TERMODINAMIČKA ANALIZA GEOTERMALNE TERMOELEKTRANE … · termodinamiČka analiza geotermalne termoelektrane na azi rankinovog ciklusa s organskim fluidom-primjer geotermalnog polja

TERMODINAMIČKA ANALIZA GEOTERMALNE TERMOELEKTRANE NA BAZI RANKINOVOG CIKLUSA S ORGANSKIM FLUIDOM-PRIMJER GEOTERMALNOG POLJA REČICE BLIZU KARLOVCATHERMODYNAMIC ANALYSIS OF ORGANIC RANKINE CYCLE BASED GEOTHERMAL POWER PLANT - CASE STUDY OF GEOTHERMAL FIELD REČICA NEAR KARLOVACNenad MUSTAPIĆ,Karlovac University of Applied Science, [email protected],Marko DRAGIĆ,Karlovac University of Applied Science, [email protected],Marko VREŠ,Karlovac University of Applied Science, [email protected],

5. MKOIEE, Beograd, 12. i 13. oktobar 2017 5th ICREPS, Belgrade, 12th and 13th October 2017

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mailto:[email protected]



Geothermal potential of Croatia


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Geothermal field Rečica

• situated approximately 8 km northeast of Karlovac and was discovered in 1983 by Ka-2 well.

• Later, during 1988, Ka-3 well has been drilled which confirmed the geothermal potential of this locality. The distance between Ka-2 and Ka-3 wells are approximately 3 km.

• The area around the wells is mainly lowland, 110 m height above sea level, and the wells are located within relatively big forest.

• It is assumed Rečica has mass flow rate of 94,38 kg/s and temperature of 120 °C geothermal water.


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Introduction

• Organic Rankine Cycle (ORC) enables electricity production from low temperature geothermal sources

• Four configurations of ORC cycles are analyzed: Simple Organic Rankine Cycle, Organic Rankine Cycle with an Internal Heat Exchanger (IHE), Regenerative Organic Rankine Cycle, and Regenerative Organic Rankine Cycle with an Internal Heat Exchanger


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a) b)

c) d)

Schematic layout of a) simple ORC b) ORC with IHE c) Regenerative ORC and d) Regenerative ORC with IHE


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Working fluids


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Definition of ORC efficiencies


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Plant efficiency

•The cycle efficiency only describes how efficient a cycle is in converting a certain amount of heat into mechanical power, but it does not tell how efficient the heat source is used


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Thermodynamic optimization process

• For thermodinamical optimization temperature of evaporation was being varied which is also temperature at the entrance of the turbine because there is no superheating

• The purpose of optimizing temperature of evaporation was to find the temperature where Wnet and ɳ are at their highest peak performances and where irreversibility is at its lowest peak performance because for that temperature the temperature of evaporation is optimal


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Operating parameters used in simulation


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• Mass and energy balances for any ORC cycle component at steady state are

• Exergy balance for any ORC cycle component is given by

where ex represent specific flow exergy.


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• Net work in a ORC cycle is given by

where the subscripts t and p represent the turbine and pump

• Exergy destroyed in the cycle and the plant, or the irreversibility in the cycle and the plant


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Thermodynamic Optimization Results

• All simulations of each ORC cycle configurations are based on the operating parameters and geo fluid mass flowrate is assumed to be 94,38 kg/s. For each plant configuration mathematical model is defined and analysis is performed using the software package EES (Engineering Equation Solver)

• Thermodynamic optimization of Regenerative ORC with IHE was not feasible because of too low temperature of geothermal temperature


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a) b) c)

• Wnet net power output per unit mass flow rate of geo fluid as a function of evaporation temperature TE (or turbine inlet temperature) for analysed working fluids and ORC configurations of a) simple ORC, b) ORC with IHE, and c) regenerative ORC cycle.


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a) b) c)

• Second-law efficiency and plant irreversibility as a function of evaporation temperature TE (or turbine inlet temperature) for analysed working fluids and ORC configurations of a) simple ORC, b) ORC with IHE and c) regenerative ORC cycle


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a) b) c)

• The relationship of the plant irreversibility and the evaporation temperature under different pinch temperature differences in evaporator a) simple ORC, b) ORC with IHE , c) Regenerative ORC


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a) b)

c)

• The exergy destruction of the components in a) simple ORC, b) ORC with IHE and c) regenerative ORC cycle


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• Results of optimal conditions for all ORC cycle configurations


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Conclusion


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Documents

TERMODINAMIČKA ANALIZA GEOTERMALNE TERMOELEKTRANE … · termodinamiČka analiza geotermalne termoelektrane na azi rankinovog ciklusa s organskim fluidom-primjer geotermalnog polja