Subcritical Thermodynamic Cycles with Organic Medium and Isothermal Expansion

Kosowski, Krzysztof; Piwowarski, Marian

doi:10.3390/en13174340

Cited by 2 publications

(2 citation statements)

References 38 publications

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“…So, the net electricity production and cycle efficiency could be increased by 20%, reaching up to 50% of the Carnot efficiency. Moreover, Kosowski and Piwowarski [6] performed the thermodynamic analysis of both a conventional ORC and an ORC with the ideal isothermal process. The incorporation of the isothermal process led to an increased cycle efficiency of up to 12% when the organic fluid reached the saturated vapor state, and up to 7% when the organic fluid reached the superheated vapor state.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic, and Economic Performance of Novel ORC Designs Powered by Low-Grade Waste Heat

Ατσόνιος

Lykas

Antonopoulou

et al. 2023

36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 20

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Waste heat recovery is one of the alternative energy sources that have been investigated by scientists in recent decades to address ongoing environmental problems, such as global warming. The organic Rankine cycle is a promising waste heat recovery technology to exploit industrial waste heat, even at low-temperature levels (<100 o C), for electricity production. The proposed study presents and compares two innovative organic cycle designs feeding with the same available heat source. The first cycle includes a nearly isothermal expander, where a small fraction of the supplied waste heat is continuously provided to the expander, aiming to approach a quasi-isothermal process instead of an adiabatic one, avoiding the temperature decrease due to the expansion process. The result is an increase in the cycle's thermal efficiency and greater power output production compared to the adiabatic expansion process. The second configuration is called the trilateral flash cycle, where the working fluid does not reach the saturated vapor state during heating at the heat recovery system, while it expands into the two-phase region of the fluid. The aforementioned cycles are investigated parametrically in terms of thermodynamics with a low-temperature heat source (80-100 o C) for different organic working fluids, such as the R1234ze(E), R1234yf, R1233zd(E), and R134a. Parametric studies are carried out through Aspen Plus software, while a techno-economic comparison of the organic cycle designs is conducted based on Aspen Process Economic Analyzer and literature data. According to the final results, R1233zd(E) seems to be the most proper working fluid thermodynamically, while the organic Rankine cycle with nearly isothermal expansion achieves higher values of both electrical and exergy efficiencies, reaching the maximum values of 10.51%, and 52.27%, respectively. In terms of finance, both cycles achieve similar payback period values, reaching the value of 1.56 years in the case of the trilateral flash cycle and assuming 8,000 operating hours per year. Finally, for the trilateral flash cycle, lower net present value levels of about 30% compared to the corresponding values for the other cycle, are determined despite its lower installation cost.

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Section: Introductionmentioning

confidence: 99%

Thermodynamic, and Economic Performance of Novel ORC Designs Powered by Low-Grade Waste Heat

Ατσόνιος

Lykas

Antonopoulou

et al. 2023

36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 20

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“…As a result, these installations achieve an efficiency of about 10%, and only exceptionally can they reach about 20% thanks to the use of various modifications [16]. It is possible to increase the efficiency of the cycle by increasing the upper temperature [17] and modifying the installation structure, e.g., by adding an additional cycle [18] or by using an additional heater [19]. As in the case of steam turbines, efficiency can be increased by using an inter-stage superheater [20], regenerators [21,22] or by using a parallel evaporator [23].…”

Section: Introductionmentioning

confidence: 99%

Organic Supercritical Thermodynamic Cycles with Isothermal Turbine

Piwowarski,

Kosowski,

Richert

2023

Energies

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Organic Rankine cycles (ORC) are quite popular, but the overall efficiencies of these plants are rather very low. Numerous studies have been conducted in many scientific centers and research centers to improve the efficiency of such cycles. The research concerns both the modification of the cycle and the increase in the parameters of the medium at the inlet to the turbine. However, the efficiency of even these modified cycles rarely exceeds 20%. The plant modifications and the optimization of the working medium parameters, as a rule, lead to cycles with the high pressure and high temperature of live vapor and with a regenerator (heat exchanger) for the heating, vaporization and superheating of the medium. A new modified cycle with supercritical parameters of the working medium and with a new type of turbine has been described and calculated in the paper. For the first time, the isothermal turbine is proposed for supercritical organic cycles, though this solution is known as the Ericsson cycle for gas turbines. The innovative cycle and the usual ORC plants are characterized by almost identical block diagrams, while in the proposed cycle, the work of the turbine is obtained as a result of isothermal expansion and not in an adiabatic process. The analysis has been performed for 11 different working media and two cycles. The calculations have shown that power plants with isothermal expansion achieve better efficiency than cycles with adiabatic turbines. For example, the rise in efficiency changes from 8 percentage points for R245fa up to 10 percentage points for acetone. The calculations have proved that it is possible to obtain efficiency exceeding 50% for organic power plants. This is an outstanding result compared with modern steam and gas turbine units.

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Subcritical Thermodynamic Cycles with Organic Medium and Isothermal Expansion

Cited by 2 publications

References 38 publications

Thermodynamic, and Economic Performance of Novel ORC Designs Powered by Low-Grade Waste Heat

Thermodynamic, and Economic Performance of Novel ORC Designs Powered by Low-Grade Waste Heat

Organic Supercritical Thermodynamic Cycles with Isothermal Turbine

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