numbered paragraphs define the quantities used to designate pumping applications. II. Volume, Standard Units (a) The standard unit of volume shall be the United States gallon or the cubic foot. The standard U.S. gallon contains 231.0 cubic inches. One cubic foot equals 7.4805 gallons. (b) The rate of flow shall be expressed in gallons per minute (gpm), gallons per hour (gph). (c) The specific weight of water at a temperature of 68°F shall be taken as 62.3 Ib per cu ft. For other temperatures, proper specific weight corrections should be made. III. Pump Volumetric Efficiency (Symbol E ) The volumetric efficiency of a rotary pump is the ratio of the actual pump capacity to the displacement, expressed in percent, at the specified pumping conditions: F = capacity „ lnn v displacement IV. Pump Input (Symbol bhp or ehp) The unit of power input to pump is the horsepower. 1 horsepower = 550 foot-pounds per second = 33,000 foot-pounds per minute = 2545 Btu per hour = .7457 kilowatts LEAR MOTORS CORPORATION A-5 ------- (a) The input horsepower (bhp) when measured by a transmission or torsion dynamometer, is calculated from the following formula: bhp = 2 * 33,000 where L = length of lever arm in feet W = net weight in pounds N = speed in rpm IT = 3.1416 (b) The electrical horsepower input to an electric motor is given by: ehp = kw^Qr Volts X Amps where kw = kilowatt input. (c) The input horsepower to a pump driven by an electric motor is: bhp = ehp X Em where E = true efficiency of motor. V. Pump Output (Symbol whp) (a) Pump output is the liquid horsepower delivered by the pump. (b) The liquid horsepower is to be computed by the following formula: LEAR MOTORS CORPORATION A-6 ------- pounds of liquid x Total head in U(hn _ pumped per min. ft of liquid W P 33,000 (c) If the capacity is expressed in gallons per minute (gpm) the formula for liquid horsepower becomes: ,,hn gpm X (total head in feet) X sp gr wnp " 3960 where: sp gr = specific gravity of liquid referred to 68°F water, weighing 62.3 Ib per cu ft. (d) If the total head is expressed in pounds per square inch, the formula for liquid horsepower, irrespective of specific gravity of the liquid, becomes: whp = gpm X (total head in psi) 17T4 VI. Mechanical Efficiency (a) Pump mechanical efficiency (E ) is the ratio of the energy delivered by the pump to the energy supplied to the pump shaft; that is, the ratio of the liquid horsepower to the brake horsepower expressed in percent: 100 or whP _ IUU or _ p bhp ehp X Em (b) Overall unit efficiency (EQ) is the ratio of the energy delivered by the pump to the energy supplied to the input side of the pump driver; that is, in the case of electric-driven pumps, the ratio of the liquid horsepower to the electrical horsepower input to the driver, expressed in percent: E, • LEAR MOTORS CORPORATION A-7 ------- VII. NPSH Definition NPSH (net positive suction head) is defined as the net pressure absolute above vapor pressure at the pump inlet. In pumping .liquids we are concerned with getting the liquid into the pump in a liquid state (i.e. without vaporization). Suction lift, friction losses, and entrance losses all conspire to reduce net pressure and in some cases interfere with the liquid getting into the pump in liquid phase. It should be remembered that the boiling ooint of a liquid is that point at which vapor pressure equals external pressure. Whether this takes place in open or closed vessels there is usually a vapor area in contact with the liquid and a liquid level line. At boiling point the addition of heat or the lowering of external pressure unbalances this equilibrium and results in the vaporization of an amount of liquid. Also to be considered is that centrifugal pumps are liquid handling machines. Although pumps will handle up to 50% entrained gas or vapor and will dispose of the air in suction lines during priming cycle they are not efficient vapor handling devices. Further,there is a great expansion of volume in the conversion from liquid to vapor state which takes up the inherent pump capacity. Reduced capacity at low NPSH is an efficiency loss permitting no revision of brake horsepower. Because of this'major consideration of maintaining liquid state during the pumping cycle it is essential to make an NPSH calculation in all applications involving a liquid at or close to boiling point. LEAR MOTORS CORPORATION A-8 ------- NPSH CALCULATION Three general cases may be considered in making an NPSH calculation. Case I - The liquid level of the supply is above the pump centerline. This is termed static suction head. Case II- The liquid level of the supply is below the pump centerline. This is suction lift. Case I is by far the most common in industrial applications. Hot water or various other liquids are pumped out of a vessel elevated above the pump. In such a case it is usually necessary to consider only four elements in calculating NPSH. CASE I Fluid Level Direction Of Flow WHERE: hs = Static Suction Head (PSIG) h = Vapor Pressure (PSIA) ha = Atmospheric Pressure (PSIA) hf = Friction Loss (PSIG) In the range of capacities involving pumps (up to 250 GPM) velocity head need not be considered. Then in any Case I system the following formula applies: hs + ha - (hvp + M = NPSH LEAR MOTORS CORPORATION A-9 ------- Case IA: The liquid is in a closed vessel in vacuum or pressure systems. In this special case vapor pressure will equal atmo- spheric pressure. CASE IA Vent Direction Of Flow WHERE: = Static Suction Head (PSIG) = Vapor Pressure (PSIA) h, = Atmospheric Pressure (PSIA) a hf = Friction Loss (PSIG) vp .'. hs - hf = NPSH In planning piping for NPSH problems it is usually desirable to increase the size of suction piping until friction loss in the suction line is less than 6 in. of liquid head. In such cases h-r may be disregarded in the application. The formulae then becomes: Case I: Case IA: ha - hvp = NPSH hs = NPSH In Case I NPSH is identical with static suction head when the liquid is at boiling point and the suction piping is large enough to keep total friction loss below 6 in. of liquid head. LEAR MOTORS CORPORATION A-10 ------- Case II can never involve liquids at boiling point since a negative NPSH condition would result and vaporization would take place. All cases of NPSH calculations involving suction lift must also involve liquids below boiling point. With the vapor pressure less than the atmospheric pressure the formula is as follows: CASE II Discharge Direction of f1ow —i-iii^^j— LI-— /—Foot Valve WHERE: = Static Suction Head (PSIG) = Vapor Pressure (PSIA) ha = Atmospheric Pressure (PSIA) . = Friction Loss (PSIG) vp ha ' hvp - hs ' NPSH Atmospheric pressure is then the only positive force in Case II Both vapor pressure and suction lift are negative factors. NOTE: Static suction head (h ) for any fluid: Inches of Head x Specific Gravity x .03613 = PSIG Feet of Head x Specific Gravity x .4335 = PSIG K* Max K. Winkler Reference: Standard of Hydraulic Inst. LEAR MOTORS CORPORATION A-ll ------- |