A computational fluid dynamics study on the heat transfer characteristics of the working cycle of a β -type Stirling engine

Salazar, Jose Leon; Chen, Wen Lih

doi:10.1016/j.enconman.2014.08.040

Cited by 42 publications

(10 citation statements)

References 17 publications

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“…In the multi-D analysis, the regenerator is frequently modelled using the porous media approach [20], [28] [30], [31]. The main physical phenomena to be considered in the characterization of the regenerator are the flow friction and the heat transfer [35].…”

Section: Regenerator Equationsmentioning

confidence: 99%

“…The dependence on steady unidirectional flow rather than unsteady flow correlations, for heat transfer and fluid friction encountered in heat exchangers, may lead to the discrepancy in results [19]. Furthermore, the rates of heat transfer in compression and expansion spaces cannot be accurately predicted by the assumption of uniform temperature distribution and constant heat transfer coefficients which are usually adopted by several models [20]. More importantly, the flow maldistribution in engine components, sudden change of flow area, flow recirculation and other important features cannot be predicted using these zero-or one-dimensional models.…”

Section: Introductionmentioning

confidence: 99%

“…The predictions were about 12 -18% different from the experimental data compared with 30% for the secondorder results. Recently, both research conducted by Salazar and Chen [20] and Chen et al [30] on a simple β-type and γ-type, respectively, characterized the complex heat transfer mechanisms inside the engine. In the most recent CFD investigation, by Alfarawi et al [31], the maximum deviation in predicting the indicated power of a γ-type Stirling engine was about 9% compared to experimental results.…”

Section: Introductionmentioning

confidence: 99%

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CFD Simulation and Losses Analysis of a Beta-Type Stirling Engine

Mikhael

El-Ghandour

El-Ghafour

2018

Port-Said Engineering Research Journal

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A three-dimensional Computational Fluid Dynamics (CFD) simulation for the beta-type Stirling engine is performed. Firstly, a thorough characterization of the thermal and fluid flow fields during the cycle is presented. Secondly, a comprehensive energy analysis for the engine is conducted to accurately identify the sources and magnitudes of thermodynamic losses. Computational results show a close agreement with the experimental results with an accuracy of about 96%. Within the compression and expansion spaces, the dominant heat transfer rates occur during the expansion strokes due to the significant impinging effect of the tumble vortices generated from the flow jetting. Furthermore, the jetting and ejecting processes into the regenerator is characterized by a significant temperature gradient and a large matrix temperature oscillation. The pressure difference between the expansion and compression spaces is the main driver for the flow leakage through the appendix gap. From the energy analysis, the regenerator thermal loss and the pumping power represent the largest part of the Stirling engine losses by about 9.2% and 7.5%, respectively.

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Section: Regenerator Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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CFD Simulation and Losses Analysis of a Beta-Type Stirling Engine

Mikhael

El-Ghandour

El-Ghafour

2018

Port-Said Engineering Research Journal

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“…Many models have been presented in recent years, including empirical [5][6][7][8], analytical [9][10][11][12][13][14][15][16][17][18] and numerical approaches. For numerical models, they can be categorized into second-order , third-order [47][48][49][50] and multi-dimensional computational fluid dynamics [51][52][53][54] methods.…”

Section: Introductionmentioning

confidence: 99%

A transient one-dimensional numerical model for kinetic Stirling engine

et al. 2016

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A third-order numerical model based on one-dimensional computational fluid dynamics is developed for kinetic Stirling engines. Various loss mechanisms in Stirling engines, including gas spring hysteresis loss, shuttle loss, appendix displacer gap loss, gas leakage loss, finite speed loss, piston friction loss, pressure drop loss, heat conduction loss, mechanical loss and imperfect heat transfer, are considered and embedded into the basic control equations. The non-equilibrium thermal model is adopted for the regenerator to capture the oscillating features of the gas and solid temperatures. To improve the numerical stability and accuracy, the implicit second-order time difference scheme and the second-order upwind scheme are adopted for discretizing the time differential terms and convective terms, respectively. Experimental validations are then conducted on a beta-type Stirling engine with the extensive experimental data for diverse working conditions. The results show that the developed model has better accuracies over previous second-order models. Good agreements are achieved for predicting various critical system parameters, including pressure-volume diagram, indicated power, brake power, indicated efficiency, brake efficiency and mechanical efficiency. In particular, both the experiments and simulations show that the Stirling engine charged with helium tends to have much lower optimal working frequencies and poorer performances compared to the hydrogen system. Based on the analyses of the losses, it reveals that the pressure drop in the flow channels plays a critical role in shaping the different behaviors. The pressure drop in the helium system is much larger and more sensitive to the frequency increase due to the much larger viscosity of gaseous helium. Hydrogen is a superior working gas for a Stirling engine. The transient characteristics of the oscillating flow and the associated thermal interactions between gas and solid in the regenerator are finally analyzed in order to have an insight of the complex thermodynamic process. The study provides a promising numerical approach in simulating Stirling engines for further understandings of their operating characteristics and the underling mechanisms.

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“…It was proven that CFD model is able to identify some geometrical features impeding engine performance, and engine performance can be improved by modifying these features. Salazar and Chen [9] reported a CFD study on the heat transfer characteristics of a b-type Stirling engine cycle. The study aimed at understanding the complex heat transfer characteristics in the engine cycle; and impingement has been identified to be the major heat transfer mechanism.…”

Section: Introductionmentioning

confidence: 99%

A CFD parametric study on the performance of a low-temperature-differential γ -type Stirling engine

Chen

Salazar

2015

Energy Conversion and Management

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An in-house CFD code has been applied to a low-temperature-differential (LTD) c-type Stirling engine to understand the effects posed by several geometrical and operational parameters on engine performance. The results include variations of pressure, temperature, and heat transfer rates within an engine cycle as well as variations of engine's power and efficiency versus these parameters. It is found that power piston stroke and radius influence engine performance very similarly, and power and efficiency both increase as these two parameters increase. In fact, the effects of the two parameters can be assimilated into those by the parameter of compression ratio. The stroke of displacer is observed to affect strongly on heat input but weakly on power, thus causing the efficiency to decrease as it increases. As expected, both power and efficiency increase as temperature difference between the hot and cold ends increases. Lastly, engine speed is observed to pose strong positive effects on power but exert weak effects on efficiency. This study reveals the effects produced by several important parameters on engine performance, and such information is very useful for the design of new LTD Stirling engines.

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A computational fluid dynamics study on the heat transfer characteristics of the working cycle of a β -type Stirling engine

Cited by 42 publications

References 17 publications

CFD Simulation and Losses Analysis of a Beta-Type Stirling Engine

CFD Simulation and Losses Analysis of a Beta-Type Stirling Engine

A transient one-dimensional numerical model for kinetic Stirling engine

A CFD parametric study on the performance of a low-temperature-differential γ -type Stirling engine

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