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ENCIT 2020
18th Brazilian Congress of Thermal Sciences and Engineering
Parametric Optimization of Organic Rankine Cycles Using Zeotropic Mixtures in FPSO Units
Submission Author:
Bruno da Silva Bunya , MG
Co-Authors:
Cesar Adolfo Sotomonte, Bruno da Silva Bunya, Thiago Gotelip Correa Veloso, Christian Jeremi R. Coronado
Presenter: Bruno da Silva Bunya
doi://10.26678/ABCM.ENCIT2020.CIT20-0493
Abstract
An increase in the atmospheric concentrations of greenhouse gases as a result of excessive consumption of fossil fuels has been a major concern for several countries. However, the use of renewable energy sources is not yet economically feasible or are still in the conceptual stage. Therefore, increasing energy efficiency in industrial processes is the best short-term option for the reduction of greenhouse gas emissions. Currently, the Organic Rankine cycle (ORC) is a commercial option to increase energy efficiency in the industrial sector converting low-temperature waste heat into electric energy. The working fluid selection and optimization of the design parameters are the main approaches to improve the performance of these thermal systems. Recently, zeotropic mixtures are proving to be promising as a working fluid option in ORC cycles as a consequence of the better match temperature profile between the organic fluid, the heat source and cooling fluid during the vaporization and condensation processes. Thus, this article aims to find the optimal design of an ORC cycle for the generation of electricity in offshore oil and gas production processes. The thermodynamic model includes two configurations of the ORC cycle (with and without heat recovery) and the use of 12 possible mixtures as working fluid in which design parameters such as vaporization and condensation pressure, superheating, pinch point and effectiveness of the heat exchanger were optimized using as objective function the net power generated by the thermal system. Preliminary results indicate that heat recovery in the main gas compression unit is maximized by RE245CB2, i-Pentane and R236FA/C7H16 as the best options for working fluid, with a net power output close to 1.8 MW and providing up to a 18% increase in energy efficiency in the compression process.
Keywords
Optimization, zeotropic mixtures, Organic Rankine Cycle
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