Comparative analysis of natural and conventional working fluids for use in transcritical Rankine cycle using low-temperature geothermal source
- 7 April 2011
- journal article
- research article
- Published by Hindawi Limited in International Journal of Energy Research
- Vol. 35 (6), 530-544
- https://doi.org/10.1002/er.1710
Abstract
Theoretical analyses of natural and conventional working fluids-based transcritical Rankine power cycles driven by low-temperature geothermal sources have been carried out with the methodology of pinch point analysis using computer models. The regenerator has been introduced and analyzed with a modified methodology considering the considerable variation of specific heat with temperature near the critical state. The evaluations of transcritical Rankine cycles have been performed based on equal thermodynamic mean heat rejection temperature and optimized gas heater pressures at various geothermal source temperature levels ranging from 80 to 120°C. The performances of CO2, a natural working fluid most commonly used in a transcritical power cycle, have been indicated as baselines. The results obtained show: optimum thermodynamic mean heat injection temperatures of transcritical Rankine cycles are distributed in the range of 60 to 70% of given geothermal source temperature level; optimum gas heater pressures of working fluids considered are lower than baselines; thermal efficiencies and expansion ratios (Expr) are higher than baselines while net power output, volume flow rate at turbine inlet (V1) and heat transfer capacity curves are distributed at both sides of baselines. From thermodynamic and techno-economic point of view, R125 presents the best performances. It shows 10% higher net power output, 3% lower V1, 1.0 time higher Expr, and 22% reduction of total heat transfer areas compared with baselines given geothermal source temperature of 90°C. With the geothermal source temperature above 100°C, R32 and R143a also show better performances. R170 shows nearly the same performances with baselines except for the higher V1 value. It also shows that better temperature gliding match between fluids in the gas heater can lead to more net power output. Copyright © 2010 John Wiley & Sons, Ltd.Keywords
This publication has 17 references indexed in Scilit:
- Experimental study on the performance of solar Rankine system using supercritical CO2Renewable Energy, 2007
- Optimum design criteria for an Organic Rankine cycle using low-temperature geothermal heat sourcesEnergy, 2007
- Theoretical analysis of a thermodynamic cycle for power and heat production using supercritical carbon dioxideEnergy, 2007
- Thermodynamic analysis of the CO2-based Rankine cycle powered by solar energyInternational Journal of Energy Research, 2007
- Maximising the working fluid flow as a way of increasing power output of geothermal power plantApplied Thermal Engineering, 2007
- Solar energy powered Rankine cycle using supercritical CO2Applied Thermal Engineering, 2006
- Study of solar energy powered transcritical cycle using supercritical carbon dioxideInternational Journal of Energy Research, 2006
- Analysis of a novel solar energy-powered Rankine cycle for combined power and heat generation using supercritical carbon dioxideRenewable Energy, 2006
- Experimental Performance Analysis of Supercritical CO2 Thermodynamic Cycle Powered by Solar EnergyAIP Conference Proceedings, 2006
- Theoretical research of carbon dioxide power cycle application in automobile industry to reduce vehicle’s fuel consumptionApplied Thermal Engineering, 2005