Parametric optimization applied to design a high-performance vaneless-diffuser for CO₂ centrifugal compressor

ABSTRACT

Carbon-dioxide (CO₂) centrifugal compressors are machines with high potential of usage in power generation plants and oil industry as it achieves high thermal efficiency in the Brayton cycles and contributes to oil production through the capture and storage of CO₂ (CCS) in EOR (Enhanced Oil Recovery) systems. High levels of static pressure at the outlet are desired for EOR applications, which are usually obtained through the insertion of vanes in the diffuser. This work intends to increase vaneless-diffuser static pressure recovery by modifying only its meridional profile, ensuring a broader range of off-design operation when compared to vaned diffusers and attending to the fluctuations of mass flow and rotation expected in EOR practical applications. Therefore, a parametric optimization through surrogate model coupled to CFD was performed with three different objective functions that were submitted to single-optimization through the NSGA-II method: Maximize total-to-total polytropic efficiency, minimize total pressure loss coefficient or maximize static pressure recovery coefficient. Additionally, a sensitivity analysis was conducted using Morris Elementary Effects and SS-ANOVA. The results indicated that the optimized geometries increased the total-to-total polytropic efficiency by 2.9%, reduced the total pressure loss coefficient by 24.0% and increased the static pressure recovery coefficient at the design point by 11.4%, which is discussed in detail after a careful phenomenology assessment. The strategy adopted in the present work through a combination of Sensitivity Analysis, surrogate models and CFD increased the vaneless-diffuser static pressure recovery without the need of inserting vanes in the diffuser, which avoid instabilities in the equipment and would restrict its range of off-design operation.

KEYWORDS:

• Carbon capture
• Utilization and Storage
• CO2 centrifugal compresso
• vaneless-diffuser
• optimization
• sensitivity analysis

Acknowledgements

We gratefully acknowledge the support of the RCGI – Research Centre for Gas Innovation, hosted by the University of São Paulo (USP) and sponsored by FAPESP – São Paulo Research Foundation (2014/50279-4) and Shell Brasil.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the Research Centre for Greenhouse Gas Innovation [2014/50279-4].

Notes on contributors

Elóy Gasparin

Elóy Gasparin – Bachelor’s Degree in Mechanical Engineering (2015), Master’s Degree in Mechanical Engineering (Thermal Sciences) and Ph.D. in Mechanical Engineering (Thermal Sciences) from São Paulo State University (UNESP). Worked as a substitute professor at the Federal Institute of Science and Technology of Mato Grosso do Sul (IFMS). Currently a Postdoctoral Researcher at the Research Center for Greenhouse Gas Innovation (RCGI), developing multi-stage compression systems for oil extraction (Enhanced Oil Recovery-EOR) that uses mixtures of CO2 / CH4 in state supercritical. Develops methodological strategies for sensitivity analysis and optimization of one-dimensional and CFD models of centrifugal compressors.

Vitor Mattos

Vitor Mattos – Bachelor’s Degree in Mechanical Engineering (2019), worked as a member of the Baja-SAE project, developing activities both in project and execution/construction of annual prototypes. Holds a Master’s Degree in Mechanical Engineering (Thermal Sciences) from São Paulo State University (UNESP) in the development of numerical optimization of a supercritical carbon dioxide compressor for the Research Center for Greenhouse Gas Innovation (RCGI).

Fabio Saltara

Fabio Saltara – Bachelor’s degree in Mechanical Engineering - University of São Paulo (1987), Master's degree in Mechanical Engineering from the University of São Paulo (1993) and Ph.D. in Mechanical Engineering from the University of São Paulo (1998). Currently a Professor at the University of São Paulo. He has experience in the area of Mechanical Engineering, with an emphasis on Transport Phenomena. Working mainly on the following topics: CFD, cylinders, aerodynamics, computational fluid dynamics, flow induced vibration and numerical methods.

Paulo Eduardo Mello

Paulo Eduardo Mello - Holds a bachelor's degree (1995), master's degree (1998) and Ph.D (2003) in Mechanical Engineering from the Polytechnic School of the University of São Paulo, working as a collaborating researcher at the Thermal and Environmental Engineering Laboratory of the Polytechnic School of the University of São Paulo. Worked at Whirlpool S.A. as a product development engineer (2008) and has been using CFD (Computational Fluid Dynamics) simulations since 1995 in both academic research and engineering projects. His lines of research are: heat exchangers; simulation; scroll expanders; centrifugal compressors.

Daniel Dezan

Daniel Dezan - Bachelor’s degree in Mechanical Engineering from São Paulo State University (UNESP). Master's degree in Aeronautical and Mechanical Engineering from the Aeronautics Technological Institute (ITA) (2011) and a PhD in Mechanical Engineering from the University of São Paulo (2015). Currently Adjunct Professor II at the Federal University of ABC, Energy Engineering course. Permanent member of the postgraduate course in mechanical engineering at the Federal University of ABC. 8 years of experience in product development (automotive industry), specifically in the area of numerical flow simulation. Experience in the area of Mechanical Engineering, with an emphasis on Transport Phenomena, working mainly on the following topics: numerical analysis of intensification of heat transfer using passive techniques applied to compact heat exchangers and solar thermal collectors, optimization of thermal systems, in addition to work with flat solar collectors and concentrators projects. Researcher associated with LETE (Laboratory of Thermal and Environmental Engineering) at the USP Polytechnic School, with topics related to the optimization of processes in offshore plants, such as FPSO. He also carries out research on compressor design with the RCGI (Research Center for Gas Innovation) at the USP Polytechnic School.

Jurandir Yanagihara

Jurandir Yanagihara - Full Professor of the Department of Mechanical Engineering (PME) and Coordinator of the Thermal and Environmental Engineering Laboratory (LETE) and the Comfort Engineering Center (CEC) of the Polytechnic School of the University of São Paulo (EPUSP). CNPq Research Productivity Scholarship - Level 1B. Full Professor in Engineering and Mechanical Sciences (2006) and Associate Professor in Thermodynamics and Heat and Mass Transfer (1996) from EPUSP, PhD in Engineering (1990) and Master in Engineering (1987) from Yokohama National University and Mechanical Engineer (1984) by EPUSP. He was Coordinator of the Postgraduate Program in Mechanical Engineering (1999-2002 and 2008-2011) and Head of the Department of Mechanical Engineering (PME) (2011-2015) at EPUSP. Carries out research in the areas of thermal engineering, optimization of thermal systems, instrumentation and bioengineering, with funding from development agencies and companies. Graduated 18 doctors and 25 masters. Published more than 160 scientific articles in peer-reviewed journals and conferences. Author of three patents. Currently coordinates research and technological development projects on the following topics: optimization of equipment and thermal systems, intensification of heat transfer, comfort in aircraft cabins, primary processing of oil and gas, heat and mass transfer in biological systems. Coordinated research projects in partnership with important companies such as Embraer, Boeing, Shell (BG Group), Prysmian, Multibras (Whirlpool), among others.

Leandro Salviano

Leandro Salviano - PhD in Mechanical Engineering (Energy and Fluids Science) from University of São Paulo (USP), Master in Energy from the Federal University of ABC (UFABC) with an emphasis in Energy (Technology, Engineering and Modeling) and Graduate in Mechanical Engineering from the University State of São Paulo (UNESP). Member of the 2RE research group - Research for Renewable Energy, and researcher associated with the Thermal and Environmental Engineering Laboratory (LETE) of the Polytechnic School of the University of São Paulo (USP). Worked for 9 years in the Product Research and Development (R&D) Department at the multinational Ford Motor Company in the area of thermal sciences, fluid mechanics and thermodynamic modeling of thermal systems. He develops research in the area of optimization of thermal systems through numerical modeling of thermo-hydraulic systems using Response Surface methods and numerical optimization tools.