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Geothermal heat cycle research: Supercritical cycle with horizontal counterflow condenser

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 the improved utilization of moderate temperature geothermal resources. To meet this objective, the program has as one of its goals to improve the performance of geothermal binary cycles to levels approaching the practicable thermodynamic maximum. In pursuit of this goal, tests are being conducted at the Heat Cycle Research Facility located at the DOE Geothermal Test Facility, East Mesa, California. The current testing involves the investigation of binary power cycle performance utilizing mixtures of non-adjacent hydrocarbons as the working fluids, with supercritical vaporization and in-tube condensation of the working fluid. In addition to the present test program, preparations are being made to investigate the binary cycle performance improvements which can be achieved by allowing supersaturated vapor expansions in the turbine. These efforts are anticipated to verify that through the utilization of these advanced power cycle concepts and allowing the supersaturated turbine expansions, improvements of up to 28% in the net geofluid effectiveness (net watt hours plant output per pound of geofluid) over conventional binary power plants can be achieved. Results are presented for the recent testing including those tests examining the performance of the countercurrent condenser at different tube inclinations. Performance of the heaters and the condenser in a vertical orientation can be predicted well with existing methods and data. The condenser in its near horizontal orientation performs slightly worse than in its vertical orientation. Some problems have been encountered in predicting the performance in the horizontal orientation. There is no evidence of departure from integral condensation in either orientation.
Date: January 1, 1987
Creator: Mines, G.L.; Swank, W.D. & Bliem, C.J.
Partner: UNT Libraries Government Documents Department

Measurement of particle size, velocity and temperature in the plasma spray coating process

Description: The quality and uniformity of coatings fabricated by the plasma spray process is controlled by the condition of the particles on impact. In this work a measurement technique for simultaneously obtaining particle size, velocity, and temperature is used to characterize the particle spray field. Particle size and velocity are obtained from a combination laser particle sizing system and laser Doppler velocimeter (LDV). The particle temperature is determined by a two-color pyrometer technique and the relative particle number density is derived from the data rate. The fraction of unheated or unprocessed particles which result from temperature and velocity fluctuations is also obtained. This fraction can approach 10% by mass of the total particle flow. 17 refs., 10 figs.
Date: January 1, 1991
Creator: Fincke, J.R. & Swank, W.D.
Partner: UNT Libraries Government Documents Department

Vaporization at supercritical pressures and counterflow condensing of pure and mixed-hydrocarbon working fluids for geothermal power plants

Description: The Heat Cycle Research Program has as its objective the development of the technology for effecting improved utilization of moderate temperature geothermal resources. Current testing involves supercritical vaporization and counterflow in-tube condensing in an organic Rankine cycle. Results of the experiments are given for both pure and mixed-hydrocarbon working fluids. The heater and condenser behavior predicted by the Heat Transfer Research, Inc. computer codes used for correlation of the data was in excellent agreement with experimental results. A special series of tests, conducted with propane and up to approximately 40% isopentane concentration indicated that a close approach to ''integral'' condensation was occurring in the vertically-oriented condenser.
Date: January 1, 1986
Creator: Bliem, C.J.; Demuth, O.J.; Mines, G.L. & Swank, W.D.
Partner: UNT Libraries Government Documents Department

A particle temperature sensor for monitoring and control of the thermal spray process

Description: The temperature and velocity of thermally sprayed particles prior to their impact on the substrate are two of the predominant determinants of coating quality and characteristics. This paper describes an instrument developed for real time monitoring of in-flight particle temperature in an industrial environment. The instrument is designed to operate as a stand alone device for verifying that a desired particle temperature is attained or for developing process settings to yield a particular temperature. The device is also suitable for incorporation into a closed loop process controller. Data showing the relationship between torch parameters and average particle temperature are presented. There is good agreement between previous measurements using laboratory instrumentation and the simpler, industrially hardened technique described here. The assumption of gray body behavior is evaluated and for known emissivities corrections are developed.
Date: December 1, 1995
Creator: Swank, W.D.; Fincke, J.R. & Haggard, D.C.
Partner: UNT Libraries Government Documents Department

FeAl and Mo-Si-B Intermetallic Coatings Prepared by Thermal Spraying

Description: FeAl and Mo-Si-B intermetallic coatings for elevated temperature environmental resistance were prepared using high-velocity oxy-fuel (HVOF) and air plasma spray (APS) techniques. For both coating types, the effect of coating parameters (spray particle velocity and temperature) on the microstructure and physical properties of the coatings was assessed. Fe-24Al (wt.%) coatings were prepared using HVOF thermal spraying at spray particle velocities varying from 540 m/s to 700 m/s. Mo-13.4Si-2.6B coatings were prepared using APS at particle velocities of 180 and 350 m/s. Residual stresses in the HVOF FeAl coatings were compressive, while stresses in the APS Mo-Si-B coatings were tensile. In both cases, residual stresses became more compressive with increasing spray particle velocity due to increased peening imparted by the spray particles. The hardness and elastic moduli of FeAl coatings also increased with increasing particle velocity, again due to an increased peening effect. For Mo-Si-B coatings, plasma spraying at 180 m/s resulted in significant oxidation of the spray particles and conversion of the T1 phase into amorphous silica and {alpha}-Mo. The T1 phase was retained after spraying at 350 m/s.
Date: April 22, 2003
Creator: Totemeier, T.C.; Wright, R.N. & Swank, W.D.
Partner: UNT Libraries Government Documents Department

Overview of recent supercritical binary geothermal cycle experiments from the Heat Cycle Research Program

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 located at the DOE Geothermal Test Facility East Mesa, California involves supercritical vaporization and counterflow in-tube condensing in an organic Rankine cycle. Results of the experiments are given for both pure and mixed-hydrocarbon working fluids. The heater and condenser behavior predicted by the Heat Transfer Research, Inc. computer codes used for correlation of the data was in excellent agreement with experimental results. A special series of tests, conducted with propane and up to approximately 40% isopentane concentration, indicated that a close approach to ''integral'' condensation was occurring in the vertically-oriented condenser. Preliminary results of tests in which the turbine expansion ''passed through the two-phase region'' did not indicate efficiency degradation assignable to these metastable expansion processes.
Date: January 1, 1986
Creator: Demuth, O.J.; Bliem, C.J.; Mines, G.L. & Swank, W.D.
Partner: UNT Libraries Government Documents Department

Supercritical binary geothermal cycle experiments with mixed-hydrocarbon working fluids and a vertical, in-tube, counterflow condenser

Description: The objective is improved utilization of moderate temperature geothermal resources. Current testing involves supercritical vaporization and counterflow in-tube condensing in an organic Rankine cycle. This report presents a description of the test facility and results from a part of the program in which the condenser was oriented in a vertical attitude. Results of the experiments for the supercritical heaters and the countercurrent, vertical, in-tube condenser are given for both pure and mixed-hydrocarbon working fluids. The heater and condenser behavior predicted by the Heat Transfer Research, Inc. computer codes used for correlation of the data was in excellent agreement with experimental results. A special series of tests, conducted with propane and up to approximately 40% isopentane concentration, indicated that a close approach to ''integral'' condensation was occurring in the vertically-oriented condenser.
Date: December 1, 1985
Creator: Demuth, O.J.; Bliem, C.J.; Mines, G.L. & Swank, W.D.
Partner: UNT Libraries Government Documents Department

Residual stress determination from a laser-based curvature measurement

Description: Thermally sprayed coating characteristics and mechanical properties are in part a result of the residual stress developed during the fabrication process. The total stress state in a coating/substrate is comprised of the quench stress and the coefficient of thermal expansion (CTE) mismatch stress. The quench stress is developed when molten particles impact the substrate and rapidly cool and solidify. The CTE mismatch stress results from a large difference in the thermal expansion coefficients of the coating and substrate material. It comes into effect when the substrate/coating combination cools from the equilibrated deposit temperature to room temperature. This paper describes a laser-based technique for measuring the curvature of a coated substrate and the analysis required to determine residual stress from curvature measurements. Quench stresses were determined by heating the specimen back to the deposit temperature thus removing the CTE mismatch stress. By subtracting the quench stress from the total residual stress at room temperature, the CTE mismatch stress was estimated. Residual stress measurements for thick (>1mm) spinel coatings with a Ni-Al bond coat on 304 stainless steel substrates were made. It was determined that a significant portion of the residual stress results from the quenching stress of the bond coat and that the spinel coating produces a larger CTE mismatch stress than quench stress.
Date: May 8, 2000
Creator: Swank, W. D.; Gavalya, R. A.; Wright, J. K. & Wright, R. N.
Partner: UNT Libraries Government Documents Department

The measurement of single particle temperature in plasma sprays

Description: A measurement technique for simultaneously obtaining the size, velocity, temperature, and relative number density of particles entrained in high temperature flow fields is described. In determining the particle temperature from a two-color pyrometery technique, assumptions about the relative spectral emissivity of the particle are required. For situations in which the particle surface undergoes chemical reactions the assumption of grey body behavior is shown to introduce large Temperature measurement uncertainties. Results from isolated, laser heated, single particle measurements and in-flight data from the plasma spraying of WC-Co are presented. 10 refs., 5 figs.
Date: January 1, 1990
Creator: Fincke, J.R.; Swank, W.D. (EG and G Idaho, Inc., Idaho Falls, ID (USA)); Bolsaitis, P.P. & Elliott, J.F. (Massachusetts Inst. of Tech., Cambridge, MA (USA))
Partner: UNT Libraries Government Documents Department