Unsteady Leakage Flow Through Axial Clearance of an ORC Scroll Expander

Song, Panpan; Zhuge, Weilin; Zhang, Yangjun; Zhang, Lei; Duan, Hao

doi:10.1016/j.egypro.2017.09.221

Cited by 25 publications

(8 citation statements)

References 17 publications

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“…Unlike the previous studies focusing on the radial clearance, the first studies modelling the axial gaps of a scroll expander were those of Song et al [37,38]. They present the flow field within a large axial clearance of 100 µm confirming the onset of highvelocity values in the radial direction.…”

Section: Introductionmentioning

confidence: 96%

Analysis of the Inner Fluid-Dynamics of Scroll Compressors and Comparison between CFD Numerical and Modelling Approaches

Cavazzini¹,

Giacomel²,

Benato³

et al. 2021

Advances in Energy Research

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Scroll compressors are widely adopted machines in both refrigeration systems and heat pumps. However, their efficiency is basically poor and constitutes the main bottleneck for improving the overall system performance. In fact, due to the complex machine fluid dynamics, scroll design is mainly based on theoretical and/or semi-empirical approaches. Designs strategies that do not guarantee an in-depth analysis of the machine behavior can be supplemented with a Computation Fluid Dynamics (CFD) approach. To this purpose, in the present work, the scroll compressor inner fluid dynamics is numerically analyzed in detail using two CFD software and two different modelling strategies for the axial gap. The analysis of the fluid evolution within the scroll wraps reveals unsteady phenomena developing during the suction and discharge phases, amplified by the axial clearance with negative impact on the main fluid flow (e.g., −13% of average mass flow rate for an axial gap of 30 µ) and on the scroll performance (e.g., +26% of average absorbed power for an axial gap of 30 µ). In terms of accuracy, the k-ε offers good performance on the estimation of average quantities but proves to be inadequate for capturing the complexity of the unsteady phenomena caused by the axial gap (e.g., −19% of the absorbed power in case of perfect tip seal). The need for Advances in Energy Research: 2 nd Edition 3 www.videleaf.com considering specific geometric details in design procedures is highlighted, and guidelines on the choice of the most suitable numerical model are provided depending on the analysis needs.

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Section: Introductionmentioning

confidence: 96%

Analysis of the Inner Fluid-Dynamics of Scroll Compressors and Comparison between CFD Numerical and Modelling Approaches

Cavazzini¹,

Giacomel²,

Benato³

et al. 2021

Advances in Energy Research

View full text Add to dashboard Cite

show abstract

“…Feng et al used ADAMS to study the dynamic characteristics of its moving parts [18]. Wei et al and Song et al carried out a three-dimensional transient simulation of a scroll expander, used in a small ORC system, and analyzed the influence of tangential leakage flow on the gas flow in the working chamber [19,20]. Emhardt et al analyzed the flow process of variable wall thickness scroll expander and compared the influence of different axial clearances on isentropic efficiency [21].…”

Section: Introductionmentioning

confidence: 99%

Internal Flow and Cavitation Analysis of Scroll Oil Pump by CFD Method

et al. 2021

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In this study, a three-dimensional model with actual clearances was established for a scroll oil pump, and the internal flow was simulated by the CFD method. The internal flows at different rotation angles were studied, and the cavitation and pressure pulsation in the scroll pump under different working conditions were analyzed. The results show that the flow in the two working chambers of the scroll pump is asymmetric due to its structural characteristics and motion mode. The high-pressure pulsation occurs in the working chamber during the end of the suction and the beginning of discharge. Under the action of high-pressure difference, there is a high-speed jet in the clearance between the orbiting and fixed scrolls, which causes a large area of cavitation downstream of the clearance. Under a low suction pressure, cavitation intensifies with the increase in rotating speed, which leads to a decrease in volumetric efficiency. It can effectively improve cavitation by increasing the suction pressure and volumetric efficiency of the pump. The pressure pulsation can be effectively improved by increasing the axial clearance and reducing the rotating speed. The method of reducing pressure pulsation by shortening the scroll profile is proposed.

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“…Recently, industries and researches have began to include Computational Fluid Dynamics (CFD) analyses in scroll machine designs and optimizations [28][29][30][31][32][33]. This tool allows to retrieve information about leakage flows nature, temperature distribution, and three-dimensional behavior of the flow inside the expander/compressor.…”

Section: Introductionmentioning

confidence: 99%

Structured Mesh Generation and Numerical Analysis of a Scroll Expander in an Open-Source Environment

et al. 2020

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The spread of the organic rankine cycle applications has driven researchers and companies to focus on the improvement of their performance. In small to medium-sized plants, the expander is the component that has typically attracted the most attention. One of the most used types of machine in this scenario is the scroll. Among the other methods, numerical analyses have been increasingly exploited for the investigation of the machine’s behaviour. Nonetheless, there are major challenges for the successful application of computational fluid dynamics (CFD) to scrolls. Specifically, the dynamic mesh treatment required to capture the movement of working chambers and the nature of the expanding fluids require special care. In this work, a mesh generator for scroll machines is presented. Given few inputs, the software described provides the mesh and the nodal positions required for the evolution of the motion in a predefined mesh motion approach. The mesh generator is developed ad hoc for the coupling with the open-source CFD suite OpenFOAM. A full analysis is then carried out on a reverse-engineered commercial machine, including the refrigerant properties calculations via CoolProp. It is demonstrated that the proposed methodology allows for a fast simulation and achieves a good agreement with respect to former analyses.

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Unsteady Leakage Flow Through Axial Clearance of an ORC Scroll Expander

Cited by 25 publications

References 17 publications

Analysis of the Inner Fluid-Dynamics of Scroll Compressors and Comparison between CFD Numerical and Modelling Approaches

Analysis of the Inner Fluid-Dynamics of Scroll Compressors and Comparison between CFD Numerical and Modelling Approaches

Internal Flow and Cavitation Analysis of Scroll Oil Pump by CFD Method

Structured Mesh Generation and Numerical Analysis of a Scroll Expander in an Open-Source Environment

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