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Geothermal Power Plants in China

Description: Nine small experimental geothermal power plants are now operating at six sites in the People's Republic of China. These range in capacity from 50 kW to 3MW, and include plants of the flash-steam and binary type. All except two units utilize geofluids at temperatures lower than 100 C. The working fluids for the binary plants include normal- and iso-butane, ethyl chloride, and Freon. The first geothermal plant came on-line in 1970, the most recent ones in 1979. Figure 1 shows the location of the plants. Major cities are also shown for reference. Table 1 contains a listing of the plants and some pertinent characteristics. The total installed capacity is 5,186 kW, of which 4,386 kW is from flash-steam units. In the report, they given an example of the results of exploratory surveys, and show system diagrams, technical specifications, and test results for several of the power plants.
Date: December 1, 1980
Creator: DiPippo, Ronald
Partner: UNT Libraries Government Documents Department

Internal Technical Report, 60 KW Test Facility Heat Exchanger Specification

Description: This report presents the thermal specifications for three heat exchangers (preheater, boiler and condenser) to be used in a 60 kW prototype power plant installed at the Raft River geothermal facility. This prototype plant is unique in that it will utilize a working fluid of 90% propane--10% isopentane (by weight) operating at super-critical pressures in a binary geothermal cycle to extract energy from a 280 F geothermal resource. Studies have shown that this super-critical cycle can provide a net performance about 20% higher than that of the optimum dual-boiling isobutane cycle currently designed for the 5 MW Raft River pilot plant.
Date: August 1, 1981
Creator: Kochan, R.J.
Partner: UNT Libraries Government Documents Department

Internal Technical Report, Heat Exchanger Sizing for 20 MW Geothermal Power Plants at MX Sites

Description: This report presents the details of the analyses used to size the heaters, steam condenser, and working fluid condenser for a proposed 20 MW geothermal power plant application at MX sites in the southwest. These units would use a mixture of hydrocarbons (90% isobutane--10% n-hexane) to extract energy from moderate temperature resources (resource temperatures of 365 F, 400 F, and 450 F were considered). The working fluid will be maintained at supercritical pressures in the heater units. Studies have shown that this cycle will provide a significant net power increase over standard dual boiling single fluid cycles currently in use, e.g., the Raft River 5 MW pilot plant.
Date: December 1, 1981
Creator: Kochan, R.J. & Bliem, C.J.
Partner: UNT Libraries Government Documents Department

Economic Studies, Sperry Low Temperature Geothermal Conversion System - Phase I and Phase II, Final Report, Volume VI

Description: At the time that the analyses contained in this volume were performed, the avoided energy costs of California's regulated electric utilities were at historic highs and were projected to continue to increase at double-digit annual rates. Since that time, oil prices have slipped, the general rate of inflation has abated, domestic electric power consumption has fallen short of expectations, and a host of other economic elements have shifted in directions which have resulted in substantial reductions in current California avoided energy costs. The question of whether these changes are merely short-term aberrations or represent a fundamental shift in the long-term energy supply and demand balance is beyond the scope of this report. Although the present depressed avoided electric energy prices are not consistent with the projections on which this report's analyses are based, a fact which results in significant discrepancies between the absolute financial returns predicted and those achievable under current circumstances, the comparative results of the study remain valid. The basic thrust of the studies represented in this report was to compare the overall economics of the Gravity Head system with that of optimized conventional binary generating plants. The study is site-specific to the East Mesa geothermal reservoir. It begins with an analysis of optimum individual well production based on the known characteristics of the reservoir. The limiting factors at East Mesa are reservoir drawdown and maximum practical brine pump impeller setting depth. The individual-well production limit is achieved when brine pressure at the pump inlet is reduced to the point at which CO{sub 2} starts to come out of solution, and fouling and impeller cavitation become imminent. The optimum pumping rate was found to be 1300 gpm (at 360 F density) and required that the Gravity Head pump impeller be set 2,033 feet below grade. The required conventional ...
Date: January 1, 1982
Creator: Harvey, Claude
Partner: UNT Libraries Government Documents Department

Direct contact heat exchanger 10 kW power loop

Description: The extraction of thermal energy for electric power generation from moderate (350 F) temperature geothermal brines, such as those found in East Mesa, California, appears feasible. In exploiting these moderate temperature resources, the use of a direct-contact process in a conventional Rankine cycle with a turbine-generator seems like a very promising configuration. While the direct contact approach, in which the brine and hydrocarbon working fluid come into physical contact, has initial economic advantages (e.g., lower capital cost of heat exchanger equipment), it also has some potential operating disadvantages such as CO{sub 2} buildup, turbine scaling and erosion, and hydrocarbon loss. In order t o identify and evaluate these problem areas, a 10 kW Power Loop was set up and run at East Mesa, California, under DOE funding. This report includes the results and conclusions of Test Series 1 and 2 performed between December 1976 and July 1978, as well as the Executive Summary of the total testing effort. It has been reprinted directly from copy provided by Barber-Nichols Engineering Co.
Date: July 1, 1979
Partner: UNT Libraries Government Documents Department

Conceptual design study for the HCRF direct contact heat exchanger modification

Description: The conceptual design of sieve trays for modifying the HCRF direct contact heat exchanger was developed as follows. The models of the prior work, EG&G subcontract No. K-7752, were extended and modified so the predicted heat transfer coincided with the experimental data of the 60 KW Raft River tests conducted by EG&G. Using these models, a hole diameter of 0.25 inches and a hole velocity of 1.3 ft/sec or greater was selected to accomplish the required heat transfer while minimizing mass transferred to the geothermal fluid. Using the above information, a conceptual design for a sieve tray column was developed. It was determined that the column should operate as a working fluid filled, working fluid dispersed column. This is accomplished by level control of the geothermal fluid below the bottom tray. The dimensions and configuration of the trays and downcomers, and the number of holes and their diameters is summarized in Wahl Company drawings 84144001 and 84144003 submitted with this report. The performance of this design is expected to be 12,000 lbs/hr of geothermal fluid for single component fluids and 11,800 to 12,000 lbs/hr for mixed fluids at a working fluid flow rate of 71% of the geothermal fluid flow rate. The flow rate limit of the geothermal fluid will vary from 9800 to 13,000 lbs/hr as the ratio varies from 83% to 62%.
Date: June 1, 1984
Creator: Wahl, E. F.
Partner: UNT Libraries Government Documents Department

Geochemical considerations for Hot, Dry Rock Systems

Description: Circulating systems intended to model the P-T conditions found in the natural HDR (Hot Dry Rock) geothermal system at Los Alamos have been built. Experiments with these systems have determined the following parameters for the ''down hole'' reservoir: sample weight loss, circulating solution composition, textural changes in the rock, mineral loss from the rock and effects of chemical additives on rock erosion. The analyses of solutions generated from rock-water interactions in the experimental systems show the extremely dilute nature of the working fluid. These solutions are not brines. Silica scaling in the surface heat exchanger was found to account for the difference between loss of sample rate and analyzed silica in the solution. The weight loss data indicate that there was continuous transport of silica from the ''down hole'' rock to the heat exchanger. Experiments contrasting felsic and mafic rocks in the HDR concept indicate that a reservoir consisting of glass bearing basaltic rock would tend to produce greater scaling problems than systems emplaced in granite. Experimental results suggest that Na{sub 2}CO{sub 3} solutions may provide a means of increasing permeability and thereby increasing the effective heat transfer area of the reservoir. A brief description is given of a small test loop for simulating the flow of a geothermal solution through a heat exchanger. This loop, which is being built, will be used to study the coagulation and precipitation of silica under conditions similar to those expected in the field.
Date: January 1, 1976
Creator: Balagna, J.; Blatz, L.; Charles, R.; Feber, R.; Herrick, C.; Holley, C. et al.
Partner: UNT Libraries Government Documents Department

Session 7: Geoproducts Hybrid Geothermal / Wood Fired Power Plant

Description: This presentation describes the 15 MW(e) hybrid combined cycle power plant being constructed at Honey Lake, near Susanville, California. The power plant will use a wood fired system topping cycle, an organic Ranking (binary) bottoming cycle, and geothermal heating of combustion air and organic working fluid. In addition to a technical description, project economics, project merits, and project status are presented.
Date: December 1, 1983
Creator: Lawford, Tom
Partner: UNT Libraries Government Documents Department

Program Geothm: A thermodynamic process program for geothermal power plant cycles

Description: Program GEOTHM is a thermodynamic process program now under development for the LBL Geothermal Energy Program. To date, the program development has centered upon the modeling of working fluid properties, developing thermodynamic process models, and modeling the design performance of geothermal power plants. When the program is completed, it will be able to optimize a power plant or refrigeration plant for minimum cost power or refrigeration. Furthermore, operation of the thermodynamic cycles at off design conditions will be able to be simulated. Program GEOTHM is currently able to calculate several types of geothermal power cycles using a wide variety of working fluids.
Date: October 1, 1974
Creator: Green, M.A. & Pines, H.S.
Partner: UNT Libraries Government Documents Department

Internal Technical Report, Management Plan for Fluid Supply and Injection System for the Raft River 5 MW(e) Pilot Power Plant

Description: This report details a plan for developing a fluid supply system for the First 5 MW(e) Pilot Power Plant at Raft River. The pilot plant has been specifically designed to use the medium-temperature geothermal water so common throughout the West. EG and G Idaho, Inc., the Department of Energy Raft River Rural Electric Co-op, the US Geological Survey (USGS) and the State of Idaho have worked together to develop a facility that will use an organic liquid as the working fluid. Four wells have been drilled in the Raft River Valley, about ten miles South of Malta, in southern Idaho. The completed well system will consist of seven wells: two conventional injection wells, three production wells, and a standby reserve well of each type. The additional three wells are to be drilled in FY-1978, in order to complete a coordinated test program before the First Pilot Power Plant is ready for operation. The system has been designed to meet the test-loop pilot plant's basic requirement: a 2450 gpm supply of geothermal fluid, at a nominal temperature of 290 F and with salinity of less than 5000 ppm. Injection of cooled geothermal fluid into the Raft River reservoir will also require a network of monitor wells. The Idaho Department of Water Resources (IDWR), USGS, EG and G Idaho, and the Department of Energy will jointly select sites for two 1500-foot and five 500-foot monitoring wells. This plan considers the work required to complete construction of the fluid supply system and obtain a preliminary check of its performance capability; the plan will discuss project management, costs, schedules, drilling, testing, environmental monitoring, and safety.
Date: January 9, 1978
Partner: UNT Libraries Government Documents Department

Advanced Binary Geothermal Power Plancts 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. The design of these supercritical Rankine-cycle (Binary) power plants for geothermal resources requires information about the potential working fluids used in the cycle. In addition, methods to design the various components, (e.g., heat exchangers, pumps, turbines) are needed. This paper limits its view of component design methods to the heat exchangers in binary power plants. The design of pumps and, turbines for these working fluids presents no new problems to the turbine manufacturer. However, additional work is proceeding at the Heat Cycle Research Facility to explore metastable expansions within turbines. This work, ...
Date: March 21, 1989
Creator: Bliem, C.J. & Mines, G.L.
Partner: UNT Libraries Government Documents Department

Parametric Sensitivity Study of Operating and Design Variables in Wellbore Heat Exchangers

Description: This report documents the results of an extensive sensitivity study conducted by the Idaho National Engineering and Environmental Laboratory. This study investigated the effects of various operating and design parameters on wellbore heat exchanger performance to determine conditions for optimal thermal energy extraction and evaluate the potential for using a wellbore heat exchanger model for power generation. Variables studied included operational parameters such as circulation rates, wellbore geometries and working fluid properties, and regional properties including basal heat flux and formation rock type. Energy extraction is strongly affected by fluid residence time, heat transfer contact area, and formation thermal properties. Water appears to be the most appropriate working fluid. Aside from minimal tubing insulation, tubing properties are second order effects. On the basis of the sensitivity study, a best case model was simulated and the results compared against existing low-temperature power generation plants. Even assuming ideal work conversion to electric power, a wellbore heat exchange model cannot generate 200 kW (682.4e+3 BTU/h) at the onset of pseudosteady state. Using realistic conversion efficiency, the method is unlikely to generate 50 kW (170.6e+3 BTU/h).
Date: May 1, 2004
Creator: Nalla, G.; Shook, G.M.; Mines, G.L. & Bloomfield, K.K.
Partner: UNT Libraries Government Documents Department

Test Plan for Heat Cycle Research Program, Phase I Supercritical Cycle Tests

Description: The 60 kW Heat Cycle Research Facility (HCRF) provides a means of examining different concepts and components associated with the generation of electrical power from a geothermal resource using a binary power cycle. In this power cycle the heat or energy in a hot geothermal fluid is transferred to a secondary working fluid. This working fluid is vaporized in the heat exchange process and the vapor is in turn expanded through a turbine which drives a generator producing electrical power. the heat or energy in the vapor leaving the turbine is transferred to a circulating cooling water in the condenser where the working fluid is condensed to a liquid which can be pumped back to the heaters, completing the cycle. This waste heat load in the condenser is in turn transferred from the cooling water to the atmosphere in a cooling tower. The HCRF allows the different components described in the cycle above to be tested as well as the basic cycle itself. This cycle may vary in that the heaters, condenser, cooling system, pumps, etc. may differ in number and type, however the basic cycle does not change significantly. During this sequence of tests, the HCRF is operated using a supercritical vapor generator and a vertical condenser where the condensation occurs inside of the tubes as opposed to the shell side more commonly used in these applications. In addition to providing the data to be used to evaluate the design of these heat exchangers, these supercritical tests provide cycle and component performance data with both single component working fluids and working fluids comprised of different mixtures of hydrocarbons. The use of these mixtures promises to improve cycle performance, in terms of watt-hours per pound of geothermal fluid, provided the countercurrent flow paths can be maintained between the fluids in ...
Date: June 1, 1983
Creator: Mines, Greg L.
Partner: UNT Libraries Government Documents Department

Well simulation using Refrigerant 114

Description: A simple method for the investigation of thermodynamic (substance) similarity in the two-phase domain is introduced based on the assumptions of a simplified model fluid. According to this method, the investigation of the conditions for thermodynamic similarity between substances in the two-phase region reveals the important role the latent heat of evaporation (h/sub fg/) plays in the definition of the property scales. These greatly influence the dynamic and geometric similarity of the process under investigation. The introduction of the thermodynamic similarity property scales into the energy conservation equations for a certain process (e.g., flow up a geothermal well) brings forth a thermodynamic length scale and kinetic energy scale. Refrigerant 114 has been examined for similarity with water substance according to this method and found to be adequate for geothermal well simulation in the laboratory. Low pressures and temperatures and a substantial reduction of mass flow rates and geometric scales are a few of the advantages of using R114 for such experiments.
Date: June 1, 1984
Creator: Nikitopoulos, D.E.; Dickinson, D.A.; DiPippo, R. & Maeder, P.F.
Partner: UNT Libraries Government Documents Department

Power System Equipment Module Test Project

Description: The technology of electric power generation when applying the binary process to hydrothermal resources had not yet been demonstrated in the United States. Accordingly, on November 10, 1977, the Electric Power Research Institute and the Department of Energy, acting through the Lawrence Berkeley Laboratory, agreed to cofund the Power System Equipment Module Test Project. The Power System Equipment Module Test Project consisted of a field test program to accomplish the objectives listed below while heating hydrocarbon fluids to above their critical points, expanding these fluids, and subsequently, condensing them below their critical points: (1) Verify the performance of state-of-the-art heat exchangers in geothermal service; (2) Verify the heat exchangers' performance heating either selected pure light hydrocarbons or selected mixtures of light hydrocarbons in the vicinity of their respective critical pressures and temperatures; (3) Establish overall heat transfer coefficients that might be used for design of commercial-size geothermal power plants using the same geothermal brine and light hydrocarbon working fluids; (4) Perform and investigate the above under representative fluid operating conditions during which the production wells would be pumped. The project was accomplished by diverting approximately 200 gpm of the flow from one of Magma Power Company's geothermal wells in the East Mesa Geothermal Field. After the heat was removed from the geothermal brine flow, the cooled flow was returned to Magma Power Company and recombined with the main brine stream for disposal by reinjection. Approximately five thermal megawatts was transferred from geothermal brine to hydrocarbon working fluids in a closed system. This heat was removed from the working fluids in a condenser and subsequently rejected to the environment by a wet cooling tower. The thermodynamic performance of both the working fluids and the system components was measured during the test program to achieve the project's objectives.
Date: December 1, 1980
Creator: Schilling, J.R.
Partner: UNT Libraries Government Documents Department

Next Generation Geothermal Power Plants

Description: A number of current and prospective power plant concepts were investigated to evaluate their potential to serve as the basis of the next generation geothermal power plant (NGGPP). The NGGPP has been envisaged as a power plant that would be more cost competitive (than current geothermal power plants) with fossil fuel power plants, would efficiently use resources and mitigate the risk of reservoir under-performance, and minimize or eliminate emission of pollutants and consumption of surface and ground water. Power plant concepts were analyzed using resource characteristics at ten different geothermal sites located in the western United States. Concepts were developed into viable power plant processes, capital costs were estimated and levelized busbar costs determined. Thus, the study results should be considered as useful indicators of the commercial viability of the various power plants concepts that were investigated. Broadly, the different power plant concepts that were analyzed in this study fall into the following categories: commercial binary and flash plants, advanced binary plants, advanced flash plants, flash/binary hybrid plants, and fossil/geothed hybrid plants. Commercial binary plants were evaluated using commercial isobutane as a working fluid; both air-cooling and water-cooling were considered. Advanced binary concepts included cycles using synchronous turbine-generators, cycles with metastable expansion, and cycles utilizing mixtures as working fluids. Dual flash steam plants were used as the model for the commercial flash cycle. The following advanced flash concepts were examined: dual flash with rotary separator turbine, dual flash with steam reheater, dual flash with hot water turbine, and subatmospheric flash. Both dual flash and binary cycles were combined with other cycles to develop a number of hybrid cycles: dual flash binary bottoming cycle, dual flash backpressure turbine binary cycle, dual flash gas turbine cycle, and binary gas turbine cycle. Results of this study indicate that dual flash type plants are ...
Date: September 1, 1995
Creator: Brugman, John; Hattar, Mai; Nichols, Kenneth & Esaki, Yuri
Partner: UNT Libraries Government Documents Department

Two-phase flow in geothermal systems

Description: The overall object was to establish a full experimental correlation between flashing flows of water-steam in actual geothermal wells and flashing flows of refrigerant-114 (R-114) in the Brown University/DOE Two-Phase Flow Facility. Our experiments show that the similarity theory developed in our laboratory during previous phases of this research project can be used to predict accurately the pressure gradient in the two-phase region of a flowing geothermal well using laboratory measurements on R-114. This conclusion holds even when the actual geothermal well contains significant amounts of noncondensable gases. In this case, however, corrections must be introduced to account for the partial pressure of the gases.
Date: August 1, 1987
Creator: Maeder, P.F. & Kestin, J.
Partner: UNT Libraries Government Documents Department

Condensation of R-11 on the outside of vertical enhanced tubes

Description: A review of condensation experiments with enhanced surface is presented in support of the program to develop improved condensers for geothermal binary power cycles. Experiments were conducted to determine heat transfer performance with Refrigerant-11 (R-11) condensing on the enhanced (outside) surface of single vertical tubes. Twelve tubes of 2.54-cm (1-in.) nominal OD and 1.22 m (4 ft) length with fluted, spiralled, roped, and corrugated surfaces were tested; several of the tested tubes also featured internal enhanced geometries. A smooth tube served as the basis of comparison. Composite heat transfer coefficients (coefficients that include the resistances of both the condensing film and the tube wall), based on total tube outside area, are repoted for all tubes, except a double-(internal/external) fluted tube, where only overall heat transfer data are presented. The main conclusions from this study are: (a) for a given heat flux, an external fluted tube can increase composite condensing heat transfer coefficients by up to 5.5 times the smooth tube values, giving better condensing performance than any of the other geometries tested; (b) a further increase in composite condensing coefficients can be achived by using drip skirts to remove the condensate from the surface at intervals along the condensing length; and (c) for a given overall temperature difference and water flow rate, internal flutes can increase the overall performance by up to 17% over that for a tube with identical outside flutes and a smooth inside surface.
Date: January 1, 1981
Creator: Domingo, N.
Partner: UNT Libraries Government Documents Department

Discussion of enhancement in condensers

Description: A brief discussion of Professor Ralph L. Webb's paper, The Use of Enhanced Surface Geometries in Condensers, is given with emphasis on the importance of overall cost optimization in the application of heat transfer enhancement. A review of ORNL condensation experiments with enhanced surfaces is presented. The work has centered on optimizing the design variables associated with fluted surfaces on vertical tubes and comparing the tube performance with available enhanced tubes either for vertical or horizontal operation. Data with seven fluids including a hydrocarbon, fluorocarbons, and ammonia condensing on up to 30 different tubes have been obtained. The primary conclusion from this work is that fluted tubes can provide an enhancement in condensation coefficient of a factor of 6 over smooth vertical tubes and a factor of 2 over enhanced commercial tubes either operating vertically or horizontally. These data, together with field test data, have formed the basis for designing a prototype condenser for the 500 kWe East Mesa, California, direct-contact geothermal demonstration plant.
Date: January 1, 1980
Creator: Michel, J.W.
Partner: UNT Libraries Government Documents Department

Theory and tests of two-phase turbines

Description: Two-phase turbines open the possibility of new types of power cycles operating with extremely wet mixtures of steam and water, organic fluids, or immiscible liquids and gases. Possible applications are geothermal power, waste-heat recovery, refrigerant expansion, solar conversion, transportation turbine engines, and engine bottoming cycles. A theoretical model for two-phase impulse turbines was developed. Apparatus was constructed for testing one- and two-stage turbines (using speed decrease from stage to stage). Turbines were tested with water-and-nitrogen mixtures and Refrigerant 22. Nozzle efficiencies were 0.78 (measured) and 0.72 (theoretical) for water-and-nitrogen mixtures at a water/nitrogen mixture ratio of 68, by mass; and 0.89 (measured) and 0.84 (theoretical) for Refrigerant 22 expanding from 0.02 quality to 0.28 quality. Blade efficiencies (shaft power before windage and bearing loss divided by nozzle jet power) were 0.63 (measured) and 0.71 (theoretical) for water-and-nitrogen mixtures and 0.62 (measured) and 0.63 (theoretical) for Refrigerant 22 with a single-stage turbine, and 0.70 (measured) and 0.85 (theoretical) for water-and-nitrogen mixtures with a two-stage turbine.
Date: March 15, 1982
Creator: Elliot, D.G.
Partner: UNT Libraries Government Documents Department

System component compatibility and R-114 stability. Volume II. Final report

Description: High temperature stability-compatibility studies of R-114 refrigerant and proposed Sperry Geothermal System components were performed. The R-114 refrigerant, geothermal brine, and ten lubricants were tested in the presence of five metals, eight metal alloys, two ceramics, two iron oxides, and twenty-two elastomers in several combinations, temperature levels, and durations. Compatibility experiments of elastomers and non-elastomeric sealants in aqueous solutions and lubricating oils were performed. The development of the downwell packer necessitated the completion of an elastomer formulation development program. The system component material selection and specifications for the pump system are given. The seal material selection for the stand-alone turbine-pump-unit is presented in detail.
Date: January 1, 1981
Creator: Goodson, J.E. Jr.; Nowicki, D.F.; Thibeau, R.J.; Toekes, B. & Wilson, D.P.
Partner: UNT Libraries Government Documents Department

Zeotropic mixtures of halocarbons as working fluids in binary geothermal power generation cycles

Description: The performance of Rankine cycle binary systems for geothermal power generation using a hydrothermal resource has been investigated. To date, in addition to many pure fluids, mixtures of Paraffin-type hydrocarbons and water-ammonia mixtures have been investigated. This paper gives the results of consideration of mixtures of halocarbons as working fluids in these power cycles. The performance of mixtures of Refrigerant-114 (R-114) and Refrigerant-22 (R-22) in combinations from pure R-114 to pure R-22 was calculated for such cycles. Various alternatives were considered: (1) minimum geofluid outlet temperature constraint/no constraint, (2) dry turbine expansion/expansion through vapor dome, and (3) use of turbine exhaust gas recuperator/no recuperator. Results of the study indicate that the halocarbon mixtures are at least as good as the hydrocarbon mixtures previously analyzed for a 360 F resource. The magnitude of the net geofluid effectiveness (net energy produced per unit mass geofluid flow) for the R-114/R-22 mixtures is the same as for the best hydrocarbon mixture previously analyzed. The percentage improvement in effectiveness in using mixtures over using the pure fluids as working fluids is comparable for both classes of working fluids.
Date: January 1, 1987
Creator: Bliem, C.J.
Partner: UNT Libraries Government Documents Department

Sperry Low Temperature Geothermal Conversion System, Phase I and Phase II. Final report. Volume VI. Economic studies

Description: The basic thrust of the studies represented was to compare the overall economics of the Gravity Head system with that of optimized conventional binary generating plants. The study is site-specific to the East Mesa geothermal reservoir. It begins with an analysis of optimum individual well production based on the known characteristics of the reservoir. The limiting factors at East Mesa are reservoir drawdown and maximum practical brine pump impeller setting depth. Using the 1300 gpm, 360/sup 0/ F resource as a starting point, detailed cost estimates and performance calculations were made for the Gravity Head and various conventional alternative well-head systems. The most cost effective of the conventional alternatives was found to be a 700 psi cycle using R114 as the working fluid (actually optimized at 682 psi). The study is in two parts. In Part I, emphasis is placed on the economic sensitivities of the compared systems to variations in capital cost, O and M cost, avoided energy inflation rates, and brine cost. In Part II, a somewhat more rigorous attempt is made to derive the actual economic performance of the systems under more realistic circumstances with contingencies, cost penalties, and multiple-unit developments added.
Date: January 1, 1983
Creator: Harvey, C.
Partner: UNT Libraries Government Documents Department

Investigation of single-substance horizontal two-phase flow

Description: Despite the abundance of work in the field of two-phase flow, it seems as though a consensus has not been reached on some of the fundamental points. Although exceptions exist, adequate physical interpretation of the flow seems to be hindered either by complexity of analysis or, in the opposite extreme, the trend toward limited-range analysis and correlations. The dissertation presents the derivation of basic conservation equations for the phases. The combined equations are used to examine the phenomenon of slip and its practical limitations, the Fanno line for single-substance flow and the effect of slip on choking. Equations for critical mass flux in the presence of slip are derived. The Mach, Reynolds and Froude numbers based on conditions at flashing are introduced as the characteristic parameters, and the importance of compressibility in single-substance two-phase flow is discussed. Experimental measurements of pressure change and void fraction for flow in the highly compressible range (.5 < Ma < 1) are presented. The working fluid is Refrigerant R-114, at room temperature, in a test section of diameter 5 cm and length 8 m. The effect of the Froude and Mach numbers is examined. The experimental facility is operated intermittently with running times of approximately two minutes and is instrumented for rapid measurements using a computer data acquisition and control system. A description of the facility and procedure is provided.
Date: March 1, 1984
Creator: Dickinson, D.A. & Maeder, P.F.
Partner: UNT Libraries Government Documents Department