Numerical Simulation of Stirling Engines Using an Unsteady Quasi-One-Dimensional Approach

Andersson, Niklas; Eriksson, Lars‐Erik; Nilsson, Martin

doi:10.1115/1.4029396

Cited by 8 publications

(2 citation statements)

References 17 publications

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“…A more general and detailed description of regenerators can be achieved by considering them as discretized continua [10][11][12][13], e.g. in terms of a one-dimensional finite volume approach, leading to a nodal model.…”

Section: Introductionmentioning

confidence: 99%

An Endoreversible Model for the Regenerators of Vuilleumier Refrigerators

Paul

Khodja

Hoffmann

2021

International Journal of Thermodynamics

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We introduce a reduced-order endoreversible model of a Vuilleumier refrigerator for waste heat recovery. Based on the Vuilleumier cycle, in this refrigerator a working gas is alternately displaced between three subsystems that are in thermal contact with external heat reservoirs. Regarding refrigeration performance, very crucial components of the Vuilleumier machine are its two regenerators. For obtaining a sufficiently accurate model of the Vuilleumier machine, it is hence essential to incorporate a proper description of the regenerators. This can be achieved by using onedimensional continuum models, e.g. with a finite volume approach, which brings about a large number of degrees of freedom and significant numerical effort. As opposed to that, the model presented in this paper utilizes a novel modeling ansatz for the regenerators that reduces the number of degrees of freedom per regenerator to three. It leads to a considerable reduction in numerical effort and computation time and is hence predestined for applications like design and control optimizations. For an exemplary set of design parameters and operational conditions, we validate the model against a detailed finite volume model of the regenerators in order to work out limitations and perspectives.

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Section: Introductionmentioning

confidence: 99%

An Endoreversible Model for the Regenerators of Vuilleumier Refrigerators

Paul

Khodja

Hoffmann

2021

International Journal of Thermodynamics

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“…With the advent of digital computers, the partial differential equations describing regenerators could be solved numerically [15][16][17][18]. In these modeling approaches, the regenerator is treated as a continuum using respective numerical techniques, such as finite differences or finite volumes resulting in nodal models.…”

Section: Introductionmentioning

confidence: 99%

A Class of Reduced-Order Regenerator Models

Paul

Hoffmann

2021

Energies

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We present a novel class of reduced-order regenerator models that is based on Endoreversible Thermodynamics. The models rest upon the idea of an internally reversible (perfect) regenerator, even though they are not limited to the reversible description. In these models, the temperatures of the working gas that alternately streams out on the regenerator’s hot and cold sides are defined as functions of the state of the regenerator matrix. The matrix is assumed to feature a linear spatial temperature distribution. Thus, the matrix has only two degrees of freedom that can, for example, be identified with its energy and entropy content. The dynamics of the regenerator is correspondingly expressed in terms of balance equations for energy and entropy. Internal irreversibilities of the regenerator can be accounted for by introducing source terms to the entropy balance equation. Compared to continuum or nodal regenerator models, the number of degrees of freedom and numerical effort are reduced considerably. As will be shown, instead of the obvious choice of variables energy and entropy, if convenient, a different pair of variables can be used to specify the state of the regenerator matrix and formulate the regenerator’s dynamics. In total, we will discuss three variants of this endoreversible regenerator model, which we will refer to as ES, EE, and EEn-regenerator models.

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