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This study focused on investigating the bottoming power cycles operating with CO2-based binary mixture, taking into account exergetic, economic and exergo-environmental impact indices. The main intent is to assess the benefits of employing a CO2-based mixture working fluid in closed Brayton bottoming power cycles in comparison with pure CO2 working fluid. Firstly, selection criteria for the choice of suitable additive compound for CO2-based binary mixture is delineated and the composition of the binary mixture is decided based on required cycle minimum temperature. The decided CO2-C7H8 binary mixture with a 0.9 mole fraction of CO2 is analyzed in two cycle configurations: Simple regenerative cycle (SRC) and Partial heating cycle (PHC). Comparative analysis among two configurations with selected working fluid are carried out. Thermodynamic analyses at varying cycle pressure ratio shows that cycle with CO2-C7H8 mixture shows maximum power output and exergy efficiency at rather higher cycle pressure ratio compared to pure CO2 power cycles. PHC with CO2-C7H8 mixture shows 28.68% increment in exergy efficiency with the levelized cost of electricity (LCOE) 21.62% higher than pure CO2 PHC. Whereas, SRC with CO2-C7H8 mixture shows 25.17% increment in exergy efficiency with LCOE 57.14% higher than pure CO2 SRC. Besides showing lower economic value, cycles with a CO2-C7H8 mixture saves larger CO2 emissions and also shows greater exergo-environmental impact improvement and plant sustainability index.
Muhammad Haroon; Nadeem Ahmed Sheikh; Abubakr Ayub; Rasikh Tariq; Farooq Sher; Aklilu Tesfamichael Baheta; Muhammad Imran. Exergetic, Economic and Exergo-Environmental Analysis of Bottoming Power Cycles Operating with CO2-Based Binary Mixture. Energies 2020, 13, 5080 .
AMA StyleMuhammad Haroon, Nadeem Ahmed Sheikh, Abubakr Ayub, Rasikh Tariq, Farooq Sher, Aklilu Tesfamichael Baheta, Muhammad Imran. Exergetic, Economic and Exergo-Environmental Analysis of Bottoming Power Cycles Operating with CO2-Based Binary Mixture. Energies. 2020; 13 (19):5080.
Chicago/Turabian StyleMuhammad Haroon; Nadeem Ahmed Sheikh; Abubakr Ayub; Rasikh Tariq; Farooq Sher; Aklilu Tesfamichael Baheta; Muhammad Imran. 2020. "Exergetic, Economic and Exergo-Environmental Analysis of Bottoming Power Cycles Operating with CO2-Based Binary Mixture." Energies 13, no. 19: 5080.
This study aims to provide a thermodynamic comparison between supercritical CO2 cycles and ORC cycles utilizing flue gases as waste heat source. Moreover, the possibility of using CO2 mixtures as working fluids in transcritical cycles to enhance the performance of the thermodynamic cycle is explored. ORCs operating with pure working fluids show higher cyclic thermal and total efficiencies compared to supercritical CO2 cycles; thus, they represent a better option for high-temperature waste heat recovery provided that the thermal stability at a higher temperature has been assessed. Based on the improved global thermodynamic performance and good thermal stability of R134a, CO2-R134a is investigated as an illustrative, promising working fluid mixture for transcritical power cycles. The results show that a total efficiency of 0.1476 is obtained for the CO2-R134a mixture (0.3 mole fraction of R134a) at a maximum cycle pressure of 200 bars, which is 15.86% higher than the supercritical carbon dioxide cycle efficiency of 0.1274, obtained at the comparatively high maximum pressure of 300 bars. Steam cycles, owing to their larger number of required turbine stages and lower power output, did not prove to be a suitable option in this application.
Abubakr Ayub; Costante M. Invernizzi; Gioele Di Marcoberardino; Paolo Iora; Giampaolo Manzolini. Carbon Dioxide Mixtures as Working Fluid for High-Temperature Heat Recovery: A Thermodynamic Comparison with Transcritical Organic Rankine Cycles. Energies 2020, 13, 4014 .
AMA StyleAbubakr Ayub, Costante M. Invernizzi, Gioele Di Marcoberardino, Paolo Iora, Giampaolo Manzolini. Carbon Dioxide Mixtures as Working Fluid for High-Temperature Heat Recovery: A Thermodynamic Comparison with Transcritical Organic Rankine Cycles. Energies. 2020; 13 (15):4014.
Chicago/Turabian StyleAbubakr Ayub; Costante M. Invernizzi; Gioele Di Marcoberardino; Paolo Iora; Giampaolo Manzolini. 2020. "Carbon Dioxide Mixtures as Working Fluid for High-Temperature Heat Recovery: A Thermodynamic Comparison with Transcritical Organic Rankine Cycles." Energies 13, no. 15: 4014.
In the last years, several fluids have been proposed to replace steam as working fluid in power cycle for converting thermal power into electricity. This paper describes the procedure to be adopted for the selection of any innovative fluid which can be even mixtures of fluids. The first step consists of the working fluid characterization in terms of thermodynamic properties through equations of state. The equations of state have to be calibrated on experimental Vapour-Liquid Equilibrium measurements while, in the second step, the maximum operating temperature is identified through thermal stability tests. Finally, the impact of the fluid thermodynamic properties on the performance of the power cycle in which it is implemented must be assessed through modelling tools. In this work, the procedure is discussed for the mixture of CO2 and C6F14 as a potential working fluid for gas thermodynamic cycles with liquid phase compression. Results of the application of this mixture in a closed cycle show the benefit of using a CO2/C6F14 mixture which provides 3% points efficiency increase at 400 °C with respect to the pure CO2 together with a preliminary design of the expander.
G. Di Marcoberardino; C.M. Invernizzi; P. Iora; Abubakr Ayub; D. Di Bona; P. Chiesa; M. Binotti; G. Manzolini. Experimental and analytical procedure for the characterization of innovative working fluids for power plants applications. Applied Thermal Engineering 2020, 178, 115513 .
AMA StyleG. Di Marcoberardino, C.M. Invernizzi, P. Iora, Abubakr Ayub, D. Di Bona, P. Chiesa, M. Binotti, G. Manzolini. Experimental and analytical procedure for the characterization of innovative working fluids for power plants applications. Applied Thermal Engineering. 2020; 178 ():115513.
Chicago/Turabian StyleG. Di Marcoberardino; C.M. Invernizzi; P. Iora; Abubakr Ayub; D. Di Bona; P. Chiesa; M. Binotti; G. Manzolini. 2020. "Experimental and analytical procedure for the characterization of innovative working fluids for power plants applications." Applied Thermal Engineering 178, no. : 115513.
This paper presents CO2‐toluene (CO2‐C7H8) binary mixture as working fluid to enhance the energetic and exergetic performance of CO2 bottoming power cycles in warm ambient conditions. A criterion for selection of CO2‐based binary mixture is defined, and 0.9 CO2/0.1 C7H8 composition is decided based on the required minimum cycle temperature compatible with ambient conditions. Bottoming simple regenerative cycle (BSRC) and bottoming preheating cycle (BPHC) configurations are selected, and their realistic operating conditions are determined based on sensitivity analysis. The performance of bottoming cycles using CO2‐C7H8 binary mixture is compared with the bottoming cycles using pure CO2 as working fluid at different ambient temperatures. It is observed that the cycles operating with pure CO2 can only perform better at lower ambient temperature conditions, whereas, at the increased ambient temperatures, bottoming cycles with CO2‐C7H8 binary mixture outperform and produce significant gains in exergetic and energetic performance compared with pure CO2 bottoming cycles. A maximum gain of exergetic efficiency for BSRC and BPHC observed is 26.83% and 18.71%, respectively, at an operating ambient temperature of 313 K, whereas an overall gain in energetic efficiencies for BSRC and BPHC observed is 28.92% and 10.12%, respectively. Taking into consideration thermodynamic performance, overall UA (product of overall heat transfer coefficient and heat transfer area for the heat exchanger) and specific investment cost, BPHC configuration is suggested as reasonable choice for higher ambient temperature conditions.
Muhammad Haroon; Abubakr Ayub; Nadeem A. Sheikh; Muhammad Imran. Exergetic performance and comparative assessment of bottoming power cycles operating with carbon dioxide–based binary mixture as working fluid. International Journal of Energy Research 2020, 44, 7957 -7973.
AMA StyleMuhammad Haroon, Abubakr Ayub, Nadeem A. Sheikh, Muhammad Imran. Exergetic performance and comparative assessment of bottoming power cycles operating with carbon dioxide–based binary mixture as working fluid. International Journal of Energy Research. 2020; 44 (10):7957-7973.
Chicago/Turabian StyleMuhammad Haroon; Abubakr Ayub; Nadeem A. Sheikh; Muhammad Imran. 2020. "Exergetic performance and comparative assessment of bottoming power cycles operating with carbon dioxide–based binary mixture as working fluid." International Journal of Energy Research 44, no. 10: 7957-7973.
This study investigates the use of pure and hydrocarbons binary mixtures as potential alternatives working fluids in a usual biomass powered organic Rankine cycle (ORC). A typical biomass combined heat and power plant installed in Cremona (Italy) is considered as the benchmark. Eight pure hydrocarbons (linear and cyclic) and four binary mixtures of linear hydrocarbons were selected. The critical points of the binary mixtures at different composition were calculated using an in-house code developed in MATLAB© (R2018b) environment. Based on the critical point of a working fluid, supercritical and subcritical cycle configurations of ORC were analysed. A detailed thermodynamic comparison with benchmark cycle was carried out in view of cycle efficiency, maximum operating pressure, size of the turbine and heat exchangers. The supercritical cycles showed 0.02 to 0.03 points lower efficiency, whereas, subcritical cycles showed comparable efficiencies than that of the benchmark cycle. The cycles operating with hydrocarbons (pure and mixtures) exhibited considerably lower volume flow ratios in turbine which indicates lower turbine size. Also, size parameter of regenerator is comparatively lower due to the lower molecular complexity of the hydrocarbons. A noticeable increase in turbine power output was observed with change in composition of the iso-octane/n-octane binary mixture at the same thermodynamic efficiency.
Costante M. Invernizzi; Abubakr Ayub; Gioele Di Marcoberardino; Paolo Iora. Pure and Hydrocarbon Binary Mixtures as Possible Alternatives Working Fluids to the Usual Organic Rankine Cycles Biomass Conversion Systems. Energies 2019, 12, 4140 .
AMA StyleCostante M. Invernizzi, Abubakr Ayub, Gioele Di Marcoberardino, Paolo Iora. Pure and Hydrocarbon Binary Mixtures as Possible Alternatives Working Fluids to the Usual Organic Rankine Cycles Biomass Conversion Systems. Energies. 2019; 12 (21):4140.
Chicago/Turabian StyleCostante M. Invernizzi; Abubakr Ayub; Gioele Di Marcoberardino; Paolo Iora. 2019. "Pure and Hydrocarbon Binary Mixtures as Possible Alternatives Working Fluids to the Usual Organic Rankine Cycles Biomass Conversion Systems." Energies 12, no. 21: 4140.
For developing a sustainable power system, the key is to maximize the use of available resources with a minimal impact on the environment. One technique for achieving this is exhaust heat recovery. In this paper, three gas turbine exhaust heat recovery supercritical carbon dioxide combined power cycles are presented. They are combined gas turbine-recompression cycle, combined gas turbine-preheating cycle, and combined gas turbine-simple regenerative cycle. For all the cycles, thermodynamic models are developed and the influence of varying mass flow rates, compression ratio, and mass split/recompression percentages in different components of all three cycles are investigated. Using genetic algorithm, exergetic optimization is done to find the optimal configuration for each cycle. The reduction in CO2 emissions in presented cycles against fossil fuel power cycles is also assessed. Additionally, a comparison with a simple gas turbine (SGT) and an air bottoming combined cycle (ABC) is presented. The results indicate that owing to exhaust exergy recovery, there is a significant improvement in the energetic and exergetic performance of combined gas turbine-supercritical CO2 power cycles compared to that of SGT and ABC. The sum of exergy destruction and exergy loss in the combined cycles is lower as compared to the sum in SGT. The reduction in losses compared to SGT is 22.89% in the case of the combined gas turbine recompression cycle and 35.8% in the case of the combined gas turbine preheating cycle (CGTPHC). Moreover, the energetic and exergetic performances of the bottoming supercritical CO2 recompression cycles (BRECs) are better than those of the bottoming supercritical CO2 preheating cycle owing to lower exergy destruction in the components of BREC. As a result of comparative analysis based on the exergetic performance and environmental impact, the CGTPHC is selected as an appropriate option for gas turbine exhaust exergy recovery.
Abubakr Ayub; Nadeem Ahmed Sheikh; Rasikh Tariq; Muhammad Mahabat Khan; Costante Mario Invernizzi. Exergetic optimization and comparison of combined gas turbine supercritical CO2 power cycles. Journal of Renewable and Sustainable Energy 2018, 10, 044703 .
AMA StyleAbubakr Ayub, Nadeem Ahmed Sheikh, Rasikh Tariq, Muhammad Mahabat Khan, Costante Mario Invernizzi. Exergetic optimization and comparison of combined gas turbine supercritical CO2 power cycles. Journal of Renewable and Sustainable Energy. 2018; 10 (4):044703.
Chicago/Turabian StyleAbubakr Ayub; Nadeem Ahmed Sheikh; Rasikh Tariq; Muhammad Mahabat Khan; Costante Mario Invernizzi. 2018. "Exergetic optimization and comparison of combined gas turbine supercritical CO2 power cycles." Journal of Renewable and Sustainable Energy 10, no. 4: 044703.