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Analysis of a radial-outflow reaction turbine concept for geothermal application

Description: The radial-outflow reaction turbine, a pure-reaction turbine designed to improve the conversion efficiency of geothermal energy into electrical power is described. It also has potential as a total-flow turbine for low-temperature water. The principle of incomplete expansion can be used to obtain a reduction in turbine size when the turbine exhausts into a low-pressure condenser. And, by adding this turbine to single- and two-stage flashed-steam systems, the conversion efficiency of systems utilizing low- and high-energy wellhead sources, respectively can be improved. The Appendix outlines the analysis of the radial-outflow reaction turbine and leads to an expression for engine efficiency.
Date: May 25, 1978
Creator: House, P.A.
Partner: UNT Libraries Government Documents Department

Hybrid Staging of Geothermal Energy Conversion Processes

Description: A hybrid system consists of two or more energy conversion processes. This study examines the use of three energy conversion machines in hybrid systems: the conventional single-phase turbine, and the two-phase expanders known as the Lysholm engine and the radial outflow reaction turbine. Two hybrid systems are presented. The first is a two-stage, single-flash system with the Lysholm engine as the first stage, and a separator and conventional turbine as the second stage. The second system adds a radial outflow reaction turbine to recover a part of the energy rejected in the second stage. A theoretical specific power of 41.3 kW.s/lb is predicted for the two-stage, single-flash hybrid system. The addition of the radial outflow rotary turbine increases performance to 44.8 kW.s/lb. Both are superior to the double-flash system, with a specific power of 37.8 kW.s/lb. In addition, the hybrid system offers operating flexibility.
Date: September 25, 1978
Creator: Steidel, Robert F.
Partner: UNT Libraries Government Documents Department

Field-test results for a two-phase nozzle operating on a Salton Sea geothermal resource, November 20-December 19, 1980

Description: The following are described: the test system, the data acquisition system, operating procedure and data acquisition, procedure for taking data, shutdown procedure, discussion of nozzle frequency, the effect of non-condensables, the results of non-condensable evaluation, the thermodynamic effect of dissolved solids, and a brief summary of scale tests.
Date: January 1, 1981
Partner: UNT Libraries Government Documents Department

500-kW DCHX pilot-plant evaluation testing

Description: Field tests with the 500 kW Direct Contact Pilot Plant were conducted utilizing brine from well Mesa 6-2. The tests were intended to develop comprehensive performance data, design criteria, and economic factors for the direct contact power plant. The tests were conducted in two phases. The first test phase was to determine specific component performance of the DCHX, turbine, condensers and pumps, and to evaluate chemical mass balances of non-condensible gases in the IC/sub 4/ loop and IC/sub 4/ in the brine stream. The second test phase was to provide a longer term run at nearly fixed operating conditions in order to evaluate plant performance and identify operating cost data for the pilot plant. During these tests the total accumulated run time on major system components exceeded 1180 hours with 777 hours on the turbine prime mover. Direct contact heat exchanger performance exceeded the design prediction.
Date: October 1, 1981
Creator: Hlinak, A.; Lee, T.; Loback, J.; Nichols, K.; Olander, R.; Oshmyansky, S. et al.
Partner: UNT Libraries Government Documents Department

Final phase testing and evaluation of the 500 kW direct contact pilot plant at East Mesa

Description: The testing performed during the last phase of the geothermal direct contact heat exchanger program utilizing the 500 kW pilot plant provided more insight into the capabilities and limits of the direct contact approach and showed that more work needs to be done to understand the inner workings of a large direct contact heat exchanger if they are to be modeled analytically. Testing of the column demonstrated that the performance was excellent and that the sizing criteria is conservative. The system operated smoothly and was readily controlled over a wide range of operating conditions. Performance evaluation showed pinch differentials of 4/sup 0/F or less and better than predicted heat transfer capability. Testing during this final phase was directed towards establishing the limits of the column to transfer heat. The working column height was shortened progressively to approximately 16 feet from a design length of 28 feet. The short column performed as well as a full length column and there are indications that the column could have been shortened even more without affecting its ability to transfer heat. The column's ability to perform as well with shortened lengths indicates that the heat transfer coefficients and criteria derived from the small scale tests are very conservative.
Date: December 1, 1983
Creator: Olander, R.; Oshmyansky, S.; Nichols, K. & Werner, D.
Partner: UNT Libraries Government Documents Department

Preliminary assessment of condensation behavior for hydrocarbon-vapor expansions which cross the saturation line near the critical point

Description: Previous analyses of binary cycles for conversion of geothermal energy from moderate temperature resources to electrical energy have shown potential gains in net geofluid effectiveness on the order of 8%, resulting from selection of turbine-expansion processes whose equilibrium states pass through the two-phase region. If condensation occurs, this gain could be reduced or eliminated by the resulting loss in turbine efficiency. Experience with many fluids, however, indicates that vapor supersaturation permits metastable pure-vapor states to exist at temperatures considerably below the saturation temperature at a given pressure; thus, by better understanding the condensation process, and properly structuring the cycle, substantial performance gains may be possible. The purpose of the present study was to assess the probability for attaining this performance gain by estimating the extent of condensation which might be expected during such an expansion of isobutane vapor. The study indicated that turbine performance should not be degraded significantly for the turbine expansions considered, and that a large fraction of the gain in geofluid effectiveness identified previously is potentially achievable.
Date: January 1, 1983
Creator: Demuth, O.J.
Partner: UNT Libraries Government Documents Department

Sperry Low Temperature Geothermal Conversion System, Phase 1 and Phase II. Final report. Volume III. Systems description

Description: The major fraction of hydrothermal resources that have the prospect of being economically useful for the generation of electricity are in the 300/sup 0/F to 425/sup 0/F temperature range. Cost-effective conversion of the geothermal energy to electricity requires the conception and reduction to practice of new ideas to improve conversion efficiency, enhance brine flow, reduce plant costs, increase plant availability, and shorten the time between investment and return. The problems addressed during past activities are those inherent in the geothermal environment, in the binary fluid cycle, in the difficulty of efficiently converting the energy of a low-temperature resource, and in geothermal economics. Explained in detail in this document, some of these problems are: the energy expended by the down-hole pump; the difficulty in designing reliable down-hole equipment; fouling of heat-exchanger surfaces by geothermal fluids; the unavailability of condenser cooling water at most geothermal sites; the large portion of the available energy used by the feed pump in a binary system; the pinch effect - a loss in available energy in transferring heat from water to an organic fluid; flow losses in fluids that carry only a small amount of useful energy to begin with; high heat-exchanger costs - the lower the temperature interval of the cycle, the higher the heat exchanger costs in $/kW (actually, more than inversely proportional); the complexity and cost of the many auxiliary elements of proposed geothermal plants; and the unfortunate cash flow vs. investment curve caused by the many years of investment required to bring a field into production before any income is realized.
Date: January 1, 1984
Creator: Matthews, H.B.
Partner: UNT Libraries Government Documents Department

Transposed critical temperature Rankine thermodynamic cycle

Description: The transposed critical temperature (TPCT) is shown to be an extremely important thermodynamic property in the selection of the working fluid and turbine states for optimized geothermal power plants operating on a closed organic (binary) Rankine cycle. When the optimum working fluid composition and process states are determined for given source and sink conditions (7 parameter optimization), turbine inlet states are found to be consistently adjacent to the low pressure side of the working fluids' TPCT line on pressure-enthalpy coordinates. Although the TPCT concepts herein may find numerous future applications in high temperature, advanced cycles for fossil or nuclear fired steam power plants and in supercritical organic Rankine heat recovery bottoming cycles for Diesel engines, this discussion is limited to moderate temperature (150 to 250/sup 0/C) closed simple organic Rankine cycle geothermal power plants. Conceptual design calculations pertinent to the first geothermal binary cycle Demonstration Plant are included.
Date: April 1, 1980
Creator: Pope, W.L. & Doyle, P.A.
Partner: UNT Libraries Government Documents Department

Advanced binary geothermal power plants working fluid property determination and heat exchanger design

Description: The performance of binary geothermal power plants can be improved through the proper choice of a working fluid, and optimization of component designs and operating conditions. This paper reviews the investigations at the Idaho National Engineering Laboratory (INEL) which are examining binary cycle performance improvements for moderate temperature (350 to 400 F) resources with emphasis on how the improvements may be integrated into design of binary cycles. These investigations are examining performance improvements resulting from the supercritical vaporization of mixed hydrocarbon working fluids and achieving countercurrent integral condensation with these fluids, as well as the modification of the turbine inlet state points to achieve supersaturated turbine vapor expansions. For resources where the brine outlet temperature is restricted, the use of turbine exhaust recuperators is examined. The baseline plant used to determine improvements in plant performance (characterized by the increase in the net brine effectiveness, watt-hours per pound of brine) in these studies operates at conditions similar to the 45 MW Heber binary plant. Through the selection of the optimum working fluids and operating conditions, achieving countercurrent integral condensation, and allowing supersaturated vapor expansions in the turbine, the performance of the binary cycle (the net brine effectiveness) can be improved by 25 to 30% relative to the baseline plant. 15 refs., 7 figs.
Date: January 1, 1989
Creator: Bliem, C.J. & Mines, G.L.
Partner: UNT Libraries Government Documents Department

Overview of the Heat Cycle Research project

Description: The Heat Cycle Research project is developing the technology base that will permit a much greater utilization of the moderate- temperature, liquid-dominated geothermal resources, particularly for the generation of electrical power. The emphasis in the project has been the improvement of the performance of binary power cycles. The investigations have been examining concepts projected to improve the brine utilization by 20% relative to a Heber-type'' binary plant; these investigations are nearing completion. Preparations are currently underway in the project to conduct field investigations of the condensation behavior of supersaturated turbine expansions. These investigations will evaluate whether the projected additional 8% to 10% improvement in brine utilization can be realized by allowing these expansions. Analytical studies of an ideal'' cycle's performance have shown that the concepts under project investigation, are approaching the practical limits of performance. Future program efforts will focus on the problems associated with heat rejection and on the transfer of the technology being developed to industry. 10 refs., 6 figs.
Date: January 1, 1991
Creator: Bliem, C.J. & Mines, G.L.
Partner: UNT Libraries Government Documents Department

Design considerations for a two-phase turbine

Description: A two-phase turbine, using a low-quality steam-water mixture as a working fluid, was designed, built, and tested in the laboratory. Two-phase fluids are found naturally in most geothermal fields throughout the world and can also be used in the conversion of waste heat from industrial sources. The thermodynamic and fluid-dynamic properties of such fluid mixtures are reviewed, with specific reference to the selection and design of an appropriate expander. Various types of practically realizable expanders are considered, and the choice of a single-stage, axial-flow, impulse turbine is explained. Also the basic design parameters, including sizing and blade and nozzle geometry, are described.
Date: May 25, 1978
Creator: Comfort, W.J. III & Beadle, C.W.
Partner: UNT Libraries Government Documents Department

Development of direct heat exchangers for geothermal brines. Final report, October 4, 1977--June 30, 1978

Description: A series of experiments during a period of eight months was conducted with the existing Direct Contact Heat Exchanger (DCHX) Loop in order to better understand the thermal and hydraulic characteristics of the equipment. Modifications were made to the equipment which were designed to improve heat transfer and reduce the cost of the heat exchangers. Additional changes were made to the equipment to conduct turbine experiments, condenser experiments, and carryover tests. Further studies of the amounts of dissolved isobutane in the geothermal brine and methods of recovering this dissolved isobutane were also made. The procedures used and the results of the tests performed are presented.
Date: January 1, 1978
Creator: Urbanek, M.W.
Partner: UNT Libraries Government Documents Department

Initial results for supercritical cycle experiments using pure and mixed-hydrocarbon working fluids

Description: The Heat Cycle Research Program, which is being conducted for the Department of Energy, has as its objective the development of the technology for effecting improved utilization of moderate temperature geothermal resources. Testing at the Heat Cycle Research Facility (HCRF) located at the DOE Geothermal Test Facility (GTF), East Mesa, California, is presently being conducted to meet this objective. Current testing involves a supercritical vaporization and countercurrent in-tube condensing system. The paper presents a brief description of the test facility and a discussion of the test program. Preliminary results on the performance of the supercritical heaters, countercurrent in-tube condenser, and turbine are given for both pure and mixed-hydrocarbon working fluids.
Date: January 1, 1984
Creator: Bliem, C.J. & Mines, G.L.
Partner: UNT Libraries Government Documents Department

Performance tests of the radial outflow reaction turbine for geothermal applications

Description: A unique pure reaction turbine, for geothermal applications, has been developed. This radial outflow reaction turbine (RORT) is designed specifically to produce power from the expansion of saturated or compressed liquid at temperatures of less than 180/sup 0/C. In the tests reported here the highest efficiency measured was 32.7%, clearly below the peak efficiency for this small machine. Extrapolations to larger machines indicate that an efficiency near 50% is a credible goal, an attractive performance as either a Total Flow expander for liquid or in conjunction with conventional flashed steam systems. A rough cost estimate indicates that a 7.5 MW RORT would cost somewhere between 0.5 M$ and 1.5 M$, and could add about 15% increase in the power output of a conventional 50 MW plant. This means that for less than a 3% increase in capital cost the bus bar energy cost can be reduced by about 10%. Another important result is that the RORT is uniquely suited for conversion of the thermal and pressure energy components in the geopressured resources. The development and proof of feasibility of efficient liquid expanders broadens the opportunities for economic power production from lower temperature geothermal resources, and possibly utilization of waste heat in industrial processes.
Date: August 21, 1978
Creator: House, P.A.
Partner: UNT Libraries Government Documents Department

Resource utilization efficiency improvement of geothermal binary cycles, Phase II. Final report, June 15, 1976--December 31, 1977

Description: During Phase II of this research program, the following elements of research have been performed: (1) improvement in the conventional geothermal binary cycle simulation computer program, (2) development of a direct contact brine heat exchanger algorithm for the cycle simulation program, (3) development of a preheater algorithm for the cycle simulation program, (4) modification of the basic simulation program to incorporate the staged flash binary cycle, (5) development of a parameter optimization algorithm to aid cycle evaluation studies, (6) sensitivity analysis of cost factors, (7) comparison of pure hydrocarbon and binary mixture cycles.
Date: January 1, 1977
Creator: Starling, K.E.; West, H.; Iqbal, K.Z.; Hsu, C.C.; Malik, Z.I.; Fish, L.W. et al.
Partner: UNT Libraries Government Documents Department

Applicability of the Hero turbine for energy conversion from low-quality, two-phase, inlet fluids

Description: The Hero turbine is frequently said to be paricularly suited for two-phase geothermal-energy conversion. Its functional simplicity makes it an obvious candidate for use of a very low-quality steam-water mixture as a working fluid. The performance characteristics for the single-phase expander derived are extended to address two options for handling the two-phase mixture in the Hero turbine. The Hero turbine is found to be best suited to fluids that are single-phase at the entrance to the turbine and to expansions that involve low enthalpy change. The turbine appears well suited to saturated liquid expansion in which the fluid becomes two-phase after entering the turbine.
Date: January 1, 1978
Creator: Comfort, W.J. III
Partner: UNT Libraries Government Documents Department

Open loop pneumatic control of a Lysholm engine or turbine exhaust pressure

Description: A Lysholm engine, or helical screw expander, is currently being evaluated at the University of California, Berkeley for staging with a conventional turbine in geothermal energy conversion. A pneumatic closed loop, proportional-integral control system was implemented to control the Lysholm engine's exhaust pressure for performance testing of the engine at constant inlet/outlet pressure ratios. The control system will also be used to control the exhaust pressure of the conventional turbine during future testing of the staged Lysholm-turbine system. Analytical modeling of the control system was performed and successful tuning was achieved by applying Ziegler-Nichol's tuning method. Stable control and quick response, of approximately 1 minute, was demonstrated for load and set point changes in desired exhaust pressures.
Date: July 17, 1981
Creator: Plonski, B.A.
Partner: UNT Libraries Government Documents Department

Laser-Doppler velocimeter for measuring droplet velocities in two-phase liquid-dominated nozzle flows

Description: A new laser-Doppler velocimeter (LDV) arrangement for measuring droplet velocities in high velocity, liquid-dominated two-phase nozzle flows was developed. The transmitting optics arrangement for this LDV system is identical to that of a dual beam heterodyne LDV, i.e., the light beam from a single frequency argon laser is divided into two parallel identical beams, which are focused to an intersection volume in the flow. The light backscattered from droplets traveling through this volume is collected for analysis using a scanning confocal Fabry-Perot interferometer (FPI). Because of the dual beam arrangement an unscattered or reference beam is not necessary, and the optical alignment ease and stability are greatly improved over similar LDV-FPI systems. Results of droplet velocity measurements in high velocity, high droplet concentration nozzle jet flows are presented.
Date: January 1, 1978
Creator: Alger, T.W.; Crowe, C.T. & Giedt, W.H.
Partner: UNT Libraries Government Documents Department

Floating dry cooling: a competitive alternative to evaporative cooling in a binary cycle geothermal power plant

Description: The application of the floating cooling concept to non-evaporative and evaporative atmospheric heat rejection systems was studied as a method of improving the performance of geothermal powerplants operating upon medium temperature hydrothermal resources. The LBL thermodynamic process computer code GEOTHM is used in the case study of a 50 MWe isobutane binary cycle power plant at Heber, California. It is shown that operating a fixed capacity plant in the floating cooling mode can generate significantly more electrical energy at a higher thermodynamic efficiency and reduced but bar cost for approximately the same capital investment. Floating cooling is shown to benefit a plant which is dry cooled to an even greater extent than the same plant operating with an evaporative heat rejection system. Results of the Heber case study indicate that a dry floating cooling geothermal binary cycle plant can produce energy at a bus bar cost which is competitive with the cost of energy associated with evaporatively cooled systems.
Date: July 1, 1978
Creator: Pines, H.S.; Green, M.A.; Pope, W.L. & Doyle, P.A.
Partner: UNT Libraries Government Documents Department

Modeling the performance of a two-phase turbine using numerical methods and the results of nozzle, static cascade, and windage experiments

Description: Performance models for a two-phase turbine were developed to verify the understanding of the loss mechanisms and to extrapolate from the single-nozzle test condition to a full-admission turbine. The numerical models for predicting the performance of the nozzle and the combined nozzle and rotor are described. Results from two-phase, static cascade tests and disk-friction and windage experiments are used to calibrate the performance model(s). Model predictions are compared with single-nozzle prototype-turbine test results, and extrapolations are made to a full-admission design. The modeling also provides predictions of performance for turbines with various blade geometries, inlet conditions, and droplet sizes. Thus the modeling provides insight into design improvements.
Date: June 21, 1978
Creator: Comfort, W.J. III
Partner: UNT Libraries Government Documents Department

Technology development for high-salinity geothermal resources

Description: An impulse turbine for Total Flow utilization of geothermal fluids was tested. Performance measurements verify the calculational model. The research goal of 70% engine efficiency remains credible. Addition of acid to the brine prevents scaling and precipitation at moderate costs. Corrosion and erosion of turbine materials for the Total Flow Process are not severe. (JB)
Date: August 5, 1977
Creator: Lundberg, A.W.
Partner: UNT Libraries Government Documents Department

Lawrence Livermore Laboratory geothermal energy program. A status report on the development of the Total-Flow concept

Description: The technology development activities of the Geothermal Energy Program at the Lawrence Livermore Laboratory are summarized. Significant progress toward development of the Total-Flow concept was made during FY 1978. The results show that the original goal of 70% engine efficiency for the Total-Flow impulse turbine is achievable, that a Total-Flow system is competitive economically with conventional systems, and that the Total-Flow concept offers the benefit of more efficient utilization of geothermal resources for electric power production. The evaluation of several liquid expanders designed for low-temperature (including geopressured) resources suggests that if development were continued, these expanders could be used in combination with conventional systems to increase overall system efficiency. Although the program was terminated before complete field testing of prototype systems could be carried out, the concepts have been adopted in other countries (Japan and Mexico), where development is continuing.
Date: October 2, 1978
Creator: Austin, A.L. & Lundberg, A.W.
Partner: UNT Libraries Government Documents Department

Study of practical cycles for geothermal power plants. Interim report, June 15, 1975-March 31, 1976

Description: The preliminary analysis is described in a study of practical cycles for geothermal power plants. The analysis is based on three different brines whose temperatures and composition span the range that is of practical interest for power generation. Only two kinds of cycles were considered in the analysis - the steam turbine cycle and the binary cycle, in which energy from the geothermal fluid is transferred to a secondary working fluid in a closed Rankine cycle. The performance of several condidate working fluids has been investigated, and the most attracive binary cycles have been selected for the various resource conditions. The results show that if brine is utilized directly in the primary heat exchange process with the secondary working fluid, the binary cycle is potentially better in terms of resource utilization than a dual flash steam turbine cycle. However, if the brine is flashed to steam and the steam is used for the heat exchange process, the steam turbine cycle will produce more power per pound of brine flow. Preliminary turbine designs have been formulated for steam and also for the most promising working fluids in the secondary or binary cycle. For all cycle configurations at least 50 MW of electrical power can be generated by a single unit without exceeding mechanical design or manufacturing limitations even when the resource temperature is as low as 400/sup 0/F. Plant economics were not considered.
Date: April 1, 1976
Creator: Eskesen, J.H.
Partner: UNT Libraries Government Documents Department