Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Comparative analysis of natural and conventional working fluids for use in transcritical Rankine cycle using low‐temperature geothermal source

Comparative analysis of natural and conventional working fluids for use in transcritical Rankine... 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. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png International Journal of Energy Research Wiley

Comparative analysis of natural and conventional working fluids for use in transcritical Rankine cycle using low‐temperature geothermal source

Download PDF
15 pages

Loading next page...
 
/lp/wiley/comparative-analysis-of-natural-and-conventional-working-fluids-for-0rGMS14Q0X

References (25)

Publisher
Wiley
Copyright
Copyright © 2010 John Wiley & Sons, Ltd.
ISSN
0363-907X
eISSN
1099-114X
DOI
10.1002/er.1710
Publisher site
See Article on Publisher Site

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.

Journal

International Journal of Energy Research – Wiley

Published: May 1, 2011

There are no references for this article.