Thermodynamic and economic investigation of an ionic liquid as a new proposed geothermal fluid in different organic Rankine cycles for energy production. (15th February 2020)

• Record Type: Journal Article
• Authors: Kazemi, Shabnam; Nor, Mohamad Iskandr Mohamad; Teoh, Wen Hui
• Is Part Of: Energy. Volume 193(2020)
• Publication Date: 2020-02-15
• Subjects: Ionic liquid -- Geothermal -- Organic rankine cycle -- Optimization -- Thermo-economic analysis; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2019.116722
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: Organic Rankine cycle (ORC) is a promising technology for electricity generation by utilizing heat sources at low to moderate temperatures. In the present work, an ionic liquid (1-butylpyridinium tetrafluoroborate, C9 H14 NBF4 ), a known green chemical and non-volatile compound with good thermal and chemical stability, and significant heat capacity are utilized as a geothermal fluid. Simulation and optimization were conducted for a basic ORC, a regenerative organic Rankine cycle (RORC) and a two-stage evaporative organic Rankine cycle (TSORC) by maximizing exergy efficiency and minimizing specific investment cost. The operating parameters considered in the optimization exercise were evaporative and regenerative temperatures, pinch point temperature difference of evaporators and the degree of superheat. Peng Robinson equation of state was used and isobutane (R-600a) and butane (R-600) were selected as working fluids. Comparisons were made between the performance of ORCs when C9 H14 NBF4 and water were individually used as a geothermal fluid. Utilization of an ionic liquid improved the performance of the three ORC configurations with the best performance generated from a basic ORC with exergy efficiency of 82.35% (R-600) and 87.70% (R-600a). From an economic viewpoint, the amount of specific investment cost (SIC) is comparatively lower when ionic liquid is used as a geothermal fluid. Graphical abstract: Image 1 Highlights: Basic ORC and RORC have better thermodynamic performances in IL than water. A 30% increase in exergy efficiency is observed in basic ORC with IL. The optimum configuration is a basic ORC with IL and R-600a. SIC for all ORC–IL combinations were lower than all ORC–water combinations. The lowest SIC obtained is in a TSORC-water combination with R-600.