Renewable Energy Global Innovations features: Efficiency and Cost Optimization of a Regenerative Organic Rankine Cycle Power Plant through the Multi-Objective Approach

Significance Statement

The organic Rankine cycle system, which uses different sources of renewable energy, has developed interest due to its favorable support towards greenhouse gas depletion. With this development, what arises as a primary concern to technologists is how to strike a right stability between energy provision and plant cost. Also, the use of multi-objective optimization approach in obtaining this has not been well studied.

Professor Alfredo Gimelli and Colleagues from University of Naples Federico II, Napoli in Italy, discussed the use of a multi-objective optimization process approach to address the organic Rankine cycle ORC while considering the electrical efficiency and overall heat exchangers area in view of cost. They made use of octamethyltrisiloxane MDM as an organic fluid.  In their study the authors solved the multi-objective optimization problem of that of an organic Rankine cycle power plant of 1MW with a biomass heat source. The work is now published in peer-reviewed journal, Applied Thermal Engineering.

In the thermodynamic modeling, the cost of the heat exchanger area was a major determinant for that of the organic Rankine cycle system, and it was indirectly linked to the study of the economic potential of the plants.

The decision variables used in the multi-objective optimization approach include thermodynamic design parameters such as the minimum and maximum pressure of the thermodynamic cycle, regenerator efficiency, subcooling at the condenser outlet and superheating at the evaporator outlet.

Results from the multi-objective optimization process, with the use of the MOGA II algorithm when imputed to determine the Pareto optimal front between the two objectives of electric efficiency and plant costs shows a reasonable trade-off. An increase in overall efficiency, characterized high overall heat exchanger area. Likewise, high global electric efficiency resulted in high regenerator efficiency.

The Pareto optimal front solutions provided a range between 12.7 and 20.7KPa for the minimum and maximum pressure of the thermodynamic cycle. Pareto optimal front solutions also had an electric efficiency range between 14.1 and 18.9%, while that of the overall heat exchangers area ranges from 446 to 1097m².

The proposed methodology in this study provided an avenue for technologists to select the preferred solution for the exact use by making use of decision variables needed for objective functions in order to have a desired balance between cost and electric efficiency.

About The Author

Massimiliano Muccillo received his degree in Mechanical Engineering at the University of Naples Federico II, Italy, in 2008, discussing a thesis addressing the study of the prototype of a variable valve actuation system for a motorcycle engine. He received his Ph.D degree in Engineering of Mechanical Systems at the University of Naples Federico II, in 2012, discussing a thesis addressing the use of the multi-objective approach for the optimization of cogeneration systems. Since 2012, he has been a Research fellow at the Department of Industrial Engineering of the University of Naples Federico II.

His research interests include modeling, analysis and optimization of spark ignition reciprocating internal combustion, CHP systems and ORC systems. SAE member since 2012. ATI member since 2012. Author of about 25 scientific publications (13 SCOPUS). “Key Scientific Article contributing to the excellence in Energy research” by RENEWABLE ENERGY GLOBAL INNOVATIONS in 2014.

About The Author

Alfredo Gimelli: Associate Professor of Fluid Machines and Energy Systems at the Department of industrial Engineering of the University of Napoli Federico II (Italy). Scientific Council Member of the Industrial Engineering doctoral since 2012. Scientific Council Member of the Mechanical Engineering doctoral since 2008. Research interests are related to: – Internal Combustion Engines: Experiments and Modeling;- Energy Efficiency; – Renewable Energy: Biomass, CSP Thermodynamic Cycles and Syngas from Waste; – Combined Heat and Power; – Multi Objective Optimization; – ORC Power Plants.

Graduated with honors in Mechanical Engineering at the University of Napoli (Italy) in 1994. Philosophic Doctor in Mechanical Engineering in 1999. SAE member since 2003. ATI member since 1997. Author of more than 70 scientific publications (40 SCOPUS – 15 ISI journals) and 1 European Patent. ACA Noise&Vibration Award in 2005. “Key Scientific Article contributing to the excellence in Energy research” by RENEWABLE ENERGY GLOBAL INNOVATIONS in 2014. Scientific responsible of more than 10 research programs/projects/contracts. Creator and founder of a high-tech company in the renewable and energy saving technologies.

Reference

Gimelli, A., Luongo, A., Muccillo, M. Efficiency and Cost Optimization of a Regenerative Organic Rankine Cycle Power Plant through the Multi-Objective Approach, Applied Thermal Engineering 114 (2017) 601–610.

DII – Department of Industrial Engineering, University of Naples Federico II, Via Claudio 21, 80125 Napoli, Italy.

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