Net power output and thermal efficiency data for single and double flash cycles of Cerro Prieto geothermal power plants

In this paper an analytical investigation has been reported on determination of the optimum flashing pressures to get maximum efficiency in flash geothermal power plants. Also, two different views on efficiency have been considered; thermal efficiency and exergy efficiency. Both views anticipate very close optimum flashing pressure and in this pressure, exergy efficiency is between 3 to 5.5 times more than thermal efficiency. It is observed that the optimum flashing pressure in a single flash power plant is between the optimum flashing pressures of two separators in a double flash power plant. Also both views predict an increase of 20–29 percent for the efficiency of double flash power plants than the efficiency of single flash power plants.

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Retrofitting a Geothermal Power Plant to Optimize Performance: A Case Study

Journal of Energy Resources Technology ◽

10.1115/1.2795996 ◽

1999 ◽

Vol 121 (4) ◽

pp. 295-301 ◽

Cited By ~ 29

Author(s):

M. Kanog˘lu ◽

Y. A. C¸engel

Keyword(s):

Power Plant ◽

Power Output ◽

Operating Conditions ◽

Optimum Operating ◽

Geothermal Power Plant ◽

Northern Nevada ◽

Single Flash ◽

Geothermal Power ◽

Net Power Output ◽

Double Flash

Performance evaluation of a 12.8-MW single-flash design geothermal power plant in Northern Nevada is conducted using actual plant operating data, and potential improvement sites are identified. The unused geothermal brine reinjected back to the ground is determined to represent about 50 percent of the energy and 40 percent of the exergy available in the reservoir. The first and second-law efficiencies of the plant are determined to be 6 percent and 22 percent, respectively. Optimizing the existing single-flash system is shown to increase the net power output by up to 4 percent. Some well-known geothermal power generation technologies including double-flash, binary, and combined flash/binary designs as alternative to the existing system are evaluated and their optimum operating conditions are determined. It is found that a double-flash design, a binary design, and a combined flash/binary design can increase the net power output by up to 31 percent, 35 percent, and 54 percent, respectively, at optimum operating conditions. An economic comparison of these designs appears to favor the combined flash/binary design, followed by the double-flash design.

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Energy efficiency comparison between geothermal power systems

Thermal Science ◽

10.2298/tsci151225074l ◽

2017 ◽

Vol 21 (6 Part A) ◽

pp. 2633-2642 ◽

Cited By ~ 2

Author(s):

Chao Luo ◽

Jun Zhao ◽

Yulie Gong ◽

Yongzhen Wang ◽

Weibin Ma

Keyword(s):

Binary System ◽

Power Systems ◽

Power System ◽

Power Output ◽

Energy Utilization ◽

Water Steam ◽

Geothermal Power ◽

Efficiency Comparison ◽

Net Power Output ◽

Double Flash

The geothermal water which can be considered for generating electricity with the temperature ranging from 80? to 150? in China because of shortage of electricity and fossil energy. There are four basic types of geothermal power systems: single flash, double flash, binary cycle, and flash-binary system, which can be adapted to geothermal energy utilization in China. The paper discussed the performance indices and applicable conditions of different power system. Based on physical and mathematical models, simulation result shows that, when geofluid temperature ranges from 100? to 130?, the net power output of double flash power is bigger than flash-binary system. When the geothermal resource temperature is between 130? and 150?, the net power output of flash-binary geothermal power system is higher than double flash system by the maximum value 5.5%. However, the sum water steam amount of double flash power system is 2 to 3 times larger than flash-binary power system, which will cause the bigger volume of equipment of power system. Based on the economy and power capacity, it is better to use flash-binary power system when the geofluid temperature is between 100? and 150?.

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A meta-study of the effect of thermodynamic parameters on the efficiency of geothermal power plants worldwide

PAM Review Energy Science & Technology ◽

10.5130/pamr.v3i0.1420 ◽

2016 ◽

Vol 3 ◽

pp. 27-48 ◽

Cited By ~ 1

Author(s):

Oscar Nieves ◽

Tomas Nancarrow ◽

Jessica MacKinnon

Keyword(s):

Thermodynamic Parameters ◽

Thermal Efficiency ◽

Geothermal Energy ◽

Energy Demand ◽

Power Plants ◽

Published Data ◽

Operation Parameters ◽

Well Depth ◽

Geothermal Power ◽

Double Flash

As global energy demand rises, the search for viable alternative fuel sources continues. The practicality of geothermal energy to meet this demand is highly dependent on optimizing thermal efficiency. While geothermal energy is currently used in places like Western Australia for direct-heat applications such as leisure centres, developing a geothermal power plant in such an area depends on predicting which thermodynamic parameters optimize thermal efficiency. This meta-study focuses on the effect of geothermal operation parameters such as inlet pressure, temperature, mass flow rate, well depth and number of production wells on the thermal efficiency of geothermal power plants. Drawing data from 61 geothermal power plants around the world ranging in design capacity (MWe) and size, a meta-study on the thermal efficiency of plants operating under different thermodynamic cycles, namely single-flash, double-flash, binary Organic Rankine Cycle (ORC) and Kalina, is offered. These various thermodynamic parameters are analysed to determine the presence of observable thermal efficiency patterns or trends that may lead to the optimization of operation parameters for new geothermal plants. Based on the available published data reviewed, there are few trends which indicate how geothermal operation parameters affect thermal efficiency. Well depth may be an indicator of efficiency for geothermal power plants using ORC and double-flash cycles, however further data is required to support this conclusion.

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OTEC Maximum Net Power Output Using Carnot Cycle and Application to Simplify Heat Exchanger Selection

Entropy ◽

10.3390/e21121143 ◽

2019 ◽

Vol 21 (12) ◽

pp. 1143 ◽

Cited By ~ 10

Author(s):

Kevin Fontaine ◽

Takeshi Yasunaga ◽

Yasuyuki Ikegami

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Pressure Drop ◽

Power Output ◽

Heat Exchangers ◽

Power Plants ◽

Seawater Temperature ◽

Carnot Cycle ◽

Ocean Thermal Energy ◽

Net Power Output

Ocean thermal energy conversion (OTEC) uses the natural thermal gradient in the sea. It has been investigated to make it competitive with conventional power plants, as it has huge potential and can produce energy steadily throughout the year. This has been done mostly by focusing on improving cycle performances or central elements of OTEC, such as heat exchangers. It is difficult to choose a suitable heat exchanger for OTEC with the separate evaluations of the heat transfer coefficient and pressure drop that are usually found in the literature. Accordingly, this paper presents a method to evaluate heat exchangers for OTEC. On the basis of finite-time thermodynamics, the maximum net power output for different heat exchangers using both heat transfer performance and pressure drop was assessed and compared. This method was successfully applied to three heat exchangers. The most suitable heat exchanger was found to lead to a maximum net power output 158% higher than the output of the least suitable heat exchanger. For a difference of 3.7% in the net power output, a difference of 22% in the Reynolds numbers was found. Therefore, those numbers also play a significant role in the choice of heat exchangers as they affect the pumping power required for seawater flowing. A sensitivity analysis showed that seawater temperature does not affect the choice of heat exchangers, even though the net power output was found to decrease by up to 10% with every temperature difference drop of 1 °C.

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Performance Analysis and Optimization of Double-Flash Geothermal Power Plants

Journal of Energy Resources Technology ◽

10.1115/1.2719204 ◽

2006 ◽

Vol 129 (2) ◽

pp. 125-133 ◽

Cited By ~ 20

Author(s):

Ahmet Dagdas

Keyword(s):

Power Plant ◽

Performance Analysis ◽

Electricity Generation ◽

Power Plants ◽

Second Law ◽

Western Turkey ◽

Geothermal Power Plant ◽

Base Points ◽

Geothermal Power ◽

Double Flash

One of the most important cycles for electricity generation from geothermal energy is the double-flash cycle. Approximately 25% of the total geothermal based electricity generation all over the world comes from double-flash geothermal power plants. In this paper, performance analysis of a hypothetical double-flash geothermal power plant is performed and variations of fundamental characteristics of the plant are examined. In the performance analysis, initially, optimum flashing pressures are determined, and energy and exergy values of the base points of the plant are calculated. In addition, first and second law efficiencies of the power plant are calculated. Main exergy destruction locations are determined and these losses are illustrated in an exergy flow diagram. For these purposes, it is assumed that a hypothetical double-flash geothermal power plant is constructed in the conditions of western Turkey. The geothermal field where the power plant will be built produces geofluid at a temperature of 210°C and a mass flow rate of 200kg∕s. According to simulation results, it is possible to produce 11,488kWe electrical power output in this field. Optimum first and second flashing pressures are determined to be 530kPa and 95kPa, respectively. Based on the exergy of the geothermal fluid at reservoir, overall first and second law efficiencies of the power plant are also calculated to be 6.88% and 28.55%, respectively.

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Performance Enhancement of Single Flash Geothermal Power Plants

Energy Conversion and Resources ◽

10.1115/imece2005-79044 ◽

2005 ◽

Author(s):

S. Barsin ◽

K. Aung

Keyword(s):

Power Plant ◽

Power Output ◽

Capital Investment ◽

Power Plants ◽

Performance Enhancement ◽

Operating Pressure ◽

Geothermal Power Plant ◽

Single Flash ◽

Geothermal Power ◽

Temperature Liquid

The present work investigates thermodynamic optimum conditions with respect to resource utilization by varying the operating pressure of flash drum for an existing geothermal power plant. The main focus of the study is to maximize the power output by minimizing the waste of liquid geothermal fluid re-injected to the well. For this purpose a double-flash system has been incorporated and the effect of operating at optimum flash pressures for both primary and secondary flash units is studied. An economic model is developed that calculates the total capital investment based on the cost of major equipments including pumps, flash drums, turbine generators, and condensers. From the results obtained it can be concluded that the plant at Svartsengi currently is working close to the optimum flashing pressure for the single-flash geothermal power plant. Providing an additional flash unit to convert the high temperature liquid coming from primary flash for Svartsengi and Nevada power plants increases the net power output by 12.7% and 28.9% respectively.

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Thermal performance analysis of organic flash cycle using R600A/R601A mixtures with internal heat exchanger

Thermal Science ◽

10.2298/tsci200507296h ◽

2020 ◽

pp. 296-296

Author(s):

Guidong Huang ◽

Songyuan Zhang ◽

Zhong Ge ◽

Zhiyong Xie ◽

Zhipeng Yuan ◽

...

Keyword(s):

Heat Exchanger ◽

Power Output ◽

Thermal Efficiency ◽

Electricity Generation ◽

Internal Heat ◽

Working Fluid ◽

Cycle System ◽

Internal Heat Exchanger ◽

Generation Costs ◽

Net Power Output

In this study, the thermal performance of an internal heat exchanger-organic flash cycle system driven by geothermal water was investigated.R600a/R601a mixtures were selected as the working fluid. The effects of the mole fraction of mixtures on the heat absorption capacity of the heater, the temperature rise of cold working fluid in the internal heat exchanger, net power output, thermal efficiency, and electricity generation costs were analyzed. The net power outputs, electricity generation costs, and thermal efficiency of the internal heat exchanger-organic flash cycle and simple organic flash cycle systems were compared. Results showed that the system using theR600a/R601a mixtures (0.7/0.3mole fraction) has the largest net power output, which increased the net power output by 3.68% and 42.23% over the R601a and R600a systems, respectively. WhentheR600a mole fraction was 0.4, the electricity generation costs reduction of the internal heat exchanger-organic flash cycle system was the largest (1.77% compared with the simple organic flash cycle system).The internal heat exchanger can increase the thermal efficiency of organic flash cycle, but the net power output does not necessarily increase.

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Assessment of Humid Air Turbines in Coal-Fired High Performance Power Systems

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations ◽

10.1115/96-gt-091 ◽

1996 ◽

Author(s):

Julianne M. Klara ◽

Robert M. Enick ◽

Scott M. Klara ◽

Lawrence E. Van Bibber

Keyword(s):

Power Systems ◽

Thermal Efficiency ◽

High Performance ◽

Power Plants ◽

Combined Cycle ◽

Humid Air ◽

Levelized Cost Of Electricity ◽

Capital Costs ◽

Air Turbine ◽

Net Power Output

The purpose of this study is to assess the feasibility of incorporating a Humid Air Turbine (HAT) into a coal-based, indirectly fired High Performance Power System (HIPPS). The HIPPS/HAT power plant exhibits a one percentage point greater thermal efficiency than the combined-cycle HIPPS plant. The capital costs for the HIPPS and HIPPS/HAT plants with identical net power output are nearly equivalent at $1380/kW. Levelized cost of electricity (COE) for the same size plants is 5.3 cents/kWh for the HIPPS plant and 5.4 cents/kWh for the HIPPS/HAT plant; the HIPPS/HAT plant improved thermal efficiency is offset by the higher fuel cost associated with a lower coal/natural gas fuel ratio. However, improved environmental performance is associated with the HIPPS/HAT cycle, as evidenced by lower CO2, SO2, and NOx emissions. Considering the uncertainties associated with the performance and cost estimates of the yet unbuilt components, the HIPPS/HAT and HIPPS power plants are presently considered to be comparable alternatives for future power generation technologies. The Department of Energy’s Combustion 2000 Program will provide revised design specifications and more accurate costs for these components allowing more definitive assessments to be performed.

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