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Journal ArticleDOI

Performance analysis of the Chena binary geothermal power plant

01 Jul 2011-Applied Thermal Engineering (Elsevier)-Vol. 31, Iss: 10, pp 1825-1832
TL;DR: In this article, the IPSEpro model of the Chena Geothermal ORC Power Plant had been developed and validated using the real data, and the validated model was used to investigate the effect of variation in the geothermal source temperature on plant performance.
About: This article is published in Applied Thermal Engineering.The article was published on 2011-07-01 and is currently open access. It has received 102 citations till now. The article focuses on the topics: Geothermal energy & Geothermal power.

Summary (3 min read)

1 Introduction

  • The world population and industrialisation had been on the increase.
  • This associated environmental danger caused by the burning of fossil fuels had resulted in a clamour by the world leaders to develop better and more efficient means of meeting the world energy demand at the least possible environmental impact.
  • From there, the utilisation of geothermal energy for electricity generation spread to other parts of the world with countries like Japan, USA, New Zealand, and Mexico exploiting their first geothermal energy in 1919, 1921, 1958, and 1959 respectively [3].
  • With the development of binary cycle power plants (Organic Rankine Cycle (ORC) and Kalina Cycle) technology, the low and medium temperature geothermal in the temperature range 70 – 100 o C and 100 – 150 o C respectively are now utilised for power generation.
  • Hence the working fluid chosen for any application is a function of the operating condition, cost, safety and the environmental impact.

2 Process Diagram of ORC

  • Figure 1 shows the process flow diagram of the ORC system using geothermal heat source.
  • In the process, the geothermal hot water/steam from the reservoir is used to preheat and vapourise the organic working fluid in the evaporator.
  • The vapour from the evaporator passes through the turbine where it expands to produce work which is used to turn the shaft connected to the generator to generate electricity.
  • The low pressure organic working fluid vapour from the turbine is then passed through the condenser where it is condensed to liquid using cold water.
  • The liquid organic working fluid is then pumped back to the evaporator to complete the cycle and the whole process restarts again.

3 IPSEpro Simulation of the Chena Geothermal Power Plant

  • The IPSEpro model of the Chena power plant was developed using IPSEpro Simulation Software Version 4.0 [9].
  • It contains Model Development Kit (MDK) and Process Simulation Environment (PSE) packages.
  • The simulated IPSEpro PSE Model of the Chena ORC power plant at the nominal operating condition (design point) is shown in Figure 2.
  • The thermal efficiency of the plant was calculated using the equation 1 M AN US CR IP T AC CE PT ED ACCEPTED MANUSCRIPT (1) where, The Number of Transfer Unit (NTU) of the heat exchangers was calculated using equation 2 (2) where Smaller heat capacity rate of the fluids that passes through the heat exchanger.
  • The state of the working fluid, at the exit/inlet of any given unit operation is defined using the enthalpy parameter, ϰ which is calculated as where, Specific enthalpy of the stream at any given pressure =.

4 Results & Discussion

  • The developed model is simulated using the IPSEpro PSE package.
  • The thermodynamic processes and the thermodynamic cycle exhibited by the working fluid are shown in Table 3 and Figure 3 respectively.
  • The heat exchangers (evaporator and condenser) T-Q diagram showing the heat exchangers pinch temperatures at the design point are shown in Figures 4 and 5 respectively.
  • The simulation result was validated with the real plant design data from the Chena Geothermal Power plant.
  • The validation was done by comparing the simulation result with the real plant design data at the nominal design point as shown in Table 4.

IPSEpro PSE Model

  • The case study carried out in this paper is neither an optimisation case study nor a design case study.
  • The temperature of the working fluid at the entrance to the evaporator is fixed to the value similar to that used for the model validation.
  • One problem usually M AN US CR IP T AC CE PT ED ACCEPTED MANUSCRIPT associated with re-injection operation is the cooling of the geothermal fluid by the used fluid which is re-injected into the production well.
  • This discharge is regulated by the Department of Natural Resources (DNR) and Chena has a permit for discharging the cooling water effluent [7].
  • Based on the above arguments, the performance case study of the Chena Geothermal ORC power plants was carried out by fixing some variables of the validated Chena Geothermal ORC Power Plant model as shown in Table 5Error!.

Effect of Variation in Geothermal Source Temperature on Plant Behaviour

  • Using the nominal design point as the reference point, the effect of variation in the geothermal source temperature from 61 o C to 80 o C were investigated using the validated IPSEpro Model of the Chena Geothermal ORC Power Plant.
  • The increase in source temperature also causes an increase in the heat input to the system thus causing a decrease in the thermal efficiency of the plant.
  • Furthermore, a decrease in the geothermal source temperature lower than the design temperature causes a decrease in the quantity of working fluid vapourised in the evaporator and this leads to a decrease in the net power output.

Net Power Output

  • Effect of Variation in Geothermal Source Temperature on Pump Power Consumption Figure 8 shows the variation in the working fluid enthalpy parameter, ϰ at the turbine inlet (evaporator exit) and the working fluid flowrate as the geothermal source temperature changes, also known as Figure 7.
  • This causes an increase in the exit temperature of the working fluid from the evaporator and thus an increase in the level of working enthalpy parameter.
  • Also contained in the same graph is the variation in working fluid enthalpy parameter, ϰ at the pump inlet/condenser outlet as the geothermal source temperature changes.
  • This condition if not controlled may cause cavitation in the pump which will be detrimental to the operation of the system.
  • Effect of Variation in Geothermal Source Temperature on Evaporator and Condenser Effectiveness Figure 11 and 12 show the variation in the turbine inlet and outlet temperatures and pressures when the geothermal source temperature changes, also known as Figure 10.

5. Conclusion

  • It has been confirmed in this paper that the production of electricity from the low temperature geothermal sources using ORC system as claimed by Chena Power in the paper presented to the Alaska Energy Authority is a technologically feasible project.
  • The IPSEpro PSE model of the Chena Geothermal ORC power plant developed in this paper is in close agreement with the plant design report presented by Chena Power.
  • The temperature of the geothermal source is likely to be fairly close to the design point, however, the effect of wide variation in the geothermal source temperature from the nominal design condition had been investigated in this report.
  • The analysis had shown that increase in the source temperature from the nominal design point will increase the plant output power up to a certain limit; however, this occurs at the detriment of the plant thermal efficiency which decreases.
  • Hence, it is recommended that ORC power plants should incorporate a great deal of automation so as to maintain the plant efficiency and design power output in order to avert the detrimental effect on plant performance associated with the variation in design operating conditions.

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Citations
More filters
Journal ArticleDOI
TL;DR: An organic Rankine cycle (ORC) machine is similar to a conventional steam cycle energy conversion system, but uses an organic fluid such as refrigerants and hydrocarbons instead of water as discussed by the authors.
Abstract: An organic Rankine cycle (ORC) machine is similar to a conventional steam cycle energy conversion system, but uses an organic fluid such as refrigerants and hydrocarbons instead of water. In recent years, research was intensified on this device as it is being progressively adopted as premier technology to convert low-temperature heat resources into power. Available heat resources are: solar energy, geothermal energy, biomass products, surface seawater, and waste heat from various thermal processes. This paper presents existing applications and analyzes their maturity. Binary geothermal and binary biomass CHP are already mature. Provided the interest to recover waste heat rejected by thermal devices and industrial processes continue to grow, and favorable legislative conditions are adopted, waste heat recovery organic Rankine cycle systems in the near future will experience a rapid growth. Solar modular power plants are being intensely investigated at smaller scale for cogeneration applications in buildings but larger plants are also expected in tropical or Sahel regions with constant and low solar radiation intensity. OTEC power plants operating mainly on offshore installations at very low temperature have been advertised as total resource systems and interest on this technology is growing in large isolated islands.

1,058 citations

Journal ArticleDOI
TL;DR: In this paper, a worldwide review using published data from 94 geothermal plants (6 dry-steam, 34 single flash, 18 double flash, 31 binary, 2 hybrid steam-binary and 1 triple flash plant) to find conversion efficiencies based on the reservoir enthalpy.

315 citations


Cites background from "Performance analysis of the Chena b..."

  • ...For example, Chena Hot Springs [6, 7] binary plant has an efficiency of only 1% due to an average fluid enthalpy of 306 and a temperature of 73°C, while Darajat [8, 9] in Indonesia reaches an efficiency of 20....

    [...]

Journal ArticleDOI
TL;DR: In this article, the authors investigated the effect of the condensation temperature glide of the zeotropic mixture on the ORC thermodynamic performance and proposed a method to determine the optimal ORC condensation pressure.

181 citations

Journal ArticleDOI
TL;DR: In this article, the performance of three configurations of organic Rankine cycle (ORC) for binary geothermal power plants from the viewpoints of both thermodynamics and economics is investigated and compared, and a profitability evaluation of the investigated systems is performed based on the total capital investment and payback period.

181 citations

Journal ArticleDOI
TL;DR: In this article, the authors present various Rankine cycle architectures for single fluids and other improved versions operating with ammonia/water mixture, and their potential for driving organic Rankine cycles are outlined.
Abstract: Various Rankine cycle architectures for single fluids and other improved versions operating with ammonia/water mixture are presented in this paper. Untapped heat resources and their potential for driving organic Rankine cycles are outlined. The nature – state and temperature of the heat source significantly influences the choice of the type of organic Rankine cycle machine. The temperature appears as a critical parameter during the selection process. Modules differ from one another from technology, size and cost viewpoints. The investment cost of an ORC project includes machine, engineering, system integration, capital costs, etc. and is closely linked to the application.

126 citations

References
More filters
01 Jan 1997
TL;DR: In this article, the analogy between heat and mass transfer is covered and applied in the analysis of heat transfer by conduction, convection and radiation, and the analysis is performed by using the handbook of numerical heat transfer.
Abstract: Handbook of Numerical Heat Transfer Free Full Download Links from Multiple Mirrors added by DL4W on 2015-04-10 02:13:35. Handbook of heat transfer / editors, W.M. Rohsenow, J.P. Hartnett. Y.I. Cho. m 3rd ed. p. cm. Includes bibliographical references and index. ISBN 0-07053555-8. Students investigate heat transfer by conduction, convection and radiation. The analogy between heat and mass transfer is covered and applied in the analysis.

1,644 citations

Journal ArticleDOI
01 Jun 2004-Energy
TL;DR: In this article, an analysis of the performance of organic Rankine cycle (ORC) subjected to the influence of working fluids is presented, which reveals that the thermal efficiency for various working fluid is a weak function of the critical temperature.

744 citations


Additional excerpts

  • ...M AN US CR IP T AC CE PT ED ACCEPTED MANUSCRIPT performance of ORC systems [5] as well as to determine the best working fluid for ORC applications [2], however, most results had shown that different working fluids show different performance at different operating conditions....

    [...]

Journal ArticleDOI
01 Sep 2007-Energy
TL;DR: In this paper, a cost-effective optimum design criterion for organic Rankine power cycles utilizing low-temperature geothermal heat sources is presented, where the ratio of the total heat exchanger area to net power output is used as the objective function and was optimized using the steepest descent method.

706 citations


"Performance analysis of the Chena b..." refers background in this paper

  • ...Although the cost of conventional steam turbine power plants seems to be lower than that of the binary power plants [2], the ability of the later to utilise low temperature geothermal energy, industrial waste heat energy, solar energy for electricity generation as well as its high flexibility and reliability with low maintenance and supervision makes it very attractive....

    [...]

  • ...M AN US CR IP T AC CE PT ED ACCEPTED MANUSCRIPT performance of ORC systems [5] as well as to determine the best working fluid for ORC applications [2], however, most results had shown that different working fluids show different performance at different operating conditions....

    [...]

  • ...Geothermal heat energy is a renewable heat energy which comes from beneath the earth surface with temperatures varying from 50 to 350 o C [2]....

    [...]

Book
08 May 2001
TL;DR: The Heat Exchanger as Part of a System: Exergetic (Second Law) Analysis and Surface Comparisons, Size, Shape and Weight Relationships.
Abstract: Selected Contents. Chapter 1 Introduction. Chapter 2 Industrial Compact Exchangers. Chapter 3 The Heat Exchanger as Part of a System: Exergetic (Second Law) Analysis. Chapter 4 Surface Comparisons, Size, Shape and Weight Relationships. Chapter 5 Surface Types and Correlations. Chapter 6 Thermal Design. Chapter 7 Compact Heat Exchangers In Practice. Appendices.

349 citations


"Performance analysis of the Chena b..." refers background in this paper

  • ...For a power plant such as Chena Geothermal ORC Power Plant which had been designed to operate at maximum performance at the nominal design conditions, the overall UA values of the heat exchangers (evaporators and condensers) [12] and the pressure drops in the units of equipment are likely to be constant....

    [...]

Frequently Asked Questions (1)
Q1. What are the contributions in "Performance analysis of the chena binary geothermal power plant" ?

In this paper, the IPSEpro Model of the Chena Geothermal ORC power plant had been developed and validated using the real data.